First impressions with 9 0 Extreme

[stradman]

So after 6 months apart I've been finally reunited with my ACR! So best way to celebrate it to go on track right? Got car on Wednesday and on Monday I was at Silverstone at one of the Grand Prix tracks here in the UK. Weather was dry clear. For those of you not familiar with my mods you can see those on my Youtube channel https://www.youtube.com/watch?v=NTFr_GHSZws

Impressions? Ok I think we all know the 9.0 Extreme sounds a bit angrier than the stock engine and this is no exception. However car runs smoothly-albeit it does has a tendency towards low speed/low revs "kangarooing" or juddering if you are not careful with the clutch(Nth moto which feels a touch lighter than the OEM one but overall no material difference). I think the fact that I am running the Gen 4 ACR gear ratios now certainly helps and its no real drama tbh so I'm grateful for Scot and Dicks recommendation for that. Car pulls strongly and it does like to rev. Also noticed that pops and crackles have not disappeared- apparently when you go to fixed cam as one does for the 9.0 the pops disappear!
At the track car was strong and could easily pull and pass 991 GT3RS's on the straight when before no chance of that so happy with this. I presume engine will loosen up a touch more as well. Temps were low never saw anything above 215 after a session albeit ambient was 45 degrees. Only significant problem I encountered was noise level and was subsequently black flagged off after a couple of sessions. Silverstone has a 102 db drive by and car was metered at about 107 db even with trying to lift off at the sensors. Car does sound louder though. I'm running Belangers headers, Prefix sports cat and OEM catback and turned down tips(in effort to reduce noise). Scot mentioned that because of the larger duration camshaft and extra displacement engine will be noisier. He also said he didn't think the sports cat made that much difference as they had experimented with different packing apparently. But sadly at the moment I have a properly devastating track tool with no track in the UK to use it on without being kicked off! A bit deflated actually. Dick suggested using a Gen 4 OEM catback which he says is quieter than Gen V and I will need to source one first. Don't know if its interchangeable though without mods.So that's all the feedback I can offer at the moment. Apart from saying that any of you experiencing heat problems with the headers and exhaust I would suggest you do the whole top to toe exhaust/headers in Swain white lighting plasma coating. The difference is huge under the hood and in the sills. For me its not news as this technology has been used in Europe for a while and have it on a couple of my other cars and its night and day difference in temps. No need to bother with wraps etc...
35421

[13COBRA]

I know this could be argued for ever...but I imagine the car would be less loud if the tips were turned up...don't you think?

[stradman]

I know this could be argued for ever...but I imagine the car would be less loud if the tips were turned up...don't you think?

Perhaps I don't know but they are a bit oblique rather than completely vertically down. Would need the services of a sound engineer! May need to chop the end off the turndowns...

[Topplayer]

I know this could be argued for ever...but I imagine the car would be less loud if the tips were turned up...don't you think?

I was always told you point it down so it bounces off the ground, lowering the dBs a bit

[Scott_in_fl]

^^^ I don't know. I recall the Corvette ZR1 test mules running these wild hockey stick looking extensions that angled away from the sensors and up into the air. So at least they thought that turning them up was better than turning them down.

[RedTanRT/10]

Stradman, glad your car made it back! Sorry to hear noise issues but I know from Laguna Seca, any sidepipe Viper with just headers may have a problem at 102. Hopefully you can get a creative exhaust and get to the sound limit

[SSGNRDZ_28]

Glad the car is back and you got to use it a little...

Just an idea before switching exhausts entirely .. fabricate to accommodate a tip that goes straight into the wheel well area? There’s the removable plastic piece that could be cut or replaced with metal. Perhaps a flat/wide tip so it could disperse it somewhat downward vs direltly on the tire?

Doug


35422

[Back In Black]

At 107db, I'm questioning their measuring equipment/method!

[Arizona Vipers]

Congrats dude! Glad you got her home!
We have a track here that has a 94db limit (I'll never run the Viper there), but 90% of the Nasa guys are able to (with exhaust mods) and they ALL have tips turned UP. All of them. Side pipe guys, rear exit guys, 4 cyl, 6, 8 etc, everyone has done testing to be able to use that track (it's our best local track) and all end up with exhaust tips pointed towards the sky. Pointed towards the ground the sound waves are guided right to the microphone.

[SilveRT8]

FWIW, I laso have the Belangers headers and changed the OE Catback mufflers for the American Racing mufllers and the exhaust sound is now lower, deeper more mellow than stock, like less agressive.
Could be an option to consider ?

[stradman]

Thanks for input guys. I think upturned side exhaust tips could pose problems for me from a practical point of view so I will be looking to see what I can do with Catback. Interesting to hear you say Silver that ARH catbacks seem quieter. Certainly Belangers catback was louder. I think however I will need to make a custom catback with Acoustifil packing to see if this sorts it out. There is an Exhaust specialist near me who deals with a lot of the Race teams in the country and spoke to them already and they say they should be able to find a solution. So I'll keep you guys posted....
Thanks for advice Doug although I would be slightly nervous about spraying hot gases onto my rear tyres on track. Not sure what the implications to the tyres would be. Also this would I suspect introduce extra air in the wheel arches as well so again not sure what implications.
But on another note as you can see, your extended splitter and diffusers look good!!

[13COBRA]

Your tires would get up to operating temperature within a minute or two...haha

I would think asphalt magnifies the sound, since it can't absorb it. I'm not going to say it would be drastically better. But imagine driving through a tunnel with your car, how loud that is compared to driving on an open road with no barriers.

Who knows, I run a dealership, not a sound booth. Just my $0.02.

[Steve M]

...I would be slightly nervous about spraying hot gases onto my rear tyres on track.

The last thing I'd want is something spraying hot gas/oil/water vapor directly at my rear tires.

About the only thing you can do is experiment - this isn't unheard of in racing, and there are people out there that have figured out ways around it (and it sounds like you've found someone that can do just that). They usually aren't aesthetically pleasing, and that's compounded by the fact that there's just no room in the side sills to stuff a large muffler.

[13COBRA]

What about doing some type of rear exit exhaust conversion?

[Jack B]

Contact Corsa and discuss your issue with them. They have capabilities and resources that most exhaust mfg do not have.

[Jprince]

After going to the 1/2 mile event, It surprised me how the viper was nowhere near as loud as all the corvettes, mustangs, camaros and lots of other cars. The corvettes were annoying loud. I don't see how they could ever run at one of those tracks with noise restrictions.

[TrackAire]

Hard to believe you hit 107 dB.....on my Gen 4 with headers, not cats and the tiny ACR-X muffler (made by Borla IIRC) it was painfully loud and the highest I popped at Thunderhill was 103 dB.

I too agree that turning the tips upward will help. Turn downs have shown to increase the sound level read by the meters....Maybe it's not louder but it transmits the sound waves more precisely?? IDK....not a sound engineer.

I would use what is essentially a stock Viper turn out but have it designed where you could clamp an up swept tip or a dual tip to it for track use. I've seen where you can change the frequency by using a dual tip with two different size tubes. It is trial and error and will look like crap on the car, but it is what it is. Changing the frequency doesn't change the sound level but different frequencies travel towards the meter at different rates. Overcast clouds, temperatures, humidity all effect how the sound reaches the meter.

Enjoy the new power and make us proud!!

[13COBRA]

Hard to believe you hit 107 dB.....on my Gen 4 with headers, not cats and the tiny ACR-X muffler (made by Borla IIRC) it was painfully loud and the highest I popped at Thunderhill was 103 dB.

I too agree that turning the tips upward will help. Turn downs have shown to increase the sound level read by the meters....Maybe it's not louder but it transmits the sound waves more precisely?? IDK....not a sound engineer.

I would use what is essentially a stock Viper turn out but have it designed where you could clamp an up swept tip or a dual tip to it for track use. I've seen where you can change the frequency by using a dual tip with two different size tubes. It is trial and error and will look like crap on the car, but it is what it is. Changing the frequency doesn't change the sound level but different frequencies travel towards the meter at different rates. Overcast clouds, temperatures, humidity all effect how the sound reaches the meter.

Enjoy the new power and make us proud!!

That's interesting...

I have a Gen IV with custom headers, and straight pipes... it's hit 111dBs.

[Pappy]

Hard to believe you hit 107 dB.....on my Gen 4 with headers, not cats and the tiny ACR-X muffler (made by Borla IIRC) it was painfully loud and the highest I popped at Thunderhill was 103 dB.

I too agree that turning the tips upward will help. Turn downs have shown to increase the sound level read by the meters....Maybe it's not louder but it transmits the sound waves more precisely?? IDK....not a sound engineer.

I would use what is essentially a stock Viper turn out but have it designed where you could clamp an up swept tip or a dual tip to it for track use. I've seen where you can change the frequency by using a dual tip with two different size tubes. It is trial and error and will look like crap on the car, but it is what it is. Changing the frequency doesn't change the sound level but different frequencies travel towards the meter at different rates. Overcast clouds, temperatures, humidity all effect how the sound reaches the meter.

Enjoy the new power and make us proud!!

Might want to check the rule book, if applicable, before extending tips too far out the side of the car. Lou G got kicked off Nurburgring for his rear extensions extending more than 2 inches beyond the rear body work. They told him it was a hazard to other cars.

Pappy

[TrackAire]

Might want to check the rule book, if applicable, before extending tips too far out the side of the car. Lou G got kicked off Nurburgring for his rear extensions extending more than 2 inches beyond the rear body work. They told him it was a hazard to other cars.

Pappy

Poor Lou, not the German hospitality that he was expecting, lol. That was a very expensive lesson he experienced.

[ACR Steve]

No you are right turning them down. You turn Down to lower noise output

[13COBRA]

No you are right turning them down. You turn Down to lower noise output

Really? That seems so strange to me.

[13COBRA]

Also, here's an option for you. A friend of mine uses this on his Z06 around Lime Rock.

https://supertrapp.com//3-disc-only-for-1-5-od-pipe-344-1505#fit-guide

[dewilmoth]

Poor Lou, not the German hospitality that he was expecting, lol. That was a very expensive lesson he experienced.

Where can we read about Lou’s effort? Haven’t seen much info on it, I’m assuming that’s because it didn’t go as planned.

[darbgnik]

Shouldn't take too much work to change your down turned tips to up turned tips? It'd be a cheap experiment......

[Racingswh]

I don't know anything about how you would make them fit but the guys at Burns Stainless would probably be able to make mufflers up for you that were quiet and not restrictive. It may have been said but it would be unfortunate to have to give back power just to make it quiet. The Burns Stainless stuff is high quality and I am only guessing but maybe they would do something custom for your application.

Other than the noise issue the car must be a blast to drive now!! Hope you get it figured out!!

[TrackAire]

Where can we read about Lou’s effort? Haven’t seen much info on it, I’m assuming that’s because it didn’t go as planned.

Here you go....Rob Feretti from Superspeeders and his youtube channel started the process and failed miserably, both in execution and promised support with Ring time, etc. Total bullshit artist.

Lou won the USA part of the event and pretty much was on his own after that. IIRC, they hit something like 130 dB over on the Ring....doesn't sound right to me buy who knows.

https://www.corvetteforum.com/forums/c7-z06-discussion/4109095-nurburgring-update.html

[Bruce H.]

Tips up for sure if anything, not down, but may not make enough of a difference to pass. Sound reaches the mic straight from the exhaust as well as its reflected sound off the pavement and ground between track and mic location. If some of the sound is directed upwards and away from the mic and the hard track surface then there's less of both direct and reflected sound. However, the lowest frequency sound waves in the exhaust aren't directional at all so the aim of the tip won't impact them reaching the mic directly or by reflection. Higher frequency sound waves are more directional so point them skyward to minimize!

TrackAire was right about various conditions affecting the level of sound. The same car will measure significantly different from one day to another and from one track to another based on the contour of the land, wind, temperature, atmospheric turbulence, reflectivity and absorption of the ground, nearby buildings, barriers and even vegetation.

Bruce

[Arizona Vipers]

No you are right turning them down. You turn Down to lower noise output

Well he failed miserably with them turned down. Like I said, we have a 96db track here and EVERYONE that needs to mod their car to pass ends up pointing their tips up. EVERYONE. Then the sound pressure goes to the sky. Pointed at the ground some of the sound pressure is forced to the microphone via the asphalt.

[SilveRT8]

FWIW, my local Mont-Tremblant track has a 92db limit and I pass with Belanger /HF cats and ARH catback

[Desert Venom Racer]

Congrats dude! Glad you got her home!
We have a track here that has a 94db limit (I'll never run the Viper there), but 90% of the Nasa guys are able to (with exhaust mods) and they ALL have tips turned UP. All of them. Side pipe guys, rear exit guys, 4 cyl, 6, 8 etc, everyone has done testing to be able to use that track (it's our best local track) and all end up with exhaust tips pointed towards the sky. Pointed towards the ground the sound waves are guided right to the microphone.

You must be talking about AMP. Years ago we were running practice sessions prior to a 2-hour enduro with ASRA in our Comp Coupes. It was the very first weekend that they brought a sound meter to the track. While competing cars sounded way louder to me, it was the Vipers getting black flagged. The sound meter was set up at only one location 50 feet off the right side of the track. We sent our crew to the nearest home depot to find a solution otherwise we can't run in the race. They came back with right-angle stove pipe extensions that we hammered/pressure fitted into the side pipes to redirect the flow from straight out the sides to back toward the rear of the car. We were concerned about the extra heat effect on the rear tires. Long story short, the fix worked. I stayed on the far left side of the track going past the sound meter. They looked awful but they worked and we finished 1-2 in the race. We never returned to run at AMP again.

[Arizona Vipers]

You must be talking about AMP. Years ago we were running practice sessions prior to a 2-hour enduro with ASRA in our Comp Coupes. It was the very first weekend that they brought a sound meter to the track. While competing cars sounded way louder to me, it was the Vipers getting black flagged. The sound meter was set up at only one location 50 feet off the right side of the track. We sent our crew to the nearest home depot to find a solution otherwise we can't run in the race. They came back with right-angle stove pipe extensions that we hammered/pressure fitted into the side pipes to redirect the flow from straight out the sides to back toward the rear of the car. We were concerned about the extra heat effect on the rear tires. Long story short, the fix worked. I stayed on the far left side of the track going past the sound meter. They looked awful but they worked and we finished 1-2 in the race. We never returned to run at AMP again.

Yeah AMP! A GTS had the all time fastest track record there since it was built and only recently got beat by a manual GT3 driven by Dave Schotz, one of the best amateur drivers in the country. Pretty cool the ol' GTS record stood for so long. Do you have any idea whose car that was?

[Desert Venom Racer]

Yeah AMP! A GTS had the all time fastest track record there since it was built and only recently got beat by a manual GT3 driven by Dave Schotz, one of the best amateur drivers in the country. Pretty cool the ol' GTS record stood for so long. Do you have any idea whose car that was?

https://nasaaz.com/race-classes-track-records/

[Snakebit10]

Stradman why not try it turned up "before" you spend bigger bucks for a solution? Seems like there are track rats on both sides of this fence. Some say down is better some say up. You know down doesnt work for you so try up and see....Best case it works and you out minimal bucks. Worse case its no better than it was down, but now you know for sure up or down wont work and now you have to hunt a solution. Measure twice cut once :)

[Arizona Vipers]

https://nasaaz.com/race-classes-track-records/

Looks like he's still got it in race group, a 12 year standing record WOW. Are you Frank??

[str5010]

Where can we read about Lou’s effort? Haven’t seen much info on it, I’m assuming that’s because it didn’t go as planned.

This channel has the bulk of the info and most anything happening on the Nordschliefe. Bridge to Gantry is the other awesome Ring news source.


https://youtu.be/wDCGR7P7JDU

[RedTanRT/10]

Looks like he's still got it in race group, a 12 year standing record WOW. Are you Frank??

AZ, yeah that’s Frank. You would have love the late ‘90’s early 2000 in PHX with Viper. Rob Foster was there too

[stradman]

Stradman why not try it turned up "before" you spend bigger bucks for a solution? Seems like there are track rats on both sides of this fence. Some say down is better some say up. You know down doesnt work for you so try up and see....Best case it works and you out minimal bucks. Worse case its no better than it was down, but now you know for sure up or down wont work and now you have to hunt a solution. Measure twice cut once :)

Well the thing is, I really can't see turning tips in either direction altering noise by more than a couple of db at absolute best. I need to find about 8 db at least!! Another solution needs to be found. The OEM stock muffler is just a straight pipe within in a cylinder. Normally, in order to improve sound deadening in an absorptive muffler, you need to have perforations along the straight pipe to allow noise/waves/gases to permeate into the packing material- this is how absorptive mufflers work. Unfortunately the OEM muffler has only a tiny handful of perforations along its route thereby not allowing much absorption to occur to reduce noise. This is great for exiting gases but not so great when you want reduced noise. So I will be getting a custom muffler made, which will a. have better sound packing material, b. multiple perforations along the straight pipe to allow absorption, c. be longer by about 6 inches. . In addition I will be considering adding an exhaust insert to the outlet of the muffler to reduce noise as well such as these https://www.carchemistry.com/3-disk-insert-2-1-2-diameter/. These apparently can be quite effective so I figure all together should help get me on track.... Custom exhaust booked in for January so I'll keep you guys posted! Cross my fingers

[stradman]

This channel has the bulk of the info and most anything happening on the Nordschliefe. Bridge to Gantry is the other awesome Ring news source.


https://youtu.be/wDCGR7P7JDU

Interesting that he wound up with turn downs rather than turn ups.....Debate rages on!

[Bruce H.]

Do you know what your car measured there before mods?

[stradman]

Do you know what your car measured there before mods?

Static db at 3/4 max revs was about 106-107 db. Now we're at 115...Only change is 9.0 engine mods and change from Belanger sports cat to Prefix sports cat.

[Arizona Vipers]

Static db at 3/4 max revs was about 106-107 db. Now we're at 115...Only change is 9.0 engine mods and change from Belanger sports cat to Prefix sports cat.

Which mufflers? I My 9 liter is LOUD, no chance of it EVER being able to run on any track with sound limits. I'm running the Viper Exchange titanium mufflers which are loud as hell. It's always the best sounding car at the track though... It's so loud I really need to start using earplugs.

[13COBRA]

Which mufflers? I My 9 liter is LOUD, no chance of it EVER being able to run on any track with sound limits. I'm running the Viper Exchange titanium mufflers which are loud as hell. It's always the best sounding car at the track though... It's so loud I really need to start using earplugs.

I had to start wearing some this season. I was noticing my ears were ringing after every session and sometimes didn't go away before the next one started. I figured at 27 years old, I should save them for a cold day instead of burn them out now.

[darbgnik]

OK, I'm just gonna throw this out there, even knowing the apples to oranges I'm slinging.....

Years ago, I threw a straight pipe exhaust on my Hummer H1, thinking the turbo behind the engine would be muffler enough. It wasn't. It was awful, especially uphill, flogging that heavy low hp pig to keep up with traffic. Embarrassing actually. Think 81 Caprice with the exhaust rotted off. But I tried an Aero turbine muffler, which is still technically straight thru design, but the ring inside does some cancellation voodoo. Apparently the higher the exhaust velocity, the more noise cancellation? Again, I know it's a different application, but the difference in SPL was astounding, and I do remember a few guys installing them in Vipers in the past. Just throwing it out there.

[USAFPILOT]

One of my favorite sounding mufflers back in the 90’s was a magnaflow straight through design. Supposedly it didn’t rob power but definitely made a nice sound on my old F Body. Anything similar should knock it down a few DBs.

[Steve M]

Well the thing is, I really can't see turning tips in either direction altering noise by more than a couple of db at absolute best. I need to find about 8 db at least!! Another solution needs to be found. The OEM stock muffler is just a straight pipe within in a cylinder. Normally, in order to improve sound deadening in an absorptive muffler, you need to have perforations along the straight pipe to allow noise/waves/gases to permeate into the packing material- this is how absorptive mufflers work. Unfortunately the OEM muffler has only a tiny handful of perforations along its route thereby not allowing much absorption to occur to reduce noise. This is great for exiting gases but not so great when you want reduced noise. So I will be getting a custom muffler made, which will a. have better sound packing material, b. multiple perforations along the straight pipe to allow absorption, c. be longer by about 6 inches. . In addition I will be considering adding an exhaust insert to the outlet of the muffler to reduce noise as well such as these https://www.carchemistry.com/3-disk-insert-2-1-2-diameter/. These apparently can be quite effective so I figure all together should help get me on track.... Custom exhaust booked in for January so I'll keep you guys posted! Cross my fingers

Here's some free advice - DO NOT do the Car Chemistry inserts. I remember people trying them back in my GM LSx days, and they KILLED power. If you need them, so be it, but be prepared to leave a lot on the table. It would be a very last resort if I were in that situation.

[stradman]

Here's some free advice - DO NOT do the Car Chemistry inserts. I remember people trying them back in my GM LSx days, and they KILLED power. If you need them, so be it, but be prepared to leave a lot on the table. It would be a very last resort if I were in that situation.

I'm sure they will rob some power. But if keeps noise levels down and it means losing 15-20 hp compared to not being able to go on track then I have to lose some power otherwise car is useless to me. No point in having a track car that I can't use on track right??

[Steve M]

I'm sure they will rob some power. But if keeps noise levels down and it means losing 15-20 hp compared to not being able to go on track then I have to lose some power otherwise car is useless to me. No point in having a track car that I can't use on track right??

People were losing 30+ HP/TQ on 380 RWHP combos. I understand on the last part, but I'd be more pissed about spending the coin on a 9.0L upgrade only to have to choke it down to what I'm guessing would be close to 8.4L heads/cam numbers, maybe less. I'd try the mufflers first, but if that doesn't work, the CC inserts are about your only other option. Are you planning any before/after dynos? The data would be very interesting.

[stradman]

People were losing 30+ HP/TQ on 380 RWHP combos. I understand on the last part, but I'd be more pissed about spending the coin on a 9.0L upgrade only to have to choke it down to what I'm guessing would be close to 8.4L heads/cam numbers, maybe less. I'd try the mufflers first, but if that doesn't work, the CC inserts are about your only other option. Are you planning any before/after dynos? The data would be very interesting.

Find it hard to believe that it would lose that much as a simple oem muffler exchange to a higher flow muffler won't give you any more than 10 hp at very best. Can't believe it would be more than double the restrictive effect of this. Anyway I've asked Dick Winkles for his thoughts who hopefully will get back to me soon.
As to your second point, deed is done now and no point in crying about it I guess. Sure it saddens me, but sometimes things just work out that way. Gotta find a solution. Sure a custom muffler is my first point of call and I'll see if that works, but need to have back up plan just in case. Heck if I had done H & C alone I would probably be in similar situation again, needing to tone it down exhaust noise wise again and lose more Hp still. Anyway let's see how it goes.

[Steve M]

Find it hard to believe that it would lose that much as a simple oem muffler exchange to a higher flow muffler won't give you any more than 10 hp at very best. Can't believe it would be more than double the restrictive effect of this.

The stock Gen 5 mufflers aren't restrictive, and that has been proven. It was the same with the Gen 4 mufflers. Those Car Chemistry inserts are hugely restrictive...you can tell that just by looking at them. It's pretty easy to tell they are selling a load of bull just by looking at their website. Take a look at their "dyno test":

https://www.carchemistry.com/cc-inserts-dynotest/

They show slight gains up to 4,000 RPMs in that test on that combo. They'd like you to believe that it must be that way across the entire RPM band, but I'd bet a pretty hefty sum that power would start to fall off rapidly beyond that, and they are choosing not to show it. It is the same with their cherry picked "testimonials" that look like they were written by an old hot rodder that fully believes his 305 with a 3/4 race cam could whoop anyone in town. Yeehaw.

I have no doubt that they would quiet your car down...anything that restrictive should. It will come at a price though, and there's already data out showing what you can expect.

[ayousef]

Are you using the Gen 4 rear end ratio, or did you swap out the gears inside the transmission to different ratios?

[stradman]

Are you using the Gen 4 rear end ratio, or did you swap out the gears inside the transmission to different ratios?

Swapped gears in the box..

[ayousef]

Swapped gears in the box..

I just watched the video and im now jealous as hell because you literally did everything that I want to do, minus a sequential transmission and a Motec lol. If only shipping cars back and forth half way across the world wasnt such a huge hassle...

How do you like the gear ratios and the new LSD? Also im wondering why you didnt get the car bump-steered by installing a bump steer kit then corner weighting, but those are things you can always still do.

[stradman]

I just watched the video and im now jealous as hell because you literally did everything that I want to do, minus a sequential transmission and a Motec lol. If only shipping cars back and forth half way across the world wasnt such a huge hassle...

How do you like the gear ratios and the new LSD? Also im wondering why you didnt get the car bump-steered by installing a bump steer kit then corner weighting, but those are things you can always still do.

Well from a couple of sessions I did on track the wavetrac made the car feel even more assured and planted in corners. I will however reserve final judgement until I take it out a few more times. Gear ratios felt spot on actually and mated very nicely to 9.0.
interesting about bump steer kit. I don't know who makes em but tbh I haven't experienced any bump steer problems with standard OEM.ACR suspension. Once I get noise sorted out I have some carbon tillett seats going in and I think cat is perfect. Only thing I might do in future is go for some surface transform carbon discs as they are lighter than the Girodiscs And more importantly last way longer than Brembo ones. But thats for next year possibly.

[Desert Venom Racer]

Looks like he's still got it in race group, a 12 year standing record WOW. Are you Frank??

That would be me.

[Arizona Vipers]

That would be me.

Wow that's awesome dude! Congrats! I think it's going to stand for a long time! Nice to meet you!

[ayousef]

Well from a couple of sessions I did on track the wavetrac made the car feel even more assured and planted in corners. I will however reserve final judgement until I take it out a few more times. Gear ratios felt spot on actually and mated very nicely to 9.0.
interesting about bump steer kit. I don't know who makes em but tbh I haven't experienced any bump steer problems with standard OEM.ACR suspension. Once I get noise sorted out I have some carbon tillett seats going in and I think cat is perfect. Only thing I might do in future is go for some surface transform carbon discs as they are lighter than the Girodiscs And more importantly last way longer than Brembo ones. But thats for next year possibly.

Have you looked into the RPS carbon/carbon brake rotors and perhaps a track specific sintered RB brake pads?

35707

http://www.viperpartsusa.com/catFrame.php?prodCat=14D

Bump steer kit, I find the car to have alot of bump steer which feels like looseness in the steering wheel, very evident as well on the ACR nurburgring video, and im also picky as hell so that might be that.

Finally about the seats, do they sell them with the brackets?

[Nth Moto]

Have you looked into the RPS carbon/carbon brake rotors and perhaps a track specific sintered RB brake pads?

We are the sole distributor on RPS carbon products for Viper and did the prototype work on the Viper application brakes for the Gen 3/4 model several years ago - it hasn't been implemented on a Gen V yet mainly because of time, but we could absolutely develop it on a vehicle if someone wanted.

True Carbon/Carbon means that BOTH friction materials are pure carbon, IE the rotor and the pad. You cannot run the carbon rotor with a non-carbon pad. True pure carbon/carbon setups are not for use on the street as they are very temperature dependent and susceptible to absorbing water. Neither of those are concerns for a track focused car or a driver that is aware of those things when using the vehicle but there is a reason that OEM's don't do brake systems like that and mix the ceramic aspect into it. That being said, carbon/carbon brakes are much more cost effective for the racer, especially when you consider consumable parts life.

[SlateEd]

Hey Guys - sorry I missed all the audio chat early in this thread when it was fresh.

The most difficult thing about SPL and audio behavior when you're talking about a car is the sharp transients that can have a moment of 109db although the average level is much lower. Every instant of car exhaust is made up of different frequencies combined, and some of them may have far greater amplitude than others... you hit that split-second just right when 50hz and 80hz and 160hz and 300hz are all at maximum amplitude and boom - extra dbs. In the studio we use things like compression on the microphones to level-off the sharpest milliseconds, but in this case you're the drummer, not the studio tech, so... moving on...

depending on how well you know the track workers you could ask if they're using RMS (an average) reading or not... The alternative looks for "peaks" but the peaks can be so quick that they're practically irrelevant. RMS would be more reasonable as a measurement standard honestly, and it's possible they have an SPL meter in the wrong 'mode' and don't even realize it.

Sound pressure levels in free air drop by 6db with every doubling of the distance, so that's your biggest factor. How close to trackside are they measuring? If moving off-line by 3 cars width would double the distance to their measurement, that saves 6db right there. (not the best idea in traffic or near corners, but in some places it could work.)

As for the question of exhaust tips up/down... A hard track surface is going to reflect the SPL right back up. hypothetically, if you had 90 degrees down or 90 degrees up and measured the SPL from the roof of the car directly on-axis, you would get almost exactly the same number. But measuring from the side, you're better off with pointed up, into free air, away from the direction of measurement. Of course, if you're being measured from a tower, pointing up might make the car a little louder to them. These directional changes all mean more at longer distances... so up or down won't matter at all from 3 feet away, but getting pointed away means much more at 100 ft.

There are several SPL applications for smartphones that work reasonably well as a reference for changes that you make as long as you place the phone the same distance from the car.

[Bruce H.]

There are several SPL applications for smartphones that work reasonably well as a reference for changes that you make as long as you place the phone the same distance from the car.

Here's one I use... https://sites.google.com/site/bofinit/audiotool

[Arizona Vipers]

Hey Guys - sorry I missed all the audio chat early in this thread when it was fresh.

The most difficult thing about SPL and audio behavior when you're talking about a car is the sharp transients that can have a moment of 109db although the average level is much lower. Every instant of car exhaust is made up of different frequencies combined, and some of them may have far greater amplitude than others... you hit that split-second just right when 50hz and 80hz and 160hz and 300hz are all at maximum amplitude and boom - extra dbs. In the studio we use things like compression on the microphones to level-off the sharpest milliseconds, but in this case you're the drummer, not the studio tech, so... moving on...

depending on how well you know the track workers you could ask if they're using RMS (an average) reading or not... The alternative looks for "peaks" but the peaks can be so quick that they're practically irrelevant. RMS would be more reasonable as a measurement standard honestly, and it's possible they have an SPL meter in the wrong 'mode' and don't even realize it.

Sound pressure levels in free air drop by 6db with every doubling of the distance, so that's your biggest factor. How close to trackside are they measuring? If moving off-line by 3 cars width would double the distance to their measurement, that saves 6db right there. (not the best idea in traffic or near corners, but in some places it could work.)

As for the question of exhaust tips up/down... A hard track surface is going to reflect the SPL right back up. hypothetically, if you had 90 degrees down or 90 degrees up and measured the SPL from the roof of the car directly on-axis, you would get almost exactly the same number. But measuring from the side, you're better off with pointed up, into free air, away from the direction of measurement. Of course, if you're being measured from a tower, pointing up might make the car a little louder to them. These directional changes all mean more at longer distances... so up or down won't matter at all from 3 feet away, but getting pointed away means much more at 100 ft.

There are several SPL applications for smartphones that work reasonably well as a reference for changes that you make as long as you place the phone the same distance from the car.

Great info here! At the sound limit tracks I've seen, the microphone is about 30 feet from the side of the track, a couple feet off the ground. As you said so many variables happen with a cars exhaust. We've seen low db cars get kicked off from backfires right at the wrong time.

[stradman]

Have you looked into the RPS carbon/carbon brake rotors and perhaps a track specific sintered RB brake pads?

35707

http://www.viperpartsusa.com/catFrame.php?prodCat=14D

Bump steer kit, I find the car to have alot of bump steer which feels like looseness in the steering wheel, very evident as well on the ACR nurburgring video, and im also picky as hell so that might be that.

Finally about the seats, do they sell them with the brackets?
That bump steer link says if for the comp coupes and not the latest Gen V ACR so not sure if its applicable. I think that when Surface transforms make the Mclaren kits I will go for them. The ST rotors easily last 20-25 track days and can be resurfaced up to 3 times for reasonable costs. Until then I'll continue with Girodiscs.


Hey Guys - sorry I missed all the audio chat early in this thread when it was fresh.

The most difficult thing about SPL and audio behavior when you're talking about a car is the sharp transients that can have a moment of 109db although the average level is much lower. Every instant of car exhaust is made up of different frequencies combined, and some of them may have far greater amplitude than others... you hit that split-second just right when 50hz and 80hz and 160hz and 300hz are all at maximum amplitude and boom - extra dbs. In the studio we use things like compression on the microphones to level-off the sharpest milliseconds, but in this case you're the drummer, not the studio tech, so... moving on...

depending on how well you know the track workers you could ask if they're using RMS (an average) reading or not... The alternative looks for "peaks" but the peaks can be so quick that they're practically irrelevant. RMS would be more reasonable as a measurement standard honestly, and it's possible they have an SPL meter in the wrong 'mode' and don't even realize it.

Sound pressure levels in free air drop by 6db with every doubling of the distance, so that's your biggest factor. How close to trackside are they measuring? If moving off-line by 3 cars width would double the distance to their measurement, that saves 6db right there. (not the best idea in traffic or near corners, but in some places it could work.)

As for the question of exhaust tips up/down... A hard track surface is going to reflect the SPL right back up. hypothetically, if you had 90 degrees down or 90 degrees up and measured the SPL from the roof of the car directly on-axis, you would get almost exactly the same number. But measuring from the side, you're better off with pointed up, into free air, away from the direction of measurement. Of course, if you're being measured from a tower, pointing up might make the car a little louder to them. These directional changes all mean more at longer distances... so up or down won't matter at all from 3 feet away, but getting pointed away means much more at 100 ft.

There are several SPL applications for smartphones that work reasonably well as a reference for changes that you make as long as you place the phone the same distance from the car.
Thanks for the useful input! Its clearly quite complex the whole noise issue and I guess just trial and error with various different configurations is the way to go until something works. Sadly I don't know the track workers. Also the noise level and metering goes straight to the local council authority to see, so they can't hide it either.!

[Werks]

That bump steer link says if for the comp coupes and not the latest Gen V ACR so not sure if its applicable. I think that when Surface transforms make the Mclaren kits I will go for them. The ST rotors easily last 20-25 track days and can be resurfaced up to 3 times for reasonable costs. Until then I'll continue with Girodiscs.


Driving at the level that you are doing in your video's I'd stay away from the sintered RB pads as it's highly likely you are going to exceed the max. operating temperature of the friction material. In regards to the ST rotors I'd be a little "suspect" of the claims beign tossed around at least when it comes to serious track use of the product. ST rotors can indeed be resurfaced up to 3 times but there is a big IF associated with that. With the Brembo CCM rotors used on the Viper, Vette etc. the entire rotor is made of a mix of carbon strands and ceramic powder which is in essence baked in a mold to form a solid rotor which you then replace when it hits it's min weight. With these surface wear is really not a problem, the rotor does pit as the exposed carbon strands oxidize but the only negative associated with that is increased pad wear.

With the ST rotors, those are so called continuous strand rotors in essence made out of layers of woven mat stacked on top of each other and then stitched together which is then baked and transformed into a carbon matrix to form the rotor blank. That blank is then machined to spec and then a final ceramic "coating" is applied to surface of the rotor. In essence it is very similar to the SGL style Brembo rotors that are used by Porsche (aka PCCB's) but with a continuous strand rotor instead of carbon cermic matrix. You may have hear of some of the issues that people have had when tracking PCCB's over the years. In any case the ceramic surface coating applied to the ST rotor blanks is the wear surface and it is only something like .25mm thick. With use that ceramic surface starts to thin and once that surface starts to show signs of wear, if you catch it early enough you can then remove the rotors, send them to ST and have them re-coated (which keep in mind can take several weeks+ to have done and is not free). But and this is the big one, if you do not catch it in time and there is any wear extending into the underlying continuous strand rotor then they are trash.

I hear of quite a few people that have the ST rotors that do an occasional track day and say they are the best thing since sliced cake but when you don't really push it (like most occasional track day driver) and only use them a couple times a year you never really see the limitations of a product. I know of one fast driver that dropped the coin on a set ST rotors regularly for track use and you probably guessed it, part way through the first season when he noticed that they were wearing he sent them in only to find out that they could no longer be re-surfaced. Keeping in mind that those rotors at the time were nearly $20k for set, it was a very expensive learning lesson for him!

I have been tracking with CCM's since 2011 normally doing 20-25 track days a year. In that time I've pretty much come to the conclusion that for occasional track use CCM type rotors use is fine. If you are a faster driver and run at a selection of tracks you will probably find that the limited amount of available brake pad compounds is a negative factor though. Once you start to get really fast and especially if you then track a lot, CCM use really starts to become a maintenance/cost issue. Going through a set of $800-$1k brake pads every 3 to 5 track days and a set or 2x front pairs and 1x rear pair at $7-$8k a set of CCM rotors every season starts to add too. Looking back over the years I have spent more on brake related expenses than I have on tires which frankly is a bit ridiculous.

My suggestion to you if you are considering making changes with your brakes for a car that is predominately intended for track use is to do what what after a whole lot of research I'm finally in the process of doing. Just get rid of the CCM's and go with a true competition level brake system. You will get rid of the very heavy, street oriented calipers (@ 11lbs each) and get much stiffer and significantly lighter racing versions with anti-knock back springs (I'm using AP Racing CP6160's at 6lbs ea). You will get rid of the very expensive, oversized brake pads necessitated by the thermal issues associated with CCM rotors that are only 17mm thick and replace them with much more commonly available shaped racing brake pads that are 25-30mm thick (which also usually only cost 1/2 to 1/3 of the price). You will get rid of the gigantic, very expensive (but light weight) CCM rotors and replace them with heavier, but much more economical racing oriented iron rotors in a smaller diameter (but with a much higher that street vane count for improved cooling). At the end of the day while the initial investment associated with doing this is not cheap it will greatly increase your selection of available pad compounds, greatly reduce maintenance, reduce replacement costs and more than likely be a wash as far as weight is concerned if not end up actually cutting a few extra lbs out. Plus in my case instead of trying to make a street oriented braking system consistently perform on track way above what it was intended to do I'm going to end up with a true, competition level braking system that is on par with what is used in current GT3 cars. Just something to think about.....

[stradman]

Driving at the level that you are doing in your video's I'd stay away from the sintered RB pads as it's highly likely you are going to exceed the max. operating temperature of the friction material. In regards to the ST rotors I'd be a little "suspect" of the claims beign tossed around at least when it comes to serious track use of the product. ST rotors can indeed be resurfaced up to 3 times but there is a big IF associated with that. With the Brembo CCM rotors used on the Viper, Vette etc. the entire rotor is made of a mix of carbon strands and ceramic powder which is in essence baked in a mold to form a solid rotor which you then replace when it hits it's min weight. With these surface wear is really not a problem, the rotor does pit as the exposed carbon strands oxidize but the only negative associated with that is increased pad wear.

With the ST rotors, those are so called continuous strand rotors in essence made out of layers of woven mat stacked on top of each other and then stitched together which is then baked and transformed into a carbon matrix to form the rotor blank. That blank is then machined to spec and then a final ceramic "coating" is applied to surface of the rotor. In essence it is very similar to the SGL style Brembo rotors that are used by Porsche (aka PCCB's) but with a continuous strand rotor instead of carbon cermic matrix. You may have hear of some of the issues that people have had when tracking PCCB's over the years. In any case the ceramic surface coating applied to the ST rotor blanks is the wear surface and it is only something like .25mm thick. With use that ceramic surface starts to thin and once that surface starts to show signs of wear, if you catch it early enough you can then remove the rotors, send them to ST and have them re-coated (which keep in mind can take several weeks+ to have done and is not free). But and this is the big one, if you do not catch it in time and there is any wear extending into the underlying continuous strand rotor then they are trash.

I hear of quite a few people that have the ST rotors that do an occasional track day and say they are the best thing since sliced cake but when you don't really push it (like most occasional track day driver) and only use them a couple times a year you never really see the limitations of a product. I know of one fast driver that dropped the coin on a set ST rotors regularly for track use and you probably guessed it, part way through the first season when he noticed that they were wearing he sent them in only to find out that they could no longer be re-surfaced. Keeping in mind that those rotors at the time were nearly $20k for set, it was a very expensive learning lesson for him!

I have been tracking with CCM's since 2011 normally doing 20-25 track days a year. In that time I've pretty much come to the conclusion that for occasional track use CCM type rotors use is fine. If you are a faster driver and run at a selection of tracks you will probably find that the limited amount of available brake pad compounds is a negative factor though. Once you start to get really fast and especially if you then track a lot, CCM use really starts to become a maintenance/cost issue. Going through a set of $800-$1k brake pads every 3 to 5 track days and a set or 2x front pairs and 1x rear pair at $7-$8k a set of CCM rotors every season starts to add too. Looking back over the years I have spent more on brake related expenses than I have on tires which frankly is a bit ridiculous.

My suggestion to you if you are considering making changes with your brakes for a car that is predominately intended for track use is to do what what after a whole lot of research I'm finally in the process of doing. Just get rid of the CCM's and go with a true competition level brake system. You will get rid of the very heavy, street oriented calipers (@ 11lbs each) and get much stiffer and significantly lighter racing versions with anti-knock back springs (I'm using AP Racing CP6160's at 6lbs ea). You will get rid of the very expensive, oversized brake pads necessitated by the thermal issues associated with CCM rotors that are only 17mm thick and replace them with much more commonly available shaped racing brake pads that are 25-30mm thick (which also usually only cost 1/2 to 1/3 of the price). You will get rid of the gigantic, very expensive (but light weight) CCM rotors and replace them with heavier, but much more economical racing oriented iron rotors in a smaller diameter (but with a much higher that street vane count for improved cooling). At the end of the day while the initial investment associated with doing this is not cheap it will greatly increase your selection of available pad compounds, greatly reduce maintenance, reduce replacement costs and more than likely be a wash as far as weight is concerned if not end up actually cutting a few extra lbs out. Plus in my case instead of trying to make a street oriented braking system consistently perform on track way above what it was intended to do I'm going to end up with a true, competition level braking system that is on par with what is used in current GT3 cars. Just something to think about.....

Many thanks for the input. That was useful! I based the ST wear from a friend who is a very fast peddler and has tracked his 675LT a lot. And he said he got 20 track days before he needed resurfacing-which he successfully did. Apart from this however I have no other source of info.
I'm currently running the Girodiscs made for the ACR(and which of course use the standard ACR CCM calipers) which seem to perform well. Unfortunately I gained 37.2 pounds in the process. Not sure which specific rotors you have been looking at but I would be interested to hear what your research and experience has showed you. Would the AP CP6160's calipers fit in the same studs or would I need to match up rotors for this and change the Girodiscs? I'm all up for losing unsprung weight again, however it was becoming a pain in the ass with the CCM rotors chewing up pads within even a day in the end so need another alternative if by the sounds of what you are saying the ST rotors may not be entirely what they are cracked up to be.

[dewilmoth]

Many thanks for the input. That was useful! I based the ST wear from a friend who is a very fast peddler and has tracked his 675LT a lot. And he said he got 20 track days before he needed resurfacing-which he successfully did. Apart from this however I have no other source of info.
I'm currently running the Girodiscs made for the ACR(and which of course use the standard ACR CCM calipers) which seem to perform well. Unfortunately I gained 37.2 pounds in the process. Not sure which specific rotors you have been looking at but I would be interested to hear what your research and experience has showed you. Would the AP CP6160's calipers fit in the same studs or would I need to match up rotors for this and change the Girodiscs? I'm all up for losing unsprung weight again, however it was becoming a pain in the ass with the CCM rotors chewing up pads within even a day in the end so need another alternative if by the sounds of what you are saying the ST rotors may not be entirely what they are cracked up to be.

I’d bet the LT is significantly easier on brakes than the ACR due to being quite a bit lighter and having an active air brake. I have zero data to back that up, just a guess.

[sharmut]

Just get rid of the CCM's and go with a true competition level brake system. You will get rid of the very heavy, street oriented calipers (@ 11lbs each) and get much stiffer and significantly lighter racing versions with anti-knock back springs (I'm using AP Racing CP6160's at 6lbs ea). You will get rid of the very expensive, oversized brake pads necessitated by the thermal issues associated with CCM rotors that are only 17mm thick and replace them with much more commonly available shaped racing brake pads that are 25-30mm thick (which also usually only cost 1/2 to 1/3 of the price). You will get rid of the gigantic, very expensive (but light weight) CCM rotors and replace them with heavier, but much more economical racing oriented iron rotors in a smaller diameter (but with a much higher that street vane count for improved cooling). At the end of the day while the initial investment associated with doing this is not cheap it will greatly increase your selection of available pad compounds, greatly reduce maintenance, reduce replacement costs and more than likely be a wash as far as weight is concerned if not end up actually cutting a few extra lbs out. Plus in my case instead of trying to make a street oriented braking system consistently perform on track way above what it was intended to do I'm going to end up with a true, competition level braking system that is on par with what is used in current GT3 cars. Just something to think about.....

Werks,
The AP Racing CP6160 looks fantastic. Are you running those a viper SRT or ACR-E? Do you know the caliper height? Wondering if it's lower profile than the OE 6-piston Brembo. If so, it would yield a higher wheel barrel clearance, beneficial for the 18" front wheel.
I tried to get Essexparts to build a package with their 9660 caliper for my TA, without access to a Viper locally, Jeff didn't get far and we ended the conversation there. Continued to use the AP-Racing rotors, later switched to the Stoptech package from VE to get more brake leverage.
On the ACR-E I have the Girodisc & ST43 pads. So far 10 20min sessions and can already see slight heat stress cracks. Something I did not observe on my TA with the ap-racing rotors with significantly more track days, but then again I was running 6-10 seconds slower around Thunderhill 3-mile. Wonder if we could get enough interest to get ap-racing or essexparts to build us a package for the ACR-E.

[sharmut]

Many thanks for the input. That was useful! I based the ST wear from a friend who is a very fast peddler and has tracked his 675LT a lot. And he said he got 20 track days before he needed resurfacing-which he successfully did. Apart from this however I have no other source of info.
I'm currently running the Girodiscs made for the ACR(and which of course use the standard ACR CCM calipers) which seem to perform well. Unfortunately I gained 37.2 pounds in the process. Not sure which specific rotors you have been looking at but I would be interested to hear what your research and experience has showed you. Would the AP CP6160's calipers fit in the same studs or would I need to match up rotors for this and change the Girodiscs? I'm all up for losing unsprung weight again, however it was becoming a pain in the ass with the CCM rotors chewing up pads within even a day in the end so need another alternative if by the sounds of what you are saying the ST rotors may not be entirely what they are cracked up to be.

According to the AP-Racing site, the caliper bolt spacing is 210mm and 42mm on center lengthwise of the caliper. Suppose to accept 390mm disc.
35745
If I have some time this weekend will take measurements of the OE Brembo caliper. I suspect a mounting spacer is needed.

Werks,
Found the information for the CP6160 caliper profile.
They called out 217.40mm from the center of a 390mm disc to the top of the caliper.

35746

[stradman]

According to the AP-Racing site, the caliper bolt spacing is 210mm and 42mm on center lengthwise of the caliper. Suppose to accept 390mm disc.
35745
If I have some time this weekend will take measurements of the OE Brembo caliper. I suspect a mounting spacer is needed.

Werks,
Found the information for the CP6160 caliper profile.
They called out 217.40mm from the center of a 390mm disc to the top of the caliper.

Cheers. that would be useful. As AP are a UK company I'll try to see what I can find out over here in terms of best package for that also.

[stradman]

I’d bet the LT is significantly easier on brakes than the ACR due to being quite a bit lighter and having an active air brake. I have zero data to back that up, just a guess.
Yes they are lighter so in that sense would be a b it easier on the brakes.

[TA Two Oh]

Also, the Macks' rear-mid powertrain layout and lack of dive under braking is likely easier on front brakes than our front-mid powertrain placement and the ride height deltas we see with our conventional suspension systems. (For those that don't already know, the Super Series McLaren's use a trick hydraulic suspension that keeps the car virtually flat. No acceleration squat. No brake dive. And despite not having any anti roll (sway) bars, no lean in the corners.)

I'm not an expert in the effects of weight transfer on braking but I would guess that the combined effects of roughly 10%(?) less weight, the air brake, the lack of brake dive, and the rear-mid powertrain placement could result in his cars front brakes having an easier life than yours.

[Werks]

Many thanks for the input. That was useful! I based the ST wear from a friend who is a very fast peddler and has tracked his 675LT a lot. And he said he got 20 track days before he needed resurfacing-which he successfully did. Apart from this however I have no other source of info.
I'm currently running the Girodiscs made for the ACR(and which of course use the standard ACR CCM calipers) which seem to perform well. Unfortunately I gained 37.2 pounds in the process. Not sure which specific rotors you have been looking at but I would be interested to hear what your research and experience has showed you. Would the AP CP6160's calipers fit in the same studs or would I need to match up rotors for this and change the Girodiscs? I'm all up for losing unsprung weight again, however it was becoming a pain in the ass with the CCM rotors chewing up pads within even a day in the end so need another alternative if by the sounds of what you are saying the ST rotors may not be entirely what they are cracked up to be.

Glad that you found the info usefull! In regards to the weight gain that you experienced with the Girodisc iron rotors a good part of the reason for that simply is that those rotors are intended as a direct bolt in swap for your CCM rotors. So they are larger than they need to be. You have to understand that when looking ar brake systems it really all revolves around managing heat (which is generated when braking). CCM rotors generate a tremedous amount of heat very quickly and also dissipate that heat equally quickly. This is why CCM rotors are larger than normal and also very significantly (from a caliper and brake pad standpoint) why the brake pads used in CCM systems are so large. A tremendous amount of heat gets dumped into them very quickly during a breaking event and having a larger surface (and hence heat sink) helps manage that. This is the main reason that CCM oriented friction compounds are so limited, most do not have the ability to withstand high enough temperatures. This is also why most of the available brake pads are based off of endurance compounds which generally use very exotic and expensive bonding agents which contribues to their higher prices too.

An example of how this comes into play, during some of the testing that I did back in the days I tired the Hamk DTC70 compound which is one of their top level race compounds and supposedly able to withstand temperatures up to 1700F. A few corners into the first lap I hit the brakes, the car starts slowing then the brake pedal goes soft, the car stops slowing down and looking in the rear view mirror I see a cloud of smoke behind the car. I engine brake the car and get back into the pits to see the sides of the car completely covered in brake dust. In a nutshell the heat generated (and released) by the CCM rotors exceeded the maximum temperature of the bonding agent in the friction material basically allowing it to turn back into a powder.

Getting back to what I was trying to relay though is that you really do not need 390mm iron rotors, you are using them because they are a designed as a direct drop in to replace existing CCM rotors while retaining the origional CCM oriented Brembo calipers and their mounting positions. The rotors are much bigger than needed and hence much heavier. I'm not sure what the specific weight of your Girodisk rotor rings are but keeping with the AP Racing product line, so true racing oriented products. Using as an example iron rotors that use a 240mm rotor hat, a 390mmx36mm rotor ring weighs between 10KG (22lbs). The comparable 380x37mm 72x vane rotor ring weighs 7.6kg (16.7lbs). So that is a difference of 2.4kg or nearly 25% less per corner by it's self! As a comparison I believe OEM CCM weighs about 5.8kg (about 13lbs). So just using the above numbers quickly for thr front axle the Ap 6160's are 5lbs ea lighter than OEM calipers, so thats a 10lb savings over stock. Using a 380x37mm rotor you will gain 3.7lbs over OEM per side or 7.2lbs total. I'd have to weigh pads again but OEM's are huge and hence witht he giant iron backing plate very heavy (while only 17mm thinck), the pads used by the CP6160's are 30mm thick and weigh a few pounds less. Now you have to add a few pounds for aluminum rotor hats for the iton set up and also a few pounds for caliper mounting brackets which you will have to have made but in essence you should roughly work out to a wash weight wise between OEM and 380x36 with CP6160 calipers on the front. Yet you end up with a professional motorsport level braking system with lower cost replacable iron rotor rings, a much better selection of brake pads and also pads that are so thick that you can probably get close to a season out of a set.

In regards to mouting the calipers, this was touched on in one of Sharmut's post. They will not be a direct bolt on as they are more of a universal type caliper, so you will need to get a set of caliper mounting brackets made. That however is something that any good quality race shop can do for you and should not cost a lot.

[Werks]

Werks,
The AP Racing CP6160 looks fantastic. Are you running those a viper SRT or ACR-E? Do you know the caliper height? Wondering if it's lower profile than the OE 6-piston Brembo. If so, it would yield a higher wheel barrel clearance, beneficial for the 18" front wheel.
I tried to get Essexparts to build a package with their 9660 caliper for my TA, without access to a Viper locally, Jeff didn't get far and we ended the conversation there. Continued to use the AP-Racing rotors, later switched to the Stoptech package from VE to get more brake leverage.
On the ACR-E I have the Girodisc & ST43 pads. So far 10 20min sessions and can already see slight heat stress cracks. Something I did not observe on my TA with the ap-racing rotors with significantly more track days, but then again I was running 6-10 seconds slower around Thunderhill 3-mile. Wonder if we could get enough interest to get ap-racing or essexparts to build us a package for the ACR-E.

Interesting, you run at t-hill too. That is my regular track where I usually run, what type of times are you doing on the 3 mile? Personally I really prefer the 5 mile but unfortunately not too many of the groups are running that layout very often anymore.

In regards to your experience trying to get the US guys to make a kit using the 9660's I'm not really surprised to hear that. Being candid the 9660's and 6160's are like comparing apples to oranges. The 9660's are multi piece calipers with iron pistons and use 18mm pads and are AP's entry level brakes. The 6160's are machined from a single block of aluminum, use titanium pistons and are designed for use with iron or Carbon/Carbon. They are used on current GT3 type racing cars i.e. the Corvette C7R etc. so it is real, high end racing parts. A complete brake kit with 9660 calipers, lines and rotos sell here in the US for around $3.7k, a single 6160 caliper new is over $6k. So while something similar can be done with more economical type products what I was outlining is really intended to be a true, best of the best type brake set up for serious track use that will put you on par with a professional motorsports car.

In regards to your questions about wheel fitment, it's not going to be an issue running these if the 18" wheel was designed to clear the OEM CCM's.

[Werks]

Cheers. that would be useful. As AP are a UK company I'll try to see what I can find out over here in terms of best package for that also.

Definitely talk to them, they should be able to help you out or point you to a race shop that can help you out there with fitment. I went with CP6160's front and CP6480's rear with 380mm front rotors and 355mm rears. It's by no means a cheap set up but after 7 years of running CCM and going through about 5 sets of pads and 1 to 1 1/2 sets of rotors per season it should pay for it's self in 2 year or so just through reduced consumables spending alone lol.

[stradman]

Definitely talk to them, they should be able to help you out or point you to a race shop that can help you out there with fitment. I went with CP6160's front and CP6480's rear with 380mm front rotors and 355mm rears. It's by no means a cheap set up but after 7 years of running CCM and going through about 5 sets of pads and 1 to 1 1/2 sets of rotors per season it should pay for it's self in 2 year or so just through reduced consumables spending alone lol.

Understood. I'm on the case! Will see what they can do for me but it all makes sense. You need to come on here more frequently!

[ayousef]

We are the sole distributor on RPS carbon products for Viper and did the prototype work on the Viper application brakes for the Gen 3/4 model several years ago - it hasn't been implemented on a Gen V yet mainly because of time, but we could absolutely develop it on a vehicle if someone wanted.

True Carbon/Carbon means that BOTH friction materials are pure carbon, IE the rotor and the pad. You cannot run the carbon rotor with a non-carbon pad. True pure carbon/carbon setups are not for use on the street as they are very temperature dependent and susceptible to absorbing water. Neither of those are concerns for a track focused car or a driver that is aware of those things when using the vehicle but there is a reason that OEM's don't do brake systems like that and mix the ceramic aspect into it. That being said, carbon/carbon brakes are much more cost effective for the racer, especially when you consider consumable parts life.

Hi guys and thanks for chiming in!

The term carbon-carbon has nothing to do with the pads at all and refers to carbon fiber reinforced carbon matrix composite, classified as a material all by itself. Here is another explanation online:



Carbon fibre reinforced carbon[n 1] (CFRC[4]), carbon–carbon (C/C[2]), or reinforced carbon–carbon (RCC) is a composite material consisting of carbon fiber reinforcement in a matrix of graphite. It was developed for the nose cones of intercontinental ballistic missiles, and is most widely known as the material for the nose cone and wing leading edges of the Space Shuttle orbiter.

Now this type of rotor might indeed require a carbon brake pad as you suggested, im clueless when it comes to that, but thats certainly not why its referred to as a carbon-carbon disk.

[Werks]

Understood. I'm on the case! Will see what they can do for me but it all makes sense. You need to come on here more frequently!

Thanks! I try to chime in when I have something useful to add but I run a different brand of car so there is a limited amount of things I can contribute to. CCM brakes though I know a lot about after 7+ years of tracking with them and I also did all of the track testing for & helped one of the earlier mentioned companies develop their CCM track pads.


Hi guys and thanks for chiming in!

The term carbon-carbon has nothing to do with the pads at all and refers to carbon fiber reinforced carbon matrix composite, classified as a material all by itself. Here is another explanation online:



Now this type of rotor might indeed require a carbon brake pad as you suggested, im clueless when it comes to that, but thats certainly not why its referred to as a carbon-carbon disk.

Actually Carbon/Carbon is a pretty common method of referring to a carbon brake rotor which is used in conjunction with a carbon brake pad. This technology actually originates in the Aerospace industry where cabon brakes are used in the brake stack of most modern day commercial airliners as well as fighter planes as it has to be able to withstand (and dissipate) tremendous amounts of heat in a short amount of time without failing. Just try to imagine the amount of heat generated by the brakes stopping a 747 or A380 when landing! In additional again something very critical to Aerospace use, the material is also significantly lighter than traditional brake materials (i.e. iron) so it's use represents a substantial weight savings.

Just for kicks as we are talking about different materials and weights I've attached 3 pictures of brake pads that I had laying around in my office. 2 pictures showing the 17mm thick brake pads that fit the Brembo CCM caliper that we use. The first, (yellow back plate) at 5.2lbs per caliper set are a yet to be released sintered pad material from a brake company. The second at 1.8lbs per caliper set are of carbon pads that I had made (so what would be used with a carbon/carbon brake set up) to test.

35750

35752

stradman, earlier I was giving you some info about the weight differences between our OEM Brembo CCM caliper (11lbs ea) and the AP Racing CP6160's (6lbs ea) so for the 3rd picture I quickly weighed a set of 30mm thick pads for the CP6160's just so that all of you guys can get a real understanding of just how big and heavy the pads needed in CCM brakes are.

35754

The 30mm thick pads came in at 3.2lbs per caliper set, so -2lbs per caliper set less than our CCM pads even though they are nearly double the thickness. So in a nutshell based on just swapping brake pad and caliper, stradman you would be looking at a total weight savings per front corner of -8lbs. You would lose about 1lb per corner for the aluminum caliper mounting brackets that you will need to have made so figure that you are looking at -14lbs on the front end for the caliper/pad swap. I mentioned above that 380x37 rotors are about 7.2lbs heavier than CCM, toss in a couple pounds for new aluminum rotor hats and hardware and you should still end up ultimately coming out a few lbs less than CCM for the swap on the front axle. Plus have significantly reduced long term operating expenses, reduced maintenance and have a significantly larger selection of pad compounds available so you can tailor your braking feel/performance to your specific preference and/or track.

If I find some time to dig around in the garage in the next couple of days I'll weigh an OEM CCM rear caliper, pad etc. to get exact weights but if memory serves me right converting over the rear to 6480's and 355mm rotors actually ends up saving something like 15 or 20lbs over OEM CCM.

[sharmut]

@werks.

Love Thunderhill, usually meet up with VENOM V and others. In the ACR it's been high 1:5x range on the 3-mile over-the-top. For 2019 my goal is to shave 2-3 seconds from my best, should be doable, only had the ACR on the track for 4 days before calling it quits for 2018. The 5-mile is so much fun, just doesn't come around enough. I'm always tentative on the back side, wish I could get more seat time.

Great points on the AP-Racing 6160s vs 9660. I read the specs after submitting my post and realized they weren't in the same ballpark. Going to check around the Eastbay for a race shop that may be willing to explore the 6160 & 6480 option.

[stradman]

Werks, can I ask what would you think of using the Girodiscs with the AP calipers that you suggest, at least in the first instance and then at a second stage change rotors?. Do you think that could work??

[Werks]

@werks.

Love Thunderhill, usually meet up with VENOM V and others. In the ACR it's been high 1:5x range on the 3-mile over-the-top. For 2019 my goal is to shave 2-3 seconds from my best, should be doable, only had the ACR on the track for 4 days before calling it quits for 2018. The 5-mile is so much fun, just doesn't come around enough. I'm always tentative on the back side, wish I could get more seat time.

Great points on the AP-Racing 6160s vs 9660. I read the specs after submitting my post and realized they weren't in the same ballpark. Going to check around the Eastbay for a race shop that may be willing to explore the 6160 & 6480 option.

I've not made it out very much this year either, I got a little bored with the 3 mile and I have a 3 year old that's keeping me busy! A big part of turning fast times at t-hill is just finding days with the right weather, it gets so hot there that it makes a huge difference. I've gotten down to 53's over the top but just like you would like to cut another 2-3 seconds off which should be doable. It's just a matter of getting back out there and shaking off the rust lol.



Werks, can I ask what would you think of using the Girodiscs with the AP calipers that you suggest, at least in the first instance and then at a second stage change rotors?. Do you think that could work??

stradman, as you have probably already found out when it comes down to cars you can do anything that you want, it's just comes down to how much money you want to spend! To mount the any aftermarket caliper you are going to have to get mounting brackets designed and made. It's not difficult but there is a cost associated with it. If you want to get them made to properly locate the caliper for the Girodisc rotor (and hat) then you can do that. However I do not know what the weight of the Girodisc rotors are compared to i.e. the AP Racing ones are nor do I know what the vane count is (which is going to affect how well the rotors cool them self). Plus I highly doubt that the AP Racing rotor's will match up to the Girodisc hats. So it's possible that if you later decide to switch to AP rotors you are going to have to get new rotor hats machined as well as caliper mounting brackets.

Personally I would do two things.

First, talk to AP Racing and/or a race shop and figure out if you are best off using 390mm front and 360mm rear rotors (like the Girodiscs that you now have) or if you should be running 380mm and 355mm. There is some thought that needs to go into this because you can also use this to alter your brake bias front to rear a bit too.

Second, then take a look at what the Girodisc replacement rotor rings cost, find out the weight of the rings, the vane count and once you have all of that compare it to the AP Racing ones and then make a decision on what to go with. You may find that it makes sense to just keep on using the Girodisc rotors or the numbers may tell you that you would be better off just selling them to recoup a portion of your money and going with the AP parts.

That will give you all of the info that you need to make an educated decision on how to move forwards. Also I should add that the CP6160 are not the caliper that you must use. They are possibly a more expensive caliper than what you need. I chose them so that I would have the option of converting over to Carbon / Carbon down the road if I wanted to but that may not be something that you are interested in or ever see your self doing. If so then you do not need a caliper with titanium pistons etc. and can probably find a more economical caliper for you but at your level I would still stick with the true motorsports caliper and not the more entry level Pro 5000 stuff. You have AP Racing right there in your country, I'd give them a call and have a chat. You are possibly going to be spending a bit of coin on their products, they should be able to help you out with technical info. Before I forget, most of these calipers are build to order typ things so if you move forward with this project remember to allow around 6-12 weeks lead time from date of order for the calipers to be made for you!

[stradman]

Well crunching the weight numbers from ones you gave it seems that the AP racing setup would wind up about 1.4 kgs more weight per front wheel compared to the OEM CCM setup, however as you say the consumables and wear and replacement parts would be considerably better. So it seems for track purposes there is no comparison and should be the optimum way for us track guys to go. Btw the Girodiscs for the front weigh 11.7kgs each and the rears 8.4kgs each. This is of course with the hats.
For illustration purposes if I am correct in my calculations:

Front OEM CCM setup : Each wheel- Rotors with hats weigh 6kgs each, Calipers 5kgs, and pads 2.4kgs Total 13.4kgs
Front AP racing setup : Each wheel 380mm rotor with hat weigh 9.6kgs, 6160 Calipers 2.7kgs pads 1.5kgs and new brackets approx 1kg. Total 14.8kgs
Front Girodisc conversion, Each wheel keeping the same OEM calipers/pads on ACR makes for a Total 19.1kgs.

[Arizona Vipers]

Well crunching the weight numbers from ones you gave it seems that the AP racing setup would wind up about 1.4 kgs more weight per front wheel compared to the OEM CCM setup, however as you say the consumables and wear and replacement parts would be considerably better. So it seems for track purposes there is no comparison and should be the optimum way for us track guys to go. Btw the Girodiscs for the front weigh 11.7kgs each and the rears 8.4kgs each. This is of course with the hats.
For illustration purposes if I am correct in my calculations:

Front OEM CCM setup : Each wheel- Rotors with hats weigh 6kgs each, Calipers 5kgs, and pads 2.4kgs Total 13.4kgs
Front AP racing setup : Each wheel 380mm rotor with hat weigh 9.6kgs, 6160 Calipers 2.7kgs pads 1.5kgs and new brackets approx 1kg. Total 14.8kgs
Front Girodisc conversion, Each wheel keeping the same OEM calipers/pads on ACR makes for a Total 19.1kgs.


Can you also go back to the non-CCB knuckle to save more weight? When I did my carbon brake conversion on my '13, I had to get different knuckles and they were a lot heavier, I forget the exact amount I think I posted it on here awhile ago

[sharmut]

@stradman
Rough measurement of the caliper bolt spacing for the front ACR-E brakes is 165mm. It will definitely need a spacer made to accommodate the CP6160 spacing at 210mm.

Did not get a chance to measure the rear caliper spacing, will see if I have time between the xmas and new year activities.

[sharmut]

Can you also go back to the non-CCB knuckle to save more weight? When I did my carbon brake conversion on my '13, I had to get different knuckles and they were a lot heavier, I forget the exact amount I think I posted it on here awhile ago

Suspect you're thinking of the rear knuckles.
For the front knuckles, I located only 1 set of part numbers.
68272306AA (Front Right)
68272307AA (Front Left)

[stradman]

@stradman
Rough measurement of the caliper bolt spacing for the front ACR-E brakes is 165mm. It will definitely need a spacer made to accommodate the CP6160 spacing at 210mm.

Did not get a chance to measure the rear caliper spacing, will see if I have time between the xmas and new year activities.

Great to know buddy! Thanks, will be looking at all this in the new year..

[stradman]

Soooo. Finally got my ACR 9.0 back from a muffler transplant in order to lower the noise levels so I can get onto track. Boy what difference!!! I lost 11 decibels!!! Hurray! Car still sounds good but tone lowered significantly, so very very happy with that. And no restriction either as we used the same internal diameter pipe as it had with the OEM one however made the muffler a touch wider in diameter and slightly longer. But importantly the internal pipe is now perforated so the sound waves can pass through the perforations and into the sound deadening material around the central pipe. The OEM pipe was basically a straight through pipe. I guess originally however as some of the sound was being picked up, restricted and muffled through the OEM manifolds and Cats noise wasn't as bad. However removing the OEM manifold and cats, subsequently made the OEM muffler the only sound deadening element. However as the muffler central pipe did not have any perforations only a couple of 5mm gaps or slits, the sound passed straight through was very loud. Now I am civilised again and ready to get on track to do the thing the 9.0 was made to do! Happy days again!!
36455
36456

[Pappy]

Congratulations. The workmanship on the mufflers looks superb. Do you know what your final, steady-state decibel number is for track purposes?

Pappy

[stradman]

Congratulations. The workmanship on the mufflers looks superb. Do you know what your final, steady-state decibel number is for track purposes?

Pappy

Cheers Pappy. Well static noise levels here in Europe are determined by a noise test at 0.5m at a 45-degree angle with the engine running at 3/4maximum revs . Mine is now about 107db. Before it was 118dbs! Here are some more pics of the muffler. Top quality work. And muffler is repackable for the future if I need to. I also got it plasma coated to reduce temps in sills by about 40%.
36458
36459
36460
36461

[Scott_in_fl]

Looks great and I love the idea of a sleeper 9L. Can't wait to hear what this sounds like.

[stradman]

Looks great and I love the idea of a sleeper 9L. Can't wait to hear what this sounds like.

Thanks Scott. Tbh I'm really not into really loud exhausts anyway. I think I'm way past that stage! Happy for it to be civilised to a large degree, yet still be super fast. That's all I'm interested in.. Don't get me wrong though its not really quiet, just quieter....

[Scott_in_fl]

Thanks Scott. Tbh I'm really not into really loud exhausts anyway. I think I'm way past that stage! Happy for it to be civilised to a large degree, yet still be super fast. That's all I'm interested in.. Don't get me wrong though its not really quiet, just quieter....

I must be at the same stage, LOL. I really do think this would make the 9L much more attractive to me.

[hans christian]

Stradman,
Wow - it looks in credible!!. I want and need one to pass noise requirements here in Switzerland. Any drone noise concerns. Any power loss noticed?.

I will send you separate email.

Best
Hans Christian

[sharmut]

@Stradman great looking exhaust. Love to hear your long term thoughts after some track time.

[Snakebit10]

Congrats Strad. So glad you can now enjoy the fruits of your hard work. That exhaust screams quality. Perfect compliment to Prefix top notch 9l work. Cant wait to read about and see your track videos on Spa etc. Enjoy in good health.

[dewilmoth]

Since we’re on the topic of mufflers, figured I’d add these TI mufflers in here for anyone looking to build a custom exhaust similar to Strad. Could probably do two per side for additional sound deadening since their large one is 17” long. They look like nice quality. Not sure how tough it would be to find someone local to build the rest of the exhaust in TI.

https://www.ticonindustries.com/collections/ultra-lightweight-race-muffler/products/3-titanium-ultra-lightweight-race-muffler-17-oal

[stradman]

Since we’re on the topic of mufflers, figured I’d add these TI mufflers in here for anyone looking to build a custom exhaust similar to Strad. Could probably do two per side for additional sound deadening since their large one is 17” long. They look like nice quality. Not sure how tough it would be to find someone local to build the rest of the exhaust in TI.

https://www.ticonindustries.com/collections/ultra-lightweight-race-muffler/products/3-titanium-ultra-lightweight-race-muffler-17-oal

Yeah they look cool. However you would certainly need 2 per side. The only problem for noise purposes is that Titanium is usually somewhat louder due to the thinner walls. Light of course. However if you're going to the effort of getting someone to build the rest of the exhaust around these, you might as well get a competent exhaust maker to make you one long piece muffler each side in titanium rather than get these...

[dewilmoth]

Yeah they look cool. However you would certainly need 2 per side. The only problem for noise purposes is that Titanium is usually somewhat louder due to the thinner walls. Light of course. However if you're going to the effort of getting someone to build the rest of the exhaust around these, you might as well get a competent exhaust maker to make you one long piece muffler each side in titanium rather than get these...

Good points. I’d guess they can custom build any length, but who knows.

[Arizona Vipers]

Yeah they look cool. However you would certainly need 2 per side. The only problem for noise purposes is that Titanium is usually somewhat louder due to the thinner walls. Light of course. However if you're going to the effort of getting someone to build the rest of the exhaust around these, you might as well get a competent exhaust maker to make you one long piece muffler each side in titanium rather than get these...

I'm pretty sure these are what the Viper Exchange titanium exhaust uses and it's LOUDER THAN HELL. I've got them on my 9 liter and it's deafening. They sound GOOD though.

[dewilmoth]

I'm pretty sure these are what the Viper Exchange titanium exhaust uses and it's LOUDER THAN HELL. I've got them on my 9 liter and it's deafening. They sound GOOD though.

Interesting, you know what length the mufflers are on the VE setup?