2016 ACR vs. Porsche GT3 at Thunderhill 5-mile

[VENOM V]

Hi guys,

I had the time of my life yesterday at Thunderhill Raceway, my fourth track in the ACR. Thunderhill is beautiful this time of year, green rolling hills with wildflowers sprinkled about. Quite a contrast to the aggressive tracking that we were doing. I was the sole Viper in a sea of Corvettes and Porsches. My friend Joe Kou and about a dozen GT3s and GT4s and a cup car or two were there, along with a group of Corvettes.

Thunderhill has their famous 3-mile course that the 25 Hours of Thunderhill is run on, along with the new "west track." They are separated by a hill. Once in a while, you can run the two tracks connected together for the Thunderhill 5-mile layout. It is unbelievably fun, you literally fly over a blind hill and drop into the west track from the other side. This happens at 1:40 in the video below.

There was one Corvette driven by Rich of Abel Chevrolet that was particularly fast. It's a C7 Z06 with Hoosier R7s. He is running in the Optima Street Car Challenge. We were both able to dip into the 3:05s. I was able to pass him on the session that we ran together, but he had a passenger (he ran a 3:08 to my 3:05). It would have been a good race otherwise.

The day was not without issues. About mid-session on most sessions, my car went into limp mode. "Cylinder misfire" was the error code, or something to that effect. Not sure why, perhaps it didn't like the RPM at the main straight (looks like about 6300). I've seen limp mode if you bounce off of the rev limiter before, but I wasn't doing that. When I turned it off and on, the error code would clear and I was good to go. However after it happened several times, the check engine light stays lit. Time for a dealer visit. I'll keep you guys posted. Still I had an absolute blast at this track layout that I've only been on once before.

Of the Porsches, there was one particularly talented driver of a GT3 that I had a bout with. Below is a video of our spirited session. Also a few shots from the day.


https://www.youtube.com/watch?v=Qc49wwByugM

https://farm2.staticflickr.com/1494/26194016746_bce18df154_b.jpg (https://flic.kr/p/FUFbAo)IMG_1367 (https://flic.kr/p/FUFbAo) by solomontodd (https://www.flickr.com/photos/20879698@N02/), on Flickr

https://farm2.staticflickr.com/1555/26153640601_d4155a6a53_b.jpg (https://flic.kr/p/FR7faX)IMG_1370 (https://flic.kr/p/FR7faX) by solomontodd (https://www.flickr.com/photos/20879698@N02/), on Flickr

https://farm2.staticflickr.com/1565/26127497882_3109617a08_b.jpg (https://flic.kr/p/FNNfRq)IMG_1369 (https://flic.kr/p/FNNfRq) by solomontodd (https://www.flickr.com/photos/20879698@N02/), on Flickr

https://farm2.staticflickr.com/1690/26219725665_9491b1f060_b.jpg (https://flic.kr/p/FWWWXB)GBMA8862 (https://flic.kr/p/FWWWXB) by solomontodd (https://www.flickr.com/photos/20879698@N02/), on Flickr

https://farm2.staticflickr.com/1501/25946856940_52893f5e98_b.jpg (https://flic.kr/p/FwQqAq)GBMA7861 (https://flic.kr/p/FwQqAq) by solomontodd (https://www.flickr.com/photos/20879698@N02/), on Flickr

https://farm2.staticflickr.com/1676/26219727995_03d17a9d06_b.jpg (https://flic.kr/p/FWWXDM)GBMA8042 (https://flic.kr/p/FWWXDM) by solomontodd (https://www.flickr.com/photos/20879698@N02/), on Flickr

https://farm2.staticflickr.com/1485/25947065270_772b67f7d8_b.jpg (https://flic.kr/p/FwRuwj)IMG_1368 (https://flic.kr/p/FwRuwj) by solomontodd (https://www.flickr.com/photos/20879698@N02/), on Flickr

Cheers,

Todd

[Darius]

Both my TA and ACR did that missfire limp mode when they were new. My ACR hasn't had a problem since I swapped out the pcm for the arrow unit.

[Rapidrezults]

Love the pics at T-Hill in the spring! I've been seeing quite a bit of the misfire stuff going on with the stock PCMs also. Arrow PCM is in your future! :)

[ViperJon]

Fantastic pics looks like a great day!

[VENOM V]

Both my TA and ACR did that missfire limp mode when they were new. My ACR hasn't had a problem since I swapped out the pcm for the arrow unit.

Any idea what triggered it in your case? I'm not hitting the rev limiter but am getting close to it. I'd hate to shift into 5th on the main straight. Tried it once and it seemed like a bad idea. You shift to 5th, losing some time, then immediately shift down to 3rd for turn 1.

[VENOM V]

Love the pics at T-Hill in the spring! I've been seeing quite a bit of the misfire stuff going on with the stock PCMs also. Arrow PCM is in your future! :)


Won't be long before we return, cannot wait. With my extended warranty I'd like to leave it 100% stock. My GTS doesn't have this problem.

- - - Updated - - -


Fantastic pics looks like a great day!


Thanks Jon :United_States:

[J TNT]

Nice runs and looks like a Fun Track !
Thanks for sharing !

[VENOM V]

Nice runs and looks like a Fun Track !
Thanks for sharing !

Thanks Jay :Canada:

[Junkie]

Man that looks really fun!

[1ststrike]

Nice job driving. Looks like a really fun track. Did you wrap your windshield? With the front fender vents out I heard of stones hitting the windshield.

[VENOM V]

Nice job driving. Looks like a really fun track. Did you wrap your windshield? With the front fender vents out I heard of stones hitting the windshield.

Thanks. Yes I did. I made the mistake of not wrapping my GTS's windshield, it is so pock-marked that I'm thinking about replacing it.

The ACR is especially bad, as you point out. I also need to clear wrap to the roof and wing. Most of the rest is covered already.

[VENOM V]

Man that looks really fun!

Just wait until you get yours out on the track. Amazing. Easiest car to drive at the limit, and soooo fast.

[esm_viper]

That was fun to watch! Looks like an amazing track and 5 miles of fun!!! Thanks, I'm starting to think I need an ACR now....

[w00tw00t]

Fantastic! Wish I could have been there but my TA is at the shop with a broken wheel stud :( :( :(

[w00tw00t]

BTW the driver of that silver GT3 is a good friend of mine... here's his video chasing you.. :)


https://www.youtube.com/watch?v=i38J-37zqlg

[TrackAire]

What a great day to be out. On the fifth photo down with the red Porsche behind you, it looks like you have at least an inch of daylight under the right front tire! Nicely done.

Rich from Abel is a good guy, he is aligning and corner weighting my Vette on Tuesday. They just installed some new alignment rack that is suppose to be the bomb diggity bomb.

[XSTAR]

Car looks amazing and that track looks like a blast!

[Dfunk]

Amazing videos!! Thank you for sharing.

[str5010]

Wow that track looks amazing. Love your car and thanks for posting the video. Nice driving!

[Bruce H.]

Hey Todd,

What a great looking track, fine driving, and glorious weather! Oh man, it was 15 degrees earlier today up here as I looked at a stack of new Corsa's in the basement... with snow coming tomorrow. Thanks for the lift buddy.

Car looks great, and those stripes are perfect! Thanks for sharing.

Bruce

[TrackAire]

Wow that track looks amazing. Love your car and thanks for posting the video. Nice driving!

The 5 mile Thunderhill is by far my favorite track, period. And I believe Todd ran the newer bypass configuration that gets rid of a couple super slow hairpins on the new West addition and makes this track world class IMO. The elevation changes are incredible.

[SinasViperTA]

What an awesome post! Looks like it was a blast for sure. Way to represent! :)

[VENOM V]

That was fun to watch! Looks like an amazing track and 5 miles of fun!!! Thanks, I'm starting to think I need an ACR now....

LOL, when the ACR came out, I began joking around with myself, thinking how absurd it would be to buy another Gen V. Next thing you know, I'm placing an order. I'm more obsessed with tracking than most so I wouldn't recommend the ACR to everyone. But if you really dig tracking, man this beast is nirvana

[VENOM V]

BTW the driver of that silver GT3 is a good friend of mine... here's his video chasing you.. :)


https://www.youtube.com/watch?v=i38J-37zqlg

He is a good driver, excellent line. He flew past me on lap two when my car mysteriously went into limp mode :(


Fantastic! Wish I could have been there but my TA is at the shop with a broken wheel stud :( :( :(

We are joining the NorCal Shelby Club on April 23-24 for another track day. About 6 or 7 Vipers signed up so far. Get that stud fixed and join us!

http://www.norcal-saac.org/springsprint/

We're also doing dinner at Casa Ramos Mexican Restaurant, Saturday:

https://events.r20.constantcontact.com/register/eventReg?oeidk=a07ecbnlsj3735b2d73&oseq=&c=f12f7ff0-f535-11e2-af96-d4ae527b8053&ch=f132b440-f535-11e2-af96-d4ae527b8053

[dkarg]

Thanks. Yes I did. I made the mistake of not wrapping my GTS's windshield, it is so pock-marked that I'm thinking about replacing it.

The ACR is especially bad, as you point out. I also need to clear wrap to the roof and wing. Most of the rest is covered already.

Where do you do the wrapping Todd? Pretty sure it's going to be one of the first things I do once I get my ACR delivered.

[VENOM V]

Car looks amazing and that track looks like a blast!


Amazing videos!! Thank you for sharing.


Wow that track looks amazing. Love your car and thanks for posting the video. Nice driving!


What an awesome post! Looks like it was a blast for sure. Way to represent! :)

Thanks fellas!

[VENOM V]

What a great day to be out. On the fifth photo down with the red Porsche behind you, it looks like you have at least an inch of daylight under the right front tire! Nicely done.

Rich from Abel is a good guy, he is aligning and corner weighting my Vette on Tuesday. They just installed some new alignment rack that is suppose to be the bomb diggity bomb.


George! Yes a gorgeous day. I may frame that picture with the wild flowers and vineyard in the background.

Rich was very cool. He loaned me a scan tool to diagnose my trouble code. Also mentioned how well the CCBs have worked on the Vettes. In fact, they are converting their serious track customers from steel to CCBs, believe it or not. He's running in the Optima Challenge. Suggested I should consider it, but I'd need 200 tread wear tires. I told him that the Kumhos ARE 200 tread wear! LOL, hard to believe because they stick like chewing gum on the bottom of your shoe.


The 5 mile Thunderhill is by far my favorite track, period. And I believe Todd ran the newer bypass configuration that gets rid of a couple super slow hairpins on the new West addition and makes this track world class IMO. The elevation changes are incredible.

^I completely agree with this- 5 mile T-Hill is just terrific. And yes, the bypass fixed my one complaint with the track. It is an excellent all-around track that rewards great handling cars with good drivers behind the wheel.

[VENOM V]

Where do you do the wrapping Todd? Pretty sure it's going to be one of the first things I do once I get my ACR delivered.


Brione Go of Go Wraps does all my clear wrap, including the Clearplex on the windshield. He also did my stripes. Excellent guy to work with. He re-did my stripes a couple of times on his own initiative because he wanted perfection.

[VENOM V]

Hey Todd,

What a great looking track, fine driving, and glorious weather! Oh man, it was 15 degrees earlier today up here as I looked at a stack of new Corsa's in the basement... with snow coming tomorrow. Thanks for the lift buddy.

Car looks great, and those stripes are perfect! Thanks for sharing.

Bruce


Haha, I feel for you Bruce. I've been to four tracks already, we are spoiled here. We've also been lucky with the weather. It's a very rainy year but seems to dodge the tracking weekends. Thanks to the mighty Viper Gods.

[Arizona Vipers]

I was the sole Viper in a sea of Corvettes and Porsches.

Isn't it always this way? LOL


And those GT3's are crazy fast on the straights, they have way more horsepower than what Porsche says! Insane for a non-boosted 4 liter 6 banger.

[VENOM V]

Isn't it always this way? LOL


And those GT3's are crazy fast on the straights, they have way more horsepower than what Porsche says! Insane for a non-boosted 4 liter 6 banger.

So true. In fact it seemed like we were dead even on acceleration. I beat him in the corners. Funny thing is that he thought it was the other way around.

[Arizona Vipers]

So true. In fact it seemed like we were dead even on acceleration. I beat him in the corners. Funny thing is that he thought it was the other way around.

Yep it's always that way, I don't know how many guys have come up to me after a session asking about my car and wondering how I'm killing them in the turns...
Did you see last months car magazine article with the ACR, GT3-RS, Z06? The Porsche annihilated the Viper and Vette in the 1/4 mile. It ran an 11.1. That's a mid 10 second car on drag radials....
No Porsche driver ever wants to admit a Viper is faster in the turns. When you beat one they always say it's in the straights....

[Nine Ball]

Great looking scenery at that track, especially with the orange Viper to accentuate the photos.

Optima Challenge is a fun event, you should give it a try. The heavily modified AWD EVO's and WRX's tend to dominate the Auto-X events, but the Vipers do well on the road course. Great group of track enthusiasts, and a big variety of new and classic cars competing.

Oh, and GT3's don't feel that fast on straights. Engines sound cool, but they do not accelerate anything like a Viper does. Could be just keeping up due to the ACR wing slowing you down. My TA walks away from them pretty awful, on any straight that sees over 120 mph.

[SSGNRDZ_28]

Love the photos of your beautiful car, the one with the flowers / vineyard is worth framing for sure. Thanks for posting the videos and as always sharing your ACR experience, issues, and methods in detail with the rest of us.

[Snakebit10]

And those GT3's are crazy fast on the straights, they have way more horsepower than what Porsche says! Insane for a non-boosted 4 liter 6 banger.

Ok I'm glad I wasn't the only one that came to that conclusion after watching the videos. I was shocked to see the ACR not gaining ground on the GT3 when they initially started out on those straights. Even at those lower speeds it seems like the acceleration was a wash. 640hp vs 500hp doesn't seem like it should be a fight on straights at all. Must be a combination of the rear weight over the tires and no driveshaft to rob additional power. It must be extremely efficient putting all of that 500hp to the rears instantly. Incredible machine.

On another note there is a video of an exhaust/header mod GT3 running away from a exhaust modded 458 Speciale from a roll so these GT3/GT3 RS's may be underated.

https://www.youtube.com/watch?v=VzZI5HQLRHY

I would love to see how a similarly modded GT3 RS with comparable tires to the ACR would fair against an stock ACR. Might be a close battle on some tracks.

[Jabba954]

NICE - I love Thunderhill, but it's so far from the South Bay. That said, I joined the T1 Club at Sonoma specifically for my ACR, so planing a couple dozen track days this year!

[RedTanRT/10]

Todd,

Great pics and great video!! I saw the video from the silver 911 and saw u pull over. Was thinking that was one of times you said it shut down. I had those issues in my viper with the original venom ecu. Dan C says the computer doesn't like to bang the rev limiter. First time it happened I was on the front straight at Fontana going 150 mph. Motor cuts out and now I'm heading into NASCAR one

I gotta get to TH someday soon. Going surfing for the week. Good luck with Josh. Keep me posted




Isn't it always this way? LOL


And those GT3's are crazy fast on the straights, they have way more horsepower than what Porsche says! Insane for a non-boosted 4 liter 6 banger.

I hear ya!! Not sure if it's hp or less arrow drag?? I'm 600 at the wheels and barely pull those 450 hp porsches

[genVer]

Spectacular driving on what looks like a very complicated track! Thanks for sharing.

[serpent]

It's the transmission that's the saving grace for the GT3. They shift fast as hell, faster than any human.
The GT3 isnt a drag car either, but there are tests showing it can do the 1/4 mile in 11.2 @ 126mph!!!

OP, I wonder how well you would have done with some hoosier A7s? I know the Viper TA with equal tires to the C7Z would be faster, but it is stuck with shitty corsa tires when magazines did those reviews.


Also concerning lap times, I think its easier to wring out the potential of the GT3 compared to the ACR. Anyone have experience with Both cars???

What I really want to see is a Mclaren 675LT vs ACR!!!

[Jabba954]

What I really want to see is a Mclaren 675LT vs ACR!!!

You'll have it May 3 or May 19th at the latest. Presuming my ACR arrives by then.

[ViperDog]

NICE - I love Thunderhill, but it's so far from the South Bay. That said, I joined the T1 Club at Sonoma specifically for my ACR, so planing a couple dozen track days this year!

I've been to both and I drove down from the state of Washington. Not sure I'd do it again for Sonoma but I would for Thunderhill. It's worth the drive. It's faster and more spectacular than Sonoma. The shelters they have there are terrific; easy to stay out of the sun or rain while parked. You have to try it at least once. I did the 3 mile east portion.

[rw99]

The 5 mile Thunderhill is by far my favorite track, period. And I believe Todd ran the newer bypass configuration that gets rid of a couple super slow hairpins on the new West addition and makes this track world class IMO. The elevation changes are incredible.

Agree 100%. When we first ran the brand-new "combo" 5-mile course, the West side was a little overdone (IMO) with the hairpins. I really like this bypass config!

Great vid, Todd. And the pics of Thunderhill with a green landscape are almost surreal. Looking forward to our visit in 3 weeks!

[w00tw00t]

You'll have it May 3 or May 19th at the latest. Presuming my ACR arrives by then.

Like!!

[Bill Pemberton]

Been a long time since I ran Thunderhill, and definitely not the 5 mile track. Your pics and video make a lot of us want to get our cars on a trailer and get out there tomorrow. Yes, follow your own lead and everyone else's -- the vineyard/meadow shot needs framing!!!

[Jabba954]

I've been to both and I drove down from the state of Washington. Not sure I'd do it again for Sonoma but I would for Thunderhill. It's worth the drive. It's faster and more spectacular than Sonoma. The shelters they have there are terrific; easy to stay out of the sun or rain while parked. You have to try it at least once. I did the 3 mile east portion.

Oh, I've run Thunderhill many times before, and demolished an LP-560 there as well. And I really love the 5 mile course - it just really is way up there when I have to other closer tracks available. And the T1 club at Sonoma is like a country club for car nuts - which means the best covered parking and pits and a crew to maintain the car on track days.

[TrackAire]

Oh, I've run Thunderhill many times before, and demolished an LP-560 there as well. And I really love the 5 mile course - it just really is way up there when I have to other closer tracks available. And the T1 club at Sonoma is like a country club for car nuts - which means the best covered parking and pits and a crew to maintain the car on track days.

What does it cost to join the T1 Club?.....their website does not appear to be working.

[Simms]

Nice driving! Car looks fantastic and that track looks like a blast.

[darbgnik]

Oh, and GT3's don't feel that fast on straights. Engines sound cool, but they do not accelerate anything like a Viper does. Could be just keeping up due to the ACR wing slowing you down. My TA walks away from them pretty awful, on any straight that sees over 120 mph.

I think that's because the Porsches are geared quite a bit lower, which helps coming onto slow to medium straights, but the advantage evaporates at higher speeds..... I think.

[Jabba954]

$9k/year and a recommendation from a member - so really just like a country club ;)

[Nine Ball]

I think that's because the Porsches are geared quite a bit lower, which helps coming onto slow to medium straights, but the advantage evaporates at higher speeds..... I think.

The GT3 has more grip on corner exit, allowing you to get hard on the throttle just past apex. It has loads of grip there, with the engine sitting over the rear tires. So, it can enter the straights at a higher mph, but then it gets passed by the Viper if the straight is long enough. Very different driving characteristics between these two cars.


It's the transmission that's the saving grace for the GT3. They shift fast as hell, faster than any human.
The GT3 isnt a drag car either, but there are tests showing it can do the 1/4 mile in 11.2 @ 126mph!!!

Lets not get carried away, now. I've timed numerous no-lift shifts that were indeed faster than the PDK. I've also ran door to door with the Turbo-S, which is much faster than the GT3. Not impossible, but also not easy :)

http://i466.photobucket.com/albums/rr29/ynotdv8/Misc/auto-vs-manual.jpg

[Bruce H.]

And don't forget about the various advantages of Porsche's much higher redline. Where one might expect Todd's 645 bhp to absolutely ape-rape the 911's 500b hp, you have to think "wheel" hp. That's crank hp multiplied by gearing, with each higher gear producing less hp at the wheels for acceleration. When Todd has to upshift ~6400 into a higher gear that puts less power to the wheels, the Porsche holds it's lower gear much, much longer, making it accelerate faster than its hp rating and power to weight ratio would suggest.

The higher redline also allows the 911 driver more flexibility to be in the ideal gear for corner entry and exit, the PDK allows him to shift mid-corner if advantageous without upsetting the balance of the car, while Todd has to select the gear going into each corner that he will need on exit to avoid running out of revs because he can't shift mid-way if he's driving on the limits of grip. That's not ideal into and through some corners, or corner sequences like esses, and tough with longer increasing radius corners where you run out of revs before getting the car straight.

And the 911's rear weight bias definitely let's it put down more power earlier on corner exit as mentioned, but also gives it a big advantage under braking, all other things being equal, and is a lot easier on its front tires. Where Todd has to manage his front tire temps and grip by not sliding it too much through the corners for the full session, the 911 can attack the corner more.

Porsche's been perfecting their 911 track performance for an awfully long time, and training their owners how to extract every bit of it, and that's a couple of reasons why they are so fun and rewarding to run hard on track with!

Bruce

[Rapidrezults]

The GT3 has more grip on corner exit, allowing you to get hard on the throttle just past apex. It has loads of grip there, with the engine sitting over the rear tires. So, it can enter the straights at a higher mph, but then it gets passed by the Viper if the straight is long enough. Very different driving characteristics between these two cars.

I would venture to say the ACR has more grip on corner exit. I can full throttle just after apex on most turns even with the HC package and not loose rear grip, especially with the wing set at the stock hole position. The ACR extreme aero and Kumhos are just on a whole different level. It feels nothing like my TA. This sentiment has also been echoed by Randy Pobst in his test at Laguna with both the RS and ACR.

There are so many variables when watching a video of an HPDE track day.

- - - Updated - - -


And don't forget about the various advantages of Porsche's much higher redline. Where one might expect Todd's 645 bhp to absolutely ape-rape the 911's 500b hp, you have to think "wheel" hp. That's crank hp multiplied by gearing, with each higher gear producing less hp at the wheels for acceleration. When Todd has to upshift ~6400 into a higher gear that puts less power to the wheels, the Porsche holds it's lower gear much, much longer, making it accelerate faster than its hp rating and power to weight ratio would suggest.

The higher redline also allows the 911 driver more flexibility to be in the ideal gear for corner entry and exit, the PDK allows him to shift mid-corner if advantageous without upsetting the balance of the car, while Todd has to select the gear going into each corner that he will need on exit to avoid running out of revs because he can't shift mid-way if he's driving on the limits of grip. That's not ideal into and through some corners, or corner sequences like esses, and tough with longer increasing radius corners where you run out of revs before getting the car straight.


Bruce

Nailed it! ^^^^

[VENOM V]

Great looking scenery at that track, especially with the orange Viper to accentuate the photos.

Optima Challenge is a fun event, you should give it a try. The heavily modified AWD EVO's and WRX's tend to dominate the Auto-X events, but the Vipers do well on the road course. Great group of track enthusiasts, and a big variety of new and classic cars competing.

Oh, and GT3's don't feel that fast on straights. Engines sound cool, but they do not accelerate anything like a Viper does. Could be just keeping up due to the ACR wing slowing you down. My TA walks away from them pretty awful, on any straight that sees over 120 mph.

Thanks Tony.

Optima does look fun. It doesn't seem like a stock supercar like an ACR quite fits what they are striving for- they seem to like classic muscle modernized and able to run with the best. Still, an ACR would open a can of whoop-ass!

I beat the GT3s in braking and in the corners, but we seem relatively even on the straights most of the time. As you said, over 120 and I begin to gain, but you're usually close to the end of the straight by that time. In racing, you would dive to the inside, late brake and take away their line for a pass, but I don't want to risk that on an HPDE day. So sadly, I usually have to wait for a point-by if it's a well-driven GT3.

Yep the wing slows you down a little, but doesn't feel like it!

[VENOM V]

NICE - I love Thunderhill, but it's so far from the South Bay. That said, I joined the T1 Club at Sonoma specifically for my ACR, so planing a couple dozen track days this year!

I'd like to check that out some time! Do they accept guests? Unfortunately I can only track on the weekends, so hopefully they run weekend club days.

[38D]

I've timed numerous no-lift shifts that were indeed faster than the PDK. I've also ran door to door with the Turbo-S, which is much faster than the GT3.

The shift times in your chart look like 997/987 PDK times. The PDK in the 991 GT3 is much different, shifting much faster. I drove my friend's 991 GT3, and it made my Cayman R PDK seem like a joke. The 991 GT3 shifts in something like 50ms...it's insanely good.

[VENOM V]

OP, I wonder how well you would have done with some hoosier A7s? I know the Viper TA with equal tires to the C7Z would be faster, but it is stuck with shitty corsa tires when magazines did those reviews.

Also concerning lap times, I think its easier to wring out the potential of the GT3 compared to the ACR. Anyone have experience with Both cars???


These Kumhos are surprisingly good. Luke and I show similar G's and he's running slicks that are probably better than A7s. I'm sure full slicks are better than the Kumhos, but man I'm impressed with these 200 treadwear gumballs. I could push harder in the high speed corners with all of the ACR's aero, working up to it gradually :)

I would guess that the ACR rivals the GT3 for being easy to drive as you approach the limit. They are probably the two best track cars available at this, except the GT3s cannot keep up. Fastest GT3 was 6 seconds slower than my ACR that day, and I think I could shave another 3 seconds with practice at this new-to-me track configuration. I've never driven a GT3, but this ACR is just ridiculously good at the limit. I have stepped the rear end out several times, it is smooth as silk and predictable. The SRT guys bull's-eyed this beast.

[VENOM V]

I would venture to say the ACR has more grip on corner exit. I can full throttle just after apex on most turns even with the HC package and not loose rear grip, especially with the wing set at the stock hole position. The ACR extreme aero and Kumhos are just on a whole different level. It feels nothing like my TA. This sentiment has also been echoed by Randy Pobst in his test at Laguna with both the RS and ACR.



So true. This is one of the most remarkable things about the ACR. Grip on corner exit is like bugs on flypaper! I had to feather my throttle to keep from plowing into the back of the GT3 on exit.

[Arizona Vipers]

I think that's because the Porsches are geared quite a bit lower,

Yes you are correct that explains the quicker 1/4 mile time, but lower trap speed Motor Trend measured at the same place, same day-
GT3- 1/4 mile 11.1 at 125mph
ACR- 1/4 mile 11.5 127mph
Z06- 1/4 mile 11.4 at 124

So the ACR was pulling away from the Porsche and Vette even with the drag of the wing...

http://www.motortrend.com/news/2016-chevrolet-corvette-z06-vs-2016-dodge-viper-acr-vs-2016-porsche-911-gt3-rs/

[Snakebit10]

Yes you are correct that explains the quicker 1/4 mile time, but lower trap speed Motor Trend measured at the same place, same day-
GT3- 1/4 mile 11.1 at 125mph
ACR- 1/4 mile 11.5 127mph
Z06- 1/4 mile 11.4 at 124

So the ACR was pulling away from the Porsche and Vette even with the drag of the wing...

http://www.motortrend.com/news/2016-chevrolet-corvette-z06-vs-2016-dodge-viper-acr-vs-2016-porsche-911-gt3-rs/

11.1 @ 125mph is insane from a close to 500 "crank" hp car. Just 2 mph off the 640hp ACR on that day. I would love to see them give the GT3 RS the full ACR-like treatment. I guess that would be the 911 GCR lol...Two incredible track/street cars in the ACR and GT3 RS.

[Jabba954]

I'd like to check that out some time! Do they accept guests? Unfortunately I can only track on the weekends, so hopefully they run weekend club days.

Unfortunately they don't really run weekends - so I convinced my boss to join. Seemed like a logical step. Each member is allowed I believe 6 guest passes, with no repeats.

[TrackAire]

Unfortunately they don't really run weekends - so I convinced my boss to join. Seemed like a logical step. Each member is allowed I believe 6 guest passes, with no repeats.

Although this is off topic, I would be interested in what they provide besides track days as Sonoma Raceway. Do you have any info you can send me or links...it appears their website was not active or working. I assume this is the correct website: www.t1club.com

TIA

[VENOM V]

Good news on the limp mode, it is a known issue and the solution is a software update. Heading to the dealership tomorrow AM :)

Todd

[darbgnik]

Awesome news! The best fix is an easy fix!



Good news on the limp mode, it is a known issue and the solution is a software update. Heading to the dealership tomorrow AM :)

Todd

[Bruce H.]

Excellent!

[NT-ACR]

Isn't it always this way? LOL


And those GT3's are crazy fast on the straights, they have way more horsepower than what Porsche says! Insane for a non-boosted 4 liter 6 banger.

The 991 GT3 only has a 3.8L flat-6, you're thinking of the RS version which has the 4.0L mill.

[NT-ACR]

And don't forget about the various advantages of Porsche's much higher redline. Where one might expect Todd's 645 bhp to absolutely ape-rape the 911's 500b hp, you have to think "wheel" hp. That's crank hp multiplied by gearing, with each higher gear producing less hp at the wheels for acceleration. When Todd has to upshift ~6400 into a higher gear that puts less power to the wheels, the Porsche holds it's lower gear much, much longer, making it accelerate faster than its hp rating and power to weight ratio would suggest.

The higher redline also allows the 911 driver more flexibility to be in the ideal gear for corner entry and exit, the PDK allows him to shift mid-corner if advantageous without upsetting the balance of the car, while Todd has to select the gear going into each corner that he will need on exit to avoid running out of revs because he can't shift mid-way if he's driving on the limits of grip. That's not ideal into and through some corners, or corner sequences like esses, and tough with longer increasing radius corners where you run out of revs before getting the car straight.

And the 911's rear weight bias definitely let's it put down more power earlier on corner exit as mentioned, but also gives it a big advantage under braking, all other things being equal, and is a lot easier on its front tires. Where Todd has to manage his front tire temps and grip by not sliding it too much through the corners for the full session, the 911 can attack the corner more.

Porsche's been perfecting their 911 track performance for an awfully long time, and training their owners how to extract every bit of it, and that's a couple of reasons why they are so fun and rewarding to run hard on track with!

Bruce

Slight correction. The 911 in the video is a 991 GT3, not an RS. So, really it only has 475hp. The RS is the one with 500hp.

[NT-ACR]

Yes you are correct that explains the quicker 1/4 mile time, but lower trap speed Motor Trend measured at the same place, same day-
GT3- 1/4 mile 11.1 at 125mph
ACR- 1/4 mile 11.5 127mph
Z06- 1/4 mile 11.4 at 124

So the ACR was pulling away from the Porsche and Vette even with the drag of the wing...

http://www.motortrend.com/news/2016-chevrolet-corvette-z06-vs-2016-dodge-viper-acr-vs-2016-porsche-911-gt3-rs/

The vehicle in the video is a 991 GT3, not an RS. These are the numbers you're looking for:

http://www.motortrend.com/news/2015-porsche-911-gt3-first-test/

[NT-ACR]

11.1 @ 125mph is insane from a close to 500 "crank" hp car. Just 2 mph off the 640hp ACR on that day. I would love to see them give the GT3 RS the full ACR-like treatment. I guess that would be the 911 GCR lol...Two incredible track/street cars in the ACR and GT3 RS.


Have you ever heard of the GT2 RS?

[Arizona Vipers]

Good news on the limp mode, it is a known issue and the solution is a software update.

Todd


Pheeeeew!

[Jabba954]

Cannot wait for the 991 GT2RS. Sources say it's coming in 2017. It's going to be pretty impossible to get unless you have a 918, or know someone with a 918 who wants to make a profit of a few hundred grand on it.

[Simms]

I tracked a 991 GT3 (non RS) at Barber Motorsports park for two days last month. Fantastic car, well balanced and very fun to drive. I would never pick it over an ACR, but if I had to chose another car besides a viper, this would be it.

[Snakebit10]

Have you ever heard of the GT2 RS?

lol. Obviously I have but we aren't talking about that and that is an older model. Is there a new GT2 RS?
If I remember correctly the last GT2 RS couldn't hang with the old ACR on the Ring so until there is a new one all we have is the GT3 RS.

If the NA GT3 RS can pull those times in a straight line its just some good amount of down force and comparable tires away from being some competition for the ACR NA to NA. That's all I'm saying.

[lmcgrew79]

Awesome laps Todd, that track looks great. The GT3 is alot closer geared than the viper and shifts much quicker. 6 seconds a lap is a pretty big gap!

[VENOM V]

Awesome laps Todd, that track looks great. The GT3 is alot closer geared than the viper and shifts much quicker. 6 seconds a lap is a pretty big gap!

Thanks Luke, I am just blown away at the ACR's handling. I'm not pushing too hard yet, as this track config is relatively new to me. I could pick up my speeds through the high speed corners, taking my time to learn the limits of this beast's huge aero. Looking forward to trying to shave a couple seconds off on next visit :)

[lmcgrew79]

Because im a data geek, 2nd to 3rd shifts was .389 seconds and spend 53 ft off gas between shifts. 3rd to 4th took .396 and was off gas 70.2 ft. Not to bad for a manual, the pdk even while shifting is still accelerating which helps a bit.

http://i119.photobucket.com/albums/o141/lmcgrew79/Autos/2016%20Viper%20ACR/shift%20time_zpsf7eswosv.jpg

[NT-ACR]

lol. Obviously I have but we aren't talking about that and that is an older model. Is there a new GT2 RS?
If I remember correctly the last GT2 RS couldn't hang with the old ACR on the Ring so until there is a new one all we have is the GT3 RS.

If the NA GT3 RS can pull those times in a straight line its just some good amount of down force and comparable tires away from being some competition for the ACR NA to NA. That's all I'm saying.

Yes, there will be a new GT2 RS.

[Werks]

Nice video! I track a C6Z and have always liked the ACR's (Gen 4 & 5) and have been giving some thought to picking up one of the new Gen 5 ACR's the last few months as I can not stand the look of the new C7's! I was considering picking up one when I made my last track car purchase (the Z) at the end of 2010 but then they unfortunately decided to stop production of the Gen 4's in 2011 which forced me over to the Vette as I consider it the only other track worthy alternative in that price bracket. I've been waiting to see some track video of a new ACR at a location that I'm familiar with to get a guage on how they perform and T-hill is pretty much my home track so it's nice to be able to see a video and be able to put speeds etc. into perspective as I've only ever seen a couple of Gen 5's out there the last few years. Compliments on your lap time, the car looks like a blast to drive and seems to have a lot of potential! I see from your video that they added a bunch of berms around corners over the winter on the new section of the track which allows you to use a more flowing line than in the past, so the track looks to be about a little faster than it was last year.

I had a blown shock and had to send my coilovers out for service so I missed that event that you ran but I know Rich and was talking to him the monday afterwards and he was commenting on how well your car seemed to handle and how much downforce the car seemed to generate in high speed corners! The white C7Z that he was driving is actually is wifes car (she runs the Optima too!) and it's stock with some used R7's from his track car on it and he mentioned that he was pushing hard to keep up with you on one of the sessions that he was alone in the car when you guys got down to in the 3:05 range. As someone mentioned earlier Rich is a very fast and very consistent driver and actually won the first round of this years Optima Challenge at T-hill back in February (ironically his wife took 2nd in her class too lol) so he was pushing the car hard and imho shows that the new ACR is a much faster car stock to stock than the C7Z! The last time I ran the 5 mile was last summer before the berms were added and it was the typical 95+ weather which slows the track down quite a bit. I'm thinking that with the cooler weather and the berms being added the track was probably 4 seconds a lap faster than it was last time we were out in August which matches up with the fact that the last time we ran Rich was in the 3:09 range with his wifes C7Z (versus 3:05 this time). That same event the last time we were out in August Rich got down to 3:01's in his C6Z without aero, I'm was in the 3:03 range with my car (with aero) and somewhat embarisingly for me Rich turned a 2:59 in my car driving it for a session. So applying the same 4 second difference that would have comparatively been around a 2:57 for him in his car, a 2:59 for me and a 2:55 for him in my car. How much time do you think that you were leaving on the table that track day?

[VENOM V]

Nice video! I track a C6Z and have always liked the ACR's (Gen 4 & 5) and have been giving some thought to picking up one of the new Gen 5 ACR's the last few months as I can not stand the look of the new C7's! I was considering picking up one when I made my last track car purchase (the Z) at the end of 2010 but then they unfortunately decided to stop production of the Gen 4's in 2011 which forced me over to the Vette as I consider it the only other track worthy alternative in that price bracket. I've been waiting to see some track video of a new ACR at a location that I'm familiar with to get a guage on how they perform and T-hill is pretty much my home track so it's nice to be able to see a video and be able to put speeds etc. into perspective as I've only ever seen a couple of Gen 5's out there the last few years. Compliments on your lap time, the car looks like a blast to drive and seems to have a lot of potential! I see from your video that they added a bunch of berms around corners over the winter on the new section of the track which allows you to use a more flowing line than in the past, so the track looks to be about a little faster than it was last year.

I had a blown shock and had to send my coilovers out for service so I missed that event that you ran but I know Rich and was talking to him the monday afterwards and he was commenting on how well your car seemed to handle and how much downforce the car seemed to generate in high speed corners! The white C7Z that he was driving is actually is wifes car (she runs the Optima too!) and it's stock with some used R7's from his track car on it and he mentioned that he was pushing hard to keep up with you on one of the sessions that he was alone in the car when you guys got down to in the 3:05 range. As someone mentioned earlier Rich is a very fast and very consistent driver and actually won the first round of this years Optima Challenge at T-hill back in February (ironically his wife took 2nd in her class too lol) so he was pushing the car hard and imho shows that the new ACR is a much faster car stock to stock than the C7Z! The last time I ran the 5 mile was last summer before the berms were added and it was the typical 95+ weather which slows the track down quite a bit. I'm thinking that with the cooler weather and the berms being added the track was probably 4 seconds a lap faster than it was last time we were out in August which matches up with the fact that the last time we ran Rich was in the 3:09 range with his wifes C7Z (versus 3:05 this time). That same event the last time we were out in August Rich got down to 3:01's in his C6Z without aero, I'm was in the 3:03 range with my car (with aero) and somewhat embarisingly for me Rich turned a 2:59 in my car driving it for a session. So applying the same 4 second difference that would have comparatively been around a 2:57 for him in his car, a 2:59 for me and a 2:55 for him in my car. How much time do you think that you were leaving on the table that track day?

Thanks, I love the C6Z and the C5Z for that matter- amazing track cars that can take on anything in the right hands. Very moddable. My friend bought a C7Z auto and suffered through overheating problems every track day, even with ambient temps in the 40s and 50s if you can imagine that. He needed the auto because his knee struggles with a clutch pedal. The solution was to short shift at 5,000rpm, but that was no fun so he just sold the car last month. Mike also felt that it was harder to drive at the limit than other cars he's tracked, he never felt comfortable pushing it to the edge. My hats off to Rich and his wife for being able to drive the car that quickly.

From what I've heard about Rich, he's a faster driver than me but the mighty ACR helped me make up for the difference, haha. Especially based on those lap times that you guys have done, that's awesome. This was my second time on the 5-mile and the first time at Thunderhill with the ACR. I think I'm leaving a lot on the table especially in turns 1, 2 and 8 where I could be several MPH faster, and I don't know the west side very good yet. I'm taking my time to work up to the limits with the huge aero that this has, and enjoying the process. I think I could shave off maybe four seconds as I get to know the track and the car better. Rich is a gracious guy, I enjoyed talking with him. He lent me a scan tool as my car went into limp mode a couple of times. The good news is that it was a known issue, and a software update at the dealer has already remedied it. I got one of the first ACRs so my software was not up to date.

I have to say that the ACR has blown my mind. I tracked my 2013 Viper GTS for the past three years before getting the ACR and can't say enough about the performance of the GTS. The GTS feels very similar to the C6Z and ZR1 (I have some seat time in both of them, and a little in a C7 Z51). However the ACR is a significant step up in every way compared to my GTS. Confidence inspiring, no drama, very predictable at the limit. Consistently, my friends that are advanced drivers have been shaving 3-4 seconds off of their lap times in their ACRs compared to their previous Vipers (most had TAs). It's not just the downforce which is brilliantly executed and adjustable front and rear, its the suspension and oh those brakes. Wow, the CCBs have really impressed. I can brake at the very last minute, over and over without a hint of fade, drama, or change in braking feel. The coilovers let you dial in not just damping, but of course the ride height which greatly affects how much downforce the diffuser exerts. And you can easily change the rake to dial out understeer if you need to. I'm an infant at understanding those adjustments but am trying to learn from those that know.

We will be at Thunderhill 3-mile on 4/23 and 4/24 with NorCal Shelby Club. Should be about 9 Vipers plus a few friends in GT3s. Come out and join us, say hi if you can make it.

My name is Todd, I'll be the only orange Viper there :United_States:

[w00tw00t]

Todd you mean 4/23 and 4/24....... ;)

[VENOM V]

Todd you mean 4/23 and 4/24....... ;)

Haha, fixed

[Werks]

Thanks, I love the C6Z and the C5Z for that matter- amazing track cars that can take on anything in the right hands. Very moddable. My friend bought a C7Z auto and suffered through overheating problems every track day, even with ambient temps in the 40s and 50s if you can imagine that. He needed the auto because his knee struggles with a clutch pedal. The solution was to short shift at 5,000rpm, but that was no fun so he just sold the car last month. Mike also felt that it was harder to drive at the limit than other cars he's tracked, he never felt comfortable pushing it to the edge. My hats off to Rich and his wife for being able to drive the car that quickly.

From what I've heard about Rich, he's a faster driver than me but the mighty ACR helped me make up for the difference, haha. Especially based on those lap times that you guys have done, that's awesome. This was my second time on the 5-mile and the first time at Thunderhill with the ACR. I think I'm leaving a lot on the table especially in turns 1, 2 and 8 where I could be several MPH faster, and I don't know the west side very good yet. I'm taking my time to work up to the limits with the huge aero that this has, and enjoying the process. I think I could shave off maybe four seconds as I get to know the track and the car better. Rich is a gracious guy, I enjoyed talking with him. He lent me a scan tool as my car went into limp mode a couple of times. The good news is that it was a known issue, and a software update at the dealer has already remedied it. I got one of the first ACRs so my software was not up to date.

I have to say that the ACR has blown my mind. I tracked my 2013 Viper GTS for the past three years before getting the ACR and can't say enough about the performance of the GTS. The GTS feels very similar to the C6Z and ZR1 (I have some seat time in both of them, and a little in a C7 Z51). However the ACR is a significant step up in every way compared to my GTS. Confidence inspiring, no drama, very predictable at the limit. Consistently, my friends that are advanced drivers have been shaving 3-4 seconds off of their lap times in their ACRs compared to their previous Vipers (most had TAs). It's not just the downforce which is brilliantly executed and adjustable front and rear, its the suspension and oh those brakes. Wow, the CCBs have really impressed. I can brake at the very last minute, over and over without a hint of fade, drama, or change in braking feel. The coilovers let you dial in not just damping, but of course the ride height which greatly affects how much downforce the diffuser exerts. And you can easily change the rake to dial out understeer if you need to. I'm an infant at understanding those adjustments but am trying to learn from those that know.

We will be at Thunderhill 3-mile on 4/23 and 4/24 with NorCal Shelby Club. Should be about 9 Vipers plus a few friends in GT3s. Come out and join us, say hi if you can make it.

My name is Todd, I'll be the only orange Viper there :United_States:

Hey Tod, my names Ron! In regards to the C7Z once I heard that it was going to have a supercharged engine I completely wrote it off as a track day car. You do not have to be a rocket scientist to assume that you are going to run into heat issues tracking a car with one of those especially as hot as it gets up a T-hill lol! Little did I know that the problem seems to be worse than anyone could possibly have assumed as you mentioned your friend experienced first hand! Plus honestly imho compared to the C5 & C6 I think the design is ugly, just to angular for me. How Rich and his wife manage to have zero issues with their car is beyond me but he beats on that thing and it just keeps on going. Compared to our cars which both have Katech engines in them it feels pretty gutless and lacks top end. He took me for a ride and on the back straight he's WOT and we both start rocking back and forth in the seats trying to make the car go faster looking at each other laughing lol!

Regarding the times l've only done the 5 mile 4-5 times now but the back side is interesting in that you can go faster than you think you can around a lot of those corners you just have to hit the right lines and have faith as a lot of the exits and entries are over little hills and crests. From the video I think that you should be able to pick up about 3-4 seconds on that side alone. You mentioned you thought that you were loosing time on 1,2 & 8 and those 3 are corners where you just have to have faith in your aero which having gone from having no aero on my car to having a setup similar to a World Challenge Vette I can tell you takes some getting used to. It's truly a viceous circle, the faster you go the more downforce you have hence the faster you could have gone. Thinking of the repercusions from finding and possibly passing the limit though in those corners is not something that I think any of us want to picture! The thing that you have to remember is that there are 20+ corners around the track, 1 and 8 are probably potentialy the most dangerous and honestly you are going so fast that a few extra mph through those is going to result in a fairly limited reduction in overall lap times. In our cars Rich is hitting 156 at the end of the straight and going through T1 in the 100 range, I get hit with aero drag so I'm doing about 148 and pretty comfortably in the 100-110 range going through T1 and T2 is in the 85+ range so I think you can probably carry about an additional 8-10pmh on T2. T8....well I tend to think that anything around 100-105mph is fast enough through there lol but you might have bigger cajones than me ;-) I'm not surprised to hear that Rich helped you out with the scan tool. We're ddrive vette's but at the end of the day we're all car lovers and track nuts. He is a service manager at a Chevy dealership but he apprecaited cars for what they are like most of my track buddies. A couple of us drive Vette's but none of us fall in that group that is blinded by brand loyalty and that feel the need to validate their purchsaing decision at the expense of anothers thankfully. If I ever see you out there I'll stop by and say hi otherwise keep your eye out for us and swing by and introduce your self if you see us. Rich is usually in his yellow c6z06 aka the rumble bee, I drive an orange c6z06 with aero and a bunch of carbon on it and my buddy Mike who came over from the P car camp with his cup car runs a light blue C6Z06 with aero on it too.

Also noticed your thread on your experience with CCM's. I think that you guys basically have them same set up as we have on our cars. I've been tracking with them CCM's on my car now for 4 seasons w/ about 20-25 days per season and done a lot of CCM pad testing both for my self and also worked with a brake company to develop their pads. You are going to be impressed with theperformance of your CCM's but you will notice that your pad wear rate is going to increase as your rotors wear. The key to CCM life is brake cooling! Although I know you have brake ducts I'm not 100% sure what exact set up you guys have on your cars but on mine I run oversized brake ducts with hoses routed driectly to spindle ducts to keep them cool. If your car does not come with spindle ducts, get them! These rotors wear through oxidation due to heat, more specifically at temps over 700c the carbon fibre strands that are in the CCM (carbon ceramic matrix) that your rotors are made of will simply start to turn to dust. You posted a side shot of your rotor and pad in your other thread and if you look at it you will notice some small voids. If you look closely at your rotors you will also notice what look like stands embedded on the rotor face. Those are the carbon fibre strands that will oxidize due to heat and when they do leave those voids. Normally CCM brakes (because the rotor surface is near diamond hard) work through adhesive friction or the friction caused by a transfer layer from the pad that is applied to the rotor rubbing against the brake pad when the pedal is depressed (similar to rubbing two pieces of rubber against each other) not abrasive friction like with iron rotors where the pad wears against the rotor surface (like sandpaper) wearing both away over time. When those voids on the rotor surface start to develop abrasive friction does start to become a factor (but only to the pad surface) which accelerates pad wear. On a new set of rotors front I will see about 5-6 track days, rears get about 40-50% more life. After about 2 sets of pads that drops down to 4 maybe 5 track days for a set of fronts, then falls further down to about 3 days on a set of fronts when the rotor is close to being worn out. If you have any questions abot the CCM's feel free to ask as mentioned I have a ton of time on these, have run through multiple sets of rotors and littleraly have stacks and stacks of used pads! Also can you look at your pads and let me know what compounds are printed on the back of them? Just curious what comes stock on your car!

Regards,

Ron

[greygt3]

HPC 4300 FF is the stock pad compound on the ACR. That's the same compound as the ZR-1.

[Werks]

HPC 4300 FF is the stock pad compound on the ACR. That's the same compound as the ZR-1.

Actually the ZR-1/C6Z06 w/ Z07 uses different cpad compounds front and rear. The OEM pads use a Textat T4300 compound front and Pagid S600 rear. If memory serves me right the front pads have the compound laser engraved on the back of the pad close to the Brembo part number. The rear pads have the compound etched into the metal back plate top center.

Are you sure about the ACR pad compound you listed and that car uses the same compound front and rear???

[greygt3]

Here is a picture of the two pads side by side. ACR pad is on the left and a new ZR1 pad on the right. These are front pads only.

[Werks]

Thanks for posting the pic and have to say I'm a little confused now lol. All of these pads are supplied to Brembo by TMD Friction who own Pagid, Textar, Mintex and a couple of other more industrial oriented friction material brands. CCM brake pads are most commonly based off of endurance racing oriented pad compounds and they (TMD Friction) then work with Brembo and the OEM (Dodge or Chevrolet) to test and find the most suitable pad compound out of their sub brands catalogue of friction compounds. For the front GM chose for the ZR1 the Textar 4300 compound and Pagid S600 for the rear as mentioned and is laser engraved on the pad. These are both brands owned by TMD friction. But on the ACR pads that you posted it does clearly show HPC 4300 as you mentioned, but HPC is not one of TMD's sub companies or even a brand that I can find any info on so that is strange. I wonder if they are just re-naming the compound to try and avoid people cross shopping the pads. Also noticed that the ACT version has dual cutouts for the pad wear sensors as you guys run them both on the inner and outer pad versus just the outer like we do. Also your pad shape has a much larger radius cut into the bottom of the pad than ours (like on the GTR CCM pads). The reason for this has to do with the finish of the inner 3-4mm of the rotor being not very abrasive so traditionaly with ZR1's as the pads wear you end up with a 1-2mm higher raised 3-4mm wide band of friction material there than the rest of the friction (pad) surface. It does not seem to affect brake performance but it does look a little weird when you pull and inspect your pads. So don't be surpised if you see that if you run ZR1 pads on your car.

[VENOM V]

Hey Tod, my names Ron! In regards to the C7Z once I heard that it was going to have a supercharged engine I completely wrote it off as a track day car. You do not have to be a rocket scientist to assume that you are going to run into heat issues tracking a car with one of those especially as hot as it gets up a T-hill lol! Little did I know that the problem seems to be worse than anyone could possibly have assumed as you mentioned your friend experienced first hand! Plus honestly imho compared to the C5 & C6 I think the design is ugly, just to angular for me. How Rich and his wife manage to have zero issues with their car is beyond me but he beats on that thing and it just keeps on going. Compared to our cars which both have Katech engines in them it feels pretty gutless and lacks top end. He took me for a ride and on the back straight he's WOT and we both start rocking back and forth in the seats trying to make the car go faster looking at each other laughing lol!

Regarding the times l've only done the 5 mile 4-5 times now but the back side is interesting in that you can go faster than you think you can around a lot of those corners you just have to hit the right lines and have faith as a lot of the exits and entries are over little hills and crests. From the video I think that you should be able to pick up about 3-4 seconds on that side alone. You mentioned you thought that you were loosing time on 1,2 & 8 and those 3 are corners where you just have to have faith in your aero which having gone from having no aero on my car to having a setup similar to a World Challenge Vette I can tell you takes some getting used to. It's truly a viceous circle, the faster you go the more downforce you have hence the faster you could have gone. Thinking of the repercusions from finding and possibly passing the limit though in those corners is not something that I think any of us want to picture! The thing that you have to remember is that there are 20+ corners around the track, 1 and 8 are probably potentialy the most dangerous and honestly you are going so fast that a few extra mph through those is going to result in a fairly limited reduction in overall lap times. In our cars Rich is hitting 156 at the end of the straight and going through T1 in the 100 range, I get hit with aero drag so I'm doing about 148 and pretty comfortably in the 100-110 range going through T1 and T2 is in the 85+ range so I think you can probably carry about an additional 8-10pmh on T2. T8....well I tend to think that anything around 100-105mph is fast enough through there lol but you might have bigger cajones than me ;-) I'm not surprised to hear that Rich helped you out with the scan tool. We're ddrive vette's but at the end of the day we're all car lovers and track nuts. He is a service manager at a Chevy dealership but he apprecaited cars for what they are like most of my track buddies. A couple of us drive Vette's but none of us fall in that group that is blinded by brand loyalty and that feel the need to validate their purchsaing decision at the expense of anothers thankfully. If I ever see you out there I'll stop by and say hi otherwise keep your eye out for us and swing by and introduce your self if you see us. Rich is usually in his yellow c6z06 aka the rumble bee, I drive an orange c6z06 with aero and a bunch of carbon on it and my buddy Mike who came over from the P car camp with his cup car runs a light blue C6Z06 with aero on it too.

Also noticed your thread on your experience with CCM's. I think that you guys basically have them same set up as we have on our cars. I've been tracking with them CCM's on my car now for 4 seasons w/ about 20-25 days per season and done a lot of CCM pad testing both for my self and also worked with a brake company to develop their pads. You are going to be impressed with theperformance of your CCM's but you will notice that your pad wear rate is going to increase as your rotors wear. The key to CCM life is brake cooling! Although I know you have brake ducts I'm not 100% sure what exact set up you guys have on your cars but on mine I run oversized brake ducts with hoses routed driectly to spindle ducts to keep them cool. If your car does not come with spindle ducts, get them! These rotors wear through oxidation due to heat, more specifically at temps over 700c the carbon fibre strands that are in the CCM (carbon ceramic matrix) that your rotors are made of will simply start to turn to dust. You posted a side shot of your rotor and pad in your other thread and if you look at it you will notice some small voids. If you look closely at your rotors you will also notice what look like stands embedded on the rotor face. Those are the carbon fibre strands that will oxidize due to heat and when they do leave those voids. Normally CCM brakes (because the rotor surface is near diamond hard) work through adhesive friction or the friction caused by a transfer layer from the pad that is applied to the rotor rubbing against the brake pad when the pedal is depressed (similar to rubbing two pieces of rubber against each other) not abrasive friction like with iron rotors where the pad wears against the rotor surface (like sandpaper) wearing both away over time. When those voids on the rotor surface start to develop abrasive friction does start to become a factor (but only to the pad surface) which accelerates pad wear. On a new set of rotors front I will see about 5-6 track days, rears get about 40-50% more life. After about 2 sets of pads that drops down to 4 maybe 5 track days for a set of fronts, then falls further down to about 3 days on a set of fronts when the rotor is close to being worn out. If you have any questions abot the CCM's feel free to ask as mentioned I have a ton of time on these, have run through multiple sets of rotors and littleraly have stacks and stacks of used pads! Also can you look at your pads and let me know what compounds are printed on the back of them? Just curious what comes stock on your car!

Regards,

Ron

Ron,

Good info on all fronts, thank you. I appreciate the feedback on CCB pad longevity Vs. rotor age, that makes sense and backs up what Rich explained to me.

I'm with you on being a track rat first and brand-loyal second. My previous track cars were a surprisingly fast late model Camaro with a forged 418 c.i. and full aero, and I raced a Mustang last year in the SCCA. I would have considered the C7 Z06 as well if it had delivered to the hype, sad that it didn't live up to its legacy. After tracking my 2013 Viper for three years with exceptional performance and virtually no reliability issues, I've become a huge fan of the Vipers. And when the ACR came out, I could not resist. Couldn't really afford it, but was weak in the knees. You only live once, lol.

One question on CCBs- What do you base rotor replacement on? We are supposed to weigh the rotors, however I know that the ACR test fleet never had a rotor failure in all the testing they performed. I am wondering if I should weigh them, or perhaps replace them when pad life has shortened significantly.

I look forward to meeting you at the track one day soon.

Todd

[Werks]

No problem giving feedback on the CCM's. Back when I started tracking with them on my car in '11 unfortunately there were really no vette guys hardcore tracking their cars with them. You had the typical I go to one or two track days a year guys but as far as getting advise or feed back from them the only thing they are really good for telling you is that the brakes seem to work lol! So it's been a bit of learning by trying type of thing for me over the years and just testing a lot of different things. Fortunately based on what I have found more and more guys with my car brand like Rich etc. are starting to come over which will benefit us all in the long run as we really need to increase the amount of cars running these in order to get costs down.

In any case in regards to your questions I base rotor replacement solely off of rotor weight. Their is a min weight printied on the hat of each rotor assembly (this is why they only come pre-assembled). Once I get to that, they get pulled and replaced. The pitting or what I call "worm wood" look that starts to appear on the rotor surface due to oxidation of the carbon fibers will get worse as I mentioned and it will accelerate pad wear but rotors cost too much to just junk prematurely so I just deal with it. If you look at your hat you may also notice that there is a min thickness listed on there too. The ceramic in the CCM matrix that the rotor is made of is near diamond hard, so that does not wear and if by chance you do somehow manage to wear a rotor to the min it will have been way, way under weight for a long time so jsut ignore the min thickness. When my rotors are new I just run the first 3 pad sets on the front and then I will start pulling the rotors and checking their weight each pad replacement after that. As I mentioned I get about 5-6 pad changes out of a front rotor on average but I also run additional brake cooling. Attached is a picture of what I call the "worm wood" look that a more used rotor is going to take on and which causes increased pad wear.

16822

And in this one you can see the spindle duct that was fabbed up attached to my drop spindle. Cool air is ducted from the front of the car through 3.5" tubing connected to the spindle duct directly against the rotor/rotor hat.

16823

As mentioned if you guys only have some type of bolt on blade or wing thingy to divert air flow over the rotor, you really shoudl consider getting something like this if you seriously track the car to cool the rotors which will cut down on wear. I'm guessing something must be availabel for the ACR-X or something if they are not on the car stock already.

Lastly here is an example of what is mostly the oxidized carbon from wear that I keep mentioning comes out of your rotor after using it for a few days at the track. There goes a few more grams of rotor weight lol!

16824

[Rapidrezults]

Ron,

Some of the best CCM brake info I've come across. Thank you for sharing your wealth of knowledge on the subject. We could definitely use more of your input in the Viper community! When are you going to place your order? Lol.

I am also a Nor Cal tracker and look forward to meeting you at an upcoming track day.

[Racingbrake]

Hello Everyone,

Warren from RacingBrake. We are the brake company that Ron mentioned to have worked with him in testing our sintered brake pads exclusively developed for CCM rotors.

We used two brake platforms "Corvette ZR1" and "Nissan GTR" to test and develop our CCM brakes with a goal in search of the ultimate brake set up. You can search GTR forum and find more information where those GTR hardcore track drivers discussing their brake issue and finding their brake solutions where Ron is also a tech contributor there.

http://www.gtrheritage.com/forum/10-handling-and-suspension/

Search "RacingBrake" or "Brake"

As to the brake pad compound, my bold observation is that both Viper and Corvette brake pads should have the same compound, the P/N variation should probably apply to the brake pad shape where Viper has more cut out at the bottom which is a newer model similar to Ferrari's F458 to F430 Scuderia which we observed on those changes very closely, as it's hard to imagine that Brembo is likely to develop a different/special compound for such a low production car like Viper, while the similar pad (although vary in shape/sensor connection etc.) was used in Aston Martin, Ferrari, Corvette (C6/C7), Camaro Z28 and now Viper.

In fact our brake pad for ZR1 the height was reduced from OE's 85mm to 78mm to eliminate the excessive bottom contact to the rotor flange which I believe Brembo has found the same discrepancy on ZR1 pad and made the change for newer models like F458 and Viper.

You can click below link describing more details about how we improved the OE pads.

http://www.racingbrake.com/Brake-Pad-RB-XR970-Corvette-ZR1-Z06-Carbon-Edi-p/pd1395-3r7.htm

[Werks]

Ron,

Some of the best CCM brake info I've come across. Thank you for sharing your wealth of knowledge on the subject. We could definitely use more of your input in the Viper community! When are you going to place your order? Lol.

I am also a Nor Cal tracker and look forward to meeting you at an upcoming track day.

Thanks! We're all car guys so anything that I can share or help you with I'd be more than happy to. As I mentioned back when I started running CCM's at first there was very little knowledge of these products (except from the P car guys but their rotors are actually different than ours) so everything I had to learn first hand. Over the years I've been able to try a whole bunch of different stuff and also as Racing Brake mentioned did all of the testing and development of his CCM pads. So I have built up a pretty good understanding of things lol. If there is ever a CCM specific thread started I'll give input and pass on any tips that I can. One little one though is I just noticed in my picture of the carbon dust under my rotor you can see a metal punch laying on the ground. That is available from Harbor Freight in a 3 pack of different sizes for something like $9 lol. The middle one (pictured) is the perfect size to use to clean out the drilled holes in your rotor face. They start to get filled with a plug of really hard brake pad deposit material over time. So as part of my regular post track day maintenance I go over each rotor and use the punch to unplug all of the holes. If you don't after a few track days your rotors are going to look like solid (un drilled) rotors because the hole will be completely covered with pad deposit and you are not going to be able to find the holes lol. So hose of you that track your car may want to start doing this too.