Gen V Drag Strip Results & C7 Corvette

[Nine Ball]

I finally had an opportunity to take the new Viper to the drag strip, Royal Purple Raceway in Houston. I had read a few posts/feedback from others like JackB, who have taken their Gen 5 Vipers to the track, where it was mentioned that the clutch didn't like slipping off the line, and that burnouts could cause the car to go into reduced power mode. I experienced both, for myself.

My first pass was the best pass. I made 2 other clean passes later, but in reduced power mode. The car never felt fast the entire night, indicated by the lower than normal trap speeds. It just felt slow, all the way down the track. I've made a lot of hits in this car, out on the streets, and I can tell the difference right away if things feel off.

Details:

2013 SRT Viper w/ Track Pack
ESC and TCS off
5000 rpm launch (clutch roasted on this)
3505 lbs raceweight (driver 180 lbs)
DA = +650'
1.82 60'
7.44 @ 96.47 mph 1/8-mile
11.43 @ 124.34 mph 1/4-mile

Video of pass:



The other two passes, the car only trapped 122 and 120. As DA got better, the car ran slower. It was clear that something was holding back the power after that first burnout I made. It didn't seem to clear up until I was about 20 minutes into driving home, after some highway miles.

Some notes to share about the car, even though I only have 3 runs of experience with it.

-The clutch isn't ideal for drag racing. It reminds me of the stock Corvette Z06 clutch, light pedal pressure and does not like any sort of heat. Once the clutch gets hot, from trying to launch it, it will not disengage properly, and it will slip on the 2-3 shift. It also has the same heat related issues with the hydraulic system, causing the pedal to get spongy. Clamping force feels okay, but not the friction material. I may have someone upgrade my clutch disks to a ceramic/bronze puck arrangement, sort of like the Bad Boyz Garage clutch. Those clutches laugh at heat, and almost grab better when they are hot.

-First gear in this transmission is too tall. It is cool for magazine racers that they can get 0-60 in one gear, but it isn't good for drag racing. You need a lot of rpm to get this car off the line, assuming you have the tire traction. I tried dumping at 4600 rpm and the car bogged hard enough for me to abort one pass. The 5000 rpm dump worked, but my drag radials held better than the clutch did. That was with 31 psi in the tires! I was on 345/30-19 Nitto drag radials, so a similar to stock height tire. Running on stock tires would have been easier on the clutch, but also a trade-off in traction.

-We really need to figure out why these Gen 5 cars lose power after doing 1 dyno run, and apparently after doing burnouts. I had the ESC and TCS turned off each time, yet it still went into reduced power mode. This is unacceptable. I can't jump out of the car after doing a burnout and pull ECM wire harnesses, like SRT showed in their dyno video. What the hell is that all about? Do we need to get a software reflash to fix this issue?

-The car didn't like doing 2nd gear burnouts, even in the wet portion of the box. Brakes were too good, haha. It wouldn't put down enough torque to keep from stalling out. 1st gear burnouts worked like a charm, however.

-The car did show wheel-hop on the later two passes, but that is likely due to the track prep going away as the night went on. It was just a normal test & tune night. I lift when wheel-hop is felt, as that can cause damage to the rear. I blame that one on track prep though. Stock tires would have been worse, in that situation.

So, I learned a lot in 3 runs. Good for mental notes. I plan on trying it again during a track rental day on Nov 3, where I'll be able to get many more passes. I may opt to run on my street tires that day. It will take perfect weather, good track, and, and figuring out why the car goes into reduced power mode, before we see 10s out of these cars.













As seen in the photos, there were two brand new 2014 Corvettes at the track. Although we never raced side by side, we did get some back to back runs. The automatic trans C7's are no joke at the dragstrip. The red C7 (has a custom dyno tune) ran an 11.73 @ 118 (1.74 60') right behind me. He later went 11.67, and then after a very long cool-down and pushing it into the water box, it clicked off an 11.47 @ 121, once the DA hit +250 around 11pm. That is a new record for C7s. I know the owner, the car is stock and is a non-Z51 base model automatic. There is something really cool about how they launch, the almost seem to have a higher stall converter on the initial bite, then once the car moves out a few feet, the converter locks up and the tires haze a tiny bit. It consistently cut 1.7 times on the stock tires, regardless of how the track prep went downhill. They are also geared perfectly for the 1/4-mile, hitting the top of 3rd gear at the finish line. The blue C7 (100% stock) went 12.52 @ 118, spinning off the line. It later went 11.8 from what I was told. It appears GM did their homework with the automatic C7's. They are solid 11 second cars. It appears the custom tune was worth 4 tenths and 3 mph!

Tony

[beckleyviper]

Sweet Pics!

11.43 @ 124.34 mph 1/4-mile ET for the Viper.

[ViperSmith]

I hope SRT can chime in here and get us V owners some info. I find it strange it is struggling with the electronic goodies disabled.

[Smog Dog]

Very interesting post! Thanks for taking the time---not a 2 minute job. Viper looks great and I still like the Hyper Black Track Pack wheels the best.

Bill Hodel

[Nine Ball]

I'd like to point out for the non-dragracers here, that my 11.4 with only 124 mph was actually good driving. LOL

(glass is half full!)

My previous bone stock C6Z06 went 11.55 @ 125 mph. Haha

[ViperSmith]

Tony, if you can get this sorted, what do you think the car has in it? 11 flat?

[Nine Ball]

If I would have had the full 128-129 mph that the cars should be capable of, they will go into the 10s with only a 1.7X 60' time. I'd say 10.7-10.8 is possible. The clutch might be the weak link, if they figure out the reduced power stuff.

[Nine Ball]

EDIT: The red C7 apparently wasn't stock. It had a custom dyno tune done already. Explains why it was 4 tenths and 3 mph faster than the blue C7. Watch this launch, pretty sweet. Still on stock tires.

[BAD BOYZZ GARAGE]

I finally had an opportunity to take the new Viper to the drag strip, Royal Purple Raceway in Houston. I had read a few posts/feedback from others like JackB, who have taken their Gen 5 Vipers to the track, where it was mentioned that the clutch didn't like slipping off the line, and that burnouts could cause the car to go into reduced power mode. I experienced both, for myself.

My first pass was the best pass. I made 2 other clean passes later, but in reduced power mode. The car never felt fast the entire night, indicated by the lower than normal trap speeds. It just felt slow, all the way down the track. I've made a lot of hits in this car, out on the streets, and I can tell the difference right away if things feel off.

Details:

2013 SRT Viper w/ Track Pack
ESC and TCS off
5000 rpm launch (clutch roasted on this)
3505 lbs raceweight (driver 180 lbs)
DA = +650'
1.82 60'
7.44 @ 96.47 mph 1/8-mile
11.43 @ 124.34 mph 1/4-mile

Video of pass:



The other two passes, the car only trapped 122 and 120. As DA got better, the car ran slower. It was clear that something was holding back the power after that first burnout I made. It didn't seem to clear up until I was about 20 minutes into driving home, after some highway miles.

Some notes to share about the car, even though I only have 3 runs of experience with it.

-The clutch isn't ideal for drag racing. It reminds me of the stock Corvette Z06 clutch, light pedal pressure and does not like any sort of heat. Once the clutch gets hot, from trying to launch it, it will not disengage properly, and it will slip on the 2-3 shift. It also has the same heat related issues with the hydraulic system, causing the pedal to get spongy. Clamping force feels okay, but not the friction material. I may have someone upgrade my clutch disks to a ceramic/bronze puck arrangement, sort of like the Bad Boyz Garage clutch. Those clutches laugh at heat, and almost grab better when they are hot.

-First gear in this transmission is too tall. It is cool for magazine racers that they can get 0-60 in one gear, but it isn't good for drag racing. You need a lot of rpm to get this car off the line, assuming you have the tire traction. I tried dumping at 4600 rpm and the car bogged hard enough for me to abort one pass. The 5000 rpm dump worked, but my drag radials held better than the clutch did. That was with 31 psi in the tires! I was on 345/30-19 Nitto drag radials, so a similar to stock height tire. Running on stock tires would have been easier on the clutch, but also a trade-off in traction.

-We really need to figure out why these Gen 5 cars lose power after doing 1 dyno run, and apparently after doing burnouts. I had the ESC and TCS turned off each time, yet it still went into reduced power mode. This is unacceptable. I can't jump out of the car after doing a burnout and pull ECM wire harnesses, like SRT showed in their dyno video. What the hell is that all about? Do we need to get a software reflash to fix this issue?

-The car didn't like doing 2nd gear burnouts, even in the wet portion of the box. Brakes were too good, haha. It wouldn't put down enough torque to keep from stalling out. 1st gear burnouts worked like a charm, however.

-The car did show wheel-hop on the later two passes, but that is likely due to the track prep going away as the night went on. It was just a normal test & tune night. I lift when wheel-hop is felt, as that can cause damage to the rear. I blame that one on track prep though. Stock tires would have been worse, in that situation.

So, I learned a lot in 3 runs. Good for mental notes. I plan on trying it again during a track rental day on Nov 3, where I'll be able to get many more passes. I may opt to run on my street tires that day. It will take perfect weather, good track, and, and figuring out why the car goes into reduced power mode, before we see 10s out of these cars.













As seen in the photos, there were two brand new 2014 Corvettes at the track. Although we never raced side by side, we did get some back to back runs. The automatic trans C7's are no joke at the dragstrip. The red C7 (has a custom dyno tune) ran an 11.73 @ 118 (1.74 60') right behind me. He later went 11.67, and then after a very long cool-down and pushing it into the water box, it clicked off an 11.47 @ 121, once the DA hit +250 around 11pm. That is a new record for C7s. I know the owner, the car is stock and is a non-Z51 base model automatic. There is something really cool about how they launch, the almost seem to have a higher stall converter on the initial bite, then once the car moves out a few feet, the converter locks up and the tires haze a tiny bit. It consistently cut 1.7 times on the stock tires, regardless of how the track prep went downhill. They are also geared perfectly for the 1/4-mile, hitting the top of 3rd gear at the finish line. The blue C7 (100% stock) went 12.52 @ 118, spinning off the line. It later went 11.8 from what I was told. It appears GM did their homework with the automatic C7's. They are solid 11 second cars. It appears the custom tune was worth 4 tenths and 3 mph!

Tony

Nine Ball and all interested Viper owners,

Our BBG Gen 5 Competition Clutch Kit is done!! If you didn't already know your running a Bad Boyzz Garage style billet flywheel in your G5 right now with of course a G4 clutch pack. Dick Winkles asked me to build the proto-type flywheels during the G5 engine development program about 2 years ago. The decision was made to choose us (BBG) since we proved to Winkles, DMS and SRT over the course of several Viper Cup race seasons that our ACR-X billet clutch kits were far superior than the stock OE steel units. SRT was looking to shed about 125 lbs off the G5 Viper and we gave them -11 lbs of rotating mass right off.. Dam near 10% of their goal before even getting started on the frame structure, body panels and other driveline components.. This was huge to SRT engineering and also gave the G5 V10 a performance advantage by free-ing up it's power output to complement its new camshaft design, valve train improvements, intake manifold, newly geared transmission and rear diff ratio's..

Our BBG G5 Competition Clutch Kits are a newly designed "Deep Dish" billet flywheel with our race proven ACR-X dual clutch discs and our quiet strapped floater specification..!! This new G5 clutch kit has the correct rotating mass to operate / run in the parameters of the new G5's PCM.. After all it's our BBG units that SRT used to develop G5 so we share the same internal mathematics as SRT..

To all G5 owners who plan on road racing and drag racing your Viper's please give us a call @ (916) 505-9026, we have the solution to your clutch issues!! 4000 rpm and drop the hammer is the typical starting technique that the ACR-X Viper's used through-out the SRT Viper Cup race series "standing starts" with our clutch kits and the only issue they had was how to keep the massive Michelin slicks from going up in smoke..

BTW - Nice drag racing data in your post Nine Ball..

Thanks for considering running a BBG product!

BAD BOYZZ GARAGE
INFO@BADBOYZZGARAGE.COM
=DISTRIBUTORS OF POWER=

Here's a few pictures of our BBG G5 Competition Clutch Kit. Snapped photos off my IPhone, will create a thread with detailed photos of entire unit when allowed too..

[SWEEN]

Great pics and video, thanks for posting!

[mjorgensen]

Possible fix for the strip and the dyno!


For trips to the strip I would suggest unplugging the front two wheel speed sensors so they are not confusing to the stability controls, do the same on the dyno. You should still have ABS because the rear wheels will provide information for it just as it would if the sensors up front failed. You will NOT have stability control any longer though and YES the stability controls are active in the back ground even when in the "off" position I bet, I would bet this on any car that claims to deacitvate it fully.

Anyway, someone head out and try this, if it works for you you can figure out for yourself how to rig a switch to make it easier to do at the strip, maybe.

[Nine Ball]

I contacted a couple SRT engineers over the weekend, and had a conference call with them today. They were concerned with what I'd reported, and want to help figure things out. They asked all sorts of technical questions about the setup of the car, weather conditions, any mods, etc.. I gave them all the input I had. We discussed the IAT (Intake Air Temp) and also engine coolant temps. I reported that my SRT Application Gauge pack showed the IAT around 111-112F while idling, and my coolant temps were 180-190F for the most part. They were leaning towards this being the most possible cause for the aggressive reduction in power. Their tune pulls out ignition timing as IAT's cross over 100F, and the coolant temps breach 190F. Neither of these would matter on a road course, as the car is moving and the radiator works more efficiently. But, when idling 10-15 ft at a time in a drag strip staging lane (think of very heavy traffic) and then idling after doing a burnout while you stage the lights - both of those temps are easily excessive to their respective sensors.


This results in the computer thinking the ambient conditions aren't good, which can pull timing and reduce power. If there was any vibrations that may have been incorrectly setting off the knock-retard sensors, then it could also result in reduced power. The problem is that once these low-timing maps are triggered, they take some engine driving cycles to fully regain the power back. That is likely why my car felt like it was back to normal, after 20 min into my drive home on the freeway. Until that drive cycle, the car might assume you have a bad tank of fuel, or it is very hot outside.


Seems like the coolant temp issue could be resolved by a simple thermostat swap.


The IAT sensor is on the intake piping, it picks up a lot of heat from the radiator when sitting still. I may try and insulate that area, so that idle/radiator temps do not skew my temp sensor. It was in the 62-65F range outside that night, which is what the IAT should have been reading. It probably did drop down on the readings as soon as I took off, but the timing map was already set for the higher temp it was reading.


I asked about their removal of the PCM pigtails on the dyno video. They said that it had nothing to do with the dyno pulls, they only pulled them to plug their computer into those PCM ports to monitor data that was logged after the pull. So, that mystery is solved.


I have the track rented out for Nov 10th, will try doing a few things differently this time. Hopefully I can figure it out.


Good discussion, so far! They asked for me to keep them updated.

[Jack B]

If I track my IAT (once normalized) versus ambient, when the car is at speed, there is usually a 30 degree diff. As the car idles it could easily be 40 or 50 degrees diff. I do not know if I totally buy the SRT explanation (although any input is good). At the zone rendezvous in August my trap speed on my first run was 120 mph, it felt like i was pulling a load of bricks. My last two runs were 127 mph and those were during higher ambient air temps and with a DA of 3500. I would still bet there is another gremlin floating around somewhere.

A lower thermostat will probably not change anything, it can be full open, however, the heat transfer via the radiator is minimal due to fact you are not moving. The car already has a 180 degree thermostat, that is where mine normalizes at in cool weather. What might help a bit is to turn on the fan earlier.

I contacted a couple SRT engineers over the weekend, and had a conference call with them today. They were concerned with what I'd reported, and want to help figure things out. They asked all sorts of technical questions about the setup of the car, weather conditions, any mods, etc.. I gave them all the input I had. We discussed the IAT (Intake Air Temp) and also engine coolant temps. I reported that my SRT Application Gauge pack showed the IAT around 111-112F while idling, and my coolant temps were 180-190F for the most part. They were leaning towards this being the most possible cause for the aggressive reduction in power. Their tune pulls out ignition timing as IAT's cross over 100F, and the coolant temps breach 190F. Neither of these would matter on a road course, as the car is moving and the radiator works more efficiently. But, when idling 10-15 ft at a time in a drag strip staging lane (think of very heavy traffic) and then idling after doing a burnout while you stage the lights - both of those temps are easily excessive to their respective sensors.


This results in the computer thinking the ambient conditions aren't good, which can pull timing and reduce power. If there was any vibrations that may have been incorrectly setting off the knock-retard sensors, then it could also result in reduced power. The problem is that once these low-timing maps are triggered, they take some engine driving cycles to fully regain the power back. That is likely why my car felt like it was back to normal, after 20 min into my drive home on the freeway. Until that drive cycle, the car might assume you have a bad tank of fuel, or it is very hot outside.


Seems like the coolant temp issue could be resolved by a simple thermostat swap.


The IAT sensor is on the intake piping, it picks up a lot of heat from the radiator when sitting still. I may try and insulate that area, so that idle/radiator temps do not skew my temp sensor. It was in the 62-65F range outside that night, which is what the IAT should have been reading. It probably did drop down on the readings as soon as I took off, but the timing map was already set for the higher temp it was reading.


I asked about their removal of the PCM pigtails on the dyno video. They said that it had nothing to do with the dyno pulls, they only pulled them to plug their computer into those PCM ports to monitor data that was logged after the pull. So, that mystery is solved.


I have the track rented out for Nov 10th, will try doing a few things differently this time. Hopefully I can figure it out.


Good discussion, so far! They asked for me to keep them updated.

[ACRucrazy]

When I would hit up the track once a month several years ago with my other cars, I had my electric fans on a switch. I would push the car in the staging lanes and keep a bag of ice on the intake manifold while the radiator fans were on. The one thing I didn't have at that time was an electric fuel pump, something I wish I did.

Not that all of that should be needed to get decent, repeatable times at the track, but tricks that can be used to get better times.

[Back In Black]

Upgrading the clutch on a GenV should be an option, not a necessity in order to track the car. WTH?

[Nine Ball]

Upgrading the clutch on a GenV should be an option, not a necessity in order to track the car. WTH?

In all fairness to the stock clutch, it works excellent on the roadcourse and on the street. I was on drag radials for this visit, and the track was well-prepped. The OEM clutch couldn't hold due to the extra grip of the tires on this track. Factory tires would have spun before the clutch would have slipped.

[FLATOUT]

I agree a factory clutch that can handle this level of power for as long as it's asked to do is a pretty tough task for any engineer to acomplish in an affordable package. As Jack mentioned maybe offer a higher end version as an option, but the stocker in my Gen 4 is still working great cosindering what I throw at it.

[Back In Black]

but the stocker in my Gen 4 is still working great cosindering what I throw at it.

As is mine which is why I made the comment. I've run the 1/4 and standing mile on drag radials without a hitch. Only time I ever had a clutch issue was on the road course when I boiled the clutch fluid. Motul 600 took care of that.

[Nine Ball]

Gen 4 and 5 use identical clutch disks and pressure plate. The only thing different is the steel vs aluminum flywheel.

[RTTTTed]

So what was the considered time for the C7? they go mid 11s with a tune on a base vette engine?

I bought a Gen4 clutch to upgrade my blown GTS stock Luk clutch. When I bought my GTS it had an aluminium flywheel and I presume a better than stock clutch. The day I flew to pick it up they installed a new clutch then night before I got there. Whatever the problem was that the car had, changing the clutch fixed it. I now have about 50,000 miles on the stock clutch and although it doesn't bark 3rd gear anymore, that might be the upgraded PS2s now. Looked under the inspection cover while rebuilding the engine and ... sh*t, the aluminium flywheel is gone too! GTS hasn't run DRs but I do win in Half and Mile competitions as well as an occaissional mini road course.

After reading this and other Gen 4/5 info I am wondering if the Gen4/5 twin disc clutches are perhaps not as good as the Gen 2/3 clutches?

[FLATOUT]

Ted what do you mean by "considered" time?

So far the A6 cars have gone as fast as 11.67@119 bone stock in about +400 DA on stock rubber cutting 1.71 60's. They leave like an auto LS1 car with a big stall in it. Most of the M6 manual cars are running low 12's at similar MPH. They trap about what a C5 Z06 does maybe a MPH faster or so.

So what was the considered time for the C7? they go mid 11s with a tune on a base vette engine?

I bought a Gen4 clutch to upgrade my blown GTS stock Luk clutch. When I bought my GTS it had an aluminium flywheel and I presume a better than stock clutch. The day I flew to pick it up they installed a new clutch then night before I got there. Whatever the problem was that the car had, changing the clutch fixed it. I now have about 50,000 miles on the stock clutch and although it doesn't bark 3rd gear anymore, that might be the upgraded PS2s now. Looked under the inspection cover while rebuilding the engine and ... sh*t, the aluminium flywheel is gone too! GTS hasn't run DRs but I do win in Half and Mile competitions as well as an occaissional mini road course.

After reading this and other Gen 4/5 info I am wondering if the Gen4/5 twin disc clutches are perhaps not as good as the Gen 2/3 clutches?

[Back In Black]

Gen 4 and 5 use identical clutch disks and pressure plate. The only thing different is the steel vs aluminum flywheel.

Then I'm not understanding what the issue is unless it has something to do with the aluminum flywheel?

[Jack B]

That could be part of it, the launch sweet spot is much smaller with the light flywheel. When you have sticky tires you have to use way too much clutch to get by the bog. A 20% higher (lower numerically) first gear doesn't help. The twin disc clutch is usually more about better shifting.

Then I'm not understanding what the issue is unless it has something to do with the aluminum flywheel?

[viperdan]

Ted what do you mean by "considered" time?

So far the A6 cars have gone as fast as 11.67@119 bone stock in about +400 DA on stock rubber cutting 1.71 60's. They leave like an auto LS1 car with a big stall in it. Most of the M6 manual cars are running low 12's at similar MPH. They trap about what a C5 Z06 does maybe a MPH faster or so.

Curiously did you read of this time or did you witness it? The reason I ask is that if it's the same thing I read I don't believe the car did not have a tune, the owner is obsessed with the C7 and has been for a year, the fact that he is the only one to run this time makes me call BS!!

[Nine Ball]

Snorman (Viper Alley member) ran the 11.6 bone stock. He was also surprised by the outcome. The same night that this 11.4 tuned C7 ran, there was another one that went 11.8s without a tune. Keep in mind, these are automatic trans cars. They launch very well, compared to manual cars. Cutting 1.7X short times on stock tires is amazing.