Looking for answers

[End3r]

We've got a 2015 Viper GT with the following mods:

1-piece ARH long-tube race headers
Underdrive pulley
Race cats
Nitrous Outlet plate kit with standalone fuel
Mantic triple disk
S1 sequential shifter
Hurst line-lock
M/T 345/35R18 drag radials
OEM PCM with HPTuners and an Arrow/Mopar PCM

Only running NA for now. The car is falling on its face on the launch. Best 60' stock was 1.79", and best 60' after mods is 2.06". Been difficult to find a very experienced tuner for the HPT in Houston area, for a Gen 5. Been to two higher end shops, but the problem persists. Quickest pass stock was 11.46 @ 126mph with the 1.79" 60'. Modded it went the same ET on a 2.06" 60' at almost 130mph.

Thought it might be the torque management tables in the HPT, but the shops have no idea how to correct it. So went to Viper Exchange to try the Mopar PCM in the meantime before we go ahead and put in the Motec. Car still bogs on the line with the Arrow/Mopar and Morgan at Viper Exchange said it was odd he could barely get the tires to turn over, even cold, in 1st gear. And yes, we've been sure that TC was completely disabled. Also noticed with the HPT that one throttle body is 13% less than the other when going WOT. It finally catches up, but it lags.

No check engine codes, compression is good, car only has 2k miles on it. Any ideas, guys? Any shops recommended that REALLY know the Gen 5 Viper?

[Steve M]

Mantic triple disk is pretty light I'm assuming? I've been having a hell of a time getting a decent 60' with a lightweight clutch assembly - enough so that I've been seriously contemplating trying a heavier setup to see if I can get this thing off the line better.

For the mods, you should be running a little quicker and faster for sure. What track, and what are the typical DAs when you run?

I can probably help you get around the torque management issues, but you need to be sure that's what is causing it. I can help there too, but it will require some legwork on someone's part. I should be able to walk someone through it if they are willing to listen. Most aren't.

[End3r]

It is lighter, true. The DA was in the 1000-1200ft range in Baytown, TX and Memphis TN. Appreciate the offer.

[Grcforce327]

Just glad you didn't fall asleep and wreck during the 11.46 run.

[Steve M]

What are the details on the sequential shifter setup?

What gear ratios? Stock with the super long 1st gear?

[End3r]

What are the details on the sequential shifter setup?

What gear ratios? Stock with the super long 1st gear?

Stock trans/ratios/ring gear. It's just the Mantic triple disk and the S1 sequential shifter.

[Jack B]

Log pedal position versus throttle position along with rpm, that may show your culprit. I have the opposite issue, I cannot buy traction.

Those mods alone will not give you that much more hp without the correct a/f ratio and added timing. The a/f and advance right after launch might also give you some answers.

[Nth Moto]

We've got a 2015 Viper GT with the following mods:

1-piece ARH long-tube race headers
Underdrive pulley
Race cats
Nitrous Outlet plate kit with standalone fuel
Mantic triple disk
S1 sequential shifter
Hurst line-lock
M/T 345/35R18 drag radials
OEM PCM with HPTuners and an Arrow/Mopar PCM

Only running NA for now. The car is falling on its face on the launch. Best 60' stock was 1.79", and best 60' after mods is 2.06". Been difficult to find a very experienced tuner for the HPT in Houston area, for a Gen 5. Been to two higher end shops, but the problem persists. Quickest pass stock was 11.46 @ 126mph with the 1.79" 60'. Modded it went the same ET on a 2.06" 60' at almost 130mph.

Thought it might be the torque management tables in the HPT, but the shops have no idea how to correct it. So went to Viper Exchange to try the Mopar PCM in the meantime before we go ahead and put in the Motec. Car still bogs on the line with the Arrow/Mopar and Morgan at Viper Exchange said it was odd he could barely get the tires to turn over, even cold, in 1st gear. And yes, we've been sure that TC was completely disabled. Also noticed with the HPT that one throttle body is 13% less than the other when going WOT. It finally catches up, but it lags.

No check engine codes, compression is good, car only has 2k miles on it. Any ideas, guys? Any shops recommended that REALLY know the Gen 5 Viper?

The 2.26 first gear is terrible to try to go drag racing with, especially with a lighter clutch in the car. That even goes for our clutch, which has really good slip-ability at first if the carbon is cool enough but the length of that ratio makes it pretty challenging to get a good leave unless you have really delicate pedal control.

The last part of my sentence there is most important and one that you don't have control of as well as you need/want on the OEM ECU. The factory based programming on the drive by wire system is just this side of awful, unless all you like to do is park at car shows. I think I understand why FCA did this, but it doesn't change the fact that when you convert the car over to something like our MoTeC M1 system you have incredibly increased capability of throttle control which helps tremendously on manipulation of clutch action.

There are some calibrations out there that astonish me how touchy they are when releasing the clutch. It will likely go as an unfavored opinion around here, but that includes the Arrow/Mopar stuff. Our programming allows a person to literally drive the car into a trailer without using the throttle, whereas much of the OEM based stuff will stall itself out if you so much as dip below target idle speed by 100-200 RPM it seems.

Did you work with the team at Pro Speed in Houston yet? Chris does a lot of OEM ECU calibration work and I'd feel as though if they haven't been able to resolve it via tune then there's a good chance nobody will on the OEM ECU.