TT car transmission & rear gears - advise

[GTSjbud]

I am considering installing a twin turbo in my '96 GTS Venom 550 Hennessey. The twin turbo will put out anywhere from 900 - 1200 rwhp.

I want the option to drive my GTS in excess of 200mph. I would like to get close to 250mph...on the occassion.

Transmission

Should I upgrade the OEM transmission? I have heard from a couple of different sources that 5th and 6th gears **** for achieving max speed!

Are there any high performance T56 transmissions available for the Viper? If so who sells them?

Rear Gear Ration

What is recommended for a rear gear ratio to achieve 250mph with a twin turbo car running 355 25 19? What manufacturer is recommend for the rear gears?

**what should I target for a max engine rpm at 250mph? I understand that the Gen. II redline rpm is 6000.


I look forward to any input!
Cheers
Jason

 

[dave6666]

Transmission...

eBay Motors: 1400 HP capable 6 speed transmission Mustang Viper (item 180172945977 end time Oct-31-07 06:18:35 PDT)

 

[Simms]

RPM Transmissions T56 T-56 4L60E 4L65E

Ask for Rodney. They can build you whatever you want. They are also a G-force rep as well.

 

[jpa99acr]

3:55 gears would be too much IMO with that much HP... others will weigh in

 

[Disturbed]

Trans go with G-force or RPM both are great. Also get the 5th and 6th gears changed out for shorter ratios.


Gears keep the stock ones, or get 3.33 Too short of a gear and you'll burn through them faster than you can shift.

 

[Disturbed]

**what should I target for a max engine rpm at 250mph? I understand that the Gen. II redline rpm is 6000.


I look forward to any input!
Cheers
Jason

You'll have to check your dyno sheet for that. You'll want match the mph with the rpm @ max hp. You could make max power at 5700rpm or 6200rpm. Depends on the tune and mods.

 

[GTSjbud]

Would 3.07 rear gears be suitable with a TT car that is putting out mega power in the low rpm range?

 

[viperdude118]

3:55 gears would be too much IMO with that much HP... others will weigh in

If he goes with a gear any shorter than stock, he'll lose top end speed. He said he wanted to go 250 mph. With the kind of power that a TT puts out you could maybe get there with the stock 3:07, but might even need something longer, though I've never heard of a longer gear for the viper since most want something shorter for 1/4 mile runs.

If he is serious about going those speeds he'll also need some better aerodynamic engineering, especially down force.

 

[Joseph Dell]

All of the cars out there making the big power running the mile (and even the 1/4 mile) use a 3.07 w/ a 28" rear tire (or bigger if they can!). for 5th gear, those who get transmissions w/ stronger 5th and 6th gears go with the .8 and the .63 for 5th and 6th. that also changes the top end top speed. but usually for the better.

I had a 3.55 and then added a SC... then i immediately went back to 3.07's.

the viper has enough low-end tq to get you going w/o changing the rear gears from stock. although if you want to make it bullet-proof, get a quaife diff. that'll help too!

JD

 

[KepRght]

If I were setting up my car up for top speed runs to 250mph I would consider a taller gear then 3.07, 2.80 or 2.70. (if you can get it made, or find it)

with this gear you will be at (about) 250mph in 5th gear at 6000rpm - which is in line with the goal you stated

with 1200 hp on tap seat of the pants acceleration feel with a taller gear will be low on the list of concerns

there are some calculators online for tire/rear gear/trans/final speed

 

[GTSjbud]

All of the cars out there making the big power running the mile (and even the 1/4 mile) use a 3.07 w/ a 28" rear tire (or bigger if they can!). for 5th gear, those who get transmissions w/ stronger 5th and 6th gears go with the .8 and the .63 for 5th and 6th. that also changes the top end top speed. but usually for the better.

I had a 3.55 and then added a SC... then i immediately went back to 3.07's.

the viper has enough low-end tq to get you going w/o changing the rear gears from stock. although if you want to make it bullet-proof, get a quaife diff. that'll help too!

JD

Sounds like a Quaife 3.07 would do the trick. It sounds like the Quaife is designed to get the power to the ground and essentially make the car faster.

Who sells a Quaife diff? The Quaife website lists Taylor Racing Engineering in Texas as a supplier.

 

[GTSjbud]

If he goes with a gear any shorter than stock, he'll lose top end speed. He said he wanted to go 250 mph. With the kind of power that a TT puts out you could maybe get there with the stock 3:07, but might even need something longer, though I've never heard of a longer gear for the viper since most want something shorter for 1/4 mile runs.

If he is serious about going those speeds he'll also need some better aerodynamic engineering, especially down force.

Better aerodynamics...such as a rear wing? My Viper has been lowered 2", does this help aerodynamics?

Cheers

 

[LS6 Molester]

Better aerodynamics...such as a rear wing? My Viper has been lowered 2", does this help aerodynamics?

Cheers

check out svs's car and other vipers that do standing mile events. they go over 220mph in them. the svs went 250 or 260 at the salt flats so their car would help get your mind going. i would say splitters or getting an aero kit designed for you car would help it. you dont want to lift off and come crashing down and tumble at 250mph

 

[Joseph Dell]

SVS's car uses a special tranny. like no other.

As for a quaife, Taylor Racing is the primary reseller of quaife for gen2's in the US. Anyone else who sells quaife in the US is usually reselling Taylor's stuff. Ask for Craig (owner) and he'll take care of you.

JD

 

[GTSjbud]

check out svs's car and other vipers that do standing mile events. they go over 220mph in them. the svs went 250 or 260 at the salt flats so their car would help get your mind going. i would say splitters or getting an aero kit designed for you car would help it. you dont want to lift off and come crashing down and tumble at 250mph

You got that right, I definitely would not want to become airborn at any of those speeds. I will definitely have to do some more investigation with regards to stability at those speeds.

Cheers
Jason

 

[GTSjbud]

SVS's car uses a special tranny. like no other.

As for a quaife, Taylor Racing is the primary reseller of quaife for gen2's in the US. Anyone else who sells quaife in the US is usually reselling Taylor's stuff. Ask for Craig (owner) and he'll take care of you.

JD

I will give Craig a call to discuss the Quaife! Thanks for the info.

Jason

 

[DrDJ]

Are you going to upgrade your life insurance policy as well?

DrDJ

 

[HI-NOS-Viper]

Are you going to upgrade your life insurance policy as well?

DrDJ

I can see it now, "Car lifts off without the need of any wings". Actually I have seen a video of a Formula car going airborne with no help but the extreme speed and lift, does a flip in the air, and crashed into a wall. Was not pretty..... I'm sure someone here has seen that video.

 

[GTSjbud]

Are you going to upgrade your life insurance policy as well?

DrDJ

Hmmmmm....I honestly never thought of that. I suspect that you think I'm a little crazy to try and attain 250mph in a Viper?

 

[GTSjbud]

I can see it now, "Car lifts off without the need of any wings". Actually I have seen a video of a Formula car going airborne with no help but the extreme speed and lift, does a flip in the air, and crashed into a wall. Was not pretty..... I'm sure someone here has seen that video.

I have seen videos of cars just doing that...lifting off the ground like an airplane. Yikes!!

 

[HI-NOS-Viper]

Let me just put it to you like this. You have guys like Hennessey and SVS, along with others I'm sure in the Viper community, experienced for YEARS in high speed Vipers, that have been going for top speed in the mile and have just hit 231(SVS hit 231)(Hennessey beat the Bugatti Veyron that claims to have a 253 top speed). I'm sure that they can tell you that it takes more than just power to get that level and above, let alone 250. Not saying you cant do it, thats for sure, but there is ALOT you have to look at going that fast to stay safe. I would honestly give one or both of those shops a call and I'm sure they will tell you what it really takes. Again I am not knocking you at all, that would be awesome to hit that mark, but at that level like others have stated, it has alot to do with Aerodynamics.

Hmmmmm....I honestly never thought of that. I suspect that you think I'm a little crazy to try and attain 250mph in a Viper?

 

[GTSjbud]

Let me just put it to you like this. You have guys like Hennessey and SVS, along with others I'm sure in the Viper community, experienced for YEARS in high speed Vipers, that have been going for top speed in the mile and have just hit 231(SVS hit 231)(Hennessey beat the Bugatti Veyron that claims to have a 253 top speed). I'm sure that they can tell you that it takes more than just power to get that level and above, let alone 250. Not saying you cant do it, thats for sure, but there is ALOT you have to look at going that fast to stay safe. I would honestly give one or both of those shops a call and I'm sure they will tell you what it really takes. Again I am not knocking you at all, that would be awesome to hit that mark, but at that level like others have stated, it has alot to do with Aerodynamics.

Those are some very valid points. I guess the other things is how much $$$$ will it cost to get to those speeds. And I suspect it is a lot of $$$$$. We'll see what happens.

 

[HI-NOS-Viper]

Unless of course you drive a Top Fuel Drag Car that hits 300+mph in the 1/4 in a mere 5.something seconds. That rush must be insane.

 

[Disturbed]

Good Luck jBud. Maybe the boost be with you!

 

[RTTTTed]

Start with the Roe front end air inlet kit. It's an opening under the nose that lets the undernose air into the engine compartment through the rad instead of it being forced under the chin spoiler. It also helps greatly in cooling the car.

Roe sells them for about $200. I'm planning to put one on my GTS.

Ted

 

[GTSjbud]

Good Luck jBud. Maybe the boost be with you!

And also with you!!

**said with a deeep Dark Vader voice