What rear gear for 650whp front fed whipple??

[liter of cola]

So my friend just ordered the new whipple front fed kit for his 2015 gt. He already has 3.73's in the car from the factory since it has the performance package. I mentioned that he should go down to 3.31's at that power level but then i started to think maybe that can be too rough on his stock mt-82. What do you guys think? What rear gear would be best for stock tranny and 650whp. Should he just keep the 3.73's so the tranny doesnt explode? Or is 3.55's maybe a safe middle ground?

 

[2010 Red&white]

depends on how he will use the car . ..street.? drag strip ? 1/2 mile ? track ?

 

[liter of cola]

Weekend street car, few 1/4 drag days.

 

[cmsnake]

3.31, if not the first 3 gears are useless on street tires. I ran this gear in my 14 Gt with TVS and loved it, nice and long on highway pulls without shifting all the time.

Gear shouldnt have any effect on trans.

I just had a VMP installed on my 16 A6 with 20s and a 3.15 gear, I love a tall gear with boost.

 

[PIKE5.0]

Gear will effect the load on the engine in higher gears (5th particularly), not really a trans issue. If you run like we do here, you have to be selective about the cars you throw 5th on.... bc we throw 5th too often haha

 

[liter of cola]

Gear will effect the load on the engine in higher gears (5th particularly), not really a trans issue. If you run like we do here, you have to be selective about the cars you throw 5th on.... bc we throw 5th too often haha

When you say throw 5th on, you mean like quick shifting into 5th from the top of 4th??

 

[liter of cola]

3.31, if not the first 3 gears are useless on street tires. I ran this gear in my 14 Gt with TVS and loved it, nice and long on highway pulls without shifting all the time.

Gear shouldnt have any effect on trans.

I just had a VMP installed on my 16 A6 with 20s and a 3.15 gear, I love a tall gear with boost.

Ok, so its actually harder on the motor not the tranny when using lower gearing. Thats something i'll have to mention to him as well.

 

[liter of cola]

Couple other things i should mention im concerned about is, what kind of reliability can he expect from running at this power level on a stock motor (650whp). I recomended he stay under 650whp to be safe as thats a number i hear thrown around a lot for whats "safe" on a stock yote (not sure if 15's can handle more i have a 14' and am on that side of svt most of the time) I recomended 625whp to be safe. Are oil pump gears an issue at this power level? Should he go for a lower number. I want him to get at least 5 years out of the setup taking into consideration he wont be putting that many miles on it and he's not the type to beat on his car.

Is this a realistic expectation at that power level running a root supercharger?

Also what weight oil should he bump up to?
Yes i know, i have a lot of questions, lol.
I appreciate any help.

That could be a whole new thread but just thought i'd put it on here for now.

 

[kcobra]

15's can handle more boost. Better bottom end.

 

[908ssp]

I have 550rwhp and really don't like the 3.73 rear gear way too short. But I do like the Torsen that comes in the PP cars. I have to change the clutch as it slips so I will change the transmission as well. Going with the T56 magnum and the road course gearing for street driving.

 

[PIKE5.0]

When you say throw 5th on, you mean like quick shifting into 5th from the top of 4th??

No just WOT in 5th. Its load. Its much harder on the motor at high speed/high gear under power, than it is from a stop in a simple term. But, its all dependent on the factors. Making anything last 5 years is a stretch, mileage, maintenance, tuning/fuel, etc.. Anything can last 5 years, all depends on the owners decisions/habits.

If all things installed/tuned well. I recommend the minor mods I've done, in my sig. 650rwhp on the '15 is completely realistic to live at for a while. But AGAIN that is assuming all things done right, and driven responsibly given the goal.

 

[dev1360]

No just WOT in 5th. Its load. Its much harder on the motor at high speed/high gear under power, than it is from a stop in a simple term. But, its all dependent on the factors.

5th is 1:1 in these cars. It's no different than shifting to 4th in many other cars.

 

[PIKE5.0]

5th is 1:1 in these cars. It's no different than shifting to 4th in many other cars.

I'm aware 5th is 1:1 but that doesn't account for the longer time in gear, at high RPM. I didn't get into micro specifics. But, go run your car out in 4th.. then do the same in 5th. See how long it last under boosted 5th gear pulls.

 

[dev1360]

It's no different than the thousands of other cars that are ran in their 1:1 gear.

 

[ViperRed91GT]

It's no different than the thousands of other cars that are ran in their 1:1 gear.

Exactly. The motor has no clue and doesn't care which gear you're in, the ratio is what matters.

 

[dev1360]

There is more load in a numerically lower gear. But it's not going to magically blow up because it's 5th. Its still just 1:1. According to his logic, my vette exploded every time I ran it out in 4th.

 

[gsxr1300]

I have 3.73's with 28.7 rear tires ( 1 inch taller than stock) so that brings my gearing to about 3.59.

 

[liter of cola]

View attachment 57415

I have 3.73's with 28.7 rear tires ( 1 inch taller than stock) so that brings my gearing to about 3.59.

whats your power level at? how do you like this ratio for street driving?

 

[gsxr1300]

This was from last Thursday. I have Kooks headers with green cats and 3.625 pulley (1 size smaller than stock)
I have no plans on changing gears at the moment, maybe when complete pumpkins are available ill give it a try.

 

[liter of cola]

View attachment 57438
This was from last Thursday. I have Kooks headers with green cats and 3.625 pulley (1 size smaller than stock)
I have no plans on changing gears at the moment, maybe when complete pumpkins are available ill give it a try.

damn 746!!! awesome!!!

are you guys running the stock clutch as well?? I was wondering if he needs to upgrade the clutch right away.