T/A KID

iTrader: (12)

I hope this is the right forum, thought about the advanced section, but I figure this will work.

Im doing a project where my vehicle (Kit car mid-engine) will weigh in at 2500lbs roughly with driver and I am using a transaxle normally used in 3,600-4,000 pound vehicles wich has a Tq rating of 300ft lbs. I know a lighter vehicle will be much easier on the transaxle, but I thought there was a formula out there to predict a new Tq limit?

I believe RPM plays a role too, but I plan to keep the engine (LS engine) around 6500, and this transaxle normally seen 7,000, so everything should be fine there.

The units Tq converter is a big weak point and I plan to beef it up before installing, so that there should raise the Tq limit correct?

I should mention, I do plan to put a soft street tire on it, nothing like a MT though, this setup will mostly be a street driver.

T/A KID

iTrader: (12)

Anyone?

To simplify what I am trying to ask, lets take the 4L60E for example.
4L60E Engine Tq rating is 360 ft-lbs/ Max gearbox Tq rating is 610 ft-lbs

Lets say in our Stock F-body's 3750 with driver can take 450RWHP

So at 2750lbs how much power could it take? What about 1750lbs? Would it be substantial gains or nominal?

Is there a percent change or equation out there?

BTW I was looking at GM's 4L80E Tq rating
Engine Tq rating 440 ft-lbs/ Max gearbox Tq rating is 885 ft-lbs.

To be honest I believe the rating at the engines flywheel be judged by the transmissions Gearbox rating??

01ssreda4

iTrader: (96)

I dont know the formula but by reducing the vehicle weight you absolutely increase input power handling ability.

T/A KID

iTrader: (12)

Thanks, maybe someone has some hard data or a percent increase?
Doing some thinking about unsprung weight on a vehicle, usually ever 100lb loss feels like a 10hp gain because the reduction of weight.

Probably highly inaccurate, but a 1500lb weight reduction may possibly add another 150lbs of Tq the the trans rating?

performabuilt

iTrader: (25)

I would think you could figure the torque capability increase would be equal to the weight reduction percentage x the original torque capability

T/A KID

iTrader: (12)

Performabuilt, I tried that and this is what I got.
Weight reduction=1,500lbs
Weight reduction percentage from 4,000lbs to 2,500lbs= 37.5% decrease

37.5 X 300ft-lbs= 11250.00

To make that remotely accuracte I suppose the decimal place needs to move making it 112.50ft-lbs Tq increase?

performabuilt

iTrader: (25)

I would say thats reasonable tough I not a math major or physist or great at spelling either but makes sense to me.

Grr

iTrader: (2)

300*0.375=112.5ft-lb increase. =412lb-ft