Trans builders typically advertise a HP rating of a given build such as good to 1200HP, or "have been used in 1600 or 1800" cars. Is a 1200 hp trans in a 3500lb car going to stand up to the same power levels in a 6000lb truck?

Also, what about torque ramp in...Is this not a factor? Is a 1200HP trans the same behind a turbo/centrifugal vs a roots style blower where most of the torque kicks in almost immediately?

 

Weight plays a huge part. Heavier vehicles mean more resistance to acceleration, so theres more stress on the hard parts. Hence why lots of truck guys who have 500+ swap to the 80e where cars can stick with the 60e.

 

That's a great question! It's nice to see guys thinking in those terms around here...

In a nutshell... no a transmission rated for a given h/p level in a 3,500# vehicle wil not withstand the weight of a 6,000# vehicle.

Let me give you an example in terms of a powerglide... When I build a racing Powerglide for a given combination I will give much thought to the power vs. weight. And then even more consideration to the power adder. The reason is, like you say a blower and a nitrous car both make torque at the hit whereas a turbo car will ramp in the power over a given time frame. That's why turbo cars have much faster back half numbers on a race track.

I will spec out a different pump and shaft combination for a turbo car than I will say a nitrous car.

Now, in your case if we're talking in terms of a trucks weight vs. a nice stroker motor with a centrifugal blower at say 20#'s of boost, then I would recommend a 4L80E with a transbrake and heavy duty custom billet shafts, a custom center support and other significant upgrades that will withstand the hit they'll be seeing.

A 4L60E would die a horrible death in a short period of time. And even if it were build with the best of the best parts from one end to the other and you didn't break any internal components... it would walk through soft parts fairly often. At least often enough that you'd get tired of pulling it in and out to have it repaired.

Hope that helps to answer your question.

g

 

Would gearing change the amount of load being put on the trans?

 

Yup. Better gearing won't load the trans as hard off the hit

 

Transmissions are rated by input torque capacity.Hp ratings are at best laymans terms for the benchracers to juggle around in conversation.

 

Input torque capacity is the amount of force required to overcome the mechanical ability of a giv3n transmission when the output is 0.<----I totally jus made that up but,it sounds convincing huh?

 

Or any time you are on the throttle. This is why guys who run stock 60e's with 3.08 gears and 35" tires and do a lot of WOT runs wonder why they keep taking out 60e's.


peace
Hog

 

Exactly my thoughts. Just saying a trans is good for XXX or XXXX horsepower really doesn't apply unless every trans is rated based on installation in exactly the same vehicle. It's convenient for marketing, but every application is different. So if I thought my combination was putting out XXXX HP, I'm not just going to do a web search for "XXXX HP transmission" and click on "Buy Now."

And when someone tells me that their transmissions have performed well behind 1200 HP turbo cars, it doesn't fully assure me that they would last in my heavy truck behind a roots blown 20 psi.

I have 3:73's now and had no traction with street tires - see my sig vid where the tires break loose every time I try to get into the throttle going down the track. Might not be an issue with the slicks though.

 

EXACTLY !!!!! That is the very reason I do not build transmissions for inventory and I never will. Every unit is custom built for the application. That's why I invite folks to call me and discuss options they may not be aware of.

I do advertise "Staged" units on my website because that's what potential clients can identify with once they have an idea of what their needs are. But, it's mainly because that's what the market bears so to speak.

g