Max HP a stock LSS 4EAT can deal with?

[BXSS]

About how much HP can a LSS 4EAT take in & put down to the ground reliably assuming fluid is fresh & a tranny cooler (air-air) is installed?

[skid542]

I too am curious about this. I have searched a bit and most of what I find is about built 4EAT's. There isn't a whole lot about actual power killing a 4EAT as it mainly seems to be solenoids and bands. Is this way high power kills the tranny? Does it just cook the TC? Any experiences with broken gears?

Does anybody have any stories of running ~200chp for extended periods of time?

[Subtle]

My stock 4eat took quite a lot of upgade on the engine, which included on the original turbo--fmic, SDS computer, and 12 # boost.

At some 150k miles the tranny, but only 2 years on the mod, was still strong, but dull on the acceleration.

Then did the "build" and the high- stall torque converter really does the launch. Then put on the vf 34 turbo, and 14 # boost.

[93forestpearl]

They are pretty stout. With some work to the valve body they can hold for a while. A buddy of mine in running a 3076R with 2.5 DOHC heads and his is holding OK. Its slowly burning up the clutches, but he rebuilds trannys for a living so he can deal with it.


If you're not trying to put down 300-400whp with it, it should be fine. I'd really suggest the converter and valve body, and the tighter shifts will help in it longevity.

[Subtle]

And good cooling for the tranny +++

[skid542]

Thank you Subtle and Dan. It's good to know that we can do the 'easy/prelim' mods and not have to worry.

Can you explain the valve body work and converter? I pressume this is something that should only be done by someone who knows what they are doing?

[Subtle]

On the valve body--yes--if you want higher flows.

On the high-stall converter--I think you can buy one directly.

[93forestpearl]

I'm not too familiar with what actually get modified on the valve body, but I know it flows more fluid so the shifts are harder/firmer, meaning less slippage of the clutches. I think some holes get drilled out a bit or something.

[dropdfocus]

Yes, a high stall torque convertor is something you would purchase not have made by someone.

Valve bodies get modified with larger internal ports for the fluid to move through. Less restriction means more flow & stronger shifts. The same thing is accomplished on V8 trannies by changing out the plate above the tranny filter. It has larger port opennings and allows for more fluid to flow.

I did this on my '80 Chevy C-10 and it was an immediate difference. OEM stuff is restrictive for smoother shifts that don't jolt you everytime the transmission goes into the next gear.