If you have broken your 4t65e-HD (that was in good sound condition) Please let us know what part broke and under what condition it broke. I am trying to validate what HP levels this tranny will really take with what mods.

I have around 380 crank HP and have launched my 3800 a few hundred times over the past 6 years or so to 11.8 second 1/4 mile times. I started with a tired tranny and had it rebuilt with just normal updates carry in for about $1100. Still works good to today. I can fully say a stock tranny with just normal updates will hold 380 HP VERY WELL.

Your turn.

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84/87 NB, 3800SC, E-85, VS Cam, 2.8 Pulley, 4T65E-HD, HP Tuners, AEM Wideband, Regal GS Gauges, S-10 Brake Booster. 1/4 mile -11.85 at 114mph

quote Originally posted by DimeMachine: If you have broken your 4t65e-HD (that was in good sound condition) Please let us know what part broke and under what condition it broke. I am trying to validate what HP levels this tranny will really take with what mods. I have around 380 crank HP and have launched my 3800 a few hundred times over the past 6 years or so to 11.8 second 1/4 mile times. I started with a tired tranny and had it rebuilt with just normal updates carry in for about $1100. Still works good to today. I can fully say a stock tranny with just normal updates will hold 380 HP VERY WELL. Your turn.

I have a completely stock 4T65E HD on my LS4 and have no issues with it after countless "launches". I say countless because I abuse the drive train with hard tackeoffs every single time I drive the car.
I have been driving the swap for several years.

[This message has been edited by Rickady88GT (edited 07-15-2020).]

quote Originally posted by DimeMachine: ... a stock tranny with just normal updates will hold 380 HP VERY WELL.

What upgrades did you do?

My 4T65eHD has held up for the past 7 years with numerous full throttle runs. Those transmission with a bit of modification work have been built to handle 900HP. That might be on the top edge, but forum member Darkhorizon ran a 9.87 @142 mph 1/4 mile time with his 3800/4T65eHD combo. Ash Scott how he likes his transmission. You won't go anywhere near that with any of the sticks that have been used or swapped in the Fiero

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

Dennis, he did upgrades to his transmission. It wasn't a stock unit.

quote Originally posted by sourmash: Dennis, he did upgrades to his transmission. It wasn't a stock unit.

LOTS of upgrades as I recall. I am trying to get a handle on what a basically stock with normal upgrades (4th gear known issue - weak part that broke for even grocery getter grandma cars) just trying to get some first hand info on who broke (not wore out) what level of 4t65e hd with what power combo doing what to it...lol...

Thanks guys!

[This message has been edited by DimeMachine (edited 07-15-2020).]

You cant go by the failures in the w body cars, with the weight difference in the Fieros, the 4t65s hold up way better than in the heavier cars