Anyone out there know about how much horsepower an 85-86 manual muncie four speed can handle??? Thanks...

Im not to sure.... I have herd of them being used in 3800SC swaps. From the feel of them in the 2.8 they feel blike a very strong transmission but it would not be my 1st choice to use in a swap. Getrag FTW

I have an 86 with a crate 350 - advertised at 330 crank HP bolted to the 86 Muncie. Seems to take the punishment! No issues yet but I have stock tires so they break loose fairly easy. Not sure what would happen if it hooked up hard?

I have been running a ZZ4 350 (355hp/405tq) for over 5 years now with my 1986 4-speed and a SPEC clutch without any problems at all.

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I'm running a slightly upgraded 3800SC with my 4spd manual... its been holding up just fine fingers crossed.

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Seen V 6 4 speeds take a lot more abuse then the 5 speed getrags and still hold up, used this tranny on many 3800SC swaps including my own which has a heavilly modded 3800SC and is holding so far.
Mind you I am collecting spares just incase because even the 4 speed is not rated for over 400WHP. Dan

Thanks everyone. I'm going to run the four speed with a 3800 v-6 in a long travel sandrail and would love to put a blower off of a grand national to up the HP....

Word is the Muncie transmissions are really well built. Considering that so many people have been running them behind high horsepower swaps for years without issue, I'm sure whatever you throw at it won't be too bad.

Just watch the beatings and, like all things automotive, it'll last you long enough.

Blew up 2 typical 80k mile V6-4speed transmissions (3rd gear stripped out each time). Had a 3rd trans that twisted the diff in 2nd gear.

3800sc, roughly 320hp.. Fairly hard driving.

I would say given the 4speed again, you COULD get by with one.. It never consistently failed under launching, it was just more so total torque that hurt it (3rd gear failures).

Later switched to a 5speed, with only 1 diff failure, but more mindful driving practices. The latest getrag is currently holding back a bit over 500HP, without any major issues. (yes, that is 4 blown transmissions in 2 years) I did really like the 4speed ratios, and was quite easily a "faster" transmission.