[Bfrancom2]

Hi all!

I am looking for input about the reliability of the 8AT (ZF8HP50) found in B58 equipped cars.

I'm currently making about 550ftlbs at the crank. I'm not really worried about that. While it's over the 369 rating, I have faith as they're wildly underrated from the factory.

My question is, I am looking to upgrade my HPFP and in turn, I'd be doing about 650 ftlbs at the crank. Is this feasible on the 8AT?

**BEFORE ANYBODY COMMENTS** I don't want to hear "It's rated at 369....you're exceeding the specifications." No shit. I am looking for B58 owners on AUTO transmissions that have been making over 500wtq (600+ at the crank) and their experiences, mileages, etc.

Thank you!

[AleksanderSuave]

the 3 series b58 forums will likely be of more use for you.

I notice the engine tuning posts in this forum are primarily a small handful of us, and its been dead for a little while.

[Bfrancom2]

Originally Posted by AleksanderSuave

the 3 series b58 forums will likely be of more use for you.

I notice the engine tuning posts in this forum are primarily a small handful of us, and its been dead for a little while.

Yep posted there as well, as the 2 series definitely isn't as popular.

[JD11937]

There are plenty of people running a lot of power on these transmissions. I have heard some complaining about slip, specifically in 6th but have only heard of one catastrophic failure. I have an upgraded turbo and daily drive my car but I don't abuse it and have had zero problems. You will definitely want to do trans fluid service, I'm doing mine at 45,000 miles. Some will suggest sooner, some later.

[hardparker]

The 8HP50 is hella stout and has the same sized clutches, though fewer, as the larger 8HP70 and 8HP90. There's enough interchange between them that an 8HP50 can be built to handle more torque than the 8HP90 itself in stock guise with equal or greater clutch count and upgraded friction material.

Look at what the big power 8HP90 cars, like heavily modded Hellcats and the like are doing for transmission upgrades. You could basically have an 8HP50 rebuilt and upgraded to something like Southern Hotrod's 8HP90 War Viking. Then you'd have a hard time putting a motor in front of it that could break it.