So it looks like I'm buying a 6.0 today. My question is will a stock 4l80e handle between 4-500hp? It's going to be a cruiser, not a track car.

 

Any 4L80 in good condition will handle 400hp with ease. A good valve body kit will help durability while improving shift quality. Keep in mind, just because a shift kit is installed doesn’t mean it HAS to shift hard enough to knock the dash out! You can have durability without the bang/screech from the tires on gear changes.

At the minimum, put a valve body kit in it. If you have no desire to pull the transmission apart for inspection, use the TransGo 4L80HD kit. Do not bother with the pressure release modifications. Follow the rest of the instructions, drill the plate for shift quality you want. Put a Sonnax reverse boost valve in the pump and enjoy.

if you are opening the trans up for inspection, use the calibration kit from Jakes Performance out of Texas. It’s a much better kit than the TransGo in my opinion, but requires transmission disassembly to install.

A 4L80 with the right valve body will easily handle 800-900hp

 

ok thanks. I found a 4l80e fresh rebuild with only 3k miles on it. Guy switched to manual. Ill probably do the transgo since im not that knowledgeable with tranys.

 

Since the trans isn’t installed, you don’t have to fight gravity.

There are lots of YouTube videos on valve body removal. Work slowly, don’t force anything. Use Vasoline to hold the boost valve together, and to keep the check ***** where you want them. Don’t use wheel bearing grease, it won’t dissolve in trans fluid.

 

Saved a screenshot from a couple years ago.

"For a cheap thrill, just plug the accumulators, drill the feeds in the plate, and throw a new boost valve in it. Also, turning the torx screw on the EPC 1/8th turn makes any 80e shift really nice. No reason to spend a ton of money on a boxed shift kit for an 80e"

 

I wouldn’t mess with the EPC solenoid. It’s hard to predict exactly what messing with that screw will do.

Pressure regulator springs are cheap in the aftermarket. And while deleting the accumulators is a well known modification, there are also a couple check ***** involved in the accumulator hydraulics that need to be left out to complete the modifications. Lastly, while drilling holes will firm up the shifts, the biggest weakness is the small apply area of the direct clutch. The dual feed modification is a huge improvement.

I have asked some very knowledgeable people why HydraMatic used the seperate chambers for 3rd and reverse, no one has a good explanation. It seems to me that it’s an overly complex system. It’s not just the 4l80 that uses it, the TH350, 400, and 2004r and the 4L80 all have they setup. The fact that it’s so easily defeated kinda makes me think the HydraMatic engineers either expected to fix it later in an update redesign, or knew it would be corrected in the aftermarket.