Engine rebuild or swap?

[ShaneM]

1999 two-door Z-71 sport LT has 186K on it and lots of oil leaks including the oil pan gasket, so at that point I might as well rebuild at least.

However I'm considering a swap instead.

The 4L60E trans was just rebuilt including heavy duty converters. My Google-fu suggests that a 427 would be too much for a stock 4L60E, but curious if anyone has experience with a beefed up 4L60E paired with an upgraded crate engine.

 

[Dantheman1540]

4l60s typically can't handle much more than a stock 5.3/5.7 even when built to the max they are iffy at best.

 

[ShaneM]

Dan, that was my concern also. If the trans hadn't been rebuilt I would consider an upgrade but it is too much of a money waste to swap the trans now, IMO. The 4L60s go out on these trucks reliably around 150K for a reason, to your point. This is obviously a bit of a collector truck and will continue to be, so any suggestions on what to do would be appreciated. Rebuild is certainly an option, or rebuild w/ upgrades or a swap to a newer crate 327?

 

[willxfs]

I'm running a "built" 4L60e in my 1998 2 door tahoe with a rebuilt 383 stroker. The 383 is supposed to be similar to the HT383 from GM. So far the transmission is holding up fine but it only has 15k miles behind the 383 and is not my daily driver anymore. Original tranny was rebuild at 220k miles due to the dreaded 1-2 super harsh shift when hot. I had the 350 rebuilt into the 383 at 260k miles.

 

[ShaneM]

Isn't that a engine that won't pass emissions? I'm in CA.

 

[latvius]

4l60s typically can't handle much more than a stock 5.3/5.7 even when built to the max they are iffy at best.

My transmission builder has a different opinion than you.

"CPT specializes on racing and performance 4L60Es. We currently have our Ultra Pro Race builds eclipsing 1200 horsepower in C5 Corvettes."

 

[Dantheman1540]

in C5 Corvettes."

The key is the weight difference which is close to double in the SUVs. A c5 weighs around 3k curb weight where a GMT800 SUV depending on trim levels hovers close to or just over 6k and is more likely to tow even more. Another thing that hurts them is rotating mass, a C5 is likely to run a lightweight wheel and tire combo for performance where most trucks and SUVs are running either big rubber or big wheels that weigh significantly more. Not saying a 4l60 can't be built to withstand serious power but it is well known or documented that they fail more often in heavier vehicles.

 

[PatDTN]

Two of the professional transmission builders I know swear the 4l60 is a very strong transmission. One of the builders does all the transmission work for car dealers and many other shops in the Charleston, WV area so he gets everything that runs a transmission. The other is a neighbor who builds race transmissions. He'll upgrade some parts when horsepower and driving conditions get extreme. He runs a 4l60 in his Impala SS and runs even 24 hour races in it.

You know you want more power, feel free to go for it. That trans will hold up for years to come.

 

[Squirrelsmith]

If your gonna swap it ls swap it. Your 4l60 will be fine