The Stupid Engine Questions Thread

[SUBURBAN5]

Hi guys, first post I think. I recently purchased the 2 door Tahoe I had 20 years ago. It’s a 99 Z-71 Sport LT, a desirable combination. Miles 186K. Trans just rebuilt. Engine leaking so much you might as well rebuild. However I am considering a crate engine upgrade instead. It’s my understanding that the 60E trans in this Tahoe, even with my minor beefing up with the rebuild, won’t survive even a modest upgrade in HP. So it appears my options are just rebuild the engine and leave it stock, or go full bore and swap the engine and trans even though the trans is just rebuilt. Thoughts?

What size motor?

 

[Erik the Awful]

It’s my understanding that the 60E trans in this Tahoe, even with my minor beefing up with the rebuild, won’t survive even a modest upgrade in HP.

It mostly depends on how you drive it. If you have a 4.3 and drive it like you stole it, yeah, it's not going to hold up. If you tow heavy stuff over hills a lot, it's not going to hold up. If you have a built 350 and drive it with regard to its durability, tow occasionally, and maintain it, it has a decent chance.

 

[thegawd]

Man that is so awesome that you got your old truck back!

My 4L60E in my Burb is a stage 3 heavy duty. I couldn't remember what it was rated for so I just called them. Mine is rated for 1000 HP.

The 4L60E gets a bad rap... I guess millions of these trannys in multiple vehicles including super cars lasting 200 000+ miles under normal use while being regularly maintained isn't good enough.

Haha I've blown 3. They probably shouldn't be in a burb but after all it did last 290 000 miles before a leakey radiator destroyed it from the inside out. And then another one 10 000 miles later. that landed me in a high performance race shop having them R&R it professionally all the while beefing it up as I wanted a 4L80E. That's why I called him and he told be it wasnt necessary as the 4L60E can be built just as strong and last just as long. My 5.7 engine is original so i have a completely stock motor, I just did not want to blow another tranny basically ever.

So if the 4L60E in your truck is built like an OEM or even if its slightly beefed up it might just surprise you. However that will ultimately depend on how you build the engine and of course how you drive it.

Al

 

[thegawd]

And heat kills trannys. Pulling heavy loads in OD kills them fast, use 3rd. Transmission cooler, is it plugged up with leaves and road debris? Open the front end, take the front valance off and clean up the outside of the rad, ac condenser ect.... make sure air can get through as a vehicle this old, if it's never been cleaned up there will be full of **** and wont cool down properly. Almost no one thinks of this. Also if you have the HD tow package, that brings you the HD tow hitch, the tranny cooler ect.... just like the 7way trailer plug the tranny cooler is not connected from the factory, it was installed by a dealer/trailer company or connected by oneself. So make sure it is actually connected. My burbs was not connected and the tranny shop hooked it up after bypassing the rad completely. Been like this for 5 years and I dont care about whatever preheat system gm incorporated into the rad... when it fails and leaks coolant into tranny lines or oil lines and then circulates back into the tranny or engine is a recipe for disaster.

Al

 

[ShaneM]

What size motor?

Sorry, that should have been more clear. I'm running the 5.7 350 VORTEC and looking to upgrade to a 383 stroker with 400-470 HP.

 

[ShaneM]

Man that is so awesome that you got your old truck back!

My 4L60E in my Burb is a stage 3 heavy duty. I couldn't remember what it was rated for so I just called them. Mine is rated for 1000 HP.

The 4L60E gets a bad rap... I guess millions of these trannys in multiple vehicles including super cars lasting 200 000+ miles under normal use while being regularly maintained isn't good enough.

Haha I've blown 3. They probably shouldn't be in a burb but after all it did last 290 000 miles before a leakey radiator destroyed it from the inside out. And then another one 10 000 miles later. that landed me in a high performance race shop having them R&R it professionally all the while beefing it up as I wanted a 4L80E. That's why I called him and he told be it wasnt necessary as the 4L60E can be built just as strong and last just as long. My 5.7 engine is original so i have a completely stock motor, I just did not want to blow another tranny basically ever.

So if the 4L60E in your truck is built like an OEM or even if its slightly beefed up it might just surprise you. However that will ultimately depend on how you build the engine and of course how you drive it.

Al

I've just seen many anecdotal reports of people who ran a 383 stroker on their stock or beefed up 4L60E and blew the trans in less than 1000 miles. I agree, it does depend on how I drive it, which will not be crazy. I'm not drag racing it, I just want the power once in a while. That said, I'm looking to go up to 400-470HP. Also, I'm not 100% sure but I thought the trans on the Suburban was beefier than the Tahoe, owing to its higher towing capacity.

 

[ShaneM]

It mostly depends on how you drive it. If you have a 4.3 and drive it like you stole it, yeah, it's not going to hold up. If you tow heavy stuff over hills a lot, it's not going to hold up. If you have a built 350 and drive it with regard to its durability, tow occasionally, and maintain it, it has a decent chance.

Thanks...what about 450HP stroked out 383?

 

[SUBURBAN5]

Sorry, that should have been more clear. I'm running the 5.7 350 VORTEC and looking to upgrade to a 383 stroker with 400-470 HP.

I'm sure it's better to get a beefier trans, I'm sure somebody gonna mention drop a 4l80e lol. Me personally. I'm looking at the gm 383. Its pushing 323hp and like 360 or something torque. Good enough for me. And I was gonna use my 4l60e trans and use that til it blows. Mine is only about a year old though.

 

[ShaneM]

I'm sure it's better to get a beefier trans, I'm sure somebody gonna mention drop a 4l80e lol. Me personally. I'm looking at the gm 383. Its pushing 323hp and like 360 or something torque. Good enough for me. And I was gonna use my 4l60e trans and use that til it blows. Mine is only about a year old though.

Exactly, I was looking at a 40L80E. For the GM 383, are you looking at the HT383E? That's not a bad option with a slightly beefed up 4L60E and with a rebuilt trans may be OK as long as you aren't going hog wild with it. My trans was just rebuilt a month ago so it might have a fighting chance... Hmmm, you've got me thinking now.

 

[ShaneM]

I'm sure it's better to get a beefier trans, I'm sure somebody gonna mention drop a 4l80e lol. Me personally. I'm looking at the gm 383. Its pushing 323hp and like 360 or something torque. Good enough for me. And I was gonna use my 4l60e trans and use that til it blows. Mine is only about a year old though.

Just realized that the Ht383 is not CA emissions compliant...