You need a better builder then. FLT builds 70s holding over 700whp in an AWD 5klb tbss. My AWD tbss was cammed, stalled, 150 shot running mid 11s full weight 4900lbs holding with a mild built ( to todays standards) 70e

 

Nah I ditched the real problem and went with a transmission capable of holding the power AND GVWR and GCVWR (I tow 7,500#) ratings in 100% STOCK form. 4L80E swap with a LKQ junkyard unit also came with a 6 month warranty on the trans. Try finding a stock rebuild on a 4L60/70E from a reputable builder with a warranty for what the junkyard swap cost me.

That was the pan/magnet on my 100k junkyard 4L85E out of a 2002 Express. It has 5 pinon planets and has a very noticeable first gear.

 

Craigslist 4L85e out of an 8.1L 2500 Suburban $500
Transgo HD2 $110
Circle D 2B $910
Circle D flexplate $150
Wiring $20
Crossmember $10 for metal and paint
Driveshafts lengthening and shortening + new spicer u-joints $475
Tru cool $100
Tru cool brackets $75
Fluid and filter $100
Transfer case input shaft, case saver, seals $200
Gm transfer case fluid $25

Total:
$2675

2wd would be waaaaay cheaper

 

How many miles boosted have you put on it? Curious about whether or not to put a built 4L80e in when my goals aren't much more than 500hp

 

Haven't put any boosted miles on it, turbo kit is still on the shelf... I like to do suspension and drivetrain first before adding any power, I don't like to do it all at once either, too many bugs to sort out.

From my research, a known good junkyard or Craigslist 80e w/ shift kit, and proper tuning and keeping trans temps at a reasonable temp should be fine at 500hp for sure. I want to make 600 and drive the truck daily. A built 80e was in the budget, but I found a known good trans and now that all the infrastructure is setup such as the VSS wiring, crossmember, segment swap etc etc if I do need a built 80e in the future, it will be a much simpler swap. I also wanted to see what these junkyard/ craigslist 80e's are made of.

 

There is a Stock high mileage 4L85E with a +3 qt deep aluminum pan and a Transgo HD2 running around behind a Duramax making nearly 800 ft/lbs and 400 hp. I tuned the setup and with the right amount of Defueling during the shifts and the right line pressure and shift time changes it has been holding up for abou 2 years and 80k of heavy towing/hauling.

 

A stock one with a Shift kit will handle that no problem assuming it's in good working order internally.

 

That's pretty impressive. IIRC, those Express Vans with a D-max came with the 4L85e stock?

I think the smart thing might be to pick up a used 4l80e and just build it over the winter. We will see what I can find locally for a good used unit to build.

Or I might just see what I can get a stock, new OEM 4l85e for.

 

Yea thats what they used in the Express and detuned the engine to 250 hp and 440 tq.

 

It's funny to see the differences between an Alli-1000 (HUGE transmission) and the 4 speeds in gassers. If the 85e lasts at 800lb-ft.....i figure it would have no problems at around 550lb ft.