cummins to 88 chevy

[BLively]

thinkin of installing a 12 valve in my first truck, ( 88 1/2 ton chevy). planning on beefing up suspension, and 4 linking the rear end. what i am wondering is, what transmission should i run behind the cummins? do any of the old autos like the th400 hold up to a 12 valve? dont want to go broke building this thing is my main worry. what are your thoughts on this??

 

[DVolk]

They run a T-400 in the Frito trucks ,but they have special parts inside how long it last depends on your foot is my guess



You will spend my guess at least 10 K before its done

 

[BLively]

i guess as long as its not all at one time, itll be ok! lol. i plan on putting a few goodies on the cummins, so the stouter the transmission, the better. so a t 400 out of a delivery truck might work? that shouldnt be too hard to find around here

 

[SOswalt]

Yes,

what you want is the P-30 set up

adapter and starter,flywheel (if going to manual- the flywheel is a special to fit gm to Cummins).

adapter, flex plate ,starter,crank spacer.



I try to keep them in stock.



The trans in the step vans ar TH475 the have a deep pan and straight cut gears,it's a up graded TH400.



Thanks

 

[BLively]

do you know how much power they hold up to? can they be upgraded, say with a shift kit if there is one made? what does the adapter, flex plate, starter, and crank spacer cost? thanks

 

[SOswalt]

Cost is $675. 00 for thge parts and extra for the trans plus you'll have the ship. The Th475 is already set for the diesel rpms and well as the converter.

If your planning on using a Th400 than the trans shop needs to know what there doing has has to set it up for a diesel.



Thanks

 

[NCovey]

If going witha GM transmission, I would use the 4L80E, it is a pretty stout transmission with O/D. You can buy a stand alone controller from the summit catalog. -Nicholas

 

[DWitcher]

How come more people don't use the 4L80E in the GM conversions?

 

[BLively]

i didnt think the 4L80E would be stout enough. i might go that route for the overdrive. plus it might be a little easier to find. what mods do you have to do to this transmission for it to hold up?

 

[NCovey]

I may be wrong, but as I understood it the 4l80e is basically an electronically shifted turbo 400 with an overdrive. There are several companies that build these trannys for high horsepower, heavy abuse applications.

 

[pmartinez]

I had a turbo 400 with a gearvendor o/d. I didn't like the slippage that the torque converter had. I converted over to a 4l80e using a compushift stand alone computer. I carry a 4000lbs camper and tow my jeep behind it total about 17000lbs. It was the best thing I have done. the lockup convert is the only way to go.

 

[DWitcher]

What kind of power is your truck putting out?

 

[pmartinez]

not sure of power numbers but engine is a 93 12 valve #16 housing 3000 rpm gov spring pump turned up 4" exhaust and K&N air filter.

 

[DWitcher]

IIRC the max torque rating for the stock 4L80E is 440ft lbs.

 

[BLively]

what can be changed in the 4L80 to make it take more abuse?

 

[DWitcher]

There is a large aftermarket for the 4L80e but most of it is gas application which has high HP but no where near the torque that a built Cummins can produce. You could build one for the right amount of money and have a converter built too but I'm sure for the same $$$$$$$$$ you could run a built 47rh/47re which has a better aftermarket designed around the Cummins output specs. I would love to see a Built 4L80e behind a "Bombed" Cummins just for the "thinking out of the box" factor.

 

[Jeepstang]

I ran a 320 hp with over 500 ft lbs of torque 6. 5 GM engine in my Suburban with a 4l80e I would call Heath Diesel power and talk to Bill he would be a good person to talk to about how much power they can handle. They make several power upgrades for the 6. 5 Engine

877-894-6266