1993 c3500 6.5 to 8.1 swap ?
 

Goodmorning fellas
I've got a 1993 chevy c3500 crew cab dually with a 6.5 detroit/4L80E. The truck came out of Texas, NO RUST. I really only use it to pull my 42ft gooseneck race trailer with a 72 c10 drag truck. Ive grown quite fond of the 93 and rather than spending $60k+ on a new truck Ive been thinking about swapping from the 6.5/4L80E to an 8.1/Allison combo to gain some power and reliability. Don't get me wrong the 6.5 runs well but its a dog and from what I understand the bottom end is a ticking time bomb.
Just curious if any of you have done this, and if you have what did it entail?

Any help would be greatly appreciated, These forums have been a godsend and have yet to let me down.

Thanks in advance!

Re: 1993 c3500 6.5 to 8.1 swap ?
 

I'd look into a Vortec 454 and go from there. They can make more torque at a cheaper price than an 8.1. Only 1 company makes stuff for the 8.1, and they are rather proud of it.

Re: 1993 c3500 6.5 to 8.1 swap ?
 

Interesting coincidence that GO-FAST posted this question... Yesterday my Son bought a '95 K-3500 Crewcab LB single wheel.. 6.5 diesel, auto, 175,000mi. Everything works & pretty fair condition. CHEAP.... WOW, what a LOOONG truck!!! Been reading about the 6.5 Turbo diesels and I was wondering if the bellhousing flange on the 6.5 is compatible with Chevy gas V8's. I have a 330hp. Mercruiser engine... (4bolt 454) in the shop & wondered if it would bolt up if the 6.5 takes a crap.

Re: 1993 c3500 6.5 to 8.1 swap ?
 

Beauty of Chevy, everything bolts to everything lol. Yes they the same so bolts right up.

Re: 1993 c3500 6.5 to 8.1 swap ?
 

Thanks b454rat, I think it'd be a lot less cluttered under the hood w/the 454 & a carburetor. Just need enough computer to run the 4L80e. Hafta see if the big 'ol truck's worth the work.

Re: 1993 c3500 6.5 to 8.1 swap ?
 

Don't most marine engines run reverse?

Re: 1993 c3500 6.5 to 8.1 swap ?
 

Some do, mainly for twin engine applications. This one is std. rotation.

Re: 1993 c3500 6.5 to 8.1 swap ?
 

I have a C3500 with the 6.5 and with some fairly inexpensive mods you can make a very dependable engine with great gas mileage. I swapped out the lift pump and wiring, I replaced the pmd with one mounted to a heat sink in the inner fender and I fitted two matching output batteries. The only expensive fix was to have the ecu re-written to bypass the security system which will fail.

Other than that I will be fitting a manual boost and gauges and carrying out regular oil changes.