Dmax/4L80E

[Curtis Mittong]

I'm getting to the good part of my project: 66 Bonneville with a duramax/built 4L80E. I can't use an Allison, first because its too large, and second because the ratios aren't the best for a car.

I will be using a factory duramax computer.

I know the 4L80E was used for just a couple years behind the duramax in the vans, but I'm wondering if any late 4L80E will work. Will there be compatibility issues with electrical connectors, torque converter bolt pattern, or bellhousing depth?

Will any duramax computer be programmable for the 4L80E, or do I need one from a van that had the 4L80E in it?

[JohnC]

Aftermarket computers are readily available for the 4L80E. If you can find an ECM for the D-Max from a manual trans...

The pickups use separate ECM and TCm modules.

I'd think the van computer would be better, though, because you could integrate the engine and trans and it'd be less likely to rip the bands off the clutches...

I'm sure there's someone out there who might figure out a way, but I'm going with "no way" you can use the Allison TCM.

[Curtis Mittong]

Aftermarket computers are readily available for the 4L80E. If you can find an ECM for the D-Max from a manual trans...

The pickups use separate ECM and TCm modules.

I'd think the van computer would be better, though, because you could integrate the engine and trans and it'd be less likely to rip the bands off the clutches...

I'm sure there's someone out there who might figure out a way, but I'm going with "no way" you can use the Allison TCM.

thanks for the help. I also looked into the 6L90, but I don't think its much smaller than the Allison. It also has a pretty deep first gear that might be useless, but the internal computer kinda has me intrigued. If I have a standalone ECM feeding info to the 6L it might make a nice package.

I even looked into some manuals, but to get enough tranny to hold the torque I'm looking at a "truck" style tranny that is too big.

Any thoughts on trannys for this swap? Or am I probably wisest to stick with the 4L80E?

[convert2diesel]

Have looked at the priliminary numbers on a Dmax conversion to the Caddy (94 Fleetwood) and like you, can't shoehorn an Alison into it. There are enough aftermarket guys that can build a 4l80 to handle the job but,as been mentioned, you would have to get a standalone tranny computer and try to figure out out how to get TPS and tach info out of the Dmax ECM.

As silly as it sounds, I have actually looked into a 400 with a Gear Vendors stuck on the back. The numbers look good. The trannys are almost indestructable and can easily be built to handle the Dmax. You lose the lockup convertor but the aftermarket can build up a really tight configuration with low stall. Just add a big cooler and no computer is needed.

Thought about a 6 speed manual but the only thing that will fit well in our tunnels would be something along the lines of a T56. While some of the "piston head" crowd are advertising big numbers on their T56 rebuilds, its unlikely this box could handle the low speed torque of the Dmax.

Sounds like a great project, though it almost seems sacreligious to replace an old 389 with a diesel. Keep us posted on the progress.

Bill

[Curtis Mittong]

There are enough aftermarket guys that can build a 4l80 to handle the job but,as been mentioned, you would have to get a standalone tranny computer and try to figure out out how to get TPS and tach info out of the Dmax ECM.

True, which is why my first thought was to go with a van Dmax/4L80 so that I had a complete package. Does anyone know if the van Dmax is derated by tune, or is there something mechanical that prevents me from putting a truck tune in it and getting truck numbers out of it?

As silly as it sounds, I have actually looked into a 400 with a Gear Vendors stuck on the back.

Not silly at all. I did that exact thing in this Bonneville. I just didn't like the complexity and (contrary to what they say on their website) I had to do a considerable amount of cutting and pounding. The GVOD landed right on one of the floorpan ribs and I had to cut it out along with part of the floorpan and make new sheet metal. The carpet never fit right.

[convert2diesel]

True, which is why my first thought was to go with a van Dmax/4L80 so that I had a complete package. Does anyone know if the van Dmax is derated by tune, or is there something mechanical that prevents me from putting a truck tune in it and getting truck numbers out of it?

Typically, they probably did most of it through a tune but it is distinctly possible they used lower flow injectors. Would have to check numbers. Mechanically, the two engines are the same.

Not silly at all. I did that exact thing in this Bonneville. I just didn't like the complexity and (contrary to what they say on their website) I had to do a considerable amount of cutting and pounding. The GVOD landed right on one of the floorpan ribs and I had to cut it out along with part of the floorpan and make new sheet metal. The carpet never fit right.

Had the same issue with a 85 Cadillac Fleetwood. Not as drastic as yours but did need a little BFH body work.

Bill

[computer-monkey]

Take a look at this link:
http://www.thedieselpageforums.com/t...ad.php?t=37512
I have using the 4L80E.