BT6 Swap

SierraM37 · Post by **SierraM37** » Wed Sep 23, 2009 5:30 am

I have a friend who has a running mid mileage BT6 he's offered up for my second M project. I know Cabel used the BT4 and I think some have used the BT6. Thoughts, who's done it, challenges, issues, problems. Pro's/Con's

I think it is in an '89 service truck so what type of Gertrag tranny would have been behind it? Would ideally like a married TC to shorten drive line and I plan to go with centered rear axle.

I have a Dodge NV4500 divorced gasser that I could use, but what would be best for shortest drivetrain?

Lifer · Post by **Lifer** » Wed Sep 23, 2009 5:49 am

I believe there was considerable discussion of the 6BT/M37 combo a couple of years or so ago and the general consensus was that the 6BT was either too long or too heavy (or both) to be a viable candidate for a swap.

Josh · Post by **Josh** » Wed Sep 23, 2009 1:46 pm

Its both. A fully dressed 6BT weighs 1200-1350 lbs, depending on the acessories chosen, and is 40" long for just the bare block and crank stub. Add in those acessories, and, the front wll be against the winch, or you'll be riding on top of the last two cylinders. On the bright side, your butt won't get cold!

the 4BT is plenty of engine for this truck, especially if you got the ISB version with electronic injection, 4 valves per cylinder, and intercooler. It makes 175 HP and 400 something ft-lb. Be forwarned the ISB only mates to the allison 1000 transmission, as the bolt pattern is cast into the block.

go to www.4btswaps.com for more info.

Another option for something a bit more "nostalgic" is a 3-53T detroit diesel (4-53 wont fit, its too long and too heavy). I would have gone this way had I done diesel, but, I like the sound of a detroit up against the governor.

They're kinda like Coffee... an aquired taste!