1957 CHEVY BEL AIR DIESEL?
I currently own a 1957 Chevy Bel Air two-door post. The car has been used for quite a few years as a Pro-stock drag car, but it is now being restored as a driver with a new modern chassis, suspension, and braking system. I want the car to be functional enough to use as a daily driver if I choose, but I don’t want to modify the body in any way that would harm its status as a classic car. I love these cars, but I would like to have a little more usability. I’m not planning to restore the car to museum quality. I simply want to enjoy it more on the open road.
Through pure coincidence, I picked up a salvage 2015 Chevy 2500 with the Duramax/allison. It appears nearly everything I need for a diesel swap was undamaged, so I got to thinking: could this engine and transmission be made to work? It would be a conversation starter, and, if it all came together, it would be great on cross-country trips. Tell me what you think.
Wayne Shoemaker Via Email
Hmm. Your email certainly got my attention. As an older guy myself, I love the '55'57 Chevy cars, too. I've owned many of them, and I wish I still did. Owning a safe and reliable classic “driver,” as opposed to a garage queen, would get my vote.
To answer your main question: yes, the Duramax/allison can be made to work, but I would recommend using a 4L80-E or 4L85-E automatic and then use programming for the engine to reduce power/ torque to what the Duramax 6600-powered vans were shipped with from the factory: 250 hp and 440 lb-ft of torque. The 4L80-E/85-E would not require any sheet metal modifications to the transmission tunnel. With 3.42 differential gearing, you should see mid-high 20s for fuel economy, and 250/440 would feel like a lot more in such a lightweight car. A secondary benefit is that this setup would not mandate an intercooler for the engine. All you'd need is a decent-sized radiator. In fact, a factory Duramax 6600 radiator could likely be adapted to the radiator core support.
Another option would be to sell the salvage truck you have and look for a salvage 2019 Silverado equipped with the 3.0L “baby” Duramax diesel and 10-speed automatic–if one exists. This is a brand-new GM diesel, which could make it hard to locate. It's an inline six-cylinder that has an ideal amount of stock power/torque (282/450) for a vintage car.
I'd be remiss if I didn't mention that the standard recommendation would be to install an LS gas V-8 from GM. They can make lots of power and deliver reasonable fuel economy. And, the sound emitted by the exhaust would melt the hearts of Chevy Tri-five fans everywhere. But, this is a diesel magazine. Good luck with whatever you decide. Let us know what develops. Jim