1991 GMC Suburban: Doomsday Diesel Part 7
Our Doomsday Diesel project was born from the idea that owning a diesel makes you more prepared for all the worst-case scenarios life can throw at you. We’ve been building this diesel-engine-swap project as a showcase for bulletproof technologies, and as a way to learn about (and share) ways to make diesel vehicles more reliable—not just more powerful.
| doomsday Diesel Part 7 suburban On Lift
Doomsday Diesel began life as a ’91 GMC Suburban 2500 4x4 with a gasoline engine backed by GM’s 4L80E four-speed automatic transmission. During the last year, we stripped the truck down to the frame and have been building it back up with a 5.9L Cummins, AAM 1150 rear axle, Dana 60-based frontend, and the whole truck rolls on a set of 37-inch-tall tires that would be at home on a military Humvee.
| The 5.9L Cummins fits the frame of ’73 to ’91 solid-axle GM trucks well, but fitting the A/C compressor is a challenge. Dodge mounted its Sanden compressor low on the engine, and it hits the frame. We moved the compressor’s mounting location using a Cummins water inlet housing and compressor mount (A) from a ’95 Ford F-800 (Cummins PN 3930888). We sealed it to the engine with a new square-cut water inlet gasket (PN 3906697). This solved one problem and caused new ones. We then needed the tensioner mount plate (B) to bolt to the compressor mount (Cummins PN 3930838) and had to find a way to mount an alternator. We bought a new Sanden compressor (PN 4666) and belt tensioner (D) to replace the worn Dodge piece (Cummins PN3978021), though you could reuse the Dodge part. We decided to upgrade to the heavy-duty truck alternator the Ford F-800 used. By adding the lower alternator mount (C) to our engine (Cummins PN 3930820), we were able to bolt on a 200-amp Delco-Remy 28SI alternator that dwarfs the alternator Dodg
When choosing the parts for our build, we wanted pieces that were off-the-shelf common. That ideology helps keep the costs down, means there’s lots of options, and if society ends—we’ll be able to get spare parts. One of the unexpected bonuses of the vehicle we’ve chosen (’73 to ’91 Suburban) is that LMC Truck in Lenexa, Kansas, sells nearly enough parts to build this vehicle from scratch!
