H1 Gasoline Conversion

From time to time we get to work on something particularly challenging and fun. A customer recently asked us to convert his military H1 into a gasoline, highway ready civilian vehicle.

So we swapped out the original diesel engine for a new crate L96 LS based engine. We also swapped out the original transmission for a crate 4L80 4 speed electronically shifted automatic transmission, with overdrive and a lower first gear. It was a challenge to marry that transmission to the original transfer case, we had to machine custom parts for all the mounts. By doing this we were able to more than double the horsepower, as well as the fuel economy. We made sure to use factory parts where available in fuel management, fuel injectors, spark plugs, belts, etc. This means that our customer can take this vehicle into any GM authorized dealer anywhere in the country and get factory trained technicians to help him should he need it.

While the gasoline engine is smaller than the original diesel, there are some tricky bits when it comes to lining everything up. The engine wasn't parallel to the frame rails, and the transmission and transfer case are on the driver side of the vehicle. The drive shaft is mounted high as well as the differentials, which made lining it up particularly difficult. We are lucky we had a lift wide enough to lift the Hummer.

The intake manifold was significantly larger, which meant we had to custom fabricate an engine cover, which gave us the chance to add some nice features like cupholders.

We kept the original 24 volt system, but added a 12 volt system which would allow for modern gauges, a GPS speedometer, and interior lights. We were able to have both electrical systems charged during runtime, so the client will be able to operate this as much like a civilian vehicle as possible.

We had a lot of fun on this one, and we're proud of it.