Do you have any fuel economy numbers? Considering a gasser 400 in a 78 would get about 10mpg. Possibly some more specs on the engine itself, besides being air cooled. Like hp/tq figures, years of production, size, etc
Deutz manufactured the engine as a "special BF4L 913" for GMC a little over three decades ago. I "discover" the engine sitting in Deutz's Richmond, IN warehouse. It was inferred to me the engine was destined for a UPS delivery van that GM was going to produce. However, the union(s) were protesting the use of a German manufactured engine and the project was discontinued. Apparently they forgot GMC was making Deutz's BF6L 913 available in their medium duty trucks about that time. Deutz was most generous in making the engine available to me.
I perfer not to disclose engine output data as it differs from that published by Deutz. The engine, along with the transmission and transfer case, was tested on our dynamometer for base line data and torsional vibration before being installed in the truck. Needless to say, the truck manages to keep up with most traffic.
I consider the truck's fuel economy to be exceptional, although one always wishes it was greater. I hesitate to offer data as we measure test fuel burn in "miles per pound" (some have suggested "miles per barrel") and that's confusing to most. The fuel we use has a wide API gravity (density) variation and the BTU's per pound can differ further complicating things. I offer the follwing link as a glimpse to what the truck can obtain under favorable conditions. Kindly use it and scroll down to the tenth "Update."
As the fuel temperature in the tank
had stabalized I think the fuel burn given is accurate.
Thanks for the inquiry and thank you for the "Thank You."