a number of moderating factors concerning using diesel for land units. One of the (but not only) limiting factors in heavy vehicles is not the engine itself but the power transmission system. A clutch and manual transmission in a heavy vehicle is very, very inefficient. The US post war helped this problem by going to faster, smoother shifting automatic transmissions. Dr. Porsche during the war (and many other engineers concurrently and since) went for a electric drive system. This is currently widely used in very heavy mining vehicles like 100 to 500 ton mining dump trucks, and when you think about it is an adaptation of the diesel electric systems used by the railroads pre and post WW2.

Here is my two-cents worth; Start out using this great article on the German fuel problems of WW2, including sort of a primer on both the Fischer-Tropsch and Bergius processes of synthetic fuel production of the time. It also explains pretty fully how the Nazis attempted to ameliorate their need for petroleum from wells, and their dependence on imported fuels.

http://www.airpower.maxwell.af.mil/airchronicles/aureview/1981/jul-aug/becker.htm

This article also posted by "JC…" explains (pretty well) the different qualities and types of fuels produced, such as wood and bio-mass converters on some late-war training tanks, trucks, and buses. Potato alcohol in others (also the V-2s), and the low grade gasoline in the V-1 "pulse jets".

About the only part of the problem I do not see addressed here is the need for controlled cetane levels in the diesel fuels produced (that is the diesel equivalent to octane in gasoline).

Please keep in mind that these next few paragraphs are just my own suppositions of course. I would think that these processes limited them to producing diesel suitable more to either extremely large engines or extremely small ones, running at very low rpms, i.e. submarines and powering small electrical generating plants and such. Not too applicable to engines for motor vehicles or AFVs of the time actually without access to major bauxite supply. The thermal cracking method of separating hydrocarbon fuels of the time may not have been cross-applicable to the sythetic fuels (I don’t know, another guess). Or it may have been so cost inefficient that it would have been stupid to even consider it in a fuel poor economy.

Putting diesel engines in tanks may have not only complicated the fuel supply logistics, it may also have been impractical as to power produced. While building transmissions and clutches to "harness the torque" is less of a problem (can be done) the straight cut rather than helical cut gears in German AFVs were a major weak point in their larger units and constantly broke down/striped out with even the less torquey gasoline engines. Another thing to keep in mind here, the Soviet diesel engines in their T-34 had an aluminum block which the Soviet’s produced from native bauxite (another raw material the Nazis had limited access to and needed for aircraft), this minimized the weight of the engine for the Soviets. With iron sleeves for the pistons to run in, and iron heads to hold the compression of the diesel to explosion pressure.

These Soviet diesels were wonderfully simple and yet reliable 500 hp, V-12 engines with gear driven fuel injection, but (I believe) normally aspirated i.e. non-supercharged. A pure iron and steel engine of the same weight and external dimensions, running on low cetane fuel, would be hard pressed to create 200 hp without supercharging, and the Nazis had other uses for their engine air-volume boosters (both exhaust turbo and gear driven), in the Luftwaffe.

Once again my URL didn't automatically change to a form which could be accessed. Don't know enough about this site format to change it if it doesn't do it auto. Sorry.

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Happy Trails,
Clint.