I know you can convert a diesel to run on propane -- how hard would it be to convert to run straight hydrogen?

Question

About 20 years ago Freightliner had a test truck that was a full diesel propane conversion. It doubled the horsepower of the diesel engine but got 1/2 the mileage. Also the diesel motor would have to have been never fired on diesel.

I am wondering if it would be possible to convert a diesel to run on hydrogen.

My main concern would be if the engine could hold up to the increased power. Diesel engines are built tough for the detonation so perhaps...

If it is likely it could hold up, what steps I would need to take to begin researching/building the solution.

If possible I would like to leave the inner workings of the diesel untouched as I can do some gas motor work but am not a diesel mechanic.

answer from ledocetrange lead me to find:
High Autoignition Temperature
Hydrogen has a relatively high autoignition temperature.
This has important implications when a hydrogen-air mix-
ture is compressed. In fact, the autoignition temperature is
an important factor in determining what compression ratio
an engine can use, since the temperature rise during com-
pression is related to the compression ratio. The temperature
rise is shown by the equation:
where:
V
1
/V
2
= the compression ratio
T
1
= absolute initial temperature
T
2
= absolute final temperature
γ
= ratio of specific heats
The temperature may not exceed hydrogen’s autoignition
temperature without causing premature ignition. Thus, the
absolute final temperature limits the compression ratio. The
high autoignition temperature of hydrogen allows larger
compression ratios to be used in a hydrogen engine than in
a hydrocarbon engine.
This higher compression ratio is re-
lated to the thermal efficiency of the system.

hydrogen is difficult to ignite
in a compression ignition or diesel configuration, because
the temperatures needed for those types of ignition are relatively high.

Answer 1

I don't think you could do it: hydrogen does not auto-ignite when compressed. A diesel engine relies on compression ignition so it would not work on hydrogen. You need something with spark plugs.

Answer 2

Not hard. I was on a team who did this in 1973.