Re: Will propane kits work with hydrogen gas cars?

I'm not quite sure what you're asking, so I'll try answering a couple of
different interpretations.  

First, can you convert a hydrogen car to run on propane?  This depends on
the type of hydrogen car.  Nowadays, most discussion of a "hydrogen cars"
is focused on hydrogen fuel cell vehicles.  A fuel cell doesn't use
hydrogen for internal combustion.  A fuel cell is more like a battery than
an engine.  So in this case, the answer would be no.  You couldn't use
propane instead.  

If you are talking about a hydrogen internal combustion engine, then the
answer would be maybe; however, a kit made to convert a gasoline engine to
propane probably wouldn't be appropriate.  It is unlikely to require a lot
of changes to convert a hydrogen engine to run on propane, but the changes
would be different than those required to change over a gasoline engine. 
For example, it's already set up to run on a compressed gaseous fuel so
those parts of the conversion would be unnecessary.  But you would need a
way to change between two different gaseous fuels.  And the two gases
(hydrogen and propane) have much different stoichiometric air/fuel ratios,
so the change over would not be transparent to the control system (whether
it be carburetion, port injection, or direct injection).  There has been
some work on engines designed to run on both hydrogen and natural gas and
even mixes of the two.  But there is some special hardware required.  

Finally, can you use a propane conversion kit to convert an engine to run
on hydrogen?  Not likely.  Running on hydrogen has some special
requirements over running on gasoline or propane.  There are some engine
hardware upgrades required to run on hydrogen.  For example, hydrogen is
very susceptible to pre-ignition so special care is necessary to avoid
backfires and such.  Hydrogen is also much tougher on injectors than carbon
fuels because it's much drier (it doesn't carry as many lubricants) and
leads to faster wear on the injectors.  

Well, I hope that answers your question (whichever question it was that you
were asking!).  If it didn't, feel free to write back and clarify what you
were looking for.

Your Mad Scientist,
Mike Scannell