On or around Wed, 07 Jan 2004 21:57:17 +0000, Peter Hill
enlightened us thusly:

Propane burns cooler than petrol (1925 vis 2030 deg C) but propane
vapor engines run hotter due to loss of cylinder head and valve
cooling (as demonstrated by some engines valve seat problems). Liquid
injection gives higher efficiency = more power, better fuel
consumption, lower engine temps, longer life ..... but it costs more
and can't be designed and fitted by plumbers so the cheap option wins.

yeah, all true, I don't doubt.

But, to do this lot, you need an engine made for the purpose. Any of the
manufacturers could do this, if there was thought to be enough market -
developing or adapting an existing injection system would be simple enough,
making a high-compression engine easy enough, if someone wanted to guarantee
a market for a couple of million of them I'm sure Ford et al would jump at
it.

none of that helps convert the millions of existing engines though, which
are stuck mostly with the design built into 'em, carburetters, low
compression etc., so a retro-fit liquid-injection system is relatively
unlikely - costs too much to be practical, I expect, bearing in mind that
you're talking about a whole new fuel system, near enough, even on a petrol
injection car.

Obviously you can go some way towards it, you can pick a high-compression
engine (my ford is 9.2:1, the latest V8 I have is 9.35:1, some of the more
modern car engines are not far short of the 12:1 you quote). But that as
you say is only part of the story. I doubt any conversion supplier can fund
the development of liquid-phase injection to the point where it can be
supplied as a kit to retro-fit e.g. my V8, and if it were, it'd doubtless be
expensive, and require a fair amount of engineering to fit, so not many
people would buy it.


--
Austin Shackles. www.ddol-las.fsnet.co.uk my opinions are just that
Beyond the horizon of the place we lived when we were young / In a world
of magnets and miracles / Our thoughts strayed constantly and without
boundary / The ringing of the Division bell had begun. Pink Floyd (1994)