mf1@project1221.com中华人民共和国<המוסד למודיעין
ולתפקידים מיוחדיםPT-141& P2 Member wrote:

Hmmmmm, I'd wanna get all touchy feelly with it in order to
decide about it. A proper mechanical only turbo diesel setup
works.

Yeah, the LPG is a fuel that will "go along for the ride" just as
petrol will in a diesel engine as long as the cetane rating of the
resulting fuel mix is enough to self ignite.

I've not looked into it, however yup, I'd agree the
quantity of gas would need to be specifically
controlled. You would still need to have enough O2
in there. I'm almost interested in playing around
with LPG fumigation, but just prolly don't get around
to it. LPG is prolly about the _only_ commonly available
fuel I have not yet tried on my diesel engine.

Yup, I can imagine this is a good fuel tax dodge
though, suplementing the diesel with an untaxed
fuel.

mf1@project1221.com中华人民共和国<המוסד למודיעין
ולתפקידים מיוחדיםPT-141& P2 Member wrote:

Mmmm, this looks interesting:

http://www.mrsharkey.com/lpg.htm

Feck Hatz, you've added an entry to me round 'tuit list !

Meh, just turn down the wastegate and up the fuel pump,
however above looks fun to play with.

You need to look at the power graph.
It's on full torque at ~2000rpm, which then slides right back to stock by
3400rpm.
Power plateaus at ~2900rpm, and drops very sharply directly after power
peak.

Also, redline appears to be 3300rpm according to the graph.

Now, something which drops that much power that fast is an absolute pig to
drive. Been there, done that with a buggered wastegate actuator.
The 400lb/ft drop in torque from 2000rpm to 3300rpm would give you a very
slow driving feeling and pathetic midrange, even if you do have a slight
increase in actual performance.

Are you sure the 20% improvement in economy is not due to the much lower
redline?
Maybe because drivers with the system need to change gears every few seconds
to keep it in the torque peak?

Give me a slightly modified VW 2L turbodiesel anyday. 400Nm, six gears. What
more do you want?

-mark

There's a few companies selling this comversion - for at least the
past 5 years, maybe longer. Welshtec in the USA claim to be the
originator of the idea, whether thats true who knows.

The cost seems horrendous for a box with a venturi and valve tho!

Maybe our gas regs. make all the other bits necessary, but the overseas
versions seem to just have a venturi into the inlet manifold, a control
valve to stop the gas when the engine is off, and another vacuum sensor
to open the venturi when the manifold vaccum drops. Nearly all
mechanical - no whiz bang silicon chips that require programming!!

Leyland Trucks experimented with a very similar system using oxygen
injection instead of an air charge. Maybe time to revisit that concept.

I was warned by one LPG installer that these dual fuel systems were
designed to operate on propane, not Autogas which has a different
burn characteristic and can cause piston crown damage. How true???

Getting 50% increases in HP and torque would be fine as long as the
engine and driveline could cope. Fuel economy would only be improved
if the improved torque was used and not the higher HP.

Anyone know where those 20 litre LPG tanks come from? I could use
one right now on a camper trailer conversion.