LPG injection for diesels

On or around Thu, 10 Aug 2006 19:41:59 GMT, "Tony" enlightened us thusly:

and instant explosion if you get it wrong.

have a look for "fumigating diesel engines". People have done it - but bear in mind that if you extract say 150BHP or more from an engine designed to make 110BHP, you're putting a lot more strain on it.

Welsh Tec (sp?) has a multi fuel system which uses the vacuum in the manifold to draw small amounts of propane to mix with the air and diesel, claims of increased power and reduced fuel consumption. They suggest modifiying the throttle to keep the fuel economy gains.

The one downside that I was warned of - the piston crowns can be burnt and melt under extended use on auto LPG mixes of propane and butane. With that news I cancelled my dreams of my SIIA burning off Ferraris at the traffic lights!

Do a weblookup on natural gas powered buses - 1,000s of those operating around the world based on diesel engines.

I think allisport did a system.

Steve

i dont think there is any info on the website, but i think that one of the guys who runs car gas LPG converters in stoke

has done it on his diesel camel disco. Ithink there was an article in one of the landy mags covering what hedid too.

I know of a Dutch company that wanted to do conversions. For the reasons already mentioned in this thread: fuel economy, emissions etc. LPG to diesel ratio would vary depending on engine load, from sth like

5% min to 30%max. Dutch law however prevents conversions on the grounds, if I understood correctly, that cars are not allowed to use two different kinds of fuel *at the same time*. Petrol and LPG are not a problem, because petrol engines run on either LPG or petrol, never LPG and petrol at the same time. British law differs from ours in this respect, I gather. The company - Iwema, Eindhoven - was not able to persuade the Ministry of Transport to approve of an experiment.

See for yourself:

[pages in English]. Don't forgetthe Link-page with links to Chris Perfect, Gordon Finlay (both UK) andcustomer reviews.

In ancient times, when I was still a busdriver for the regional transport company, I drove buses with diesel engines converted tot running on natural gas (not LPG!). The experiment failed due to (very) high costs of maintenance.

Richard

T> Anyone know any webs site with info about this, apparently instant bhp boost

They got that formula right here and used them for a long time.

Arriva Watford had a fleet of gas-powered buses, they were so uneconimical both in terms of performance and maintentance costs, not to mention chronic problems with engines due to them running a lot hotter on gas, that they have now converted the fleet back DERV.

Alex

The chap that did some welding for me was a chassis welder for Dennis, he said much the same. It's understandable if you consider how a diesel cycle works compared with a SI engine.

AJH

In message , Tony writes

Played around with it a few years ago on my 200TDi.

Yes you can get a lot more power without much additional stress on the engine and no increase in any engine temperatures. (Info from MIRAS tests) But any gain in economy is primarily dependent on the price you would normally pay for your diesel and gas. It's a relatively small gain, nothing like a petrol/lpg conversion and there is no economic sense in doing it. Also we never saw any improvement in emissions, quite the opposite.

Ours was a very simple mixer system, maybe they're more sophisticated now.

On or around Sat, 12 Aug 2006 22:43:45 +0100, AJH enlightened us thusly:

I think the only sensible way to run on gas is to have a dedicated engine, although there is a history of fumigating diesels for more power. Mind, these days diesels are developing more power anyway.

Yes and this is the way it was done for the buses but the base engine was a diesel. It was converted to run with a spark plug and as a SI engine. As I said this would indicate higher combustion and exhaust temperatures, so probably more heat ending up in the coolant for a given power output.

This is a different kettle of fish. I have tried it with a straight 6 DI tractor engine but at low levels I think burning was incomplete (gas:air mixtures don't support burning outside of a fairly narrow range) at higher levels detonation set in quite quickly. I think you would need quite a complicated derv:lpg:air map.

Largely because they have moved away from the slow speed Diesel cycle toward the Otto cycle.

AJH