Mixing a dose of LPG with diesel to improve power and economy

[meelis11]

Hey,
I found this interesting article.

Mixing a dose of LPG with diesel to improve power and economy

...

However, the magic comes in the addition of LPG to the diesel fuelling mix. The LPG is added in vapour form prior to the turbo (in turbo engines) or prior to the inlet manifold (in naturally aspirated engines). The LPG, comprising about 25 per cent of the diesel flow, burns along with the diesel in the cylinders. The combination of the diesel/LPG fuel gives the greater power output and lower emissions. The reduced running costs come from an improvement that is realised in diesel fuel economy – and the fact that LPG is a cheaper fuel than diesel.

...

It seems like promising thing if you have diesel engine. Unfortunately I dont have. Maybe some garage-inventors can make their home-brewed version?

Meelis

[Peter7307]

LPG for diesel works like Nitrous Oxide for gasoline engines.
Been happening for a while and so far as I can find no real disadvantages apart from the extra complication and small loss of space for the LPG cylinder to go somewhere.

Pete.

[Big Dave]

Diesel performance guys do this for quick, cheap HP. What you are doing is making the engine a dual-fuel engine. Propane is nothing more than an auxiliary fuel. Propane won't compression-ignite. The injectors squirt some diesel into the chamber and it acts as a spark plug, blowtorching the propane to ignition. The propane, once ignited combusts very quickly, so if you use propane you can't use a lot of injection advance. Too much injection advance and you bend rods.

[Peter7307]

I managed to find someone who has actually done this addition / conversion.
The end result is an increase in power and a decrease in costs (about 7%) since LPG is cheaper than diesel with no reliability problems so far.

Pete.

[Christ]

It's not quite like Nitrous use in a gasser, though... Nitrous is an oxidizer... you can also use it in Diesel engines. Propane is a fuel, and can also be used in gasoline engines.

I wasn't aware that propane won't auto-ignite under compression? Or did you mean under the compression that normally occurs in a combustion engine?

OK - LPG will auto-ignite at ~1000degF, so probably not going to happen in a normal combustion engine.

[Christ]

Reference for the above post -

[gone-ot]

...auto-ignition point vs. CR?

[Big Dave]

It all depends on the price of propane. Around here LPG cost maybe 20 cents a gallon less than taxed No. 2 diesel.

For every gallon of diesel you offset, you'll burn a gallon and a half of LPG.

[Piwoslaw]

Could the reduced emissions be b/c there is LPG displacing some of the atmospheric air (mostly N and some O) going into the cylinder, creating less NOx?

[Big Dave]

I doubt that LPG displaces enough air to matter. Most street diesels run a lot of excess air.