According to the sites I have seen, addition of 20-30% LPG allows for more effective combustion of the diesel (as the diesel engine can only burn 70-80% of the diesel fuel injected - I suppose this is at maximum delivery - full power), up to around 95-98% complete.

The more complete combustion (greatly reducing smoke emissions) gains you more power from the existing diesel injected and the extra propane/LPG also contributes to the total power.

The claimed power gain varies from 10-30% more depending upon the model and age of the diesel engine.

In addition to the power gain, there is also claimed to be a significant gain in fuel economy varying from 10-20%.

Because of less efficient injection, older model diesels gain more power and fuel economy than the newer Common-Rail designs.

The injected LPG poses no explosion hazard as the amount added to the inlet air is less than the lower ignition threshold of LPG in air.

To put it simply, the LPG-air mixture added is just too lean to ignite and burn on its own without external help.

This is where the conventional diesel injection comes in, conventional diesel injection and combustion start as in the standard engine, but the presence of LPG in the air speeds up and makes the combustion more complete and efficient.

If properly done, LPG injection should give me around 20-30% more power and 10-15% better fuel economy!

Puttering around engines is my passion and hobby, so for me it is worth a little trouble.

I thank you again in advance for any help you can provide.