Propane Conversions

put simply you need higher hot strength aluminium in the pistons to handle the heat load. Valves can normally stay the same as long as the fuel is intoduced at low temperature, which is usual as it is stored as a liquid. You can also increase your compression ratio as Propane has very high octane properties, compensating for the drop in fuel heat value. In Australia we have quite strict standards on tank placement and venting; they only last for ten years as well.

I have had many cars converted to run on LPG (propane) and have not noticed any difference in the running temperature in any of them (between petrol and LPG). The problem with the heating generally comes from running too lean (and this can happen with any fuel). It is very easy to lean off the LPG mixture with little apparent loss of power but a noticeable reduction in consumption.

I know of two people who have come to grief. One is my Father in Law, who boasted what good economy he was achieving with his 265ci/4.3l Valiant only to almost destroy the head by burning out 6 valve seats in a very short time.

The two engines I have used on LPG mostly over the years have been a 351c Fairlane that ran faultlessly for many years, through inland Australian summers with no heating problems. The Ford engine has nothing in particular that seperates it from any other as far as pistons or combustion chambers. My current vehicle is a '79 Inter Scout with 345ci V8. This engine runs really well and will probably last forever as it has (standard) hardened valve seats and is probably the biggest, heaviest lump of high quality cast iron that has been fitted to a car (or RV), although I believe the Jeep 360 is also a solid lump. This extra bulk will obviously help to dissipate any percieved additional heat.

There is a loss of power although I have heard that the conversions are getting better and they are closing the gap. Consumption is also higher but the better conversions are also helping change this. What about CNG?