Fuel Economy: Propane vs. Gasoline

Propane contains about 80% of the energy that gasoline contains.

Can you give a relative unit comparison so I can relate a $ to mile ratio? Drew

From Wiki:

thanks for info about using propane on motorcycle engine,how to change from gas to propane,seen a chevy truck that when ran out of propane,just switch back to gas,any help

THANKS FOR INFO ABOUT GAS VS PROPANE,USED TO HAVE CHEVY TRUCK THAT PROPANE COMPANY CONVERTED TO PROPANE AND GAS,WANTING TO CONVERT BIKE ENGINE IN TRIKE,WANTED TO KNOW IF YOU KNEW ANY DEALERS WHO HAD PROPANE KITS FOR ENGINES,SUCH AS USED ON FORK TRUCK,,100 HP ENGINE,DEBOO

Drew K thanks for info,trying to convert a bike engine to propane,trying to get info about gas vs propane,seen fork trucks and trucks why not bike engine

Only problem I can see on a bike is storage. You would need to store a pressure vessel in the bike somewhere. On a sport bike, you might fit something under the seat, or replacing the petrol tank, but both areas do not easily accomodate a pressure cylinder.

Otherwise, the conversion should be the same as with any vehicle. As I understand it, they inject propane into the air intake before the carb's. What I do not know (if I got the first part right) is how to throttle it.

Drew

It depends on a number of factors.

Is the engine of a design that could be propane friendly efficiency wise? 9:1 or higher compression and some method of easily advancing the ignition.

What is the cost and source of your propane? Around here bulk sells for around 1/3 the cost per gallon of gasoline and with road tax factored on it still around half that of gasoline. But if you buy it by the bottle at the local rip off mart you may end up paying double the cost per gallon of gasoline.

Propane has less energy by volume (gallons) but more energy by mass. (weight)

Many places unfortunately don't sell high quality propane (HD5 commercial grade or similar) but often have heavily diluted propane with butane and some other low grade vapor fuels mixed in. This alone can drastically affect the realistic fuel mileage and power you may get as well. You don't notice it when heating your house or running the barbecue grill but in a vehicle its easy to see it at times.

With a good compatible engine and a properly set up conversion you should expect around equal power in most cases and slightly less long term average fuel economy.

In the older engines there was more power loss due to the lower compression ratios used. Plus the modern vehicles are often quite detuned in stock form in order to meet emissions requirements. propane allows you to get around that detune so you can gain what was normally lost years ago. Hence why if its done right there will be little or no power loss. My 1999 Ford F250 with the V10 gained power and has the same average fuel mileage (maybe slightly better in some instances) on propane just because the factory detuning for gasoline dropped its efficiency so bad to meet the emissions requirements at the time.

Have you kept your truck as dual fuel? Can you still convert back to Gasoline if you run low on propane?

Drew

Yes! I always set up my pickups to be dual fuel capable. My present pickup has a switch under the dash that simply turns one system off and the other on.

Its as simple as flipping a switch so can do on the go change overs without problems!

When done correctly a proper dual fuel system conversion is reliable and very cost effective. Its the bad ones done years ago that still have people shying away from doing now, it I think. The old system designs and less than capable engines from years ago gave propane a bad image that seems to still linger on.

THANKS,USED TO HAVE A CHEVY TRUCK WITH DUAL FUEL,DID NOT THINK MUCH ABOUT IT SO I DID NOT GET ANY INFO ABOUT IT,WHAT COMPANY SELLS CHANGE OVER KITS,PARTS,THINK IT HAD A ROUND SPRAY BEFORE THE CARB,IN AIR FILTER,THINK SOME TRIED NOS GAS JUST FOR FUN,WANT TO CONVERT A BIKE ENGINE TO RUN ON PROPANE ,ANY HELP THANKS

DREW,THANKS,USED TO HAVE A CHEVY TRUCK THAT A PROPANE COMPANY HAD,WAS SET UP TO RUN ON GAS OR PROPANE,DID NOT THINK ABOUT IT MUCH THEN,THOUGHT YOU MIGHT HAVE TRIED TO CONVERT A BIKE ENGINE,LIKE ON A TRIKE FOR EXTRA STORAGE,ANY HELP IS GOOD ,DEBOO