Rob Agnew wrote:
>
> Not true. There is 30% less energy in a litre of propane than in a litre
> of gasoline (therefore fuel economy falls - miles per gallon). However, by
> advancing the timing (higher octane), you increase you're fuel economy a bit.
Correction:
Quoted from U.S. Department of Energy, Alternative Fuels Data Center at:
http://www.afdc.doe.gov/misc/cngfacts/cn12.html
Start Quote:
Vehicle Performance
Converted vehicles drive very much the same as gasoline vehicles. The
most significant difference a driver may notice is a slight power loss.
Because all engine parameters are not fully optimized in converted
vehicles, full emissions, power output and fuel economy benefits are not
achievable. For example, use of CNG in an engine may result in a 10-15%
reduction in power. Propane use may result in loss of power up to 7%.
The power loss is primarily related to the displacement of intake air by
the fuel vapor. Since gasoline is metered as a liquid, there is very
little
displacement of the intake air. Excessive loss of power, however, may
indicate improper installation or tuning of the conversion system. Just
as
with conventional gasoline vehicles, power and performance can be
optimized through engine adjustments of the air/fuel mixture, ignition
timing
and compression ratio.
End Quote
> Depending upon your application, fuel economy may stay the same or drop off.
I have seen an improvement in fuel economy with a slight decrease in
performance in my '85 pickup. The engine is stock, with only the
carburator replaced.
The increase of fuel economy is usually due to an inefficient carburator
being replaced with a more efficient mixer.
IMHO.
Tom McCabe
'96 Dakota CC, 2wd, 5.2L, Auto, 3.55SG, Gibson Cat Back Exhaust
'85 D250 P/U, 2wd, 5.2L, Auto, On Propane (Awaiting 340 transplant)
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