Alternative Fuels

[Jason S]

To keep gaskets on a carburetor in good shape, it should be run with some gasoline every so often.

I've seen a many 87-up (TBI & MPFI) trucks with LPG setups but don't have any photos or info to offer on them.  I will say this much, in 2011 one farmer with a '88-up truck (I think it was  a '93) said that his setup had 'paid for his truck'.  In addition, Swan's food delivery ran some Chevy 4500 trucks with the 8.1L that were LPG.  In SW Oklahoma, there are several companies that take the 4500 trucks and install a flatbed in place of the refrigerator body. They seem to do quite well on LPG as farm trucks pulling some heavy trailers.   
 
With fuel prices as they are, I'm ready to pull the trigger and spend the money to have my 2005 Chevy 2500 4x4 switched over to a bi-fuel propane/gasoline rig.

[Jason S]

Update on prices and MPG. At this point, the GMC has not had any additional tuning or changes since installation back in 2012.  As for the MPG part, I have to say that I am pretty much mirroring Stewart G Griffin's post about gasoline MPG ...

8/19/2013 prices: LPG is $1.70/gallon; No-ethanol Gasoline ranges $3.45 - $3.52 per gallon

LPG tank filled to approximately 60%, as usual for test... So far with the 425 mixer on the '73 GMC, i've had to get fuel every 4-6 weeks. Price has been around $70-75 per refuel. 

335 miles driven on approximately 43 gallons LPG = about 7.85 miles per gallon driving in town. Mileage is down from last fill up; been using the air conditioner.

$72.59 for 42.7 gallons of LPG from 7/12/13 to 8/19/13.

Comparison of LPG to gasoline using current prices and fuel usage data from the '73 GMC K2500:
LPG: $1.70 per gallon/ about 7.85 mpg =  about $0.2165 per mile
Gasoline: $3.50 per gallon/ 10 mpg = $0.35 per mile

[Stewart G Griffin]

That's still a little better/cheaper than how i'm doing;   My last tank = .2404 cents per mile.  The same when i started the thread in 08!

i'd be curious to know what your highway mpg would be?

[Jason S]

Unfortunately, I didn't keep very good records when I was driving the truck on LPG and on the highway.  I can say that the monthly fuel bill was less than driving my 2005 K2500 on gasoline; I can also tell you that the 1973 GMC didn't get much more than 10-11 mpg-highway while on gasoline.  So it probably wouldn't be a significant amount of difference in cost per mile between highway and city driving. 

With your gears and setup, Stewart,  I would expect that on LPG (at Muskogee prices) you'd be quite a bit below my $0.2165 per mile.

Of course, all this is food for thought as gasoline and LPG prices vary quite a bit across the nation.