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73-87 Chevy _ GMC Trucks => 73-87 Chevy & GMC Trucks => Topic started by: Jason S on January 23, 2013, 09:48:08 pm
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I wanted to start this thread because there were several questions relating to LPG and CNG that were taking away from 78Chevyrado's thread on MPG (i.e., http://forum.73-87chevytrucks.com/smforum/index.php/topic,25286.30.html (http://forum.73-87chevytrucks.com/smforum/index.php/topic,25286.30.html) ).
I know there are few people on here running LPG (propane) on their vehicles, myself included. There are several people that seem to have an interest, or at least questions about LPG.
I am not the foremost expert on LPG as a motor fuel, however I have found that for me it really is so easy that it is almost a no brainer. For some of the discussion about LPG and CNG that was started on the previous thread, please post them here to keep 78Chevyrado's thread on topic...
Here is a posting that I put together a while back about the process of installing a bi-fuel propane system on a carbureted Chevy truck with a 350 (Impco 300 and Impco 425) : http://forum.73-87chevytrucks.com/smforum/index.php/topic,23550.0.html (http://forum.73-87chevytrucks.com/smforum/index.php/topic,23550.0.html). These Impco systems would cover most 350 through 454 trucks, and other makes with similar engine sizes (e.g. Dodge 360-440, Ford 351-460, AMC/Jeep 360-401, etc.).
I personally would be interested if anyone else has photos of their installed propane systems, especially those on smaller displacement engines such as 292 I-6, 307, 305, etc.
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I would like to know if you or others could post some links to articles on LPG & CNG so I can do my homework and read up on this topic.
I know I am being a little lazy by not searching myself. But I figure to take advantage of your hard work and educate myself in the process.
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Bake74, there is no use in reinventing the wheel. Below are some pretty useful links that have a lot of information.
Here is a link that has good overall information: http://www.rasoenterprises.com/index.php/alternative-fuels/propane (http://www.rasoenterprises.com/index.php/alternative-fuels/propane). Actually, the site discussion board also has good information too http://fuelsforum.rasoenterprises.com/ (http://fuelsforum.rasoenterprises.com/).
Here is a link covering many aspects of LPG. This fella put a LPG system on a 1963 AMC Rambler, but there is very useful information and links here http://www.wps.com/AMC/LPG/index.html (http://www.wps.com/AMC/LPG/index.html). However, what you probably want to read first is here http://www.wps.com/AMC/LPG/LPG-book-final.html (http://www.wps.com/AMC/LPG/LPG-book-final.html).
Information from the U.S. Department of Energy - Alternative Fuels Data Center, the propane link is here http://www.afdc.energy.gov/fuels/propane.html (http://www.afdc.energy.gov/fuels/propane.html)
Franz Hofmann is now with the Texas Railroad Commission (RRC deals with energy and oil). He posts a lot on the Raso Forum. Here is a link to one of his blogs: http://blogs.rrc.state.tx.us/TPF/?p=2678 (http://blogs.rrc.state.tx.us/TPF/?p=2678)
Here is a link for manuals that Franz Hofmann had a hand in producing http://www.autogasusa.org/resources-landing-page/ (http://www.autogasusa.org/resources-landing-page/)
Bake74, there is a ton of information in the various links; happy reading!
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Have you noticed a loss or gain in power with lpg? What are the negatives of a setup?
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Power is about the same. Cold weather startup is awesome as compared to a gasoline carburetor.
Negatives:
>Giving up bed space for a tank;
>Propane suppliers are not as plentiful as gasoline stations (however, if one has a house propane tank they can refill the automotive tank at home);
>Auto parts stores likely won't have kits/parts (Some propane suppliers keep those parts, but not all);
>As a bi-fuel (LPG & Gasoline) with the engine tuned to operate adequately on either fuel will not deliver the full potential of either fuel. In other words, an engine tuned for the best gasoline operation will not be optimal for LPG operation and vice-versa. So while I can switch between the two, I could get better LPG performance if I were setup the ignition to better match the LPG needs, which is generally a performance curve with all in by 2800 rpm and 30-34 degrees total.
> Detonation with LPG needs to be avoided as it is generally much worse for the engine than detonation occuring with gasoline, again this is where ignition tuning is important (especially at higher compression ratios).
>To take the most advantage of LPG, higher compression ratios are needed. An engine with 10:1 or more would be more efficient than one at 9:1 or 8.5:1.
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Power is about the same. Cold weather startup is awesome as compared to a gasoline carburetor.
Negatives:
>Giving up bed space for a tank;
>Propane suppliers are not as plentiful as gasoline stations (however, if one has a house propane tank they can refill the automotive tank at home);
>Auto parts stores likely won't have kits/parts (Some propane suppliers keep those parts, but not all);
>As a bi-fuel (LPG & Gasoline) with the engine tuned to operate adequately on either fuel will not deliver the full potential of either fuel. In other words, an engine tuned for the best gasoline operation will not be optimal for LPG operation and vice-versa. So while I can switch between the two, I could get better LPG performance if I were setup the ignition to better match the LPG needs, which is generally a performance curve with all in by 2800 rpm and 30-34 degrees total.
> Detonation with LPG needs to be avoided as it is generally much worse for the engine than detonation occuring with gasoline, again this is where ignition tuning is important (especially at higher compression ratios).
>To take the most advantage of LPG, higher compression ratios are needed. An engine with 10:1 or more would be more efficient than one at 9:1 or 8.5:1.
and it wears out the valve guides a whole lot quicker than gasoline...plus side is that the engine doesn´t accumulate oil sluge or carbon deposits like they do with gasoline...
i run lpg on my daily driver its a nissan d21 pick up...
i´m thinking about adding it to my chevy stepside i´m currently building... where i live its about have the price of gas...
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Thanks Jason S for the links.
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Thanks Jason S for the links.
No problem. I hope it helps some, it is at the very least informative food for thought.and it wears out the valve guides a whole lot quicker than gasoline...plus side is that the engine doesn´t accumulate oil sluge or carbon deposits like they do with gasoline...
i run lpg on my daily driver its a nissan d21 pick up...
i´m thinking about adding it to my chevy stepside i´m currently building... where i live its about have the price of gas...
When you say LPG wears out valve guides quicker than gasoline, at how many miles would you say? I have read of a few cases where guides were worn after 100K miles, the rest of the engine looked spotless with wear like an engine with less than 50K miles.
Currently LPG is $1.80/gal (plus federal tax) versus the price of $3.03/gal (pure gasoline- tax included) for 87 octane here (Muskogee, Oklahoma).
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When you say LPG wears out valve guides quicker than gasoline, at how many miles would you say? I have read of a few cases where guides were worn after 100K miles, the rest of the engine looked spotless with wear like an engine with less than 50K miles.
Currently LPG is $1.80/gal (plus federal tax) versus the price of $3.03/gal (pure gasoline- tax included) for 87 octane here (Muskogee, Oklahoma).
oh yeah, i´m talking about over 100k miles... you know most gasoline engines are fine at 100k with their guides but the lpg wont be so good especially if the mixture is lean... the only real negative thing i see in lpg is the smell... not that great of a smell when it burns other than that, it runs cleaner in the engine, cheaper than gas, if its cheaper than gas by 30% i think its worth the conversion...
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Here in Puget Sound, propane flirts around $2.10-2.25/gal with large home deliveries, but propane prices in general are all over the place. If you go with small stations you can pay around $3/gal and regular unleaded is around $3.25 right now. That means that you really have to watch what you pay for with propane! Because it takes about 1.36 gal propane to equal 1 gal of regular 87 octane unleaded we would want to see a Propane price lower than about $2.38/gal. Which for us doesn't really work-out unless you are buying large quantity home deliveries.
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ehjorten: There are many LPG suppliers around here that will give a good price break if you place an order in summer (when demand is down) and pay for half or a third... They will store it, it's just that your commitment to buy say 1,000 gallons for a half year or year will help their bulk order. You may have to pay several hundred dollars up front, but then you get discounted fuel afterwards.
If gasoline prices come way down and propane doesn't then there definitely isn't a cost advantage. However, I personally don't see gasoline prices going down anytime soon.
You're right in that you have to watch prices and compare one supplier to another. If you're using propane at the house, you're likely already doing that anyways.
gildardo01: The propane exhaust does have a different odor, but I find its way better than exhaust from 'old gasoline' or a poorly tuned engine.
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GTO109 asked on a different thread:
Jason S will your set up run on natural gas as well? With me living in central pa where they are doing a lot of gas drilling right now they are starting to put up natral gas stations around here.
I initially said pretty much no. After doing more research (though I only had a chance to skim through a good deal of the write-up) there is a way that a Impco setup running LPG could be used for compressed natural gas (CNG). As compared to an LPG setup, the tank would still have to be replaced with one rated for CNG (>2,000-3,000 psi) with high pressure steel lines running from the tank to a CNG specific "regulator" then to the model E regulator then to the 300 or 425 mixer. So, GTO109 the answer to your original question is yes (with additions).
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Last year I removed the Impco 300 mixer from the '73 GMC and and installed it (with a propane system) on the '74 Chevy K10. I then installed an Impco 425 on the GMC. The conversion/swap can be found here http://forum.73-87chevytrucks.com/smforum/index.php/topic,23550.msg207683.html#msg207683 (http://forum.73-87chevytrucks.com/smforum/index.php/topic,23550.msg207683.html#msg207683)
So at the time I was doing the swaps last year: we had a tornado, had a baby, work relocated me, bought a house, moved across the state, had to unpack, set up a shop, etc.
Fast Forward: I've finally had a chance to drive the '73 GMC K2500 with the 425 Impco mixer. Propane prices are $1.75/gallon here (versus $3.33/gal for 87 octane gasoline).
Drivability with the 425 has been really good, even with the Q-jet still installed. However, I'm starting to think about just eliminating the Q-jet and adapters and going straight propane. That project, I'm quite certain, will be further down the road.
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Update on prices and MPG.
7/12/2013 prices: LPG is $1.70/gallon; No-ethanol Gasoline ranges $3.47 - $3.55 per gallon
358 miles driven on approximately 40 gallons LPG = about 8.95 miles per gallon driving in town.
LPG is dispensed in gallons, but the tank gauge is in percentages of full; so it is difficult to get accurate to tenths of a gallon. I've been having the supplier fill the tank to 60%, but it isn't exact.
Comparison of LPG to gasoline using current prices:
LPG: $1.70 per gallon/ about 9 mpg = about $0.19 per mile driven
Gasoline: $3.50 per gallon/ 10 mpg = $0.35 per mile driven
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I have had some time spent with LPG conversions . The Impco Unit was a very nice setup . It's been a while but the other units (can't remember the brands ) were a fiddle with every other day deal .
The dual fuel conversion has one big draw back on trucks with carburetors . If you run On LPG for an extended amount of time the carb gaskets will dry out . Most leaked or Run lousy when switched back to gas . The guys that switched back and forth seems to do OK .
I haven't seem this setup on an injected truck but for giggles and grins would like to . that might be the best of both worlds .
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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.
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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
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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?
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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.