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Who's got Propane???

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mudbog42

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Who is running a propane injection conversion on their gas powered trucks and how do you like it?:cool:

Performance?:ooo:

Gas Mileage?:thinking:

And any recommened companies to go with?:deal:

86:usaflag: :k5:
 
I been reading up on this topic all night. May be trying it in the near future as well.

From what I read, bumping Comp. Ratio is a must. Cam selection can help as well.

One thing I've been trying to find out is, how does cylinder head flow effect things? Does a propane burning engine need the same flow characteristics as a gasser?

gotpropane.com I hear good things about this place.
 
First off, it is not propane injection a gasoline engine. It is strict propane fueling. Diesels inject propane for extra power, gasoline engines RUN on propane.

Everything is basically the same as far as performance parts are concerned. Compression bump isn't a must, just doable, and advisable.

Propane makes less power than Gasoline. If you take a good tuned, running 350 and go from gasoline to propane, you will lose power if you make no changes.

Now propane has a octane rating of about 108 on average. So that means you can bump your compression nicely, and advance your timing more. Both of those will make for more power(regain some of what you lost, and go beyond that as well.

Cam selection? I have never gotten a clear answer on that from people. To me, being as propane is a gas when it is in the chamber, something with limited overlap would be the best situation, but I have never found any confirmation on that.

Intake manifolds. I've been in debates about this. I've read previouslly that a single plane low rise manifold is best for propane. Lets the gas spread to all of the cylinders evenly, and will make more torque than a dual plane. However, some have told me that is incorrect. Personally I am going with an old holley single plane lowrise manifold I have in stock, I want to try it out.

My engine is a 383, roller LT4 hot cam, 10.5:1 compression with centerbolt 9C1 police engine heads ported out, Holly Street Avenger single plane, MSD distributor with MSD 6 Off-Rod box and an Impco 425 mixer on top. I have yet to run the engine, so I can't speak on it too heavily, just going off the info I have gathered in my build. Compression can gain back the lost power, as well as timing, but propane really likes a strong spark(thus the nice distributor and ignition box for me).

Oh and mileage, you will likely lose fuel mileage. For the same reason that it makes less power, it won't move the vehicle as far with as little(basically because of the lost power), so you likely won't gain any mpg. However, propane on the whole is slightly cheaper(used to be a lot cheaper, but it is catching up), and it burns cleaner. So you can go longer between oil change intervals and have less emissions out the tailepipe. I've heard of guys doing 3,000 mile oil changes and getting damn near clean oil out. My 383 will be Propane run from day 1 so it will be a good test of that information.
 
sled_dog said:
centerbolt 9C1 police engine heads ported out,

quote]

Any particular reason for the port work? Obviously there are gains to be had on a gasser but does it really help with Propane?
Click to expand...
 
A buddy of mine is runnin propane on his 72 Blazer with a 350. He got a kit from gotpropane.com. He's pretty happy with it. Mileage isn't so great as he hasn't modded his engine any except for timing. Power is roughly the same. The carb he had on there wasn't running so great at the time. He's runnin the 450 mixer. Runs real well. Install was easy too.
 
Previous comments are accurate, propane injection helps diesels burn the complete charge that is why they gain more power with it. Otherwise you reach a point of diminished returns with diesel, just dumping too much fuel into it without burning it, that's why they smoke so bad. Propane helps with this.
The higher compression ratio is the best way to go with a propane only engine. Get it up to 12:1 to 14:1, Shave heads or swap pistons to achieve this. As for the cam, minimum overlap is best, run a mild cam to get high compression at low RPM, and the torque will be large off idle.
 
Don't get caught running propane on the street. Even if you were using DOT approved tanks, the fine is thousands of dollars if you dont have the right permits. The government likes their taxes.
 
I started to piece together a propane kit for my 350 but it got too expensive and the big problem I ran into was finding a decent motorfuel container. You can run forklift tanks but they only hold somewhere around 8-10 gallons of LP so I was going to need multiple tanks. The decent sized motorfuel taks were 30-50 gallons and are expensive. I bought an old three chamber 50 gallon tank pre 1980's that needed rebuilt but no one would touch it.

So I found a guy in Canada who had good tanks but shipping was truck freight and then I gave up and threw everything away and went with a truck avenger.
 
8_YOUR_H2 said:
I started to piece together a propane kit for my 350 but it got too expensive
Click to expand...
Expensive? I've got like $400 in mine so far, with a BRAND NEW mixer, and BRAND new lockoff. If you bought used stuff you could get everything for that much. I am comparing it to the fuel injection system I was going to run, and its ****ing cheap in comparison to a decent TPI setup. All said and done I don't expect to spend more than $1000 and have everything(except the tanks are used) brand spanking new in the system.

As for the "Permits", not sure about that, I don't think there is any such requirements in PA. Except that the fuel tanks must be DOT approved, and checked yearly at inspection for damage or rust.

I have forklift tanks. 2 30 gallon tanks hold 16 gallons. Enough for a trail only rig.


And Cybrfire: Performance principles are the same whichever fuel you run. Just think of propane like you would 108 octane gasoline. Its going to run better with more timing and higher compression, beyond that the same performance principals apply. So the ported heads will just make more power. Granted I am puting a mid range power motor in a rock crawler, so its kind of strange, but I think it will be fun :D
 
It was cheap until I started shopping for the motorfuel tank.
 
sled_dog said:
I have forklift tanks. 2 30 gallon tanks hold 16 gallons.
Click to expand...

Huh? :confused: 2x30 = 16? Is this the New Math, or is 'pane somehow different than gas?

-- A
 
I've been thinking of puttng 425 heads on my 500 cad for the bump in compression. Supposed to be somewhere around 13:1.

All the Cadillac sites talk about the loss of flow with the 425 heads. However, most of those sites are geared more toward drag racing and are trying to flow mass quantities of fuel at higher rpm's.
 
find any flow charts comparing the 2 heads? Some heads flow well down low but not up top, but IMO usually when heads just don't flow well, they don't through the whole power band.

I think 13:1 may be pushing it, but I'm no octane expert. We ran a 12:1 350 on 108 leaded gasoline for a while. Ran pretty well, no noticeable detonation. So don't really know for sure.
 
I've talked to a few now with up to as much as 16:1 static. Unfortunately that doesn't mean a whole lot.

Just pm'd the gotpropane.com guy to see what his thoughts are. I could have Superwrench do some port work on the heads as well. I think I'm gona try it. The carb that's on there now really aggravates me and I just can't get into fixing it or getting a different one. In the end its still a carb.

mudbog42, Sorry if I hijacked your thread. Hopefully it all applies to the information you were seeking. Might as well keep it all in one place!:wink1:
 
when i was lookin into this over the summer i made some phone calls and it cost like $10-15 to get the sticker to make it completely legal here in LA to run it in a motor vehicle. there was a $150 flat, yearly tax on the propane. and the propane itself came out to $1.85 a gallon once the flat tax had been paid, this was when gasoline was running $2.85-$2.90 a gallon

even with a 10-15% loss in MPG and the $150 tax, I figured id still save $300+ in fuel costs per year, if i continued to drive the same amount that i have the last 3 years
 
This is a very interesting thread. I'm glad it came up because I'm in the process of doing research on converting a gas engine to run on propane. I think this is what I'm going to do to the engine in my next rig.

Scott
 
A friend of mine plans to convert his 170 ci slant6 Valient to a turbo & propane. He got a mixer from somewhere & was monkeying around with how it would fit when he needed to move the car. Hooked up his bbq tank to the mixer & it lit right off & idled. Did not have to set anything. Tossed the bbq tank in on top of the engine so that he could move the car across his backyard. Reportly drove just fine.
Kids, don't try that one at home. He's a professional. A professional what we shouldn't debate. :D


From "Alternative Fuels Guidebook" (Bechtold, SAE, 0-7680-0052-1, pg 66-67):
Propane's ideal A/F ratio is 15.7:1 vs. gasoline's 14.7:1
It's Research octane rating is 112, Motor Octane is 97 vs. gasoline's 88-100 & 80-90
It has 82,400 BTU/gal vs. gasoline's 109,000-119,000 BTU/gal (roughly 72% of the energy of gasoline per gallon)
 
Cajun4x4 said:
when i was lookin into this over the summer i made some phone calls and it cost like $10-15 to get the sticker to make it completely legal here in LA to run it in a motor vehicle. there was a $150 flat, yearly tax on the propane. and the propane itself came out to $1.85 a gallon once the flat tax had been paid, this was when gasoline was running $2.85-$2.90 a gallon

even with a 10-15% loss in MPG and the $150 tax, I figured id still save $300+ in fuel costs per year, if i continued to drive the same amount that i have the last 3 years
Click to expand...

Where are you finding propane that cheap?
 
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