I have an LLY that I bought in mid July. It has 4700 miles on it now, 4000 of that with propane supplement. I took it from Ohio to Dallas and back two weeks ago, averaged 30 mpg at 75 mph on diesel. Don't know exactly how much LP I used, probably around 35 mpg on it. I need to quantify the LP usage using a small tank that I can weigh. Has anyone else played with LP for continuous use rather than just for shots of power? I have used LP on gas motors for 15 years, but this is my first diesel. At present, I think it is only saving me about 1 to 1 1/2 cents a mile, but that is about 10 to 15%. Also, the engine is much quieter at highway speed.

i havent yet but am considering putting on in next week. what system are you using ?

I took it from Ohio to Dallas and back two weeks ago, averaged 30 mpg at 75 mph on diesel. Don't know exactly how much LP I used, probably around 35 mpg on it.


Are you saying you got 30mpg on just Diesel or am I reading this wrong??


If so I would liketo know what you did to achive this???

He got 30 mpg on the diesel but it costs propane to do it. If I understand him correctly he also uses a gallon of propane every 35 miles.

i believe with some applications like the holeshot where its a variable flow injection based on boost, that an 8 gallon propane tank would last about 1000 miles, atlease thats what ive been told by distributors and a buddy who runs one. Other systems that are set up differently may not yield that amount and the parameters for flow, CFM, boost, etc can all be changed meaning you could use more or less depending on set up and application

Max Power is correct: You use both fuels at once. I get 30 on diesel, but at the same time I am using almost as much LP. If diesel is $1.80, that comes to $.06/mile. My LP is $1.02/gal, which comes to about $.03/mile. I would get about 18 mpg on diesel alone, which would be $.10/mile. So it only saves about a penny or so, but the motor burns alot cleaner and quieter and the oil stays like new. I have a really simple setup, it is an Impco model E vaporizer/regulator piped directly into the intake pipe ahead of the turbo. I have a 3/4" hose with a ball valve to adjust how much gas it gets. This regulator requires vacuum to let fuel in, so it varys fuel by the amount of vacuum. This regulator is plumbed in series with the heater core to provide heat for vaporization. It uses enough LP that it would freeze the tank if I were drawing vapor instead of liquid from the tank. This is a common regulator on LP gas motors. The only other item is a fuel filter/lock solenoid that is on a toggle switch. I had a 30 gal tank for my first trip, which was to Milwaukee and back. (1100)miles It ran out before I got home, so I put my 100 gal tank from my previous truck in for the trip to Dallas. I estimate I used 60 to 70 gallons on the trip.

How much more power do you get with propane setup like that? What do you do if you need to go to the dealer ?

marcdeluca, I'll have to take a look at your set-up sometime.


We are down at the Boyscout camp quite a bit.

I bought this truck locally, and traded my '00 that had LP from the day I took it home. (I removed the LP, it was worth nothing to them) I have a pretty good relationship with them, and explained that I was doing this for mileage and clean burn and not for power. This thing has so much power already that I can't imagine why I would need more. The LP certainly does give more power, but you have to be careful and not give it any while it is upshifting. The motor will spin up if you do. This is because the program cuts engine power during the shift to take strain off the trans, then gives it back right after the shift. If LP is on, the engine still makes power during the shift. I either accelerate slowly to keep from pulling in much LP, or turn if off until I get into 5th. Another thing, you never want to give it so much that the mixture approaches 16:1, otherwise it will preignite under compression and can give a harsh ping. I have been conservative with it and haven't had that happen.

Hey marc, welcome. Where did you get your propane setup? How much does it cost. Did you get 700 miles to the tank while you were using the gas? how do you adjust how much propane goes to the engine? I dont really care about the performance boost because I already have the edge/attitude and this truck hauls already.

I went 950 miles on the first tank of diesel with my current setup. It took 29 gal to fill. Half of that was at 70 mph, the other half at 75. With my first setup, the one where I drew vapor from the tank, I got 27.5 on diesel at 70 mph. It would be interesting to check the mileage at 5 mph increments, because I think the ratio of LP to diesel goes up with load. In other words, the faster I go, the better the diesel mileage! Of course, the combined mileage would be less with more speed. This setup is straight off of my '00 crew cab 454 that I traded, minus the electronics. It doesn't have any type of controller that is necessary to interface to the computer on the gas rig. All I have to control flow is a ball valve in my 3/4" inlet line. That changes the ratio across the board. Ideally, It would be nice to have some switches on it to turn it on automatically once it is in 5th gear, etc. I got most of my LP stuff used, some on ebay, some new that I couldn't find used. ebay has Impco regulators on there pretty often. If you want to try it, let me know and I'll send you some pics of the setup.Edited by: marcdeluca

send em on down, thanks!!

Anybody have the Bulley dog propane kit???

what about the kits selling on ebay - are those decent or not worth it - it looks like its the set up, pretty cheap, then you just need the propane tank and filler, not too costly again.... anyone ?

OK, I'm always out in left field somewhere, but what about Compressed Natural Gas??? Is there a system for that? Is it cheaper than Propane? What will it do for mileage?


I always see the City Buses running CNG- They sound like a diesel engine...???


Ed

CNG is certainly an alternative to LP that works just as well. It's major drawback is that since it is compressed and not liquified, you have to have alot larger tank for the same amount of range. It is definitely cheaper than LP because there is no road tax on it. We have a CNG refuel station in our town, and it is $1.20 per gallon. (You don't actually buy it by the gallon, since it is a gas, but the pump converts cubic feet to equivalent gallon. Something like 125 cu ft would equal the same BTUs of a gal of gas.) You can get regulators pretty easily. I have free gas at my house because we have a gas well on the property, but compressing it is the expensive part. There are residential compressors available, but they cost over $5000 plus take electric to run. So free gas isn't free on a vehicle. The buses you see running on it still make noise, but the higher percentage of gas to diesel that is run, the quieter they get. My truck seems quieter at 75 than at 60 when getting gassed.