Really? funny how my family has been in the trucking industry since the 40's I believe and not once have we seen a diesel semi with propane injection.

 

Gensets and stationary engines use a lot of propane, not so much the semis. Its a bit hard on the head gaskets if not used correctly. Most people running trucks these days don't want anymore repair bills than they get normally.

A lot of independents used to run it with the smal engines to give a little more kick on grades and such but they knew what they were doing with it.

The last numbers I remember that made sense was on the order of 300k to make the gained mileage pay for the system. Could be high, could be low, a lot depends on your perspective.

The easy way is just ignore the cost of the propane and base all your figures like that. Who needs those messy costs anyway.

 

Let's make sure we stay on topic guys. This isn't a thread for arguing it's use, just who uses it and how well it works. I have seen a few semis with propane injection btw.

 

I have a propane fumigation system on my big rig. Truck definitely runs better with it turned on than it does without it .. lots better. As far as fuel mileage is concerned, I use about 40 gallons of propane every 5,000 miles. The system only comes on when boost on diesel only exceeds 30 psi. My fuel mileage is pretty good for a 600 hp + setup. I average about 6.5 mpg on diesel on summer fuel, so when you figure it up I use about 770 gallons of diesel for every 40 gallons of propane. That makes for a combined average of about 6.17 mpg, running between 65 and 75 mph, which I think is OK. The price of the propane is significantly less than the diesel per gallon. The biggest downside of my system is the weight. I have a 60 gallon Mansfield saddle tank setup and the tank alone is heavy --- well over 200 lbs, I'm sure. Including mounting brackets, lines, safety straps etc. I propably have nearly 300 pounds in the system exclusive of the propane itself. The key to successfully running propane is to never get a rich enough mixture of the propane and the air you're feeding the engine to let it support combustion on its own. That keeps the timing dependent on the diesel injection event and also prevents colliding flame fronts and pressure spikes within the cylinder. You get the nice flame front of the diesel injection plume propagating across the piston to the cylinder walls, just with much better combustion along the edges with the propane. Too much propane and the propane air mixture can start burning ahead of the diesel flame front and that's where the problems start. Oh yeah, I've had my system installed on my truck for several years and probably 800,000 + miles with no engine problems.

 

The point is to put out info , if some one hasn't seen or does not think it works , then the best way to respond is either ignore , or question it till you understand .
To take a position of basically calling someone a lier or snake oil salesman is short sited at best .
If like many things I've done [ have worked on trucks that have propane & know some that do ] I would do this if I found the equipment cheap enough to do , not retail prices .

 

I have the Superchips Digital Propane System . I get 17 miles per gallon without it turned on and 19.5 to 20 with it turned on . When you add the cost of the propane ? Now if diesel goes over $4.00 and you can get propane for a little over $2.00 ? . What I realy like is going 600 miles on a tank before I have to fill up .

 

In answer to the original posters question. Many vehicles use propane fumigation for mileage gains. The key to getting mileage gains is to not try to displace diesel with propane, meaning don't try to run the truck on propane. The problem with homemade and some manufactured systems, is that there is no variance or control to the amount of propane. They all come on at a certain boost pressure, but then some just flow at one rate, on and then off. Using a lot of propane to do so,and will negate your mileage gains/savings. If the flow of the propane is varied and proportionate to the boost pressure, it will yield higher mileage gains, because you are not using a ton of propane. It is also a smoother more driveable onset of power and ultimately safer. Hopefully people who have actual experience with propane fumigation systems, will respond to your question. I think you will find among them, that they have used them for years, love them and get moderate mileage increases.

My 05, the former fuel pig, gets 17-18 without propane on, with I see 24-26mpg, sometimes as high as 27-28. Now of course that is not free mileage, I am using propane to get that, but it still works out to be a net gain.
My cost per mile, even using 2 fuels, goes down. My 30 gallon propane tank, lasts around 2500 miles. Of course, you have to buy the propane at a reasonable cost. For example, every Flying J, Pilot Travel Center, now has propane and it averages from around 229- to 319. Still cheaper than diesel. If you buy it at a U Haul, you may pay more which would then bring your $$ /mileage savings down.

There actually are several companies that cater to the over the road truck market in propane fumigation, The Enhancer, Acme Carb and Fire Em Up, all have system designed for semi's. Catepillar actually has a patented propane injection system, although it is more of a theory patent than one that could actually be produced for the masses.(cumbersome and involves a series of modules) Cummins has a dedicated propane engine. Roush has just built a F150, that runs on liquid propane injection. It does work, just have to do it the proper way, as with anything.

You will see more and more fleet companies, will turn to propane injection as a means to reduce emissions, (cheap retrofit) and increase mileage.

 

Thanks Powershot1, Now I know I'm in the ball park with my homemade system. I'm getting 3 1/2 tanks of fuel to a 20lb thats roughly 2000 miles. I refill my own tanks off my tank at home, very cheap my last fill at the house was filled last summer 1.69.

 

DiezelSmoke, Do you have a breakdown of the parts and installation method you used on your homemade system. I am interested in installing one myself in my 2000 RAM 2500. Thanks. I have tried the Hydrogen Generation systems with no success. Propane sounds promising.

 

I would like to know about the propane system too. maybe post another thread?

Thanks......

 

"My 05, the former fuel pig, gets 17-18 without propane on, with I see 24-26mpg, sometimes as high as 27-28."

wow..sign me up , up to 10 more MPG

I`ve heard propane isn`t good for the common rail trucks.

 

ya if the govt sees you getting 28mpgs with a fullsize truck they will probaly take it from you,ive never seen a 3rd gen get any better than 23 and thats a 2whdr with high gears.maybe a older 160hp 1st gen may get over 25 babying it.

 

I will second Powershotone's results. I just got my home made kit in and runnig and have seen similar results. Seeing ~24 on average with a 4x4 on 35s.

 

Nope...not me , no propane here.

I was quoting someone who posted earlier.

Are you calculating ACTUAL mileage with your trucks computer re-set for the 35s or going by the overhead readout?

 

Oops. Thats what I get for skimming. Sorry. I have not corrected for the 35s and as such, based on previous hand calculations, I have determined the overhead is pretty close to correct when actual mileage is used, not displayed.