Has anyone tried A propane injection system to increase their fuel economy?
It has been advertised that power and increased economy is a result when adding propane injection?.
Does anyone have any real world numbers on this?
Doug.

 

(LONG)

Where to begin. This information will much more than answer your question. I'm an engineer and I work with a company that produces the majority of MSD ignition's billet parts. As such, I have gotten to know a number of the engineers at MSD. In case you didn't know, the Superchips propane injection was originally marketed as an MSD product.

Anyway, down to the point. Their propane injection is much different than others on the market, it is on all the time, ran by its own computer that is tied into the signals for your computer (with many safety features, like no propane injected below 1,000 RPM). I spent quite some time talking to the Engineer who developed it as well as the first beta tester. The engineer explained that the rate of injection is adjustable, but comes from the factory set at a 1:1 ratio. The propane computer actually decreases the amount of diesel fuel being injected into the cylinders.

So, lets see if i can explain this. You are running the same volumetric amount of diesel as propane. Propane has a lower energy content, but you aren't injecting propane to burn propane only, you are injecting propane to increase the combustion rate and efficiency of the diesel fuel. Think of the expansion of a flame front of diesel fuel as the fingers of an open hand. There are spaces between the "fingers" that haven't started combustion. Propane is in a homogeneous mixture in the cylinder with the air. The ignition of the diesel instantaneously ignites the propane in the cylinder. The propane then ignites the remaining diesel fuel in the cylinder creating more efficient combustion.

Hang on, it gets closer to the point below...

To get to the point, you will most likely double the mileage on diesel fuel, but you are also adding another fuel. Say your truck gets 16MPG on diesel only. With propane injection, you will effectively get 32 MPG diesel with 32 MPG propane, which gives you a total of 16 MPG. There are some increases in fuel mileage, but not what you may expect. The power is increased because of the more efficient and complete combustion, and you EGTs are also decreased because of the lower energy content of propane.

I can tell you that the beta tester, who happens to be the service manager at the dealership i take my truck to, gets about the same mileage as he did before "combined" as i stated above. He doubled his traveling distance, but thats about all.

The other advantage is you 50% of the fuel you are burning is a cheaper fuel, costing somewhere around 2.50-3.00 per gallon verses the 4.00 a gallon for diesel. I did a little figuring a while back and at an average of 20k miles a year, you would save around 1k in fuel which would pay for the system, but not the tank. Oh yeah, and you will most likely pass most emissions tests off of idle.

I hope I didn't bore you to death...

 

I have the Superchip system on my truck . My truck went from 17 mpg to 19.5 , 20 mpg . When you figure in the cost of the propane ? I don't think I am saving much . But if propane stays the same and diesel goes any higher , how Knows ? What I really like is 650 miles on a tank before refueling .

 

Not at all; however - several of your non sequitur statements are eyebrow-raising...

Is this interpretation of propane's benefits in a 4-stroke turbodiesel an MSD engineer's explanation of the process?

Did your service manager try to sell you a system?

What is your engineering specialty?

 

The explanation of the benefits and the combustion process is what I learned in my thermodynamics and Internal Combustion Engines course I took in college, taught by the man who developed Nitromethane who consequently taught MSD's Engineer as well, a few years before me. I have also had the great opportunity to work with this professor many times since and enhance my knowledge.

No, the service manager didn't try to sell me a system, we were talking about many things including biodiesel, propane, and the Superchips chip, which he was also a beta tester on.

Sorry if I couldn't conclude things logically, it was late last night when i wrote this.

oh, and I possess a Mechanical Engineering Degree.

 

Neat!

Were they still teaching Henry Petroski when you were in college?