If I might chime in- propane does not burn until around 1400 degrees + - and diesel is in the 400-500 degree range. In effect- the diesel burns the propane. What the propane does is burn slower (higher octane -116) and longer so it burns the rest of the unburned diesel on some tests upwards of 90% efficiency. It also is a fuel (of course!) and it provides carbon (hydrocarbon) that we need for the power. So it helps burn the unburned diesel- raises octane - is cheaper than diesel (yes! the amount of propane I use is 15 dollars for every 1000 miles!) My mileage increase end result is 24-25.2 mpg on interstate at the speed limit up from 18-19 natural diesel only. Here is the interesting part- my self designed system is variable- flow (more at higher rpm's and load) and I use a hobbs switch set at 1 pound! The reason is that I use mine for mileage and at 65 mph on highway I am running 3 lbs boost flat ground cruise control. I want the propane on at cruise. While towing- my truck rarely downshifts out of overdrive with propane on 16000 lb fifth wheel. I also use a two selenoid system to save propane in regulator so that on letoff (downhill or braking) the propane is off but saved. My system really works- and the power amazes me. Remember I had hemi cars (426 not 5.7) and am hard to impress. I can sell the kit complete for (pm me) but it is lower priced. Also you do not want to turn your propane on until 170 degree water temperature to prevent pinging. Other than that- no problems and street racing is fun- I've surprised a lot of people.

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Also propane bottles are usually at 80lbs pressure so would work in intake manifold on engine but would be better pre-turbo to not only mix it up but there is no boost in that tube between the air filter and turbo. All things work better when better atomised -diesel and methanol included. That is why the trend will be with water methanol injection to go to a higher pressure pump - some racers use 600+ lbs of pressure pumps. All in the interest of vaporization.

 

Good info...some pics would be great.

 

This is what I want to know. Your thread and input has been very informative.
Thanks
Dave Bybee

 

Plus one!

 

16MPG 98 dually 20ft gooseneck 4 horses 70 MPH for 4 hrs

 

i've been lookin for some all around info on propane injection an you my friend have just saved me alotta time searchin. not many guys i know have ventured into the lp era of diesel... but then again im not many guys

 

I might have some add-ons on using propane in a diesel:

-propane does not mix very well with air, so it has to be added as soon as possible to get a good air-propane mixture.

-propane won't ignite itself as long as Diesel is injected and autoignites itself. The minimum ignition temperature of propane in air is 842°F. Diesel itself ignites at 494° F. This makes the use of propane in a diesel possible.
So when the Diesel(15-25 octane) ignites it raises the temperature to a level the propane(110 octane) gets ignited.

BUT:
-the fuels start to compete for the oxygen left in the combustion chamber.
And propane does burn a lot faster(!) leaving a lot of unburned diesel in the chamber.
Propane is already in a gaseous form- this is the reason to burn a lot quicker than diesel.

The unburned diesel will be regnited again from the propane flame front causing a delay and a second flamefront. This is what we call detonation...

Sure, propane works- its just a question of proper adjustment and release timing.

Having all the written stuff above in mind it seems to be smarter to add more diesel first.


So what is propane good for:
- as a use as a moderate power adder
- as an increase when the powerlimit with conventional methods is already reached

 

How much more efficiency will the propane add to the burning of diesel? I have been thinking about a systems that would inject propane pre turbo and turn on at 3-5 psi and off at 10 psi so that it would only be used for economy instead of high HP (bigger injectors and power box to take care of that)

Just looking to make the engine more efficient at low-mid range power level.

 

this is the reason you should put it pre-turbo as shown in the pictures.

 

Zero. It will actually reduce diesel efficiency because of the two fuels and flame fronts competing for oxygen.

There is actually no actual mileage or money savings with propane, its just a substitution fuel. The small difference in the cost per gallon of propane and diesel will take years to recover the cost of the propane system.