Compressed Natural Gas System

[res0wc18]

hey guys just finished reading my recent issue of diesel power.

In the section of the fuel mileage test one of the guys in the test had a regular cab gmc and he had a CNG system on it and was getting 38mpg!

this could be a folly, but still i am interested in such a system.

I know there is propane injection systems that help burn the fuel, but i think the system in the magazine he burned mostly CNG.

So my questions are does anyone have experience with these systems?

Where can you buy them?

Anyone made their own?


i guess it would be considered a duel fuel system? Because if it were on CNG it would need spark correct?

 

[RKOCH]

A compression ignition engine will not light off CNG or propane by it self the diesel fires and lights off the A/F mixture in the cyl. Not enough heat by compression alone to fire it.

 

[93turbo_animal]

if you can't light propane from from the compression heat then why if you add to much it detenates

 

[geonc]

Isn't the purpose of adding propane to increase BTU's? And that in turn maximizes the combustion while helping to vaporise the carbon/soot keeping the oil cleaner....

As far as detonation, the only reason I can think of is exceeding cyl pressures

 

[RKOCH]

if you can't light propane from from the compression heat then why if you add to much it detenates

It dosen't detonate that is a misconception. In a IDI the lighting of the fuel takes place in the pre combustion chamber where only a small amount of propane is mixed by volume as the flame exit that chamber it ignites the large amount contained in the Cyl and give you the big bang that is what you are hearing. The heat generated by a diesel from compression is well below the flash point of propane. A gas engine you use a spark plug no problem. Hold a propane bottle to a diesel engine with no diesel in the fuel system it will crank all day and never fire. Adding propane to any diesel creates a secondary explosion so to say. Now on a NON IDI such as a stroker the diesel is lit off in the presense of the entire A/F mixture in the CYL because it is direct injected so you don't nearly get the bang but the more you add the more of the bang you will hear.


http://www.speeddemontrukworx.com/principlesofpropane.html

 

[res0wc18]

right.

but has anyone hear used them with success. Im talking about what they call a dual fuel system, or a propane injection type system.

 

[RKOCH]

Yes I am running one on a 7.3 IDI right now. All homemade works great fuel milage increased and so did seat in the pants power.

 

[res0wc18]

home made huh?

How did you accomplish this?

 

[RKOCH]

First of all you don't flood the engine with gas. 5 to 7 percent of total air is fine. I made a nozzle that fits in the air intake stream just infront of the turbo with a 3/16 orfice. I am using liquid propane tank now which requires more parts much as a vaporizer to flash the fuel to gas before entering the engine. This I stole from a forklift and uses engine coolant. As far a delivery a good adjustable propane regulator @ the tank. Plumbed SS braid lines up to a NOS solinoid and to the nozzle pretty simple there. There is a switch in the intake hat that closes @ 4 psi this is what activates the automatic injection under normal cond. I also have a by pass momentary switch on the floor that I can hit and inject propane @ anytime. I have master arm switch that turns everything on so if the switch is not on the propane does not come on. At the pulls I turn up the reg and let the gas flow and use the foot switch off the line till the turbo catches up.

 

[res0wc18]

that is genious. Got some more info on the wiring and possibly some pics?

How much are the vaporizers? Adjustable propane regulator? I dont know if ive ever seen one of those.

Does this work on the new OPD tanks?

 

[TooManyTrucks!]

I have that issue of diesel power and can't understand how they calculate the MPG using Diesel and a secondary fuel such as CNG. In that article in the magazine, they calculate only the diesel fuel for him to win the category handsdown.

 

[res0wc18]

i too was wondering about the gas consumed during that. But either way at 70 cents a gallon!