propane and CNG

[bir7514]

I was wondering if anybody is running propane or CNG. And also how much it helped and how hard the installation was.

 

[farmboy99]

All ive heard is that the power gains arent worth the harm it does to ur block, id use da juice before pane...

 

[Hoss 350]

I was wondering if anybody is running propane or CNG. And also how much it helped and how hard the installation was.

What is it that you are looking for? This is the first step in the answer. How much it helped what? Fuel economy? Power? Insane tractor-pulling (I don't care if the engine explodes i want more) power, or trailer towing on the weekends power?

These are all important things to know in developing an answer on whether pane is right for your truck.

Here is what I think I know about pane, for your perusal:

Pane is an intake-delivered fuel in a compression-ignition engine, which is a dangerous thing if not done right and intelligently. This is because YOU CANNOT CONTROL IGNITION TIMING with an intake delivered, compression-ignition fuel setup. Gasoline engines are intake-delivered fuel systems, but the ignition is controlled by spark, so you can dictate when ignition occurs simply by timing the spark properly. Diesel engines are injector-delivered fuel systems, meaning that you can control ignition by timing when the fuel is injected into the compressed cylinder.

You can do neither of these things with propane. It goes into the cylinder on the intake stroke, and then arbitrarily explodes during the compression stroke whenever the conditions are right (ie, it gets hot enough). This is the definition of pre-detonation, and pre-detonation is very, very hard on reciprocating piston internal combustion engines. YOu have a piston compressing gasses. Then the gasses combust and expand like crazy, all while the piston continues to compress them. What do your cylinder pressures look like in this situation? Yeah, it will make power, but at what cost? Also, keeping in mind that conditions in the cylinder change all the time, the timing of your pre-detonation event will be all over the map. Hot day, high load? Hell, it might detonate at 25 degrees rotation. Cold day, cold engine, cruising? it might not go off until the diesel gets injected. Seems pretty crude to me.

I want to pause here and re-iterate that while the technical details of this setup are not in dispute, how hard that is on the engine is 100% my opinion, and nothing more. I am sure that there are a lot fo guys that use pane that haven't hurt a thing. But I'll bet they do it sparingly and carefully. i know for sure that there are guys that have blown holes in blocks because of not being sparing and NOT being careful.

That being said, I think (opinion alert!!!) propane has it's place in diesel engines. And that place is as an efficiency booster, not as a fuel that gets burned to create power IN AND OF ITSELF. This means using a very small amount of propane to more efficently and fully burn the diesel fuel, which is where the added power mostly comes from. Let me explain.

Sans propane, your piston compresses the air to a point to where it gets hot enough to ignite diesel, thent he diesel is injected into this hot air, and BOOM. Power stroke. But was the air hot enough to fully burn the diesel before the burn squelched?

With propane, the same thing happens, only, prior to injecting the diesel, the propane pops and ignites, causing the diesel to be injected, not into hot air, but into a FIREBALL. Seems like that would cause the diesel to burn faster and more completely, right? That is where, IMHO, you shouldbe getting your power increases from propane. Not from propane itself as a fuel, but from propane as a helper to get more from every shot of diesel.

Again, my opinion.

 

[02stroker]

Very well stated Hoss.

 

[JayBird05]

Introducing LPG into the combustion air intake of a diesel acts as an accelerant, promoting even burning of the fuel & more complete combustion resulting in more power. Not a "catalyst" LPG creates no change in molecular makeup of either air or fuel.

Propane will not self ignite inside a diesel-fuel compression-ignition engine. During compression the air/LPG is compressed & temp. is raised to about 400*C, not enough to ignite the LPG which has an iginition temp of about 500*C. When the diesel fuel is atomized into the cylinder under high pressure, it immediately self ignites (diesel ignites @ about 385*C ), & causes the LPG to burn as well. Since the LPG mix is in the air, the flame from the diesel spreads more quickly, & more completely resulting in a cleaner burn. Percentage of combustion from about 75% for a well tuned engine on fuel to about 85-90% with LPG. More complete combustion = boost in power, increase in power,better fuel enonomy & less pollutants.
Lots of info on web. Deluca makes "fumigators" that will utilize LPG or CNG. Check articles in Diesel Power Mag. on trucks that got 38 mpg in tests (diesel fuel) not counting CNG. It's gonna be one of my next moves. Like anything else....there's a right way & a wrong way. Lots of info out there.

 

[bir7514]

thanks jaybird. I think I'm gonna go with CNG since its cheaper to fill back up. I was reading before i posted the thread that there is a duramax gettin around 60 mpg with the cng setup from Deluca.