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Discussion Starter #1
A couple of questions...

You're not suppose to run propane fumigation with a timing box like the EZ because the propane give a timing advance so with the EZ you have too much timing. I've also heard propane gives you a little power boost.

So for performance and MPG which one would be better, the EZ by itself, or propane by itself?

And what about Compressed Natural Gas, how does that work with our trucks? Can I run CNG fumigation with the EZ or does the CNG advance the timing too?
 

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Interesting question. The truck I drive at work is a bi-fuel, pump gas/CNG. There is no problem with timing when you switch between the fuel types because the OBDII computer in those 1991 Ford F-150 trucks automatically adjusts the timing. Which begs the question, wouldn't our trucks do the same?
 

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Propane doesn't actually advance timing.

Propane floats in the cylinder until it's ignited. It has a high enough octane that it doesn't ignite by itself until it sees a flame or a spark, unless you're running lots of boost or compression; at that point you get detonation, just like on a gas engine. The 7.3 liter PowerStroke guys are the experts in propane fumigation, and they have enough pictures of bent rods to prove it.

But propane burns faster (more evenly and efficiently) than Diesel. When you advance timing, you are injecting Diesel farther away from top dead center. Diesel burns slower (unevenly, inefficiently), so you can put it into the cylinder early and it won't get to efficiently burning until the cylinder's at TDC. But if a cylinder full of propane is ignited as soon as the Diesel is injected, then you can't get away with that timing increase; when the propane goes off that far before TDC, you might get excessive cylinder pressures.

So, with propane, you want to decrease the timing. And you want to decrease the timing farther as you get more propane, or more boost pressure.

Any fumigated fuel is going to act like that. The amount of timing that you can get away with depends on the octane of the fuel.

But, our engines are built like tanks, so you'd probably have to be experimenting pretty harshly to actually break anything. Too much propane at too little boost and you start burning your eyes out...

I wonder what Cummins uses to throttle their natural gas and propane engines based on throttle/ boost pressure? I want to retrofit one of those, personally...
 

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Discussion Starter #4
Propane doesn't actually advance timing.

Propane floats in the cylinder until it's ignited. It has a high enough octane that it doesn't ignite by itself until it sees a flame or a spark, unless you're running lots of boost or compression; at that point you get detonation, just like on a gas engine. The 7.3 liter PowerStroke guys are the experts in propane fumigation, and they have enough pictures of bent rods to prove it.

But propane burns faster (more evenly and efficiently) than Diesel. When you advance timing, you are injecting Diesel farther away from top dead center. Diesel burns slower (unevenly, inefficiently), so you can put it into the cylinder early and it won't get to efficiently burning until the cylinder's at TDC. But if a cylinder full of propane is ignited as soon as the Diesel is injected, then you can't get away with that timing increase; when the propane goes off that far before TDC, you might get excessive cylinder pressures.

So, with propane, you want to decrease the timing. And you want to decrease the timing farther as you get more propane, or more boost pressure.

Any fumigated fuel is going to act like that. The amount of timing that you can get away with depends on the octane of the fuel.

But, our engines are built like tanks, so you'd probably have to be experimenting pretty harshly to actually break anything. Too much propane at too little boost and you start burning your eyes out...

I wonder what Cummins uses to throttle their natural gas and propane engines based on throttle/ boost pressure? I want to retrofit one of those, personally...
Thanks for the response guys...

So with the EZ connected on level 3, do you think a very, very lite fumigation of propane would be beneficial? Like .5 or 1 psi of propane starting at 2-3 psi of boost. This is on a mostly stock truck. (in my sig) I'm not looking for any power increase, just MPG. And I also don't want to risk any damage to my engine.

My other question was, if propane doesn't advance the timing, but it's characteristics act the same as advanced timing, will performance with propane by itself be similar to an EZ by itself? Or does an EZ do more than just timing?
 

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Watching this thread too...

If we only need .5 to 1psi of propane. I'm just going to buy a BBQ regulator tomorrow from the store. I've got my solenoid. Just waiting on my hobbs switch.

For safety sake I'm going to turn the XZT+ off for the first run. Establish a EGT baseline, then test it in timing mode for a baseline and compare. I don't think I'll try to arm my 'pane system with the 3K tune high though...
 

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How do you inject 1 PSI of propane? Shouldn't the amount of propane going into the engine be measured in terms of flow? Wouldn't the flow depend on pressure and nozzle size?

I don't know if the amount of propane you guys are talking about is even going to be noticeable. I wouldn't expect it to be dangerous with an EZ unless you were running significantly more boost than stock.
 

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How do you inject 1 PSI of propane? Shouldn't the amount of propane going into the engine be measured in terms of flow? Wouldn't the flow depend on pressure and nozzle size?

I don't know if the amount of propane you guys are talking about is even going to be noticeable. I wouldn't expect it to be dangerous with an EZ unless you were running significantly more boost than stock.
Propane is going to be introduced at the air filter. (Injected into the intake manifold would need to be pressurized higher than boost pressure.)

We're not going for power here. Just as a supplemental fuel for our trucks. (At least I am, I believe he is too)
 

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Discussion Starter #8 (Edited)
Propane is going to be introduced at the air filter. (Injected into the intake manifold would need to be pressurized higher than boost pressure.)

We're not going for power here. Just as a supplemental fuel for our trucks. (At least I am, I believe he is too)
Exactly. :thumbsup I'd like to know if if just a light dose of propane into the air filter would be ok with a timing box like the EZ and if it would help mileage.

It looks like the EZ is increasing my mileage by a couple MPG (I'll know tomorrow) so If I could get even 1-2 with propane on top of that, while being safe, I'd be happy. What I would hope for is that the mileage benefit from the propane largely outweighs the cost because of the low volume of propane used.
 

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I have DIY propane injection. 1 lbs is completely un-noticeable. Ive ran as much as 10lbs and still can't notice it. I know its going in there its just not all that noticeable. I dono it might boost mileage a small bit. I can't say that i really recommend it though. With 5 lbs running, I left mine on getting off the highway and pulling into a store, down all the way down to idling for 15 seconds before i realized it, couldn't even notice it. Just glad i didn't destroy anything.

No effect on boost. I dono know exact numbers on milage, but i jumped about 5mpg from straight diesel, going to 5lbs of propane and a 80% WMO / 20% diesel mix. I think some of it was due to the increased btu's in oil, and possibly some due to LPG fumigation
 

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Why propane ? CNG seems better

I know the availabliyt suck for CNG. I am also old enough to remeber the tons of troubles folks had in cold weathre using propane in gas engines.
I have not got the parts yet for CNG ( $1500 for kit from Deluca Fuel Products )

The science seems very sound and SIMPLE. What say you?
 

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I know the availabliyt suck for CNG. I am also old enough to remeber the tons of troubles folks had in cold weathre using propane in gas engines.
I have not got the parts yet for CNG ( $1500 for kit from Deluca Fuel Products )

The science seems very sound and SIMPLE. What say you?
I too remember the probs with LPG in cold weather, but you have to realize that there is a very small amount going in to the deisel, so freeze up will not be a issue.
I also want to try LPG as a fumigant in my truck, but haven't got all the pieces yet.
 

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The problems with LPG-powered vehicles in the old days had to do with poor water flow to the converters and excessively long hoses between the converter and mixer. Modern gasoline-propane injection systems do not have this problem at all. The older Impco carburetor systems could start fine down to -40°F when they were converted properly and the starting & ignition systems were in good condition.

Diesel-propane fumigation (liquid withdrawal) systems would also require a good water supply to the converter to prevent freeze-up. The danger with a freeze-up is that a propane mist would be supplied to the engine and propane expands 270 times as it changes from liquid to gas. An excessively rich mixture would stall a spark-ignition engine but could severely damage a diesel.

I would be very careful about building a DIY diesel-propane system. The critical compression ratio for propane is ~12:1 so excessive amounts can lead to detonation. You can supply a relatively high ratio of propane to diesel at low loads but you need to cut back to zero as you approach full load. You can't do this with a simple regulator-controlled system. DeLuca Fuel Products expects to have a controller in the fall of 2009. The better diesel-LPG (and diesel-CNG) systems have a software set-up with a customizable fuel map.

See Diesel Dual Fuel Fumigation for more information.

The science IS sound and simple. The implementation just needs to be done right.
 

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I understand what you're saying, but, fumigating from tank as a gas, not a liquid should nulify the problem, as you are using a relatively small flow of propane.
 

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Diesel/LPG or CNG Injection Systems

Greetings all,

Take a look at the EcoDiesel System now available from Technocarb, this is THE state-of-the-art vapour fuel blending system. Completely computer controlled, can be installed Pre OR Post turbo (compensates for up to 50lbs of boost) and has numerous adjustment features. This is NOT the 45 year old tractor technology that has typically been available for diesels....have a look at technocarb.com for info.

Alt Fuel Pete
 
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