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Discussion Starter · #1 · (Edited)
I saw this post and will be searching for others:

http://www.cumminsforum.com/forum/alternative-fuels-additives-oils-lubricants/39896-who-else-using-propane.html#post389086

But am wondering does it give some MPG benefits misting 1-2psi of propane into the airbox?

Most importantly, is it safe? Is it safe compressing LPG through the turbo? What about the combustion chambers, can the head handle burning propane in small amounts with no extra wear?

I'm just looking for a simple diy kit to help with mileage. They say we might see $5/gal for regular gas this summer, diesel will be through the roof!

Also, it seems like a boost pressure switch of some kind would be the best way to turn on the propane. Something that activates the propane when there's 5psi of boost pressure. But it would be easier to put in an oil pressure switch that turned it on when the engine started. Would it be bad to idle the truck with propane? What about shutting it off with the propane going?

Any info would be appreciated.
 

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Don't forget to add in the cost of propane and the system when you figure your mileage and savings. Also, cummins don't really like propane. Not to say it hasn't been done successfully but I tend to shy away from adding an extra fuel to combust in my motor.
 

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Discussion Starter · #3 ·
Don't forget to add in the cost of propane and the system when you figure your mileage and savings. Also, cummins don't really like propane. Not to say it hasn't been done successfully but I tend to shy away from adding an extra fuel to combust in my motor.
From the limited things I've read small amounts of propane acts as a catalyst to help burn unburnt fuel that is otherwise wasted out the exhaust.

I think the cost of the propane would be minimal compared to the efficiantcy of being able to burn a lot more of the diesel going in. Course I'm just going by what I read...

Why doesn't a Cummins like propane?

I'm just trying to get all the info I can. I definitely don't want to screw my engine up trying to save money on fuel.
 

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It would act as a catalyst if you have a lot of unburnt fuel. From what I'm seeing in your sig your pretty stock so you shouldn't have a lot of unburnt fuel.

Don't quite know why our motors don't like propane but everything I've read and the people I've talked to say don't use it on a cummins. Ford's eat the stuff up like candy. Dunno bout the dmax's.

What's the current cost of propane? I'm not discouraging you cause by all means I'm one of the biggest advocates of thinking outside the box, just wanna make sure your aware of stuff.
 

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I've also heard of guys running it in their trucks for 60K+ miles and not having any problems AND achieving 2 to up to 6 mpgs better. The best thing to do is to do a DIY kit with a switch to turn off the propane when you exit the highway, and only add it at a low PSI right into the turbo. That's IMO through research though. Good luck and play safe with it.
 

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propane does not act as a catalyst, it is a separate fuel. there can be some benefits, but those figures of 2-6mpg do not include the propane fuel, just diesel.

propane has 90k btu per gallon, Diesel is about 150k. You need to get propane for almost half the cost to start saving anything.

Problem with too much propane is cylinder head pressure = head gasket. way too much propane can be catastrophic. 30-40hp is max without shead studs/ O-ring.

Timing from boxes does not stack well with propane either.
 

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Here is an article on a professional engineering website.
He states that there is some benefit, but lots of hype. Most people do not calculate the extra fuel used in their MPG.

It is not a good thing with extra timing or the extra compression on the HO motor. I get free propane. It is $200+ for a homemade vacuum based system if you already have the tank. I have not yet decided on doing it.

Diesel and Gaseous Fuels, DualFueling - Engine & fuel engineering FAQ - Eng-Tips
as follows:
Diesel and Gaseous Fuels, DualFueling - Engine & fuel engineering FAQ - Eng-Tips
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Discussion Starter · #8 ·
Ok, thanks guys. It seems like if you did it at all the safest way would be the manual switch for just highway use ,and very low pressure. I'll keep reading up on it and looking for other contraptions I can hook up for better MPG. :lol3:
 

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Discussion Starter · #9 ·
Oh, BTW, with the 4" exhaust, BHAF and a fuel cooler on the return line I'm getting about 22-23mpg freeway and probably about 17-18 in town hand calculated. I put in 20gal at a time. This last tank I did about 70% freeway and 30% in town. I got 20.5mpg. Before any mods I could only get 19 straight freeway. I don't know which one of those things helped more but I glad I'm seeing some improvement. And my truck is 2WD but has a ladder rack and two hi-side boxes that stick out a little and catch wind.
 

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I used to run a powershot 2000 kit, It's definatly the simplest kit and cheapest out there, although not as cheap as DIY. if propane is used, I think it'd be best used on a stock truck I.E. no timing and or fueling boxes.
Shortly after starting to use propane, my headgasket started to leak coolant. coincidence? I dunno.
 

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Discussion Starter · #11 ·
I used to run a powershot 2000 kit, It's definatly the simplest kit and cheapest out there, although not as cheap as DIY. if propane is used, I think it'd be best used on a stock truck I.E. no timing and or fueling boxes.
Shortly after starting to use propane, my headgasket started to leak coolant. coincidence? I dunno.
Ooh. Thanks for the post. Might have been related, don't think I want to take chances...

I think I might just put an Edge EZ on it and set it to the lowest setting. With that, my mods and pumpin' up the tire s a little I should see some good mpg. :lol3:
 

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propane does not act as a catalyst, it is a separate fuel. there can be some benefits, but those figures of 2-6mpg do not include the propane fuel, just diesel.

propane has 90k btu per gallon, Diesel is about 150k. You need to get propane for almost half the cost to start saving anything.

Problem with too much propane is cylinder head pressure = head gasket. way too much propane can be catastrophic. 30-40hp is max without shead studs/ O-ring.

Timing from boxes does not stack well with propane either.
The BTUs produced by the propane are not the important part. The fact that the propane combusts JUST before the diesel is sprayed in is what makes the diesel completely combust as well as adding a little bit through its own explosion.
For safety reasons, the venturi is a very good idea.
 

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The BTUs produced by the propane are not the important part. The fact that the propane combusts JUST before the diesel is sprayed in is what makes the diesel completely combust as well as adding a little bit through its own explosion.
For safety reasons, the venturi is a very good idea.
our engines are very efficient, there is not 8-12% of unburned fuel/ power to be scavenged like some propane fitters would have you believe. Propane is not a catalyst either. It is another flame/ fuel that does not mix with diesel. It does burn faster and can make it a more complete combustion, but it will be in low percentages. Much of the power/ MPG comes from the extra BTU of the fuel.
 

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It really depends on how much you're pumping in. If you keep it at a low pressure, maybe 1.5-3 depending on how much boost you use then yes, it creates an environment that burns the diesel that would otherwise be ejected out in the exhaust. and of course, it being a combustible, the BTUs do help however, it's primarily diesel burning as it has 155K BTUs/gallon while propane only has 91.5K BTUs/gallon according to Diesel and Gaseous Fuels, DualFueling - Engine & fuel engineering FAQ - Eng-Tips
 

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The BTUs produced by the propane are not the important part. The fact that the propane combusts JUST before the diesel is sprayed in is what makes the diesel completely combust as well as adding a little bit through its own explosion.
For safety reasons, the venturi is a very good idea.

Not true, propane won't combust at at heat and compression level of our diesels. It burns only AFTER the diesel is injected and combusts. The diesel has to combust to ignite the propane. Because it is a gas, it will have perfectly evened itself out thoughout the cylinder, creating an even and full burning combustion...
 

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That is correct. The propane is ignited by the fuel, but spreads the flame. DI engines benefit from it more, as they are lower compression. I did a homebuilt propane injection on my skid steer with a petter air cooled twin with direct injection and 16.5:1 compression. The tricky part is the orifice for the gas. Even regulated down, the orifice must be nearly microscopic. I machined an adapter to fit a hand blowtorch tip to use the regulator and orifice, and used a relay controlled by the kill solenoid to operate a valve to turn it on/off. I didn't regulate the flow in regards to the throttle position/rpm. Way too complicated for me.

It worked. Mainly I was sick of breathing the smoke. It ran cleaner, burned slightly less fuel, even compensating for the propane cost. I ran the valve higher and lower, and the fuel efficiency seemed about the same, but it's really hard to tell in this kind of machine. The only way I figured it was by logging fuel use over hundreds of hours for an estimate.

The whole thing was a COMPLETE waste of time. I love to tinker and don't have better sense, and eventually just tossed a Perkins (same as a CAT) in it. Don't waste your time. It is not worth the hassle. Neither homebuilt or factory makes ANY sense whatsoever unless you are just looking for power and lower egt's. Now I DID consider putting in a h2o to hydrogen electrolysis system... See? don't listen to me!
 

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I just installed a diy propane kit and love it! it adds power and hoping on mpg gain havent eaven run one tankof diesel yet but already hooked on the power!Thanks Zack!
 

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FYI propane will combust under compression and it does so at pressures/temps close to diesel. But there needs to be a lot in there. Running too much propane can detonate on its own. Just like coal and sawdust are combustable at the right ratios in the air. Propane won't pre-ignite if the ratio is too high or too low. I do not remember the ratios where it combusts.
 
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