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Discussion Starter · #1 ·
Milage can go up I gather, Very efficiant, I am considering it but have a ways to go yet.
 

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I am definitely going to implement a propane fumigation system on my truck once I finish everything on my 'must do' list. Here is a link to a site that has very detailed information on the good, bad, and ugly of building/installing a propane fumigation system.

http://www.mrsharkey.com/lpg.htm
 

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I don't believe many of the claims that are being made about LPG fumigation.

For example, on MrSharky's site, he mentions that typically only 75% of diesel fuel is burned without fumigation and 85-90% with.
If that were in anyway true, you'd be blowing massive amounts of black smoke, everywhere.

The claim that fuel economy will improve. The only reason fuel economy can improve is if you don't count the energy from the propane that you're burning. Replacing diesel with LPG is false economy as diesel is cheaper per kJ (or BTU if you prefer).

The main thing to remember is every bit of propane you run into your engine displaces oxygen. So you're not only adding more fuel, you're reducing the amount of oxygen available to burn your diesel.
Keep an eye on your EGT and exhaust condition. You could simply be reducing large particles of soot, into smaller almost invisible particles of soot.
 

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I don't believe many of the claims that are being made about LPG fumigation.

For example, on MrSharky's site, he mentions that typically only 75% of diesel fuel is burned without fumigation and 85-90% with.
If that were in anyway true, you'd be blowing massive amounts of black smoke, everywhere.

The claim that fuel economy will improve. The only reason fuel economy can improve is if you don't count the energy from the propane that you're burning. Replacing diesel with LPG is false economy as diesel is cheaper per kJ (or BTU if you prefer).

The main thing to remember is every bit of propane you run into your engine displaces oxygen. So you're not only adding more fuel, you're reducing the amount of oxygen available to burn your diesel.
Keep an eye on your EGT and exhaust condition. You could simply be reducing large particles of soot, into smaller almost invisible particles of soot.
It is my understanding that you lose smoke due to a better burn because pain combines with the oxygen that the diesel doesn't...
 

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It is my understanding that you lose smoke due to a better burn because pain combines with the oxygen that the diesel doesn't...
If you're smoking, then there isn't a lot of air left.
Adding propane to that reduces the amount of air further.

The unburnt soot emissions from a diesel are as harmless as anything can be that comes from an exhaust pipe. On the other hand the emissions from an LPG engine are invisible, soo small that if breathed in they can enter the bloodstream directly through the lungs.
 

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I had toyed with the ides of adding it to my 6bt but Charles has scared me off it.
I was under the impression that propane needed 500c to ignite and that compression in a diesel engine only gets to about 400c so untill the diesel is injected there is no pre ignition, I appreciate that the flame propogation with propane will be quicker and thats what in effect advances the ignition some. I know the dodge guys advance there timing a bit and then adding propane advances it some more but how much more? If they hadn't advancd it would adding propane at a lets say 15% be OK? . Sounds like the gains are outweighed by the risks.

Gaza
 

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I had toyed with the ides of adding it to my 6bt but Charles has scared me off it.
I was under the impression that propane needed 500c to ignite and that compression in a diesel engine only gets to about 400c so untill the diesel is injected there is no pre ignition, I appreciate that the flame propogation with propane will be quicker and thats what in effect advances the ignition some. I know the dodge guys advance there timing a bit and then adding propane advances it some more but how much more? If they hadn't advancd it would adding propane at a lets say 15% be OK? . Sounds like the gains are outweighed by the risks.

Gaza
Well lets see.
Assuming adiabatic compression and an inlet temp of 100 deg C (equates to about 12psi with no intercooler) and a compression ratio of 17.

The charge temp hits 565 deg C.

So yeah, it's dodgy.
 

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Charles, you just stated the two things that I was going to say as I read down through everyone's posts, including your first one on this subject.

It can be an economy tool. And it can also outweigh the cost of the additional fuel through increases in combustion efficiency (effective timing, flame front propogation and cylinder pressure).
This is why I specifically stated that I was going to implement a propane fumigation system for my truck, and not a propane injection system. All I want is the small amount of power and the accompanying fuel mileage increase that misting a very small amount of propane as an accelerant can provide. To sum up this point; yes, I am one of those 1% of people that can resist cranking it up in the quest for more power.

Another important aspect is that y'all are running B-series Cummins engines, and I'm running a 7.3 powerstroke. Y'all can get away with much more than me. The bottom ends of these respective engines is far from an even playing field.
I have read a few of your other posts and knew you were a Powerstroke guy, so I was going to offer a comparison of bamboo sticks to 4"x4" fence posts as an analogy comparing the strength of our bottom ends, but I see that you already have a handle on that. :D
 

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Discussion Starter · #12 ·
All I am after is economy

WC 53 , NV4500 , twin transfercases running 4.88 gears . The top speed I want to do in this thing is 65 . Quite happy to toodle around here at 50 and crawl at an old farts pace in the bush . Most of the rpm,s will be around 1800- 2000 . It depends on the happy zone of the engine .
And NO I do not think black soot is cool. looks dumb actually and reminds me of the guys running the spreadboar 850 hollys on their small block chevs in the 70s .
Now the guy running the hilborn injection system was cool.

BAM
 

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i think twin transer cases is 100% a waste of money, esp with 4.88 gears.

im running 4.88 gears in mine, and am nervous about the 2.72 low range of the nv241.

i cannot reiterate i NEVER ran 1st gear and the np205 (1.98 low range) with 4.56 gears and 38.6" tires. i kept it in second and idled so slow i was forced to the rear of the offroad convoy.

i think 4.88 gears would be even worse.
 

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Discussion Starter · #14 · (Edited)
yah but all those levers are so cool

That and i am trying to access some real tough areas . I do not worry about going up the darn hill , I want to go down real slow .
I want bead locks too and the ability to air down to 2 to 5 lbs .
I am not sure how the bead locks would handle the queen sized water bed . But with on board propane i could keep the fridge running nice and cool .
After doing alot of math i went for the 4.88 gears . In 5th I will be running at 60 and change and the engine will be dead center in the happy zone .

Bruce
 

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That and i am trying to access some real tough areas . I do not worry about going up the darn hill , I want to go down real slow .
I want bead locks too and the ability to air down to 2 to 5 lbs .
I am not sure how the bead locks would handle the queen sized water bed . But with on board propane i could keep the fridge running nice and cool .
After doing alot of math i went for the 4.88 gears . In 5th I will be running at 60 and change and the engine will be dead center in the happy zone .

Bruce
Bruce, you mention going down hill real slow. Keep in mind that diesel engines offer no engine braking like a gas engine does. That is the reason Diesels run different types of engine brakes to keep control of the vehicle on downhills. Thus even with the low range of daul T Cases, the engine is not holding you back. There is a good presentation at the link below;

http://bankspower.com/tech_howexhaustbrakeworks.cfm

Paul
 

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Discussion Starter · #17 ·
Thanks paul you are 100% correct

I do plan on adding an exhaust brake. then perhaps I can go really slow down hills. Hopefully i can find one at a decent price.
Bruce
 

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I wanted to use a Jake E Brake on my Carryall and M37. I just dont have the available space to fit one. In the future, I want to talk with Jacobs Brake and get their thoughts of mounting one further down the exhaust pipe, closer to the muffler.

Paul
 

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Bruce, you mention going down hill real slow. Keep in mind that diesel engines offer no engine braking like a gas engine does. That is the reason Diesels run different types of engine brakes to keep control of the vehicle on downhills. Thus even with the low range of daul T Cases, the engine is not holding you back. There is a good presentation at the link below;

http://bankspower.com/tech_howexhaustbrakeworks.cfm

Paul
I disagree on that, I've found diesels offer a lot more engine braking than a comparable size petrol engine.
The reason is simple, 18:1 compression instead of 9:1.

Exhaust brakes are for keeping a ridiculously heavy vehicles speed in check without burning the brakes.

1st gear high ratio with my Isuzu is sufficient to gently ease 5 ton of 4wd and trailer down the local mountain pass without using the wheel brakes.
The same vehicle with the factory 3.5l petrol V8 can't do that.
 

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