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  #1  
Old 11-07-2001, 07:39 PM
dzldog
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Question Propane fumigation = more power/torque??????

Hey, I was reading the performance section of the TDI club discussion page and found several threads regarding the use of propane fumigation. Apparently the addition of propane to the intake allows the fuel to burn more completely, thus yields better economy, power, and engine longevity as well as cleaner oil. Has anyone here considered this mod.?
Anyhow, here is a site that actually sells a propane kit: http://www.bullydog.com/
Bully Dog boasts of power and torque increase of up to 66% and fuel economy increase of up to %40.
I'm intrigued!

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  #2  
Old 11-07-2001, 08:22 PM
Steve019
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I just went to the site.

My questions:

1) how much?
2) if propane runs dry will engine continue to run as before?
3) They were a little vauge on how much propane is used. They stated that tank size should be 25% of fuel tank size. I would think that is 4:1. If I had to get propane with every tank of fuel it would drive me nuts. And propane isn't cheap. They sited a minimum 30% fuel savings excluding propane. That means you may get a 5% increase of economy. Thats about another 1 or so mpg. It would take a long time for the system to pay for itself. Not forgetting the propane cost. I am assuming this system is not cheap because there were no prices listed (usually the case)
4) I wasn't impressed that the only thing they had under the order online button was some overpriced t-shirts.
5) just what kind of mods. Are they easily reversable?
6) Would this aid in cold weather starting?
7) with propane through the intake would you have to adjust the fuel input so as not to run too rich as there would be less oxygen coming in. if so then if you ran out of propane the engine would not run properly.


I am always open to new ideas. But always like to check them out completely.
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  #3  
Old 11-07-2001, 08:26 PM
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Join Date: Aug 2001
Location: Evansville, Indiana
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Too much propane will remove the head bolts the hard way -- straight out up, with thread from block included.

There is a lovely 300CD sitting about three miles from me that had just this happen when someone tried to start it (weak engine) with "extra" boost from acetylene. Pretty sad end to a nice car that really needed a starter.....!

If you want more power, buy a bigger engine. Leave the propane trick to people who have the money to replace the engine often!

Peter
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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!
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  #4  
Old 11-07-2001, 09:08 PM
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If you are really interested in propane do a search in the forums at www.ford-diesel.com , there is a lot of info about how this increases torque and hp there. On larger V8 engines (7.3L) there doesn't seem to be any ill side effects, these engines were built for much higher torque and hp than a little mb engine, also they are much newer.
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1985 300D Turbo ~225k
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  #5  
Old 11-07-2001, 10:50 PM
RThomas
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Propane fumigation is a hot topic of discussion on the diesel truck sites. The propane seems to act as a "catalyst" of sorts promoting a much cleaner/complete burn resulting in less smoke/cleaner oil and more power. I have read the Bully-Dog info and some others and the systems seem proven and well designed for their application-trucks that tow a lot. The problem I can see is where do you put the tank? The kits I have seen do not include the tank, it must be sourced from an RV dealer, etc. Installation in a truck bed would be easy, not so easy in an MB. I would think that this is just too much trouble for anything other than a pure towing vehicle. RT
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  #6  
Old 11-07-2001, 11:24 PM
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Join Date: Oct 2001
Location: Newton, MS
Posts: 123
Propane is a wonderful fuel. I built a home made unit and ran a duel fuel system on a truck for over 100K with no problems. Duel meaning I was either on one or the other, gas or propane. I could switch on the move without missing a beat.

I don't know about mixing with diesel, but as a previous poster stated, there are problems having a tank in the car. I remember that someone, either the feds or the state required the trunk to be thoroughly sealed from the interior and vented to the outside.

Also, my state of Mississippi required that I purchase and display an LP Fuel decal on the rear window. It was $100 a year. Mileage in other states may vary.

Without those two details taken care of, propane folks would not fill your tank.

Harry
86 300 SDL
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  #7  
Old 11-08-2001, 01:25 AM
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I suspect propane in a pre-chamber diesel like MB's will cause serious pre-ignition unless injected with the fuel -- same reason it isn't very smart to use ether to help start one. I've tried it, it won't work -- ignites so early it stops the starter. Most American truck diesels are direct injection -- start fine on ether.

Propane will burn cleaner than diesel fuel for sure -- so will ethanol. Propane power is wonderful -- no soot in the oil, no deposits, vehicle runs forever. Probably does help the diesel burn cleaner, but I still wouldn't try it in an MB -- good way to break the ring lands.

Peter
__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!
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  #8  
Old 11-08-2001, 02:37 AM
RThomas
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Propane fumigation works fine on IDI type diesels and direct injection. I've seen it on GM 6.2-6.5's and Ford 7.3's.... The higher compression engines like the GM's don't seem to like the propane as much as others. The higher the compression the smaller the combustion area and the more fine the line between acceptable and exceeding peak combustion pressure limits.... Head gasket time!! Propane is not as volatile as ether or acetylene, it won't burn until the diesel is injected. While this certainly do-able on a MB, the cheapest propane kit I have seen is @$500, and then you need an approved tank, installation, etc. I don't see the cost benefit. RT
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  #9  
Old 11-08-2001, 02:24 PM
Steve019
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I just got a reply from them. Kit cost $699. Comes with on-demand toggle switch for dash.
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  #10  
Old 11-08-2001, 06:29 PM
dzldog
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Arrow

Powershot 2000 Here is another company that markets propane fumigation kits and sells them cheaper than Bullydog.
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  #11  
Old 02-01-2002, 10:46 AM
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After seeing an instillation of a Bullydog system on a big turbo diesel truck I wondered how something like that would apply to a MB diesel. I was thinking of a small(safe,noticeable) amount into the intake with some sort of manual system(toggle switch, push button, WOT) just to help maintain speed going up mountains. Does anyone have any fist hand experience with propane and MB diesels(mine is a non-turbo 300cd)? Please share experience or opinions. thanks, andy.
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  #12  
Old 02-01-2002, 07:31 PM
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It may be of interest to note that MB diesels are 21:1 or 22:1 compression ratio IDI -- I would investigate before I added propane. I am under the impression that the big V8s in american manufacture light trucks are mostly direct injection engines. Some use unit injectors (not the Cummins in the older Dodges, they use IDI with a VE pump). Much different application, usually have low rpm motors, too.

Peter
__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!
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  #13  
Old 02-02-2002, 01:03 AM
LSMITH
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Propane is widely used in the light trucks for extra performance. In a 5.9L Cummins engine up to 125 HP can be gained, but the strength of the rods and crank are in a league of their own. I would suspect that 25-40 HP would be more in the range for the MB diesels. Done right it is safe and will not harm the engine. Done wrong and it can be extremely destructive. If too much propane is inducted it can ignite on its own in a high compression diesel, and is called detonation. Detonation will lift the head, the diesel is injected into a hot flame and combustion control is lost. The timing and duration of burn are critical for a diesel to operate. Propane can also ignite in the air induction system if a valve is partially open or there is a corbon hot spot etc, and when it does the result to the turbo is usually catastrophic failure.

Some quick points.
Propane is injected into the air induction system, not into the cylinders.
Combustion temps rise little if any with moderate charges.
Fuel economy is improved quite a bit, but how much depends on when and how much is used.
Tanks must be DOT certified, and are more reasonable than you might think, around $200 to start.
Smoke and particulate emissions are reduced.
Power and throttle response are dramatically improved.
It will not help starting, it is only used in high power situations.

The number one thing you guys should know about propane is that it is used on an as needed basis, not continuously. Most systems are boost triggered ensuring that the propane is only injected when conditions warrant and are correct for its use. A Hobbs type switch is used to trigger the propane solenoid, and a regulator determines the injection quantity.

It would make tight freeway ramps much less interesting, and the response of the engine would be much better in all high power situations.

I would think a charge air cooler would be safer and easier on a MB with cost being the about the same. The market of MB owners willing to use propane would be small in my estimation, so you would be developing the system for yourself with assistance from the component supplier if you decided to do it. Developing the system is not for someone that is not capable of making any repair necessary, monitarily or physically.

Hope this helps.
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  #14  
Old 02-02-2002, 10:45 AM
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An intercooler will be difficult on most MB applications, requiring extensive modification of the intake manifold. The turbo is usually bolted right up to the intake!

There is also the issue of just where you would put it -- engine compartment is a bit tight at the frongt. Good project, though.

Peter
__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!
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  #15  
Old 02-03-2002, 03:24 AM
Car Killer
 
Join Date: Jan 2002
Location: Northern VA
Posts: 178
Due to the high resistance of autoignition, propane is quite safe. It works great, since it helps you achieve complete burn of the fuel, its easy to dump more fuel on the fire without adding soot. If your after more power, its definently the way to go. If your after economy, this is one mod that will never pay for itsself. How could it? Propane aint cheap! I tried this in my volvo... just rigged up a regulator from a king kooker that blew propane into the turbo inlet. Switching it on would result in an increase in power, decrease in soot, and some beautiful clutch slippage. I since removed the system, it was too crude to be used on a regular basis, as it simply ran off a 6lb camping cylinder.

If i was gonna drag race my diesel.. I would do it. for street use, its simply not worth the trouble.

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2003 Jetta Wagon TDI 145,000MI
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