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  #1  
Old 09-07-2005, 10:18 PM
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Compressed Natural Gas?

Now there is a new question for us. How can I make my 4.5 run on Compressed Natural Gas? What would it require as far as injectors and such, anyone have any idea? 1972 4.5 D-injected
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Old 09-08-2005, 07:40 AM
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Quote:
Originally Posted by tosbt
Now there is a new question for us. How can I make my 4.5 run on Compressed Natural Gas? What would it require as far as injectors and such, anyone have any idea? 1972 4.5 D-injected
I would think you would want to introduce the natural gas or propane into the throttle body after you disabled the gasoline FI system. Disabling the FI is probably pretty easy to do, it's just a matter of finding the source of power to the fuel management computer and disconnecting it. Once you plumbed a gas line into the throttle body it would just be a matter of regulating the flow of gas while coordinating it with the opening of the butterfly valve to allow throttle control.


A friend of mine has a 50's Bentley which was adapted as a dual fuel vehicle (gasoline or propane). IN that conversion you shut the flow of gasoline off and run the carb bowl dry before introducing propane. My recollection of other cars which have had this done is that they do not operate significantly more efficiently on gas than on gasoline...in other words it will not cost you much less to run a car on LNG or propane than on gasoline, but you never know until you try it I guess.

Then there is the tendancy for LNG to explode if the tank were to rupture in an accident...could be something of a downside
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Old 09-08-2005, 11:25 PM
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Quote:
Originally Posted by tosbt
Now there is a new question for us. How can I make my 4.5 run on Compressed Natural Gas? What would it require as far as injectors and such, anyone have any idea? 1972 4.5 D-injected
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Old 09-09-2005, 07:31 AM
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There are no shortage of cars in the Netherlands that run on alternative fuels LPG or CNG. Their motivation is the different tax structure on these fuels.

As much as gas is expensive in the US now, it's always been this bad or worse in europe as an incentive to not have big gas guzzling cars.

-CTH
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Old 06-08-2006, 07:53 PM
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speak of the devil!

http://cgi.ebay.com/ebaymotors/Mercedes-Benz-200-Series-280-SE-1972-280-SE-4-5-CLASSIC-ONLY-118K-MILES-STUNNING-COND_W0QQcmdZViewItemQQcategoryZ6329QQihZ002QQitemZ4645080463QQrdZ1
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Old 06-09-2006, 07:02 AM
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I have my basic K jet 500sel running on dual fuel, petrol/propane. Its a pretty easy conversion if you go for the single point system.
You need to introduce the gas by means of a Mixer. This simply plums inline with the air inlet of your engine. The mixer is then attatched to a vapouriser/reducer, which converts the compressed liquid gas into low pressure vapour for introduction into the engine. This is plumbed into the tank, which I have located in my trunk.
On my car, I simply have a relay to turn off the fuel pump when the propane solenoid opens. I would imagine on an older EFI, you could disconnect the injectors by removing the common earth, so the computer is still running and controlling the idle etc, and the fuel pump is still running, to maintain pressure for when you next start the engine.

Hope this helps
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Old 06-11-2006, 09:18 AM
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CNG is a real technical nightmare,It has been used in New Zealand for over 30 years,it's NOT Propane!.To obtain the gas ,you either have to have access to a CNG supply station or you can have a pump in your home garage connected to the town gas supply.This can take several hours to fill so you connect the car in the evening and leave it to fill by itself.In the morning the car will be filled and will have shut itself off from the pump.

In this city ( Brisnyland) we also have Volgren Busses running on CNG,the range is only about 400kms and if the level is getting down ,the bus must be returned to a depot and refilled,its a major headache if it runs empty.

The ONLY set up with either CNG or LPgas ( propane today is to have Injection.You will actually have more Horsepower with the injection than gasoline.
The number of injection suppliers is grownig by the week.
http://www.blazegas.com/kits2.html
http://www.lpg2000.com/products.html
http://www.classiccartimes.co.uk/features/Workshop/LPG/Feature.asp?ArdSI=2a2f396967c7706d5d172ac64e0a16e0
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Old 06-11-2006, 12:17 PM
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Quote:
Originally Posted by mercmad6.3
The ONLY set up with either CNG or LPgas ( propane today is to have Injection.You will actually have more Horsepower with the injection than gasoline.
Actually propane and CNG suffer a volumetric loss compared to gasoline so you need more to get the same energy output as gasoline. CNG is like 30% loss. Not sure about propane. The effective octane level is very high, about 130 for CNG so this obviously lends itself to turbo or supercharging since you would not have detonation issues.

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Old 06-11-2006, 12:43 PM
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I think I pointed this one out in another thread a while back... I said
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Check out the rust in the trunk. If it's that rusty inside the trunk you KNOW that's a fresh paintjob merely hiding other rust. How well was it repaired? The interior is a mess - the heater levers aren't just broken, the chrome surround is too. The armrest(s) are falling apart, and the dash wood is crap. The rubber gasket on the cluster isn't seated right - which may mean anything from a lazy install to a cracked dash - And I don't know what's going on on top of the dash, but the speaker grille is definetly not right. Plus I HATE how they retrofit 116 steering wheels onto 108's... It just doesnt fit IMO. The seats and carpet look like crap for a car he wants over $4k for.
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Last edited by Tomguy; 06-12-2006 at 09:44 AM.
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Old 06-11-2006, 01:25 PM
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The ignition timing curve is different too, as at one point it goes flat.

My folks had a two motorhomes with propane ability. The first one wasn't all that great, but the second one (Promatic, I think) worked quite well.

Back then, the GM chassis had a lot of problems with vapor lock - this could easily be "cured" by running on propane until you got back into some cooler air. (GM's fix was to have you run a 1/2" steel line from the tank, along the outside of the frame, and then to the carb.) It also helped to wrap the lines in asbestos rope, and have plates that consisted of alternating layers of aluminium and asbestos gaskets, mounted between the carb and the intake.

The big advantage for my folks was, filling up in Mexico city for less than $10
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Old 06-12-2006, 09:02 AM
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Quote:
Originally Posted by Larry Delor
The ignition timing curve is different too, as at one point it goes flat.


The big advantage for my folks was, filling up in Mexico city for less than $10
Again..."forklift " mentality,Sorry,but it annoys me everytime this old chestnut turns up.It's 2006 now,not 1956 and the whole LPG setup situation has moved on considerably since the days of the primitive Impco mixers that dumped raw LP gas into the manifold.
for a start,it's NORMAL to have a igniton module wired in so that when the car is switched over to LPG the igniton is advanced to take adantage of the LPG's 110 octane,NO MORE flat spots.
Conversions today are on new vehicles with ELECTRONIC ENGINE MANAGEMENT and injected LPGAS will give a LOT more power than you can imagine. I have seen conversions on Hot chevies pushing out an easy 600+HP on the dyno with twin vaporisers to keep up with the Fuel demand and certainly no worries about flat igniton curves etc .
As for the chance of an LP gas tank exploding in a crash...yeah right,the tanks are made from steel that is 1/4" thick with safety valves etc which automatically shut off the fuel if the lines break. . and then have a look at your gasoline tank sometime and tell me how thick the sheet metal is.
With the Fuel companies robbing us blind and lieing to us with the lamest excuses offered since Nuremburg 1946, LPG etc is going to be the best option for most of us in the years to come.
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Old 06-12-2006, 09:13 AM
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Quote:
Originally Posted by Tomguy
I think I pointed this one out in another thread a while back... I said

Plus I HATE how they retrofit 116 wheels onto 108's... It just doesnt fit IMO. The seats and carpet look like crap for a car he wants over $4k for.
Hey,those are 108 wheels!!!! ,Have a good long look at a set of those wheels sometime ( factory ) and check the part number.I have a 250S here with a set that the car came with in 1967.
You may not like it,but they were fitting them in 1965 in Germany at Daimler Benz and 41 years of mercedes owners having been fitting them ever since....
in fact my W126 has a set fitted new in the factory which also have 108 part numbers.

what you didn't comment on was the Truck LP gas tanks in the back.those are for underbody mounting on large trucks not for mounting " end on " in a car.
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Old 06-12-2006, 09:43 AM
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I meant the steering wheel, NOT the bundt cakes! Should have made that clearer!
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  #14  
Old 06-12-2006, 10:11 AM
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Quote:
Originally Posted by mercmad6.3
Again..."forklift " mentality,Sorry,but it annoys me everytime this old chestnut turns up.It's 2006 now,not 1956 and the whole LPG setup situation has moved on considerably since the days of the primitive Impco mixers that dumped raw LP gas into the manifold.
for a start,it's NORMAL to have a igniton module wired in so that when the car is switched over to LPG the igniton is advanced to take adantage of the LPG's 110 octane,NO MORE flat spots.
Conversions today are on new vehicles with ELECTRONIC ENGINE MANAGEMENT and injected LPGAS will give a LOT more power than you can imagine. I have seen conversions on Hot chevies pushing out an easy 600+HP on the dyno with twin vaporisers to keep up with the Fuel demand and certainly no worries about flat igniton curves etc .
As for the chance of an LP gas tank exploding in a crash...yeah right,the tanks are made from steel that is 1/4" thick with safety valves etc which automatically shut off the fuel if the lines break. . and then have a look at your gasoline tank sometime and tell me how thick the sheet metal is.
With the Fuel companies robbing us blind and lieing to us with the lamest excuses offered since Nuremburg 1946, LPG etc is going to be the best option for most of us in the years to come.
You mention "hot" chevies which means the cars were juiced before LP was added so your point is pretty much moot on the benefits of LPGAS as being more powerful. You can't cheat physics and thermodynamics, a 30% volumetric loss is just that. You can compensate with more fuel but thats not exactly the way you need to go.

That said, the cleaner emissions of LPGAS, CNG, propane, and butane are good things on their own merit.

Also, you seem to miss the important difference in fuel tanks is not purely the flammability issue, but the PRESSURE issue. You can have a pressure explosion in addition to a combustion explosion. Not just a big boom, but a big boom with shrapnel.

And your comment about oil companies robbing you blind shows a large amount of ignorance and what appears to be a reliance on urban legend and mis-informed media. If you were in the oil business (as I am) you would laugh at the folly that is spewed by the "news" every day.
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