Gasoline engine with a shot of NG

[porcupine73]

Would it be possible to take a gasoline engined car and say at cruising speed simply introduce a flow of NG into the air intake stream to arrive at a dual fuel setup? I'm envisioning something like a tank with a regulator and then a Rotameter to meter the flow. Once the engine computer is in closed loop if the NG were introduced, would the computer be able to simply cut down on the amount of gasoline injected (at least as far as the fuel trim will allow)? Or do other things such as timing have to be adjusted too? I'm wondering if this would cost less than a full CNG conversion but cut down on the amount of gasoline required. -Louis

 

[n8wvi]

I've been wondering the same thing (though I was thinking of propane). Dave

 

[Master ACiD]

i suppose you could. modern obd2 computers have a trim range of very roughly + or - 30%, so you could in theory add 30% of the engines total fuel uptake at a given load and not do anything bad. although i would probably stick to something more conservative like 10%-20%

 

[porcupine73]

Thanks for the info Master ACiD. I would imagine then if too much NG (or propane) were introduced you would get a MIL with some code about fuel trim exceeded. I want to give it a try but I would first have to figure out how to compress NG from the home pressure of 4inwc into a NG cylinder at whatever pressure those run, 3000psi? I always see NG cylinders for sale on eBay. n8wvi I would think propane would work too. I always see those kits in the Summit Racing catalog for propane injection for diesels. Maybe I'll look closer at Mogas Fuel Systems site to see if I can learn more about how this setup might work. I haven't really found many other sites that have this kind of equipment. -Louis

 

[n8wvi]

Not sure about NG, but IIRC, propane is about 100 octane Dave

 

[SixPak]

FWIW, I used to work in a shop where we deburred parts by burning the burrs off with compressed natural gas. I won't go into a lengthy explanation of how this happened, but suffice it to say we compressed the NG with a sears and robuck compressor right off the shelf. we just replaced the air filter with a pipe from the gas meter, and, well...... we did have to upsize our service. we noticed once winter arrived that we had sucked the flame out of our furnace. it got kinda cold there for a while. a short while, I might add.

 

[porcupine73]

Thanks for the info SixPak. Sounds like an interesting process you had there! I kind of wondered if that would work but I was afraid to try it because I didn't know if the NG would like 'detonate' in the cylinder when compressed. I've been trying a little propane injection; not sure if it boosts mileage yet. It's a very low flow (think hardware store torch) because I read a little propane can help gasoline burn more completely so I'm doing it more as an MPG improvement test at this point. I have a source for 500-600psi NG, but I think the cylinders in NG powered vehicles are like 3000psi. I don't think NG liquifies under low pressure like LPG which might have only 50-200psi in the cylinder depending on temp.

 

[Shaman]

Are you using a Nitrous injection style system? Just a nozzle with a hose hooked up to it? There are several sites that make propane injection for diesels and gas engines, but it is used as a knock retarder rather than a supplemental fuel, except in the dual propane/nitrous kits that are being used for the big boys. I would really like to know how this works out for you.

 

[porcupine73]

I'm just using a very simple $15 setup for testing. After a couple more tankfuls of gasoline I'll stop propane injection to see what if any mileage difference there is. My original plan of using NG or propane as a supplemental fuel with gasoline has kind of changed at least for now into just some experiments to see if I can increase MPG cost effectively. I'm trying this experiment based on info from LubeDev.com where they say: Quotes from here:

quote:

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In fact we have added propane to gasoline with great success but this in not to be attempted by the average person. Note propane and neopentane are great vaporization aids.

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Quotes from here:

quote:

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Propane and neo-pentane are excellent MPG additives. Propane can be added to gasoline to improve vaporization and therefore improve MPG. In fact propane IS added to gasoline but they do not add enough.

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That info just has me curious enough to see what kind of results I can get.

 

[Master ACiD]

heres what you can do for peopane. im not sure about cng as i dont have any expierence with it. first you need to buy some items. you get a new bbq grill tank regulator. (the thing with adjustable settings for low med and high that every bbq grille in america has.). you also grab a propane 12v disconnect solenoid and a reverse hobbs switch. peobably get the disconnect at an rv dealer. the hobbs switch can be bought online. wire the hobbs switch into the oil pressure light on the gauge of the vehicle, so that when there is oil pressure, the hobbs switch makes a closed circut and activates the 12v propane disconnect solenoid. when there is no oil pressure, the hobbs switch opens and cuts offpower to the disconnect solenoid. this way, the propane will ONLY work whern the engine is running. the second you shut off the engine or stall, the propane stops flowing. next hook up the disconnect to a 20# tank and add the bbq regulator after the disconnect. set the regulator on "low" and plumb it to the intake manifold probably the best plkace would be around the throttle body.. you can probably use low quality cheap rubber hose as there is no pressure after the regulator. now you need to buy a obd2 tester which can show you short term and long term fuel trims. you need to check the fuel trims while running the engine and venting propane into the engine. adjust the bbq regulator untill you get the % you desire. note that sence the regulator vents at a constant rate, the propane will be more concentrated in the engine at idle compared to highway cruising so you may want to set it for 20-30% at idle, and see what that gets you at highway speeds.

 

[porcupine73]

Master ACiD, yeah buddy now that is some sweet practical info! I was also trying to think of a way to maybe vary the flow based on TPS or something, but anything like that probably gets complicated fast. I guess the obvious question is, would it save money. Probably would keep the oil from getting dirty as fast. I'll have to try to run some numbers. I can get 20lb tank propane filled around here for $13 but it's out of my way. 20lb cylinder exchange anywhere around here is at least $20 now. Then there's the time involved in getting the cylinders filled. Plus I'm guessing setting up 20lb cylinders in the back of the car, how shall we say, might not meet automotive industry manufacturing best practices.

 

[Master ACiD]

propane would net you come savings, just on the fact that its cheaper per btu than gasoline. what im trying to say is that propane isnt as fuel efficent as gas, but it cost substancially cheaper so you use a little more but youre price per mile drops. the real savings would be with cng. cng is roughly half the cost of gas per mile. youre mileage will be lower with cng but youre cost per mile would double because cng is alot cheaper. i just dont know anything about cng. all of my expierence is with propane. i use to be a propane forklift mechanic.