Air compressor to gas engine

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#1
Okay, here's something I've had in mins for a while. Lowes and HB sell these v twin air compressors that are relatively cheap. They put out between 2-7hp. Im wondering how feasible it would be to convert it to a combustion engine. It seema like all the parta are there, sans the cam shafts and a carb. What do you think?
 

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#2
They don't put out any power, they require a 2-7 HP motor to turn them.

If you're a really talented machinist you could make new cylinder heads and use Kohler v-twin parts for the valvetrain. If you're not, then it ain't gonna happen.
 
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#3
People have done it on YouTube. Jonathan w made a Quincy air compressor into an engine. compressor pistons are different might need modification or substitute them for a different piston. I took apart a tiny compressor used to inflate tires and thought the same thing. Also makerj101 turned a refrigerator compressor into a 2 stroke engine. A flywheel from a riding mower engine may work but you would have to setup the ignition so it works. Would be cool to see a vtwin motorized bike. Would look like one of the original motorcycles. Also just because the electric motor used to drive it is 3hp, that doesn’t mean once it’s converted to gas it will be 3hp.
 
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#4
People have done it on YouTube. Jonathan w made a Quincy air compressor into an engine. compressor pistons are different might need modification or substitute them for a different piston. I took apart a tiny compressor used to inflate tires and thought the same thing. Also makerj101 turned a refrigerator compressor into a 2 stroke engine. A flywheel from a riding mower engine may work but you would have to setup the ignition so it works. Would be cool to see a vtwin motorized bike. Would look like one of the original motorcycles. Also just because the electric motor used to drive it is 3hp, that doesn’t mean once it’s converted to gas it will be 3hp.
So probably more work than it's worth?
 
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#5
$79 isn’t that much for the 3hp one and if you can get used free parts or have a mill might be a cool project. You would have to bore a hole for the shaft on the one side and machine a place for a bearing and seal. The other day at work I noticed an in-line twin air compressor but might even be able to get a compressor from a junk yard for a couple bucks.
 
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#7
$79 isn’t that much for the 3hp one and if you can get used free parts or have a mill might be a cool project. You would have to bore a hole for the shaft on the one side and machine a place for a bearing and seal. The other day at work I noticed an in-line twin air compressor but might even be able to get a compressor from a junk yard for a couple bucks.
not a bad idea. I don't tthink it would be too hard to bore a hole and place a bearing. I love the idea of the 3 cylinder radial set up. They're very nice looking and would work great on my morgan 3 wheeler project.
 
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#8
$79 isn’t that much for the 3hp one and if you can get used free parts or have a mill might be a cool project. You would have to bore a hole for the shaft on the one side and machine a place for a bearing and seal. The other day at work I noticed an in-line twin air compressor but might even be able to get a compressor from a junk yard for a couple bucks.
My only concern is whether or not the pistons would hold up to the combustion. They're cast iron which worked great for older motorcycles, but would they work for this kind of project.
 
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#9
I’m assuming they would if the compression was lower than modern engines like the early 1900’s vtwins. Back then a 500cc engine would only rate as 3hp. Long pushrods would need to be sourced. Might be able to find some forged pistons to fit the bores.
 
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#10
I’m assuming they would if the compression was lower than modern engines like the early 1900’s vtwins. Back then a 500cc engine would only rate as 3hp. Long pushrods would need to be sourced. Might be able to find some forged pistons to fit the bores.
Why the pushrods? From what I cann tell, the compressor already comes with valves in place. I wonder if I can get away with using those.
 
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#11
Pretty sure they have a type of reed valve meant for the air they compress but it’s like a disc from what I saw, but different designs too interesting. They aren’t the conventional solid valve with the 4 strokes.
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#12
Why the pushrods? From what I cann tell, the compressor already comes with valves in place. I wonder if I can get away with using those.
No, because of the way an engine works as opposed to a compressor.

An air compressor builds pressure in the tank. The cylinder is just a pump to move air into the tank. Compressor valves are merely one-way valves that keep the air moving the right way. At no point in the compressor's cycle is there enough pressure in the cylinder to enable combustion, and if there was, the ignition event would open the exhaust valve. Disconnect the tank and the compressor isn't a compressor anymore, it just moves air from one side of the room to the other, like a very noisy fan.

4-cycle engine works this way:
Intake: piston moves down with intake valve open, cylinder fills. OK, this part works with compressor parts. Not optimally, but it works.
Compression: Piston moves up, both valves closed. Not how a compressor works. As a compressor's piston moves up, the intake valve closes and the exhaust valve opens, letting air into the tank. There is no cam to do this, they're just spring-loaded reed valves. Without compression in the cylinder you don't get...
Ignition: Spark ignites air/fuel mixture, both valves remain closed. See paragraph above. Also, you need to put a spark plug in there, as well as a way to fire it. Will the reed valves take the heat of combustion? No, they will not.
Exhaust: Valve opens, piston moves up to expel the gas. A compressor does this.

So of the 4 cycles, a compressor can do two of them.
 

curtisfox

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#13
Somewhere someone took a compressor, put a carb on one cylinder, ( V-twin ) pushed gas to the second cylinder, with a spark plug in it. And actually made a engine, it ran good and was mounted on a bike. Was posted on here or the other forum, may even be on U-tube..............Curt
 
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#14
Somewhere someone took a compressor, put a carb on one cylinder, ( V-twin ) pushed gas to the second cylinder, with a spark plug in it. And actually made a engine, it ran good and was mounted on a bike. Was posted on here or the other forum, may even be on U-tube..............Curt
I'll take a look around. Think you might know the title?
 
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#15
So let’s get this straight it was a vtwin that only fires on one cylinder? Sounds inefficient to me. With more modification it should be able to run on both, guy was probably lazy. You have almost twice the weight with the extra cast iron cylinder and piston. It was like a poor mans fuel injection from what I’m hearing. One cylinder would push gas into the other?
 

curtisfox

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#16
Sorry been a while that i seen it. Just know it worked, sounded kool, be sorta like a old Briggs thump-er. Couldn't be to lazy as he built it, LOL, would think be more fun doing this then just slapping a engine on a bike, and try to see how fast you can go. Experimentation is what got the Model T to were it is today,LOL.............Curt
 
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#20
Gues what i found while snooping................Curt

Curt, I've spent at least 3 hours pouring over that video and his literature, but i can't seem to grasp everything about this engine. It seems somewhat easy enough if i understand it properly, but i feel like I'm missing something crucial. From what i can see it's essentially a stock compressor with a hole bored into one of the cylinder heads for a spark, a magneto attached somewhere and a carb that runs to the cylinder with the spark. And for charging purposes, a pipe that runs between both cylinders. What else am i missing here?
 
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