Converting a small engine into air compressor

[avz]

Hi all
Let's hope that I would'nt considered to be too weird. I would like to ask if anybody had turned a small engine into an air compressor pump (head). I would like to build my own compressor and since I have the tank and several electric motors (so I can choose the right one) I need the air pump. any ideas will be thanked.

 

[alchemysa]

I recently discovered it wasn't even worth repairing a compressor let alone building one. You need more than a pump. You'll need gauges, fittings, auto-shut-off switch, etc etc.

 

[vpd66]

I've tossed this idea around quite a bit in the past and still think about it. My thoughts would be you'd get much better performance and volume from a small car engine (4cylinder). After all, I've never heard of anyone complain of having too big or too much air volume from a compressor. The right way to convert an engine would be to use an overhead valve engine and just fabricate a flat plate cylinder head with 2 pipe fittings welded over each cyinder. Then build 2 manifolds that connect the pipe fittings over the cylinders. One for exhaust and one for intake. The key is that you will need to have check valves in the manifolds so when the piston goes down the intake check valve is open and when the piston comes up the intake valve is closed and the exhaust valve it open. I've yet to see any check valves available that would fit the bill, but I don't think it would be all that hard to fabricate some. Just my ideas.

 

[BHD]

not worth the hassle simply stated,

yes one could get a "spark plug pump" and screw it in to the spark plug hole and have a compressor, but the valves in the motor will only allow it to pump on one out of two strokes,

and to convert the valves to work on ever stoke is not impossible, (one needs to take the lifter out of the exhaust valve and then put very very light springs in the intake so it will open on it own when there is suction, (a spark plug pump was some what normal on the old 1940 to the 1960 or so, it was check valve that was threaded to the same as a spark plug and one could take one plug out of there motor and screw it in and have a emergency air compressor, I do not know if you can buy them new or not any more, Ebay would most likely be your best bet,

but one can buy a pancake air compressor for $100 and my guess is by the time you get all the things round up and make it safe, (pop off safety valve) pressure switch, pulleys, check valves, mounts and time you can buy one cheaper than make one, and the efficiency of it will be much better,

you would at least be better off at least buying the pump,

here is a Google search for air compressors under $150, many under $75,
air compressor - Google Search

the other factor is most check valves are not desigend to handle the heat that is created by a compressor head, air compressors use reed vales or disk valves normaly, and I think you would have spring and seat/seal failues if used much,

 

[NormL]

Hi all
Let's hope that I would'nt considered to be too weird. I would like to ask if anybody had turned a small engine into an air compressor pump (head). I would like to build my own compressor and since I have the tank and several electric motors (so I can choose the right one) I need the air pump. any ideas will be thanked.

Over the years I have made air compressors using automotive air-conditioner pumps. The ones I used came out of older Chrysler Corp. vehicles. They had 2 cylinder pumps back then and I even used them for my mobile shop back in the day. You have to remove a restictor on the intake side and if you are not using the electric clutch, just spotweld around the edge of it in three places to have it engaged full time. I'm guessing aftermarket single cylinder units would also work but i never tried any of those (always had easy access to the chryco stuff).

This setup supplied enough volume for light use of air tools and painting but not so much for air grinders and high volume uses such as raising a tubeless tire onto the bead.

 

[zonta223]

One of the most common mobile air compressors used to be the old volkswagon beetle engine. the front 2 cylinders were left as normal car engine configeration.
The rear 2 cylinders had the exhaust valve pushrods and rockers removed.....and non return valves fitted into the spark plug holes.
neat compact unit...electric start.no pulleys or gears required.
No pressure switches etc the air tank only fitted with twin safety blow off valves. produced enough air to run full sized jack hammers etc..............but may be to big for what you want.

 

[kelloggguy]

It might be possible to do, but why try when you can buy a brand new Kellogg 5HP pump for under $500, and a Saylor Beall design for under $400? Slightly less than double for a 10HP model.

 

[BHD]

here is a picture of a little compressor I made, it uses a regular pump,

it uses what is called a unloader valve, (which is different than a pop off valve) the pop off will just dump air out of the tank down to a safe level, not nessarly at a minimal level it may be 100 or it could be 20 before it re seats,

the unloader is like a pressure switch but only dumps the air out of the compressor head, not the tank, there are number of different configurations for different valve types and so on, some work by holding a valve in the head open and some just dump the air coming out of the head, the second type is usually used on smaller pumps, if your compressor is stop starting very rapidly then a unloader is a good choice over a pressure switch or if you have a gas engine operating the pump,

 

[Snaker]

I grew up using an old lawn mower engine for a pump. It didn't have a tank at all. The hose came from the sparkplug hole and if I remember right, the exhaust was blocked off completely. It was good for filling tires and that was about it. We had to hurry with it and as soon as we unhooked the air chuck we had to unplug the power cord because the belt would start to slip. I think it was only good for 60-70 psi. One of the problems with that setup is that you need a "like new" engine to get the higher compression psi and that will cost you these days. A worn out engine will be a worn out compressor.

I also would have to believe that setup wouldn't be all that effiencient with electricity and that can add up also.

 

[mainegoatman]

Hi all
I would like to ask if anybody had turned a small engine into an air compressor pump (head). I would like to build my own compressor and since I have the tank and several electric motors (so I can choose the right one) I need the air pump. any ideas will be thanked.

Yes I did this when I was 14 years old, more or less out of boredom and just because I like to tinker around with stuff. (I'm now 58 - my dad thought I was crazy)

I took an old lawn mower engine, remove the camshaft, ground off a lobe, drilled and tapped the shaft 180 degrees and threaded a bolt in, reground the bolt head to resemble the opposite cam lobe. This made each up stroke of the piston compress air. My dad had this thing that you could screw into a spark plug hole to pump up a tire etc. (on a multi cylinder engine) I don't know if you can still buy these things.

I rigged up a motor to it and it worked.

If I would do this again I would build up the cam with weld instead of a bolt head.

Yes this was very primitive, but that's the general idea if one would refine it.

It would be a fun project if you have the time but I'm thinking it would be easier to find a used air pump at a yard sale or something.

I also know people who have convert auto air conditioner compressors into air compressors on there trucks using the engine to drive it. The only problem with doing that is you must devise a way to add oil to the air intake and then filter it out)