# Air compressor idea



## sparky961 (Aug 2, 2008)

Has anyone ever heard of a conversion of a small IC engine - like from a string trimmer or lawn mower - to an air compressor? Considering that an air compressor is a very simple engine being driven, I don't figure it would be a lot of effort to give it a go.

I think a 2-stroke may be an easier conversion, but it doesn't seem too difficult for a 4-stroke either.

Are there any reasons that this really isn't feasible or practical? Any ideas? Links to web sites showing it has been done? Any potential issues with lubrication and/or cooling?

Thanks
-Sparky


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## Powder keg (Aug 2, 2008)

I converted a 5 hp Briggs into an air compressor. It worked great for a few years. I made a new head for it and installed 2 check valves on top. That way it had compression on every stroke. Sorry, no pictures. 

Good luck, Wes


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## Tin Falcon (Aug 2, 2008)

I would think it could be done A buddy of mine used to have a work truck with a built in compressor that was gas powered IIRC it was a chevy 350 block that had two of the cylinders acting as a compressor the rest of the cylinders acted as a regular engine. This was a second engine that sat in the back of the truck. 
Tin


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## cfellows (Aug 2, 2008)

From a technical stand point, air compressors that I've had apart tend to have a longer stroke to bore ratio than modern gas engines, particularly 2 stroke engines. Compressors also tend to have a lot less clearance between the piston and head, giving a higher compression ratio.

However, for lower pressure compressors of 50 or 60 PSI, I should think a gas engine would work just fine.

Chuck


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## BobWarfield (Aug 2, 2008)

These fellas here have air compressor engines:












That second one looks Scandinavian to me.  ;D

Cheers,

BW


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## Bernd (Aug 2, 2008)

That second one looks like it doesn't come with a heater.  :big:

First time I've ever seen such a contraption.  I bet it's never been out doors in the winter. Probably a trailer gueen. :-\

Bernd


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## Lew Hartswick (Aug 2, 2008)

Powder keg  said:
			
		

> I converted a 5 hp Briggs into an air compressor. It worked great for a few years. I made a new head for it and installed 2 check valves on top. That way it had compression on every stroke. Sorry, no pictures.
> 
> Good luck, Wes


What sort of valves did you make? Reed or flat washer with a coil spring . The inlet valve is the 
difficult one to get a handle on.
  ...lew...


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## Powder keg (Aug 2, 2008)

I used some reed valves. They were a one way check valve for an air line on a truck. A check valve with a ball and spring would probably work fine. The intake valve is put on upside down. That way it sucks in one valve and exhausts into the tank through the other valve. 

Wes


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## Brian Rupnow (Aug 31, 2008)

Back when the earth was young, about 1967 or so, I used to make wrought iron railings and room dividers. These were an absolute pig of a thing to paint with a brush, so I built a small compressor from an old Briggs and Stratton 4 cycle lawnmower engine. You used to be able to (and still may be able to) buy a thing called a "sparkplug pump". The idea was, you carried it in your glove box, and if you had a flat tire you could remove any sparkplug from your auto engine and screw this thing into the sparkplug hole, start your engine, and blow up your tire. (they came with about 10 foot of hose and a tire valve chuck.) They were relatively inexpensive, about $12.00 at the Canadian Tire Store. They had a poppet valve arrangement that would let air from the cylinder out, then the poppet would seal when the piston went down in the cylinder and a set of flap valves would let the piston suck in fresh air from the atmosphere for the second stroke. I removed the camchaft from the Briggs engine, sealed the intake and exhaust valves with a bit of epoxy, and drove it with a 1/4 horsepower electric motor. It worked really well, and in order to even out the surges of air from the piston, I ran the air into a peice of 4" diameter steel well casing with endplates welded into it to act as a surge chamber, then took a line from that to my spray gun. I cobbled up my own safety valve with a spring arrangement which I adjusted to bleed off anything in excess of 50 PSI, and bought an "air bleed" type spray gun to use with it. It worked very well, and it sprayed a lot of iron railings for a few years, and even my aunties 1963 Valient car.---Brian


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## crankshafter (Aug 31, 2008)

sparky961  said:
			
		

> Has anyone ever heard of a conversion of a small IC engine - like from a string trimmer or lawn mower - to an air compressor? Considering that an air compressor is a very simple engine being driven, I don't figure it would be a lot of effort to give it a go.
> 
> I think a 2-stroke may be an easier conversion, but it doesn't seem too difficult for a 4-stroke either.
> 
> ...


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## Bogstandard (Aug 31, 2008)

I think you will find that nowadays, anything that is going to take more than a few hours to convert, just isn't worth the bother. You can buy brand new ones now for peanuts, in all shapes and sizes.

Unless of course, you want to do it, just to prove it can be done.

Bogs


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## Brian Rupnow (Aug 31, 2008)

Bogstandard---You are probably correct.---However,--you have no concept of how poor I was in the mid 1960's. Lawnmowers engines were free, and my time was free, and ---well, you get the picture. I built a lot of my own machinery back then, because I simply could not afford to buy it. I built my own air compressor, my own drill press, my own forming machine for putting the spiral into 1/2" square bars for ornamental railings, my own power hacksaw, my own vertical stationary belt sander---the list goes on and on. Over the years, as my finances have improved I have replaced most of the stuff with "store bought" machinery, but I still have the power hacksaw (that can saw anything up to a 5" diameter billet) and the vertical stationary belt sander.


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## lathe nut (Aug 31, 2008)

I built one and still use it, used the compressor out of an 18 wheeler, works great, Lathe Nut


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## baldrocker (Aug 31, 2008)

Brian you and I obviously belong to the "neccessity is the mother of invention" school
Half the fun sometimes is making a machine do something else. As a side thought 
car (auto for those over the water) air conditioning compressors can make fine
straight air compressors.
Paul aka Baldrocker


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## Brian Rupnow (Sep 1, 2008)

baldrocker  said:
			
		

> Brian you and I obviously belong to the "neccessity is the mother of invention" school
> Half the fun sometimes is making a machine do something else. As a side thought
> car (auto for those over the water) air conditioning compressors can make fine
> straight air compressors.
> Paul aka Baldrocker


Paul---Many times in my case it was "Poverty is the mother of invention"!!!---Brian --(I have to admit though, I loved designing and building my own machinery so much that it was more pleasure than pain.)


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## baldrocker (Sep 2, 2008)

Ah>
The memories keep coming back! Atlas Copco construction site compressors
Volgswagen Beetle engines two cylinders to run, two cylinders to compress air,
feeding tank all mounted on two wheels for towing.
Paul


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