# DIY(Air Compressor)



## Blumpud

hi guys! so... had an idea of converting a 4stroke motorcycle engine into an air compressor.... i just wanted some second opinions before taking on the project.  . sooo any thoughts and opinions would be highly appreciated! thanks!


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## Vegassparky

Would the engine be used to run an auxiliary air pump, or would you be using the engine exhaust as the utility air?

The former may work if you can keep the RPM of the engine within the operating range of the pump. 

The latter would be dicey. Heat control would be difficult. The combustion byproducts would be run through your connected equipment. You'd probably have problems keeping the engine running with the exhaust backpressure increasing as your tried to achieve working pressure in your tank.

Can you explain your plan in more detail?


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## Blumpud

Vegassparky said:


> Would the engine be used to run an auxiliary air pump, or would you be using the engine exhaust as the utility air?
> 
> The former may work if you can keep the RPM of the engine within the operating range of the pump.
> 
> The latter would be dicey. Heat control would be difficult. The combustion byproducts would be run through your connected equipment. You'd probably have problems keeping the engine running with the exhaust backpressure increasing as your tried to achieve working pressure in your tank.
> 
> Can you explain your plan in more detail?



XD. Oh no not that.. no combustion will be done during the process.. i will use the engine as the AIR PUMP not the motor that will be running the pump. My idea is ill just remove the cylinder head of the engine and replace it with a fabricated cylinder head that has 2 one way check valves attached on the cylinder head. one input check valve and another output check valve. The engine will be run by an electric motor attached to the output sprocket of the 4stroke engine. As the piston inside is being pulled downwards(Bottom Dead Center) it sucks in air into its cylinder through the input one way check valve and as it pushes upwards(Top Dead Center) the air inside the cylinder will be forced through the output one way check valve and stored into an air tank..... i hope i explained it thoroughly.


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## Wrench97

It was common years ago to see both v8 and inline 6 and 4's converted to air compressors half the engine ran and the other half of the cylinders were the compressor.
Schramm was one of the developers of this process problem was the cost of machining the heads and eliminating the exhaust valves, casting a new intake made the costs too high it became cheaper and more fuel efficient to use screw type compressors driven by a stock industrial engine.

Is this a overhead valve engine or a flat head?

What pressure and CFM do you need?

A simple way may be to eliminate the exhaust valve operating mechanism remove the carb and use the spark plug hole to adapt a check valve to.


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## Blumpud

Wrench97 said:


> It was common years ago to see both v8 and inline 6 and 4's converted to air compressors half the engine ran and the other half of the cylinders were the compressor.
> Schramm was one of the developers of this process problem was the cost of machining the heads and eliminating the exhaust valves, casting a new intake made the costs too high it became cheaper and more fuel efficient to use screw type compressors driven by a stock industrial engine.
> 
> Is this a overhead valve engine or a flat head?
> 
> What pressure and CFM do you need?
> 
> A simple way may be to eliminate the exhaust valve operating mechanism remove the carb and use the spark plug hole to adapt a check valve to.


I think it's an overhead valve that ill be using and the volume of the engine is 125CC. and. i was aiming for 200psi and roughly about just 1 cubic feet per minute.


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## Wrench97

You will not get 200 PSI, it's physically not possible to get more then the compression of the engine.


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## Vegassparky

Glad to hear you weren't planning on running your tools with exhaust gasses. I had to ask for specifics because you never know exactly what someone has in mind, specially on the net. 

I don't see why you couldn't make it work with a check valve, and storage tank. 



Wrench97 said:


> You will not get 200 PSI, it's physically not possible to get more then the compression of the engine.


Since detonation isn't a concern, how about checking the clearances, milling the head(s), and bumping it up?


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## Blumpud

Wrench97 said:


> You will not get 200 PSI, it's physically not possible to get more then the compression of the engine.


yeah i think the compression of the engine is about 150psi. but i can deal with that.  i just need it for everyday use for the other builds that i have i mind


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## Blumpud

Vegassparky said:


> Glad to hear you weren't planning on running your tools with exhaust gasses. I had to ask for specifics because you never know exactly what someone has in mind, specially on the net.
> 
> I don't see why you couldn't make it work with a check valve, and storage tank.
> 
> 
> 
> Since detonation isn't a concern, how about checking the clearances, milling the head(s), and bumping it up?


milling the engine would be too much work and money. im afraid i don't have such tools for that too XD


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## kendallt

remove lifters or cam(s) if direct operated (would need to do some work to prevent loss of oil pressure if cam(s) are pulled), replace the intake valve springs with very weak ones, replace spark plugs with ball type check valves that can be routed to a tank.

Weak springs open with atmospheric pressure, you don't need the exhaust valves to operate at all, with the check valves in the plug ports, you'll get pressure at every stroke.

edit, they used to sell 'anti-foul' plug extenders, could be used as a base to mount a check valve out in the open.


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## zbeckerd

not sure what your planned use is. I have a compressor. But for cleaning a pc I got a metro datavac. Best tool I have bought in the last couple of years


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## wavemaker

Gooday Blumpud. What you want to do is totally feasible, and was quite common before China, but why would you bother, unless it's just because you can. Where I live, Oz, you can get compressors of a wide variety for not a lot of money.


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## kendallt

Not sure of his reason, but sometimes it's just fun having unique self-built equipment in the shop


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## Basementgeek

Probably need some kind of fan to cool the pump.

BG


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## joshaughne

I once sold a 441 cc one-cylinder motorcycle engine to a guy who used it to power a sawmill. But it was an air cooled engine and he had to put a fan on it. No way to run antifreeze through a radiator.


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