You don't need a lot of pressure to run a TE. 20 – 30 psi will run it over but you need a lot of volume. Air does not have the expansion rate of steam and the reservoir is quickly emptied.

I have a larger engine with a 3.25" piston dia and have an 8 cfm compressor. It takes about 10 minutes to charge the air receiver to 80 psi and will run my engine for a minute or two before it is exhausted. The compressor cannot supply enough air to run continually. A 5 cfm compressor would probably keep a 2" engine running continually without a load.

Paul.

Compressor output is usually quoted as x cfm but often miss the last bit "free air delivered" or running at atmospheric pressure.

Not sure what pressure they attain? That have a reasonable volume but pressure would drop off quickly so personally I doubt it but prepared to be proved wrong!

Paul.

Join your local model engineering club, is my advice. Someone will have a possible suitable compressor to demonstrate if it runs or not and would likely help you out in making your decision.  A new engine might need rather more pressure than when run in a bit.

Lidl recently sold a small compressor of about a kiloWatt, claimed FAD of 180 litres per minute. Very noisy and without a particularly long continuous run time, but might suffice. They cost about fifty quid.  There is a review video on you tube.

Time of run will clearly depend on tank pressure and size, for a conventional type of compressor.

I personally would not want to buy a modern “buzz box” compressor. An old cast iron unit, running slowly would be a far nicer prospect for me.

PI D^2 h/4 the volume of a cylinder, where Pi is 22/7, D is diameter and h is length of stroke in this case. Paul’s suggestion is a good starting point. Less than that volume would be no good without some form of pressure regulation, fed from a much higher pressure air receiver., for continuous running.

A profile, with location, might help you get some practical assistance. My air line would likely not reach your location!

Edited By not done it yet on 21/01/2020 07:01:30

"no good without some form of pressure regulation"

Most shop compressors come with a reducing valve which can output air to a lower pressure

A large receiver could extend the runtime of a small compressor as long as you are prepared to charge it up, of course once you run out of air then it’s game over until you charge up again.

Mike

You have to pay for air these days at most garages. May be cheaper to gat a compressor in the long run.

There are lots of small compressors with 25 litre recievers which would not only power models during testing, but also be very useful for a home shop airline and for blowing up your car tyres.