4" agg engine RPM range

Hi all, looking at building a device that can run from my 1/2 completed 4" agg engine as a static working display. I need to work out some gearing ratios. In order to do this, I need to have a reasonable idea of a what a comfortable RPM range the engine would be happy to run at without inducing any adverse side effects. After the required reduction in crankshaft RPM my final required shaft RPM is approx 80. This will be done with a 2-step pully reduction. Estimate that the load applied to engine would be light to medium in torque required. Any help on this would be greatly appreciated. Thanks Steve

An interesting question that unfortunately I cant advise on, I can though say the Agri will produce about 1hp at full chat, although I wouldnt want to maintain that kind of output for any real time frame, as when I did it on a Dyno it definitely gave it something to think about and made the flywheel come lose

Thanks for your feedback, every little bit helps to solve the problem

I've had a bit of a thought on this subject and might have come up with a way of getting a rough idea, have a rummage through some youtube videos for a single cylinder 4" Agri running and listen to the exhaust beats.
Get and idea of the rate of chuffs its giving at a speed you feel is reasonable for what you want to do.
Then go here https://www.beatsperminuteonline.com/ and tap the beats out that you hear from the exhaust from the youtube video, now remember because the cylinder is double acting i.e you get an exhaust beat after each stroke you must divide the figure from the BPM meter by 2, and that I think should give you a "rough" idea of the RPM

I used this video https://www.youtube.com/watch?v=It-waLWlCqE and recorded just over 300 bpm counting the exhaust beats, divide that by 2, makes me think the engine was doing about 150rpm or there abouts, which I'd say is about right.

Its never going to be super accurate but it might give you a starting point I'd think

Thanks so much, sounds like an excellent idea, will most defiantly check that link out after work today
thanks Steve.

Here's my 4 inch agi, although running a little fast it's 1 bhp ( I have had it tested) running my set up. It can tick over t 100 rpm but dosnt make steam easy as not enough draft up the funnel https://youtu.be/BR1HCw7BNRI?si=0myVHnVe78F6EHpH

Yeah I'd say running that set up she's doing around 130rpm. thats a nice set up you have there by the way.

I think all the Agri's seem to peak at around the 1hp mark, we put a number of them on a dyno at Hollycombe and they all came out around that figure, I dont think you'rs on the rig is doing that kind of figure, its working fairly hard but its not got the 1hp bark when they are maxed out, the pressure didnt look high enough to be doing that kind of figure. We only generally saw 1HP with the safeties lifting with a wide open regulator.

Lovely set up though :-)

Thanks for the link showing your engine, I have just joined up with CSMEE so no doubt will be able to catch up soon. I will also be at McLeans Island on the Saturday, did try to catch up with you last year there but you seemed very busy, Thanks Steve