Air compressor RPM??

[overland47]

Anybody know off the top of their head a good RPM for a 2 stage air compressor?

I picked up an old (WWII era) gas powered Curtis air compressor the other day. It has a Briggs and Stratton Model Z engine on it. Got the B&S running good, but it's old and no fun with a hand crank. The compressor works good, so I'm gonna swap it out with a nice electric start Kohler I have laying around. Now I just need to figure out a good RPM to spin it at so I can get the pulley ordered.

The compressor has a tag that says minimum RPM is 400, but no max listed. The OEM was absolutely useless in helping me... kind of rude even..... that stuff gets on my nerves, but oh well...

The way it was set up, the engine was governed at ~2400 rpm which turned the compressor at ~600 rpm. It was pretty underpowerd with the B&S (about 5 hp) and really labored when it started to get up to pressure.

It's gonna be a little overpowered now with the Kohler on it (Magnum 12), so I'm thinking about slowing the engine down to 1800 rpm or so, but spinning the compressor a little faster... maybe 800 rpm or so.

Any ideas??

Can see a pic HERE if interested.

Thanks

[K D Redd]

Briggs Model Z has a standard high idle speed setting of 2900 RPM. Figure out the ratio of the pulleys on the compressor now and turn the compressor the same speed. That said, the new engine you will use has a high idle speed of 3600 RPM. This is only 700 rpm higher that the engine you now have so if you keep the same drive ratio I do not think you will over speed the compressor. I have an old Worthington 2 stage compressor that is gear driven from a 6.5 HP Clinton engine. The gear ratio is 2 to 1. I sure the old Clinton does not turn 3600 RPM but most likely about the same as the Z. This would make the compressor speed about 1450 RPM.

Kent

[overland47]

Thanks KD.

I decided to go with a 7" pulley which will turn the compressor about 800 rpm at 1800 rpm on the engine. I can fine tune it with engine speed from there.

With the Z on there, at 2900 rpm the compressor would have been about 1075. I'm finding the typical max for a compressor like mine is 1200-1400.

My goal is to keep the engine speed (noise) down which I don't think will be an issue with the power I'll have now. I don't want to go any lower than 1800 rpm as to not lug it too much, and as long as I don't go over about 2700 on the engine (1200 on the compressor) I think I'll be fine.

I dunno... it's an experiment so we'll see.....

[Big Phil]

there,s an outfit in Florida called Air Compressor Works that can tell you all about your compressor i have one thats almost identical to yours they sent me a complete parts order form give them a call they,re real nice folks # 1-516-844-4559 good luck

[overland47]

Thanks Phil... will check them out for sure

[jcruise]

it looks like your pump uses a slinger for oiling,800 rpm is a std speed for 2 stage pumps,I would not feel comfortable at 1400rpm without having a pressure lubricated pump.

[GADavis]

i have a curtis 2 stage compressor made in 1938 and it runs at 900 rpms with a 1&1/2 hp eletric motor. Gene Davis

[Mikey4026]

As I remember, 600 to 900 RPM is the normal operating range of most medium size air compressors. So, it sounds like you are right on track.
Mikey

[overland47]

Thanks guys. Got the new pulley the other day and now I'm just waiting to find the time to finish putting it together...