old SpeedAire 3z040C w/3z181 pump

[Aruba1]

Hi everyone,

I recently purchases an old SpeedAire compressor. It came with a 10hp Kohler motor. Its missing the starter and carburetor. Instead of spending money on these parts I am looking at replacing the motor.

The pump is an unloader type and is also made by SpeedAire. Its a 3Z181 that is rated for 3-5-7.5hp. What is the best motor to go with? Should I get a replacement motor that is at least 10hp or can I use a 6.5-8hp motor?

Or... can I use my 5hp industrial 220v motor to run the pump? I heard that the unloader pump will eat up the belts. Is that correct?

Thanks

 

[Fixnair]

First lets define "motor". Motors are operating from energy generated somewhere else. Engines are operated by energy generated within themselves. Did you remove an engine and intend to replace it with a motor?
If you are a homeowner you probably don't have three phase power so I would look at a single phase 5 horsepower electric motor. If you have three phase power then a three phase motor would much cheaper to operate.
As far as the unloaders go, you won't need them. They are only necessary with the engine drive because you can't start and stop automatically so you run the compressor continuously and load and unload it. They really have no effect on belt wear. You should plug off the inlet to each unloader.
As for what size motor sheave to use I would turn the compressor @ 860 RPM. To find the sheave size multiply the comp speed, times the comp flywheel diameter and divide that product By the motor RPM.

 

[TheGrooveking]

You are going to want the 10 hp, gas powered engines have different torque curves than electric motors, this why you always see higher horsepower engines on compressors. Remember horsepower is a calculation of torque and rpm. I'd recommend finding out what type of shaft the existing engine has as that is what will fit your drive sheave.

TheGrooveking

 

[mayday0017]

I'd really like to see the picture of the pump, that will tell me a lot about what your motor options really are....

 

[metal4130]

I am very sure the 3z-181 pump is a Champion R15 which is supposed to have a 5-7.5 HP motor on it. MAX pump RPM is 1000 but more common is 845. That is a good pump and you will have no problem putting a 5HP electric motor on it. If you need more air you can go with a 7.5HP.

 

[Aruba1]

So yesterday I went to Harborfreight and I noticed they had one of those twin compressor pump in their open box section but since their system was down (no credit card, no debit card or check) I decided not to inquire about the "best price" on the pump. Someone wrote $120 on the box. Today I went back asked the manager how much for the pump and if I could make an offer. She said that they will consider offers and that they wanted $25.00. I did not even care about making an offer, lol, the compressor comes with a FIVE day warranty. Based on the reviews online it should last me a couple of years at the least and I will be break it in properly. So I walked away with a brand new $190 pump for only $25. Woot woot. So now I will have 3 soon-to-be working compressors (just need time to put them together):

1. 20 gallon, 5 hp single stage with a debilbiss pump. Compressor is no name brand.
2. 60 gallon, 5 hp single stage (much larger motor than compressor #1) with a HF pump. The cheap pump replaces my 234c4 pump that went bad.
3. 40-60 gallon, soon to have a 10 hp gas engine with a speedaire/champion pump.

 

[firebox40dash5]

I am very sure the 3z-181 pump is a Champion R15 which is supposed to have a 5-7.5 HP motor on it. MAX pump RPM is 1000 but more common is 845. That is a good pump and you will have no problem putting a 5HP electric motor on it. If you need more air you can go with a 7.5HP.

That sounds about right IIRC. If so, I have one at work running off an old 5hp single phase GE motor. Runs great, just don't flop it and break the valve seats like the PO did.