Ingersoll-Rand Compressor, how much hp required?

Andrew Mackey

Moderator
Re: Ingersoll-Rand compressor, how much hp required?

depends on what you intend to drive it with. Electric motor - I would thing around 5 HP or better if you intend to use at full pressure (100 PSI). if you intend to use a gas engine, at again full pressure, I would think15 to 20 HP minimum. You have to remember, an electric motor has constant drive motion, unlike a gas engine that only puts out power for a 1/4 of its 2 revolutions (power stroke) unless it is a multi cylinder engine. As for using a hit and miss engine to power it - by the time you get done with the reduction in speed, a 6 or 7 HP engine will be laboring pretty hard to keep up with the load, and it will take a long time to fill a reservoir at full pressure. From the looks of it, this is not a multi stage compressor, no? All cylinders the same size from the looks of the cylinder mounts?
 

dalmatiangirl61

Subscriber
Re: Ingersoll-Rand compressor, how much hp required?

Andrew
Read the tag! I'm thinking its going to take more than 5hp electric, my guess is minimum 20hp. I'm sure somebody can do the math and get better than a guess.
 

Vanman

Subscriber
Re: Ingersoll-Rand compressor, how much hp required?

Yeah, that's a big beast of a compressor. I was thinking that the model 25 might be about right- 25 hp. :D
 

K-Tron

Active member
Re: Ingersoll-Rand compressor, how much hp required?

In that condition, a 5 horsepower motor will be more than sufficient.

My friend has a T25 in his workshop with a 10 horsepower general electric repulsion start induction run motor belted to it. The compressor does not turn very fast, maybe 350rpm, so he can get away with the smaller motor. I would tend to agree that a 20-25 horsepower motor would be necessary to turn that compressor at speed based on those cylinder dimensions. Do you have the rest of the compressor? The T25 was one of the last good compressors Ingersoll Rand built. They were made in the good ole USA. Now if you buy an IR no matter the price it will be made in China. No thanks!

Chris
 

s100

New member
Re: Ingersoll-Rand compressor, how much hp required?

Agreed on the 20 - 25HP. That's a big compressor with TWO primary cylinders feeding the second stage. I suspect the 100 psi referenced on the tag is the interstage pressure not the final output pressure.
 

Vanman

Subscriber
Re: Ingersoll-Rand compressor, how much hp required?

Chris, PLEASE post photos of your friend's GE Motor and compressor! :D

In that condition, a 5 horsepower motor will be more than sufficient.

My friend has a T25 in his workshop with a 10 horsepower general electric repulsion start induction run motor belted to it. The compressor does not turn very fast, maybe 350rpm, so he can get away with the smaller motor. I would tend to agree that a 20-25 horsepower motor would be necessary to turn that compressor at speed based on those cylinder dimensions. Do you have the rest of the compressor? The T25 was one of the last good compressors Ingersoll Rand built. They were made in the good ole USA. Now if you buy an IR no matter the price it will be made in China. No thanks!

Chris
 

Merv C

Member
Re: Ingersoll-Rand compressor, how much hp required?

I have a T30, 150 psi, American build, in the workshop that I have had for at least 30 years. It has a 5.5 kilowatt electric motor, that is almost 7.4 electric horse power.

It is a two stage compressor and dumps pressure from the cylinder when the motor shuts off so it can start up with with no residual air pressure.
I don't remember the rated free air delivery. It is either 25 or 35 cubic feet per minute, but it would handle everything we threw at it. including spray painting and my sand blaster.

If it is set up the same as mine a 7 or 8 hp motor would easily handle it.

Merv.
 

ronm

Subscriber
I think that looks a lot like a compressor somebody posted a pic of a while back that was powered by a V4 Wisconsin. Probably 25-30 HP.
To need a 5-groove pulley, it ain't no weed eater engine...
 

Tracy T

Subscriber
it looks the same as a tow behind model i had years ago just smaller. mine had a waukesha i guess i spelled that right 4 cylinder engine powering it. sadly the engine was beyond repair, what i found out was its not about horse power so much as torque. i replaced the 4 cylinder with a 6 cylinder hercules and it didnt have enough torque!
 

BHoward

Subscriber
I had a 2 cyl. Davey compressor that came from the factory with a Model A ford engine. It was belt driven, and probably about the same capacity as your,s.
 

Vanman

Subscriber
That big three cylinder compressor reminds me of the ones I used to see in the "old" EMD locomotives. They were driven right off the end of the crank, so maximum ~900 rpm when the engine was at full tilt. I don't know what size they were, but they looked BIG.
 

84prerunner

New member
All depends on how much pressure and how many CFM you want. that post above shows 25hp at 870RPM. If you slow it down you wont need as many hp. Might be about to get away with a 15hp at something like 650rpm. def wouldnt go under 500rpm as you risk starving it for lube.
 
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