Can I put a larger motor on it

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Hey y'all, I have an old Craftsman 1HP 20gal air compressor.  My question is can I replace the 1HP with a 5HP without damaging the compressor.  I hope to be able to use my die grinder and have a faster recovery cycle on the air supply.  Right now I use all the air and blow the house breaker trying to keep up with demand.Thanks, TroyLincoln 175Monkey Wards 230v.  Stick
Reply:You can put as large a motor as you want.But you won't get any more air out of it.Each rotation of the compressor will displace (compress) a fixed amount of air.A faster motor or larger motor with a bigger pulley that will spin the compressor faster can process more air. But you definitely will overheat the compressor.First let's get your setup running efficiently:Check and adjut the oil level in the compressor; Low oil will create all kinds of problems.See if the motor can be reconfigured to run on a 220V 15A or 20A circut. By doubling the input votage you drop the current needed by 1/2 for the same total wattage used. The motor will run cooler.Then start looking for a larger complete compressor/motor/tank setup. If you have a big a motor/compressor on too small a tank, you'll short-cycle the thing to death.Any 5X conversion is in the realm of "risky". A modern 1.5HP motor with a 10% larger pulley could probably get you what you want now. Then, when you buy the replacement unit, go 20%-30% bigger.Good Luck![I've got a 125CFM 3 cyl Diesel compressor available, if you'd like.]Last edited by mike837go; 09-25-2013 at 01:27 PM.Be wary of The Numbers: Figures don't lie,. but liars can figure.Welders:2008 Lincoln 140 GMAW&FCAW2012 HF 165 'toy' GTAW&SMAW1970's Cobbled together O/A
Reply:Most of those compressor heads have an RPM limit around 1000 to 1100 RPM.I did the same thing on my compressor not too long ago, I replaced a 1hp 1800 RPM motor with a 1.75hp 3600 RPM motor and slightly smaller pulley.I bumped the compressor shaft speed from about 800 rpm up to nearly 1000rpm.No matter how you slice it that 1hp compressor head isn't going to be able to move enough air to feed a die grinder. Most of the time I run my 1.75hp compressor and a 2hp compressor together, if the die grinder comes out I drag out my 3rd compressor, a 1hp unit and that still isn't enough.old Miller spectrum 625 Lincoln SP-135 T, CO2+0.025 wireMiller model 250 and WP-18V torchCraftsman 100amp AC/DC and WP-17V torchCentury 115-004 HF arc stabilizerHome made 4 transformer spot welderHome made alternator welder
Reply:If your tripping the breaker now with the 1 HP, then a 5 HP will trip it 5 times faster. Is the breaker rated for the electrical needs of the compressor, and is the compressor the only thing served by this breaker? If there are other things plugged in on this circuit, can you turn them all off for the time you need to run the compressor? That way it only has to supply the compressor and nothing else. If this breaker has been tripped repeatedly/multiple times it WILL start to get weaker(takes less amp draw to get it to trip). You may want to get it replaced with a newer one of the same amperage.If this compressor is still in good shape, just doesn't always provide enough air volume, then you can always add a second compressor to the set up without having to buy a much bigger compressor for your needs. Run one when you need SOME air, and run both when you need a LOT MORE air. Just make sure they are powered off different circuits, and plumb them both together in the same system. That way one compressor can use both tanks at one time to store more volume, but you can kick in the other when you have higher air demands to be met. You don't necessarily need to have only one compressor that can keep up with your Highest air consumption, it can be a combined total of 2 or more compressors to meet the needs. Then just pick and choose how many you need to run to satisfy what your needs are for the time being.Myself, I have several that can feed into one 25 gal. tank, but generally only use the little 2HP unit for most of my needs, like airing up tires. But when I need to do some large amount of spray painting I will turn on the 4 HP compressor along with it. If that's not enough, then I break out the gas powered compressor that outputs 14 CFM. That usually does the trick, so with three compressors running, I can blow and go for hours with out loss of volume of air.Last edited by Bistineau; 09-25-2013 at 04:55 PM.
Reply:As mentioned above, the ability of the compressor to feed cubic feet per hour has to do with the compressor unit itself. If you are running 120 VAC on a 1 hp motor, you will need to go to 240 VAC for a 5 hp motor. My compressor has a 5 hp motor that is running on 240 VAC. It draws 22 amps per line when it's running. You need a larger compressor with matching motor with a 240 breaker and correct sized wire to get more throughput from a compressor. There is no free lunch with air compressors.Miller Millermatic 252Miller Syncrowave 200Liincoln AC-DC 225Victor O-A Set
Reply:Hi, back in the 70's I worked for a firm that had an old big compressor......Ingersol Rand or something like that......one day it threw a con rod and literally disintergrated.....pretty spectacular.The blower guy said we were exceeding the supply rate and were overworking the thingo, so the boss went for a different type......a Hydrovane direct on-line compressor....no storage tank etc, works on a rotary moving vane type principle.When that compressor works it's a continuous hum, no thump thump thump like a rabbit scratching his ear thing.......and fitted with an aftercooler, worked 12 hours a day 7 days a week......that beats any piston compressor any day.Ian.
Reply:They are fine machines, are they not, Ian?For your Craftsman, likely not. You can try and discover the pump maker, them find some specs on it and see if you can spin it any faster, but odds are not in your favor. Best thing to do is keep an eye on CL for a used 60 gallon with a 3-5 hp motor on it. With those you will likely not need to improve things, but you will have more options. I can run my t-30 from 3-7.5 hp, and from 800-1200rpm (lower rpm is for the lower hp motor) IIRC. I used a 3hp belt drive for many years (really it think it was 2 hp, as it drew 15 amps) you can find them used for under $100. They last for years, can handle some air tool use, I ran die grinder, sanders, impacts, etc.
Reply:Thanks for all the input on more output.  I will rewire the existing motor to 220 and see how that works.  As far as the breaker issue, the only time it blows is when I'm running constantly for 20 minutes or so.  Thanks again.Lincoln 175Monkey Wards 230v.  Stick