Talk me out of it, guys!

Lanse

Well-known Member
So, I've found that I might be in the market for a "new" air compressor sooner rather than later - and I've had this idea on what to get next!

Many of us know that gasoline powered engines can be re-purposed into very effective air compressors, sometimes folks keep one cylinder bank running to spin the thing, sometimes they do what's in the YouTube video I've linked to... Which is basically what I have in mind.

To make a long story short, what I want to do is buy a beater engine on Craigslist, machine (I have a lathe) adapters which will go into the spark plug holes and end in a check valve, which will then join a manifold system that's plumbed into a 60 or an 80 gallon tank! The exhaust would be capped off, and just like the gentleman in the video did, I'd leave the carb up there only to hold the air filter which cleans the air to be compressed. I'd cut off the exhaust rocker arm portions, so the exhaust valves stay closed.

I'd run the thing with a 220 volt electric motor (maybe 2-3hp? 5? What do you think?) and a standard pressure switch, just like a normal air compressor.

If you're wondering "why", its because I'm tired if burning through poor quality commercial air compressors every handful of years (I'm on my third one... And I'm only 23 years old!!!). Also, because it would be a cool project for my welding show on Youtube.

Anyway - if I do this - I'm thinking a 6 cylinder engine would likely be enough - if not all the electric motor could run! I dont know, I'm just speculating right now but this would be a blast to make. Building this for commercial use in my business might be one of my whackiest ideas yet.

What do you think?
Video here
 
I can't comment on turning a gas engine into a compressor, but I just can't understand why you have such bad luck with your air compressors. All of the shops I have worked at all had big Saylor-Beall or Quincy compressors that ran 16+ hours a day. Not once did any of the shops I worked at ever replace a compressor in the years I worked there. The heavy equipment dealer I worked for had 2 hooked together, when one turned on, the other turned on 2 psi less than the other. One was a Quincy with an 80 gallon tank and the other was a Saylor Beall with an 80 gallon tank. And they made 215 pounds of air all day long, and had been in there long before I started there, the 9 years I worked there, and are probably still in there. Sometimes a line would blow over a weekend or after 2nd shift had gone home and they both would run until someone got there the next day or after the weekend was over. Put in ball valves on the tank after about the 3rd time of that. Gotta be something going wrong there.
 
Due to the unswept volume of the combustion chamber in the head/piston top area of a typical gas engine it would be VERY inefficient, but it's been done and obviously will work, up to a point.

It's gonna be a SMALL 6-cylinder engine if you are going to spin it with a 2 or 3 HP motor and make useful volume of air at PSI useful in a shop, typically 175 PSI, give or take.

"I'm tired if burning through poor quality commercial air compressors every handful of years"

It would be interesting to hear the rest of the story, what brand of "commercial compressors" are you buying, and what is failing necessitating their replacement, and what are you doing with them/what is the duty cycle?
 
Lanse,

I say get an actual AIR COMPRESSOR - that's what they are designed to do, is make air.
I recall my uncle trying to do this years ago with an old 4 cylinder tractor engine.

It worked "somewhat", but the engine (compressor) produced a lot of heat, and actually boiled.
He scrapped it, and it was a very huge and cumbersome thing.

There certainly are very good commercial compressors out there.
Not sure what you are using a compressor for, but sounds like you want one that is portable.

My vote is for scrapping this idea; spend the money on a proper compressor designed for your needs.
................ maybe check out some industrial/construction type auctions.
 
Well a long time ago my dad had I think it was a Smith compressor. Made down in bowling green? Had a special head that bolted on top of a Model "A" engine. Number one and four were the engine and the two center pistons were the compressor. Used the original manifolds but numbers two and three are blocked off. Had a great big wire screen air filter on top for 5he compressor part. It ran pretty good. You are in for a lot of fabrication. Have no idea where you can get or make parts. Might work with one bank run and the other bank compress. As I said, the ones I have seen they use the centers of the engine for the commpressor. You need a load of special parts including a govenor, throttle controls, and pressure regulators. Smith is long gone.
 
Honestly I dont really need the PSI - I need VOLUME! I run a plasma on the CNC table (~120 psi IIRC) and occasionally a hand tool or two (Impact, die grinder, etc) at the same pressure at the same time. This is where my current compressor doesnt hold up.

The story on compressors! Yes - sure thing. So the first one I bought used and I cant remember the brand of it... It blew hoses (those plastic tubes) constantly, and the pressure switch didnt work right. I remember cobbling together another pressure switch that I bought locally to kind of work, but I got tired of replacing hoses/lines on it constantly and sold the pump and motor for about what I paid for the whole thing, then made the tank into a BBQ!

After that I bought a Campell Hausfeld 60 gallon from Tractor Supply. It was a great compressor, I used it for a few years until I moved and sold it... Shoulda kept it. Currently, I have a Quincy which is my least favorite out of all of them... Everything about it is CHEAPLY made and its ~14 months old currently, it gets HOT as it runs, takes forever to charge up and whizzes oil EVERYWHERE. I think the pump is leaking oil in at least two plus places. Quincy only warranties their machines for 1 year now, so theres no help from them with it.

I'm not impressed. I understand that some of their high end stuff is fine, but this was SUPPOSED to be a commercial compressor, and I bought it from Lowes. Won't be buying another.

Honestly what I want is VOLUME and reliability. How big of a motor could I run off a 30 amp circuit? 50 amp? I want that coupled to an engine that will still be spinning when my grand kids inherit it. Thats about it, it doesnt need to be fancy otherwise...

Do you think a 5 horse motor would spin a chevy 4.3? Theres a bunch of them, CHEAP on the local craigslist. I've had the thought of using a couple of pulleys to "gear down" the motor from ~1700 rpm to ~1000 or so, to both prolong engine life and increase volume/reduce pressure. At least thats how it looks in my head hahaha
 
I believe you will end up with a better product by purchasing.

A good industrial compressor should last you a lifetime.

What have you purchased and did you adhere to the duty cycle rules?
 
I have had my Quincy compressor for four years now and it is the compressor I should have bought in the first place. I bought a cheaper brand and realized the ratings that were used such as horse power was totally over rated. The Quincy works great. It will keep up with my blasting cabinet which is the biggest air hog I have. If you really need that kind of volume then you should save up for a rotary screw compressor. I think you will waste more time fiddling with a gas motor than you think. My opinion.

OTJ
 
5Hp will spin the 6 cyl engine with a 5 to 1 reduction, but not pump air!. It takes as much power to make compressed air as displacement in the engine driving it, Ford V8 302 small block have been made into compressors using 4 cylinders for power, and 4 for compression. A new head is installed on the compressor side to allow 2 stroke operation. Cooling of the engine must be done with radiator etc.
Ingersoll Rand, and Chicago Pneumatic make real compressors. Jim
 
You bought a home owner compressor, from a home owner supply house.(I don t care what the sales person told you) You need to find the local company that sells and services the industrial companies in your area. Ask at your welding supplier, they will point you in the right direction.
Then ask at the biggest private garage in town. Look at Champions.
 
Here's a picture and a link.
a157552.jpg

Auction
 
I have seen aircompressors made from engines. Neatest one was a 6 cyl Chevy. It ran on the front 3 cylinders and compressed on back 3. Intake and exhaust were just cut and plugged. Never saw under valve cover. But was told he took rocker arms off. And put weak valve springs on intake valves. Like old single cyl engines. Took out exhaust valves. And put brass one way valves in each exhaust port. Just leave wires in cap like they were only take every other one. 5 6 4. They fire 153624. I think will take serious hp to pull it. If you use a whole car motor.
 

A good new compressor it going to run close are over 2K bite the bullet and get one when we are all dead and gone you can brag about its 30 years old and still getting it done...

The other side of the coin is most continuous duty rated compressors are rebuild-able get it cheap enoufh and take the gamble.

I know money is the player you pay for what you get and that is why there are so many new $900 compressors out there its inviting... If all you were gonna do is run a nail gun are air up a tire every now and again blow $200 on one when it takes a dump buy another one..
 
Lanse,

What pressure do you need for your plasma?

fans produce high volume at low pressure much easier than compressors.
 
We did exactly this once in the R&D lab at Quincy Compressor but we made a custom valve plate and head for one side of an 18hp Kohler v-twin. Used one side as engine and the other as
Compressor. It worked. Not great.

Engines have high oil carry-over compared to a compressor. They can tolerate to carry over due the the combustion event burning it off. Compressors dump carried oil into the pressure tank or it turns to carbon on piston crown, valve plate, and tank check. If you used the engine head your compressor would run very hot and have really low volumetric efficiency.
 
I vote for a good compressor also. Lowes sells no commercial industrial quality compressors, no matter what the name.

I'd buy an older Champion/Quincy or similar is 5hp or greater and no less than an 80 gal tank. If it should fail, just rebuild the head or put a new quality motor on it.

I'd only consider a gas engine conversion if a LOT of volume was needed, like 30 cfm or more.

A lot of parts making, fiddling with spring tensions, design etc and still will be less efficient than a quality air pump. driving one with an electric motor will use a lot of hp, just to overcome friction, cam/valve drag etc, before you start to pump air.
 

I got another suggestion raise your prices buy good equipment life is to short to be dealing with issues like this... The hardest part about self employment is how much can you get you will never know till to reach that limit... It will be a ongoing process...
 
I think you are setting your self up for more frustration.

Trying to set up an engine for use as a compressor takes more than just replacing the spark plugs with check valves. Doing it that way would be horribly inefficient. The factory set ups that do that with 1/2 of a V8 engine, like the Sullivan compressors, they replace one head with one that is designed for use as a compressor, much larger valves, higher compression ratio... Completely different from an engine head.

Trying to buy a commercial or industrial compressor from Lowes, Home Depot, Tractor Supply, ain't gonna happen! They are a completely different animal, like comparing a S10 to a Mack truck!

Do some home work, determine your maximum pressure and CFM requirements. Your equipment should have the requirements listed in the owners manuals. Add everything up, add some cushion for future expansion and calculation errors.

Then take your calculations to an industrial compressor dealer. Get ready for sticker shock, but don't let them know how shocked you are, pick their knowledge as to size recommendations. Try to find a dealer that is not brand specific and deals in used and reconditioned compressors. I use Marcuse and Sons, on N Main in Ft Worth.

If you can't make a deal there, at least you have some information and know what to look for. You can then take that information to other sources, like auctions, Craigs List, etc.

I can assure you, if you find a good used industrial compressor, even if you have to rebuild it, for home shop use, it will last the rest of your working years!
 
Hi, on the racine , kenosha wi craigslist there is a schram air compressor
that is a wisconsin v4 running on 2 cylinders and has 2 cylinders with
factory built cylinder heads for the compressor part, there are many models
Of schram units from tractor type to hit and miss , My thoughts about
using engines as compressors is the psi is would be low and most
likely would get oil in air . I dont think 5 hp electric would be enough to
run more than 2 cylinders ,so google the schram and check them out
 
Snap-on man was trying to sell me a compressor, so I took him in to show him mine. He says "Oh, you have a Quincy." end of conversation right there.
 
Just get your advertisers/sponsors to provide you with a good one where their name & money are on the line, You know the game!!!
 
That would be a great youtube project. You would get a lot of interest and questions/comments.
However if you listen close to your video link fellow and see he is now using a 90 horse tractor not a coupla a horse motor.
I bought an Ingersoll Rand 10 horse upright on an 80 gallon tank 35 years ago to use in the factory. It was about 2 grand then. The only thing I have done is change the oil a few times and make sure it doesn't run low. It runs air cylinders on molds as well as bearing presses. In my opinion you would be happier with a good air compressor the size of mine. I see the 5 to 7 horse in the farm stores for under a thousand. I do wonder about the quality of those.
 
I have an old single-stage Quincy, probably close to 40 CFM. 10 horsepower. I bought it from a guy who needed money twenty years ago for $500. It will run my bead blast cabinet and not break a sweat. It is on an 80 gallon tank. The thing is huge, but it runs and runs, quietly. I would not hesitate to recommend a Quincy compressor. Mine hold five quarts of oil and has an oil pressure gauge. Best money I ever spent. I will never understand why a fellow would go to so much trouble to shoot himself in the foot. Buy a good commercial grade compressor from a company who sells commercial grade compressors and be done with it. Life is way too short to fool around with cobbled-up junk.
 
Lanse just find and buy a used Curtis or Quincy two stage commercial compressor. I have bought two good ones in the last year for under $400. One way is to buy a 3 phase compressor and replace the motor with a single phase one. The 3 phase compressors usually sell cheaper than single phase ones.

You have been buying residential grade compressors. Buy a commercial grade two stage compressor and be done with it.

As for your car motor compressor. You can do it BUTTTTT they usually take higher horse power to turn them than normal compressors. You also need to adapt a cooling system too. The act of compressing the air will generate heat. The car motor is not design to dissipate that heat so you will need the cooling system working.

The conversions I have seen are usually for LARGE CFM compressors. I mean in the 30-40 CFM size. That usually also means 20-30 horse power electric motors turning them.
 
You're thinking too hard. Buy a decent compressor and maintain it well, compressors are not use it and forget it. I do commercial auto repair with a 60 gallon, twin cylinder Ingersol Rand from TSC. Paid $800 for it new 7 years ago. Other than a pressure switch, which could have been repaired, no other problems, not even a belt. It is maintained very well, using the Ingersol synthetic compressor oil they recommend at recommended intervals. Being self employed with no employees, you, like myself do not have time for down time.
 
Buy an air compressure off or for a Volvo truck Hook it up some how and you will have volume faster then anything in my opinion. Not sure how you would cool or oil it though
 
Lanse:

You really haven't been "burning through" compressors. You bought a cheap used one, and got your money back, then bought one you wish you had not sold.

I don't know what is wrong with the Quincy from Lowe's, but you can buy Quincy compressors online. Power Equipment Direct is a good one. I bought a QT 5 hp for $1,200 and am very satisfied with it. 50,000 hour pump life.

Everyone else has pretty much covered the problem with engines. Primarily you are turning a cam and valve train which is a drag. You are also low on efficiency if you don't put on a flat head to lower the head volume. You also are compressing only every other stroke unless you get the intakes to open every revolution. That increases heat and decreases efficiency. If you spend an extra $50 per month on electricity running an inefficient compressor you soon could have paid for a good compressor.

They used to make a spark plug replacement that used engine compression to run a shuttle to pump air so you could air up a tire using engine compression. About as fast as the little cigarette lighter jobs.
 
I have a tired old two stage Quincy that'll run 24/7 without a hint of trouble. It's on the small side. I have 150 gallons air storage. When I'm on certain jobs it runs all day non-stop.

Glenn F.
 

After my little one stopped as I was nearly done painting my discbine, I started looking for a replacement on Craig's list. After 2-3 weeks I found a 5HP Campbell-Hausfield cast iron unit with 70 gal tank for $400.00. It had come out of a hobby shop, that three guys had set up and then closed down.
 
I learned when I was young watching my dad build and modify things,then have to go spend just as much money to replace something when it all went south,to just save the money and aggravation and just go buy what I want in the first place.
 
It would be an interesting project, but when you are done you will have an inefficient air compressor with no resale value.
 
Lance,
Why reinvent the wheel unless you are interested in making money on a U-tube video?

Put a compression guage in an old beater engine. Spin engine over one time and look at how much pressure it will not make.

There is a good reason why they make two stage compressors. A single stage compressor isn't going to make a large volume of high pressure air.

If you want to know what type and where to get a good air compressor, go to your local body shop and pick their brains.

geo
 
Here's a better idea. Take one of your old compressors and convert it to a gas engine ..... then use the gas engine to drive a store-bought compressor.
 
I bought an industrial Ingersol Rand w/T-30 pump / 80 gal/ 5hp way back in 1981 and made a living in the auto body/paint/collision business for 30yrs with it and still use it today (retired). At 25 yrs replaced motor ($300) . Still has original belts on it. Will pump up and shut off with air hose end completely removed, wide open. Never been apart and does not pump oil. Cost me $ 1800 in '81 but was a pill well swallowed. Save the "engine" idea for when you're retired and have nothing but spare time to screw around.
 
Have you been talked out of it yet? I would hope so. I'll ad my vote to buying a good, REAL commercial two-stage compressor. Get one that's cast iron.
When I built my milking parlor , the requirement was a two-stage (for drier air, not for the higher pressure - it runs 65 psi on the other side of the regulator) and at least a 60 gallon tank. I went with an 80-gallon vertical C-Aire from my local Car-Quest, with an all cast iron pump. C-Aire is Wyoming, MN. So far, I've replaced one pressure switch, one manifold gasket, and one set of belts. Last month marked 20 years of use.
You should also consider space. A 6-cylinder engine plus an electric motor is going to take up as much space as a 120 gallon horizontal compressor. A vertical compressor takes about 1/3 the floor space.
 
If you were a hobby shop fine but you are a professional shop. Buy a suitable compressor and regularly service it and it will last long.
 
I won't get in to the pros and cons of building your own. I see most people tend to be against it. I will say homemade ones can be built successfully if done right. I have one my grandfather built in the 50's that works flawlessly to this day. I still use it. The thing I would like to insert here is - please be careful. I see mention of cobbling pressure switches below. A kid I went to school with grew up with out a dad because he was cobbling pressure switches. When it didn't cut out the compressor the tank blew and killed him.
 
if you are running a business, get a good quality compressor. if you use large volumes of air, get a rotary screw compressor. heres a link to some.
poke here
 
Don't do it.

Go on CL, or go to some estate sales. Find a big, old US made IR, or Quincy from the 60s or 70s. Working or not. Buy it and take it home.

Change the oil, smell the motor, and drain the tank. run it, take care of it. Mine has lasted since 1979. Put in a new motor, had to replace one piston, and one of the poppet valves. I'll give it to my kids.
 
Home built, no thanks . Don't know if it would hold together long enough to build a coffin.

Vito
 
Just a thought. I have a 5hp single stage in my shop. Works great for everyday use. I bought a tow behind for high volume air use (sandblasting, etc.) Maybe it would work for you. I can say I have a heck of alot less money in the 2 compressors than if I had bought a large commercial grade electric compressor that could do the same.
 
As someone who uses a compressor ALOT, you may have been told you were buying 'commercial' compressors at Lowes, but they lied to you.

I've seen IR's, Quincys, and others, run for years at a time without incident in a variety of applications. The main thing is they were large enough, or had enough CFM for the job at hand, without running them wide open all the time. I can't remember what brand Dad has on his service truck, but it has been out in the weather, run for hours at a time, run on 30 degree days and run on 100 degree days, and it's been going since he set up his truck in 1986. yes, 30 years with no actual issues with the compressor, even though the old Kohler engine was changed out for a Honda about 15 years ago.....and the Kohler now runs a log splitter.

That said, Dad had a 7.5HP, continuous run, compressor in his shop set to maintain about 125 psi. I've got a 5HP in mine set up to cut in at around 100 psi, and back out at 125 psi. Both have run for years handling everything from a sandblast cabinet, to a plasma being used for gouging, to painting, mist cooling while machining etc, etc, etc. . Other than doing the valves on Dad's once, neither has ever given a minutes trouble, and Dad's ran several days out of the week, 8 plus hours a day, for over 20 years, and mine's been going strong for close to 15 years now...................Funny thing, both compressors were already well used when we both bought them.

Like I originally said, you need one with enough CFM to handle what your doing without over working it. Below is a list of the average air consumption for common air tools, as well as for different size nozzles when used for sand blasting. As the one links shows, air tools are rated with a 15 second run time, so go 4 times what's listed for the CFM actually required, especially for continuous run tools. This can be somewhat overcome with a large enough air tank, but as the old saying in the car industry goes, there is still 'no replacement for displacement'.

Ultimately, don't be afraid to find yourself an older, used compressor. With some TLC, and a little routine maintenance, the older ones will still be running 20 years from now.
tool requirements

sand blasting requirements
 

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