[Wmarden]

Originally posted by Kultured
The Vw modification uses a modified Cam shaft and Runs Off the #2 and 4 Cyl. where 1 and the 3 are used as the Air Pum...

Oh.. and the specs... 100% duty..
56!!!CFM @ 120 PSI...


YEAH 56!!! last time I saw the kit was like 265 or something...

if People are interested..I dig the link back up...

Yes I am interested. Get that and a good used tank and I would be in business.

[michvee]

if you do try taking the air from the plug holes, you might be able to use a check valve and hose from a cheapo compression testerand then hook them into a four into one manifold. interesting idea. not so sure i would be worried about cooling system as you are not causing any combustion , but i think oil would be needed.

[Weimer]

Just curious....Other than bragging rights, why would you want to put the time and money into building an 'engine' compressor? Why not just shop around and buy a decent compressor? I am not trying to be a downer, just curious as to why.
Later,
WEIMER

[cboy]

If you could build an engine compressor for $400 with comparable output to a 2-stage unit with a price tag of $1,000 - who wouldn't?

Obviously the big question is - can the above be done. To me it's at least worth exploring.

Dewey

[Weimer]

I would think that you would have close to $1'000 in trying to build one out of a car engine...after you buy the engine, the eletrical motor(if you go that route) the tank, all the trial/error parts, etc....I may be way off here also. Also, if you are buying a good 2 stage for $1'000, that seems a little on the low end also, so It may be worth it to try out something new. Thats how new inventions come about right?
Good Luck, and keep us posted
Later,
WEIMER

[BOBCRMAN@aol.com]

When I was a kid. The guy who painted our barns used a four cylinder engine that ran on two and pumped air with the other two cylinders. He ran the engine at about 1800 RPM. It was enuff to run two spray guns shooting barn paint..

Another thing... We used to carry a tool box on the tractors. In the tool box was a spark plug wrench with a gizmo that Ford marketed. This device was a check valve that went in the spark plug hole and a hose with an air chuck on the other end. If you had a flat, in the field. Remove the s-plug. Insert the check valve thingy and start the tractor. Instant air!! worked good. Tho there were fuel fumes in it.

[Gearhead forever]

I think it would only be worth it if you already had a spare engine or electric motor to use. I suppose if the engine was any good, you could sell it and use the dough towards a new compressor....Its still neat to see what people can do with a little ingenuity though...Anyone know what size electric motor would be required to run a 4 cyl compressor?

[Toyman]

No need to reinvent the wheel. Heavy construction companies use "Tagalong" compressors every day. The ones that I have seen and purchased have a Ford 351 where 4 cylinders run the motor and 4 compress the air. The are very common, and I picked one up at auction this summer for $300. You would just have to make the connection between the tagalong and your tank, since they only have a minimal storage tank. Although with the amount of cfm that they put out, storage and running is not really a problem. Whatever way you go you will need good water & oil traps. Check out your local newspaper for heavy equipment auctions, even one that is pretty beat would probably last a hobbyist a lifetime.

[cboy]

Toyman,

Is there any special provision for cooling the engine? I assume, since the motor is actually firing, that you have to circulate the engine water through a radiator. And, to your knowledge, does it have the stock oil pump?

[Wmarden]

Originally posted by Toyman
No need to reinvent the wheel. Heavy construction companies use "Tagalong" compressors every day. The ones that I have seen and purchased have a Ford 351 where 4 cylinders run the motor and 4 compress the air. The are very common, and I picked one up at auction this summer for $300. You would just have to make the connection between the tagalong and your tank, since they only have a minimal storage tank. Although with the amount of cfm that they put out, storage and running is not really a problem. Whatever way you go you will need good water & oil traps. Check out your local newspaper for heavy equipment auctions, even one that is pretty beat would probably last a hobbyist a lifetime.

Sorta like this
http://cgi.govliquidation.com/auctio...&convertTo=USD
If one was reasonably close, I would consider something like this, overkill I know, but would be able to run any air tool.

[donbryce]

Here's a different approach. I'm looking to make a small compressor for the house, mainly for a miniature sandblasting cabinet for the wife's jewellery shop. I've got an old nippondesso A/C compressor that I might try this with. Thinking of using an old propane tank for the receiver. Anyone find any other articles on this subject, please post. http://www.motherearthnews.com/arc/3616/

[oldred]

These compressor-engine combos are quite common on service trucks here mostly based on Buick v6 engines with a special head manufactured for this purpose. These things put out a ton of air and are great for running large impact wrenches, sandblasters and other high volume tools but they would not work well at all in a shop. If you are running common shop tools such as small(1/2") impact wrenches, DA sanders or air grinders these things are overkill and will break the bank in fuel costs not to mention the noise. If you need mobile air and a lot of it then this may be just the ticket but for shop air just the fuel cost alone will quickly pay for a good 2 stage shop compressor and even if you already have a suitable engine you will still need a tank,safety valves,fittings,plumbing,air cooler and a frame to mount all this in. Even if you can build a valving system for the existing head instead of buying one designed for that purpose($) you still must have a governor on the fuel system to control engine speed coupled to a kick-down mechanism for idle control. These engine control systems are a MUST HAVE and are not practical to engineer at home and would be quite costly even if you could find what you would need. In my opinion this project would be impractical due to the expense and building time involved only to end up with a very noisy,maintenance intensive,horrendously expensive to operate compressor that will in all probability cost more than a new 2 stage shop compressor. Now if you intend to drive the engine with an electric motor and compress air with all cylinders then it gets a little more practical but when you consider the work and expense involved a good 2 stage just seems to make more sense to me.

[oldred]

Donbryce-Interesting article but the fact is Wal-Mart and Harbor Freight sell "junk" compressors about that size already built for only a few dollars more(one on sale for $89.95 recently) and these will probably produce more CFM to boot as that A/C compressor is probably quite small. Of course the factory built ones I am talking about are only practical for airing up tires and the like but then like the one in the article that is what they are meant for. One thing in that article that points out something important is when they mentioned the 113 HP motor. While this is obviously a typo it brings up the question of just how big of a motor are you going to need to turn a four cylinder engine never mind a V8. One just cannot produce a lot of CFM without a lot of power and to use an electric motor to produce the 56 CFM @120 PSI like the VW conversion running on 2 cylinders and pumping on the other 2 that was mentioned earlier would require probably 15 HP or more and to run a V8 would get into heavy industrial motors. Even running Motors big enough to produce the 56 CFM @ 120 PSI would probably mean using three phase power.

[donbryce]

Yeah, I realize that there are lots of cheap small compressors to be had, but I need something that can meet an air requirement of 25-100 PSI at 2.4 CFM. For $100.00, or even $150.00, the pressure is available (most will put out a max of 100PSI, likely for a brief period only) but not the scfm. Most are under 1 scfm, so I wonder what the A/C compressor could put out driven by a typical 120V AC electric motor, 1750RPM or 3400RPM maybe with the right pulley set-up?

[oldred]

If 2.4 CFM is all you need I would bet the A/C compressor would do that with no problem. I think the little Campbell Housfeld compressors I am talking about would probably beat that but not by much and speaking for myself I just like building things since there is a lot more satisfaction in using a tool I built myself than one I just hauled in and hooked up, for me anyway. I was not trying to knock that project as it would be well worth doing for several good reasons but I don't think one would save enough money to make it worth while if that was the ONLY reason for doing it. Mostly I was just commenting on the engine/compressor conversions and the pitfalls one could run into trying to do a project such as that. It might seem like a good idea when thinking about all that air capability but when you consider the complexities involved and power required it looks a little different. Even that A/C compressor would need around 1 HP to operate properly at 2.4 CFM but these can be found at some of the surplus places cheap.www.surpluscenter.com they have a wealth of goodies for the do it your selfer.