Convert wounded GM 6.0 into a compressor?

[aczlan]

Many other candidates such as motorcycle or small air cooled stationary engines. Belt driven refrigeration compressors in the larger sizes should not be overlooked either. These already have a valve plate, their only disadvantage is that some of them don't have oil scraper rings and can blow a lot of oil fog into the air stream. That might be an advantage for air tools, but not for spray painting !

Many (most?) larger (20+ HP) refrigeration compressors are designed to be used with an colascing oil seperator after the compressor to get most of the oil out of the compressed refrigerant.

Aaron Z

 

[Warpspeed]

My own 10Hp air compressor uses an old refrigeration compressor (twin cylinder 2" bore, 3" stroke from memory) direct coupled running at 1,450 Rpm (50Hz power here).
I found that the 10Hp drive motor was not sufficiently loaded. So I did some porting of the inlet holes around the intake reed valves, and that certainly raised the current that the motor required up to its full rating.

The whole thing is junk really. It literally cost me nothing to put together. Its bolted onto the top of an old vehicle propane tank.

 

[Warpspeed]

Aaron is absolutely right.
When I blow down my air tank to get rid of the water condensate, more than half of what comes out is compressor oil. Still, I have had it here working for over thirty years, and it still provides all of my compressed air.

 

[strantor]

I don稚 think a commercial built air compressor that pumps the volume you want has anything close to 6 liter displacement.

Absolutely right. But as piston compressors go, higher displacement and lower compressor RPM generally indicate higher quality. Higher displacement and lower rpm wears less so lasts longer, and is more quiet. The cheapest consumer grade disposable compressors have tiny pistons and scream away at 3600 rpm and 90 decibels. If plotting a graph of cost+quality+service life vs displacement, you would probably find Using a 6L V8 compressor is way off the chart. It's not economically feasible to install a compressor this big on commercial units (among other reasons).

I知 thinking a v twin lawnmower engine converted to pump every stroke would be a lot better candidate for this.

You're probably right but I don't have one of those. I do have a 6L v8 though. If I go out and buy something it won't be another engine, it will be a compressor.

The v8 has huge parasitic losses and and weighs like 800 pounds.

I don't care about the weight. I do care about the losses. Where do they come from? How can they be mitigated? I'm thinking a huge part of the losses come from the cam, and valving, which if replaced with flapper check valves, would go away. Not sure anything can be done about piston friction; 8cyl is a lot of sliding surface area. Not sure how much parasitic loss that translates to by itself.

 

[Ken]

While in the Army '54/'57 Used a mobile machine shop that had a flat head Ford V8 engine 1-3-5-7 had reed valves in head and engine ran on 2-4-6-8 at idle engine sounded like a ford with 1/2 of the spark plugs removed. Wheezed, belched and blew oil
Once the tank pressure increased engine would run guessing now to 1500 RPM and developed good flow of air for sandblastings
Had no tools or painter so cannot add to this area.
The engine vibrations continued until the air was used. commercial built don't remember by who.
I never planned on modifying a working engine for the air compressor.
ken

 

[aczlan]

Absolutely right. But as piston compressors go, higher displacement and lower compressor RPM generally indicate higher quality. Higher displacement and lower rpm wears less so lasts longer, and is more quiet. The cheapest consumer grade disposable compressors have tiny pistons and scream away at 3600 rpm and 90 decibels. If plotting a graph of cost+quality+service life vs displacement, you would probably find Using a 6L V8 compressor is way off the chart. It's not economically feasible to install a compressor this big on commercial units (among other reasons).

Off the chart? Not really, but it's bigger than anything you will see outside of commercial use.
50-300HP compressors are not uncommon in commercial use, many (most?) of them are refrigeration compressors, but when you get to that size, a lot of those compressors are rotary screw compressors rather than piston compressors to allow for more fine grained capacity control.

Aaron Z

 

[Warpspeed]

I think this is a great concept, reducing the rpm will have enormous noise benefits.

A current project (that is still coming together) is running a single cylinder Wisconsin air cooled engine off natural gas to provide some backup power for my off grid solar system whenever there are several gloomy grey days in a row. The whole thrust of this exercise is to make the system as silent as possible, as I have neighbors very close.

The Wisconsin engine runs at 1,200 rpm and produces only 46dba of noise at full power. The secret is the big blue exhaust muffler, which consists of a huge and very heavy air receiver tank made from 5/8 steel that is stuffed full with fiberglass wool. The exhaust noise is essentially zero, the exhaust pulses at only 20Hz at that rpm, which is inaudible and without any harmonic energy. I can feel the exhaust pulsing, but can hear nothing even with my ear right up to the exhaust exit. The 46dba is direct mechanical noise from the engine and external moving parts .

I am sure a virtually silent air compressor should also be possible if it were built along similar lines, especially if it was powered from either a well silenced water cooled engine, or an electric motor.


Dare to be different !!
And yes, the exhaust does have a slip joint.

 

[texasranger556]

That might be the largest muffler to engine ratio I've ever seen! Neat project

 

[Industrial Toys]

Yes, well done. I thought it was some kind of compressor/alternator setup. How much power does that motor make at 1200rpm?

 

[strantor]

That's really cool! That "silent sound" effect is weird. My neighbor across the street has a diesel truck that isn't loud, but something about its idle frequency and the spot/angle he parks it at, makes my bedroom reverberate/resonate like someone tuned a huge subwoofer to an obnoxious bass frequency and forgot about it. It's loud as **** in my room and I snap awake when I hear it, as it indicates I've overslept. Step outside and you can hardly hear it.