Has anyone here ever built an air compressor using two of the four cylinders to pump air?
I need a large compressor and keep eying the old 914 engine sitting there.

I was thinking of making a new intake manifold so two cylinders would get only air. Maybe pull the exhaust pushrods and take the air out of the sparkplug hole thru a check valve.
Or, maybe I could take it out the exhaust ports and leave the exh valve operational.
Now that I think of it, closing both intake and exh valves and using check valves on the intake and exhaust ports would result in a "pump" every stroke.

has anyone ever done that?

I bet the idle would be sooo horrible

I remember reading an ad from a company that did comversions such as this...they called it "VolksAir".

Found a neat website made by a guy who did the conversion...

http://mywebpage.netscape.com/AlphahR/volksair.htm

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2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car

I don't know, but I've seen a V8 snowblower

and a V8 chainsaw
http://www.youtube.com/watch?v=FvAI7-Qa2Io

And my uncle built a big-block powered wood chipper.

You might be the trend-setter! You won't know if you don't try.

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1980 300TD-China Blue/Blue MBTex-2nd Owner, 107K (Alt Blau) OBK #15
'06 Chevy Tahoe Z71 (for the wife & 4 kids, current mule) '03 Honda Odyssey (son #1's ride, reluctantly) '99 GMC Suburban (255K+ miles, semi-retired mule) 21' SeaRay Seville (summer escape pod)

That's a pretty neat & tidy conversion! Very cool! Looks like a new cam, different pushrods and changes to cylinders 1 and 3 and your in the compression business.

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1980 300TD-China Blue/Blue MBTex-2nd Owner, 107K (Alt Blau) OBK #15
'06 Chevy Tahoe Z71 (for the wife & 4 kids, current mule) '03 Honda Odyssey (son #1's ride, reluctantly) '99 GMC Suburban (255K+ miles, semi-retired mule) 21' SeaRay Seville (summer escape pod)

More trouble than its worth if I have to split the case and replace the cam.

Why would check valves on the intake and exh ports not work?

I think check valves would work fine. That's what most, if not all, other compressors use. You would need to either block the valves open or remove them, not a hard task either way.

Get 2 engines and bolt the cranks end to end. Use one to run as an engine, the other becomes the compressor. Need to build in some check valves in the exhaust manifold and plumb the outlet piping. Actually lining them up properly might be a pain, so use a chain drive between them. That way you can also play with sprocket sizes etc....

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MB-less

$500 kit
http://www.thesamba.com/vw/classifieds/detail.php?id=272415

rebuilding a VW engine is probably the easiest to do... I helped do one... but you said a 914 engine..

its a flat four correct?

What if you use the sparkplug hole with a check valve for the compressed air output and replaced the stock valve springs with soft springs, and remove the push rods. Each time the piston moves down, the air enters from around the intake and exhaust valve due to the soft valve springs. On each upstroke, the compressed air exits through the check valve in the sparkplug hole.

A long time ago up here some guy we met had a VW bug engine powered saw rigged up to cut wood. It was real cool to see that.

Those Mexican gardeners who come around here every week with their leaf blowers, to hit the driveways, I swear..........those noisy things must be powered by VW engines strapped to their backs, by the sound of them!!!!

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1991 560 SEC AMG, 199k <---- 300 hp 10:1 ECE euro HV ...

1995 E 420, 170k "The Red Plum" (sold)

2015 BMW 535i xdrive awd Stage 1 DINAN, 6k, <----364 hp

1967 Mercury Cougar, 49k

2013 Jaguar XF, 20k <----340 hp Supercharged, All Wheel Drive (sold)

That would be for a "type 1". I have a spare T4 from the 914GT V8 project.

This was my plan although, I see a problem with removing the pushrods.

Oil flows thru the pushrods to lub the rocker arms and stems.

Any spring at all would not open due to simple suction like that. Thats why 2 strokes use reeds in the intake.

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MB-less