Holy frakking coins-on-a-piston!
07-07-2011, 12:46 AM
#8
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It's a standard automobile piston.
It is sitting inside of (and protruding from) a cylinder from a standard air-cooled automobile engine. Specifically, a cylinder from a 1600cc VW Beetle engine. (In this picture, the piston has been inserted into the wrong end of the cylinder, the end which would normally face against the crankcase. The cooling fins are much wider, and the finless skirt portion much shorter, on the end that and that mates with the head.)
And of course they're not coins. That is two small pieces of cut aluminum dowel, sitting on top of a piece of aluminum plate cut to match the diameter of the piston, and the entire assembly is bolted to the face of the piston.
With bolts.
Countersunk bolts that go completely through the piston and come out the back.
It is sitting inside of (and protruding from) a cylinder from a standard air-cooled automobile engine. Specifically, a cylinder from a 1600cc VW Beetle engine. (In this picture, the piston has been inserted into the wrong end of the cylinder, the end which would normally face against the crankcase. The cooling fins are much wider, and the finless skirt portion much shorter, on the end that and that mates with the head.)
And of course they're not coins. That is two small pieces of cut aluminum dowel, sitting on top of a piece of aluminum plate cut to match the diameter of the piston, and the entire assembly is bolted to the face of the piston.
With bolts.
Countersunk bolts that go completely through the piston and come out the back.
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07-07-2011, 02:28 AM
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It's a standard automobile piston.
It is sitting inside of (and protruding from) a cylinder from a standard air-cooled automobile engine. Specifically, a cylinder from a 1600cc VW Beetle engine. (In this picture, the piston has been inserted into the wrong end of the cylinder, the end which would normally face against the crankcase. The cooling fins are much wider, and the finless skirt portion much shorter, on the end that and that mates with the head.)
And of course they're not coins. That is two small pieces of cut aluminum dowel, sitting on top of a piece of aluminum plate cut to match the diameter of the piston, and the entire assembly is bolted to the face of the piston.
With bolts.
Countersunk bolts that go completely through the piston and come out the back.
It is sitting inside of (and protruding from) a cylinder from a standard air-cooled automobile engine. Specifically, a cylinder from a 1600cc VW Beetle engine. (In this picture, the piston has been inserted into the wrong end of the cylinder, the end which would normally face against the crankcase. The cooling fins are much wider, and the finless skirt portion much shorter, on the end that and that mates with the head.)
And of course they're not coins. That is two small pieces of cut aluminum dowel, sitting on top of a piece of aluminum plate cut to match the diameter of the piston, and the entire assembly is bolted to the face of the piston.
With bolts.
Countersunk bolts that go completely through the piston and come out the back.
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07-07-2011, 11:56 AM
#10
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Believe it or not, there are actually tons of these out there in daily service. Just not the way you think.
There is (was?) a company called Dunn-Right Inc. which manufactured a rather interesting kit called the Volks-Air.
Basically, if you happened to have a spare VW Beetle engine lying around (as was common in the 70s and 80s), you could convert it into a 28 HP air compressor capable of delivering 58 CFM at 100 PSI, which is just unheard of in terms of what's commonly available from compressors for the home workshop.
Remembering that the Bug used a horizontally-opposed flat 4 engine, what you did was to convert the #1 and #3 cylinders (the two nearest the flywheel) into an air pump, and run the engine on the #2 and #4 cylinders to power it. The kit consisted of a set of modified intake manifolds, a modified camshaft, some check valves and various fittings and plates, custom pushrods, etc.
Due to the design of the system, the exhaust valve was kept slightly open all the time (with a checkvalve at the exhaust port opening on the side of the head) and so the volume of the exhaust port was effectively added to the volume of the "combustion" chamber, thus decreasing the effective CR. These plates compensated for that by raising it back up. I honestly don't know if these plates were a standard part of the kit or whether they were a homebrew modification. Information is hard to come by on this old system.
There is (was?) a company called Dunn-Right Inc. which manufactured a rather interesting kit called the Volks-Air.
Basically, if you happened to have a spare VW Beetle engine lying around (as was common in the 70s and 80s), you could convert it into a 28 HP air compressor capable of delivering 58 CFM at 100 PSI, which is just unheard of in terms of what's commonly available from compressors for the home workshop.
Remembering that the Bug used a horizontally-opposed flat 4 engine, what you did was to convert the #1 and #3 cylinders (the two nearest the flywheel) into an air pump, and run the engine on the #2 and #4 cylinders to power it. The kit consisted of a set of modified intake manifolds, a modified camshaft, some check valves and various fittings and plates, custom pushrods, etc.
Due to the design of the system, the exhaust valve was kept slightly open all the time (with a checkvalve at the exhaust port opening on the side of the head) and so the volume of the exhaust port was effectively added to the volume of the "combustion" chamber, thus decreasing the effective CR. These plates compensated for that by raising it back up. I honestly don't know if these plates were a standard part of the kit or whether they were a homebrew modification. Information is hard to come by on this old system.
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07-07-2011, 01:17 PM
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And what's really clever is that you don't need a big tank to do it with. Since the engine runs continuously (it just unloads and idles down when not needed), folks typically run 10 gallon tanks on these, mounted above the engine. So the footprint winds up being only marginally larger than a typical electric compressor.
I wonder if anybody has put a megasquirt and a turbo on one of these?
Actually, now that I think about it, there are probably numerous other engines which are more commonly available today that this concept would work on as well. Imagine taking something like a Honda B16 and actually milling out the portion of the head that covers the #2 and #3 cylinders, leaving just enough metal in place to house the camshafts as a bridge over those two cylinders, but totally removing the combustion chambers and intake/exhaust ports. You weld plates over the cut ends of 1 & 4 with holes drilled in them for access to water and oil, and then bolt a heavy flat plate over 2 & 3, with fittings in it for air.
Hmmmmmmmmm. Does the starter go on the engine-side or the transmission-side of a B16 bellhousing?
Can anybody think of a cheap, commonly available pushrod inline-4 that doesn't weigh much? That setup would be ridiculously simple. Just cut the head completely into three pieces with a bandsaw and throw out the part you don't need.
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07-07-2011, 01:58 PM
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I distinctly remember pumping up a tire on a Ford 8N tractor with a hose that was put into the spark plug hole. We didnt change anything to the engine at all, just put the hose in. Was a "field repair" for implementation devices if you hit something to cause a leak.
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07-07-2011, 02:13 PM
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How about one of the early civic engines? Tiny little buggers, and fairly simple. Alas, not so common these days, either.
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07-07-2011, 02:15 PM
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I remembered those while reading the thread about exhaust-powered airbag/jack thingys, which reminded me about the tire inflator (and the resultant tires full of gasoline vapor) which then reminded me about the old VolksAir system.
Ah, yes:
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07-07-2011, 02:24 PM
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What about motorcycles? Can anybody think of a liquid-cooled 4cyl bike engine that used pushrods? A V-Max would be perfect, but I'm not sure that it fits the "common" or "cheap" criteria.
I've got it: two Ninja 250 motors back-to-back! (Or one Ninja 250 as the powerplant and one CB250 as the compressor.) (Or just two CB250s and a big-*** fan.)
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07-07-2011, 04:26 PM
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Well, for starters, I was 18 then, I'm 35 now.
And of course, it's one thing to have a skull full of wacky ideas. Being able to commoditize them is something entirely else.
Having the option to find work as a cog in the corporate machine has its upsides. The money is good, the work is relatively stable, and it allows me to **** around with random projects (or not) without having to worry about making a living off of them.
I mean, how big of an empire do you think I could build selling kits to turn half of a 30 year old engine into an air compressor? There's a reason that little niche companies like that spring up and then vanish without a trace all the time.
I suck at uncertainty and failure.
And of course, it's one thing to have a skull full of wacky ideas. Being able to commoditize them is something entirely else.
Having the option to find work as a cog in the corporate machine has its upsides. The money is good, the work is relatively stable, and it allows me to **** around with random projects (or not) without having to worry about making a living off of them.
I mean, how big of an empire do you think I could build selling kits to turn half of a 30 year old engine into an air compressor? There's a reason that little niche companies like that spring up and then vanish without a trace all the time.
I suck at uncertainty and failure.
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07-07-2011, 04:34 PM
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Tell me about it. A mechanical desiger by trade, I've come up with all sorts of ideas, some of which I've actually made. But making money from them? Hasn't happened yet, and I wouldn't want to have to make my living that way.
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