Egon
Epic Contributor
There was a time some of the old engines had intake valves that operated in that fashion.
Engine Air Compressor?
- Thread starter BrentD
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There was a time some of the old engines had intake valves that operated in that fashion.
Iplayfarmer
Super Member
Okay, here's a brainstorm: What if you make your engine into a two stage pump? Pull ambient air into two of the cylinders, and have those two cylinders exhaust into the third. The third pulls in the partially compressed air and compresses it further. You'd probably need some kind of small surge tank (<1 gal.) inbetween unless you could time the two first stage cylinders to both be exhausting at the same time the third is sucking air in.
Would this be any better?
Egon
Epic Contributor
Usually when compression is staged the cylinder volume changes and inter coolers with fluid drains may be required.
slowzuki
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Would have loved too but the car was hard against a wall and another car. I had to take the siding off the building to even get the air chuck onto the two of the valves.
Iplayfarmer
Super Member
I should have known it would be something like that.
bobodu
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Usually when compression is staged the cylinder volume changes and inter coolers with fluid drains may be required.
Yep....the higher compression (secondary) cylinder would have to contain less volume (smaller). This could be accomplished by having two cylinders dumping into one but the would probably require a different crank.
Iplayfarmer
Super Member
Do you think it could be done with a small surge tank?
Redneck in training
Elite Member
It would work but not as well as you might think. If the compression ratio is 8:1 then the second stage will have to be much smaller than half of the first stage. It will also require substantial intercooler.
To overcome this the compression ratio of the first stage would have to be lowered. To lower compression ration of the 1st stage is actually quite easy to do. You just need to increase so-called "dead space" by placing discharge valve certain distance from the head. Lower ratio of the first stage will also lessen demand for intercooling.
Egon
Epic Contributor
unloaders.
Iplayfarmer
Super Member
I guess one of the things I'm shooting for is to lower the power consumption. I was guessing that if each of the pistons were only compressing the air halfway (i.e pistons 1 and 2 are taking it from 0 to 50 psi and piston 3 is taking it from 50 to 100) it would lower the power consumption. It would also lower the output, but it seems pretty well accepted amongst us that for the task at hand this setup would be more than sufficient.
By increasing the dead space to change the compression ratio like you suggest would it also decrease the amount of heat created? Even if it didn't would the heat created be more that normal operating temperatures of an engine. You'd have the radiator and engine cooling system there that could be used to cool.
