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In direct-injection engines, only air goes through the intake ports, and the fuel is injected inside the chamber.
Valveless pulsejet engines use the same pipes for inlet and exhaust, and rely on the elasticity of air to determine when it is flowing in or out.
It might be possible to use all the
valves in the head of an engine for both intake and exhaust, if the pipes coming out were tuned properly.
I'm not sure what the advantages of this system might be, but it would be a cool engineering exercise and would allow for only one valve at the top.
Annotation:
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It would be a modified 2-stroke? |
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No, this would be a four-stroke. Although you could probably make a two-stroke version too. |
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Simply a matter of messing with the valve actuation system, and timing the separation of the intake and exhaust manifolds, by mechanical means. |
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How you could control intake and exhaust, without adding complex and failure-prone mechanical devices, is going to be the major problem. |
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I don't think this idea will result in greater fuel efficiency. |
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True, exhaust blowback will actually decrease efficiency, with less oxygen you will have more unburned fuel in the exhaust gases. |
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Wouldn't you have trouble with ignition timing? All that fuel-air mixture flowing over hot exhaust valves would surely lead to some nasty pre-ignition. |
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It's direct-injection, so you would only inject fuel when you wanted to have a power stroke. |
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OK sorry missed that bit. But having heated (and thus expanded) air might not be such a good thing. |
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On second thought, I don't think this
would work at all. Or if it did, it would just
be the same as a two-stroke, many of
which use the elasticity of air to control
exhaust flow. |
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After reading this again, I realized that pulse jets really have no compression phase. If this was ever a well-though-out idea, I don't remember how it worked. |
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