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Re: Rotary valve engines
A very interesting concept and it certainly looks good on paper. The rotary valve concept has been around for years probably coming into its own now because of advances in material technology. The ability to eliminate the valve head, stem, guide and guide boss as restrictions to flow is certainly appealing.
Consider this, however. Probably further along in development at this point is direct injection of fuel in gasoline engines. Here, the fuel injector is mounted directly in the head and injects directly into the combustion chamber rather than injecting into the port. Such a placement obviously requires much higher injection pressures than port placement. In other words, direct injection in gasoline engines is similar to that used in diesels. There are many advantages to this method, performance and otherwise, as opposed to port injection, but to stay on topic I'll only mention one. The intake port and valve, as in the case of the 4-stroke cycle diesel, now only has to flow air as opposed to an air-fuel mixture. All else being equal, as a consequence an inherently higher VE obtains, making conventional poppet valve restriction less of a factor. In such a situation, the advantage of the rotary valve over a conventional one may not be as great, at least on the intake side.
I read the entire article which I found very interesting. However, on page 10 there is a serious error which somewhat weakens one of the arguments for rotary valves.
"In addition, valves in high compression engines cannot open before top dead center. If they do, they will make contact with the piston and engine destruction occurs."
Clearly, this is incorrect. As the piston is moving towards TDC on the exhaust stroke the intake valve is already beginning to open and is substantially open at TDC. The exhaust valve of course is still open at TDC of exhaust stroke. If this didn't occur, valve overlap would not be possible and scavenging and charge filling would suffer. Many high compression pistons are cast or forged with valve cutouts to prevent contact.
In any case, a new technology that seems to have some promise and worthty of attention.02 DX Millenium Red - The Penultimate Driving Machine
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it gets rid of the problems of valvetrain rpm limitations.
on the other hand, it'll flow like ****... always. so you just nullified your benefits."Never run out of real estate, traction & ideas at the same time"
-93 MR2, 129 ES
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Originally posted by WTFRemember low compression makes more space for AIR, HEEELLOOOO!
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