Originally Posted by
wingracer
I am quite sure they saw big gains because they are comparing it with a stock motor. Conventional valved Ford 5.0's have been built that make even more power then that.
It is very easy to make something that will improve a stock Ford's performance. When they bolt it on an F1 motor and start winning races, then I will believe. Yes, poppet valves are old tech and have some major drawbacks but they are still in use for very good reasons. No one has as yet figured out a way to make any sort of rotary valve with a non linear type motion. Until they do, poppet will rule.
I see the best bet for future 4 stroke innovation being electro-mechanical valves. Keep the poppets and their motions but ditch the cam shaft.
EXACTLLY!!!
Common maximus
aples to aples dude! reading...
? a stock Ford 5.0 flows nothing, but there are enough aftermaket heads for that engine that flow close to 400 cfm. A ported modern Hemi head flows around that too. And max flow is just one part of the equation! the speed that the poppet valve design allows the valve to open, and after it
stays fully opened for a while, close, will never be attained with - at least - that design, it's just phisically imposible. It's area under the curve what gives you power. That head flows 319cfm for a degree or two, and is the other 90 deg or whatever following a linear curve from 0cfm to 319 and back to 0, not the case at all for apoppet valve, you can use the first 10~15 deg to raise it to the max for full flow, be there for ~60 deg and bring it down to 0 in the last 15 again and sudenlly the head flowed an average that is huge compared to the rotax head.
LOL, almost all modern stock heads do about 315cfm with good porting.
that type of head can ONLY do maximun flow at precisely the cam position that the valve is fully opened, lets give it 5 degrees for example if you make the hole bigger than the port, a poppet valve can be opened at maximum for whatever degrees you want - it not linear!!! And you cant do the holetoo big because it takes degrees to do it because of its linearity, not the casewith poppet valves.
AND again, I'm not saying is imposible, I'm just saying that as long as the valve opens with a linear relation to the crankshaft/camshaft position, the poppet valve will have a chance to shine if done correctly.
But as the wingman said, the big dogs would be using it if it where that good, at least when full blown racing is what you want.
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