Quote:
Originally Posted by freebeard
I was already backing away from the flow bench. What sensor would you say are used on the dyno. A high-speed recording manometer? Microphones?
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The only sensors regularly used during dyno testing are exhaust gas temperature (EGT) and air-to-fuel ratio (AFR), to ensure proper running, not to determine flow. Vacuum is also measured, but to determine "streetability" of a combination, signal to the carburetor or sensors, or if portions of the intake tract are a restriction, but again it's not to determine flow. In any case, the point dyno testing is to determine actual running effects via the resulting calculated torque and horsepower.
Quote:
Originally Posted by freebeard
I did this to illustrate the end-cuts I proposed. The collector would have three tabs. Convergent angle is not represented. This is thirds of a Christmas wrapping core, not what you were thinking. |
That's a goilet, as has been pictured and discussed before in this thread.
Quote:
Originally Posted by freebeard
What is the relationship between scavenging and anti-reversion. It seems they are at cross purposes.
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They are not at cross-purposes. Scavenging is to help ensure the exhaust gases are pulled from the cylinder and anti-reversion is to help ensure the exhaust gases are not pushed back into the cylinder by pressure waves or flow from that cylinder or others.
Quote:
Originally Posted by oil pan 4
What if its too efficient and vacuums out the cylinder causing more air and fuel to be pulled in?
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Quote:
Originally Posted by RobertISaar
possibility, generally one would design a cam around it with a tiny amount of overlap
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Yep, this does happen at higher speeds and excessive overlap is a primary culprit (and at low speeds, the same physical configuration will usually cause some
backwards flow into the intake tract). Not only will over-scavenging hurt power and efficiency, the unburnt gases will cause problems with the sensed AFR. One might think this would be sensed as a rich mixture, but due to the excessive oxygen, it is sensed as a lean mixture, causing the ECU to add more fuel.