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| I agree with Ernie. However I don’t think it is PEAK pressure in the exhaust chamber as it is most of the way through the expansion stroke by the time the apex seal crosses the plug hole - the exhaust port is about to open whether it is a side port (rx8) or peripheral port (rx7). It is probably higher pressure than the intake chamber, but not by a whole lot.
I think the way it is currently implemented (as a hole rather than a slot) leads to some EGR (exhaust gas recirculation) which isn’t supposed to be a bad thing, at least for emissions. I imagine however that the bad thing about making it a slot is it would be more difficult for the F/A mixture to get into the spark plug antechamber, and it also might affect the flame front propagation out of the antechamber. Both of these things would be bad for a rotary, IMHO.
— James
You are correct, Jeff. That is what he is saying. The problem is, he is wrong. When the apex seal is crossing the plug hole, there is no compression on the intake side yet (it's actually below ambient for an NA engine) and the exhaust side is at it's most extreme pressure. Look at the volume of the chambers. The intake side has just finished pulling F/A mixture in, the exhaust side has been ignited and is providing the power pulse. If anything, some burnt mixture from the previous burn is going to be pushed BACK into the upcoming one.
In fact, providing more of a slot might just blow the F/A mixture away from the apex seal and solve half of the quenching problem.
What he’s saying is the spark plug holes inside the rotor housing are too large (much larger than apex seal width) so at peak compression and just prior to combustion, a percentage of compressed air/fuel mixture enters the spark plug hole and leaks ahead of the apex seal into the exhaust cycle, creating spontaneous combustion in the exhaust and higher exhaust temperature. His theory is if the holes were slots, similar in width to an apex seal this would stop any leakage into the exhaust cycle – more complete combustion = higher efficiency – don’t put air fuel into the exhaust for spontaneous combustion. Jeff From: | | Subject: | RE: [FlyRotary] My next engine | Date: | Sat, 24 Jan 2015 23:03:22 -0600 | To: | |
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