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I just made an interesting find with this setup . At WOT and with the valve left open something very interesting happens:
Clean air from the combustion chamber is forced back into the adjacent chamber and this air displaces the remaining spent exhaust gases in that chamber .IE some air is lost from the compression stroke , but as it displaces inert exhaust gas and the charge air ends up virtually free of exhaust gas , the remaining clean air makes the same power .
End result of this is that the engine makes the same power with less air ! Or to put it another way ...the engine uses less fuel to make the same power !
This could mean that we not only get better fuel mileage from cruise , but in all other drive modes as well !
I just made an interesting find with this setup . At WOT and with the valve left open something very interesting happens:
Clean air from the combustion chamber is forced back into the adjacent chamber and this air displaces the remaining spent exhaust gases in that chamber .IE some air is lost from the compression stroke , but as it displaces inert exhaust gas and the charge air ends up virtually free of exhaust gas , the remaining clean air makes the same power .
End result of this is that the engine makes the same power with less air ! Or to put it another way ...the engine uses less fuel to make the same power !
This could mean that we not only get better fuel mileage from cruise , but in all other drive modes as well !
Interesting. How did you figure out this was what was happening?
Interesting. How did you figure out this was what was happening?
I took a drive over the mountain/hills near me and noticed that at full throttle N/A loads (0psi) up the hill ...it was running extremely rich . I then set about dialing in the tune and realised from the logs that the actual loads derived from the maf were really low ...like 80% when they normally are over 90% in that rev range . Yet - it was still making the same power as a normal engine would . WTF ?
Why would the engine run rich and make the same power if it was using less air ? I should mention that this engine is also boosted and I'm used to seeing an engine run rich from a boost leak because it sends more air past the maf that the engine doesn't see. This was the opposite. WTF ?
I then did a compression test .
I was expecting to see fantastic numbers on the compression test because it's a brand new engine and it starts better than any other engine I've owned! Well .... when I saw the results ......I went straight to the kitchen to get out the knife and slash my wrists ! Even numbers, but a TERRIBLE result !
Luckily I tripped over the cat ,banged my head, and forgot what I was about to do .
When I woke up, it dawned on me ... the apv opens at 6250 rpm because if you open it any sooner air pulses out into the intake from the engine . Meaning the APV port (which I use in my engine for the egr valve) actually vents air that would have been compressed if it opens too early.
So ,with my design, I have opened a channel from the APV port back into the adjacent chamber which is at that point in the final stages of exhaust . So that air that would have been compressed, is instead being pushed into that chamber , which in turn pushes out the exhaust gas from at the opposite end of the chamber.
It all adds up ....
VTEC for a rotary ! YO !
I'm quite excited by the possibilities for this ...
Someone via pm has just pointed out to me that what is happening here is similar to the Atkinson cycle where air from compression is used to clean out the residual exhaust gas .
02-06-2018, 07:25 PM
