Quote:
Originally Posted by RETed
You basically did the same thing a bridge port does but by moving the exhaust port?
How do you address the increase in overlap?
Or are you moving the intake port(s) too?
-Ted
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Actually, I am not trying to achieve the same effect as a bridge port. I am not desiring overlap, but rather better cycle efficiency. I will get overlap, but not a lot, as the rotor will be mostly shielding the cusp on the housing during the overlap time.
Believe it or not, the overlap generated by this modification would be very minimal.
I will attempt to illustrate:
This is a stock 4-port rear iron with the RX8 housing on it and a rotor installed upside-down (just to make it easier on the housing, as there are no planetaries in the housing right now). You can see that the exhaust port is already nearly shielded (the dish is almost past the cusp). The engine has already passed BDC, but the volume is barely changing at this point. This is the big reversion enemy, but only occurs for about 10 degrees of eccentric shaft rotation.
This image shows the intake port open. The dish has completely passed the cusp on the housing, allowing the rotor to housing clearance to effectively block the exhaust port from communicating with the intake port.
At this point in the process, the exhaust port is closed.
I agree that I may have reversion issues, but I am hopeful that they will be minimal.
I have no intention of modifying the intake port timing at all. (I will use my other housings with the very mild street port).