Has anyone tried messing with when the 5th & 6th ports open with any success? Not increasing the size of the port openings, but at what RPM they actually open? Would there be any benefit to having them open at a lower RPM?

 

yes n no

Yes

No

next ....

 

I have been wondering the same on a Bridgeport motor.

Surely with any ported motor feeding the ports more air would be beneficial?

More particularly the VDI valve that according to Mazda tutorial videos opens very high rpm and creates a shortcut for the airflow.

I was thinking about T piecing with the SSV vacuum so the VDI opens at the same time as the SSV?

I've not heard it discussed on a ported engine.

Could meddling with these vacuums cause any damage to the engine?

Is there a aftermarket intake manifold for the RX8? Apart from Racing Beats carb kit?

 

A BP doesn't get any more air (or power)though the engine than a stock port and it doesn't help to change the valve timing.


VDI and SSV at same time ... wont do any damage but will lose you some power.
Mazda designed a good intake and valving system to maximise NA power ............ just about anything you do will cause it to lose power.

There have been a few intake manifolds over the years but good luck getting hold of one these days - they don't do anything for power anyway.