Originally Posted by David Clifford
I have heard, and am hoping, that the Renesis is a little bit quieter with the three port exhaust as apposed to the two port 13B. I am also wondering if the egt's might be a little lower also because of the three ports?? I do plan to use a small muffler as far away from the collector as possible to tame the ear splitting sound of exhaust.
The EGT on a given engine design is mainly related to compression ratio, ignition timing and AFR. I don't expect this is significantly different on the new Renesis.
I've never noticed much difference in sound levels between PP and conventional port Wankels. In unmuffled race mode, both are well over 120 decibels. I did some sound measurements on a street ported 13B for a rally car with various mufflers on my dyno, years back. The factory Mazda race muffler brought the sound from 124 to 109 with a loss of only 6 hp. Still pretty painful. This was a BIG muffler carefully designed by Mazda.
The SuperTrapps often used did little with a lot of plates and lost major power when only a few plates were installed. I was never fond of these. The sound pressure level of the Wankel is brutal on mufflers. This combined with the high EGTs makes muffler life short.
I remember watching a night endurance race in BC about 20 years ago. When the RX3s rounded the corner we were at and wailed up the straight, you could look right up that 4 inch pipe and see the fires of hell inside glowing red hot at the back of the car. We're talking maybe 1500F 10 feet back from the engine! Between this and the red hot brake rotors, I was awed. Cool S**T.