Possible 4-Port N/A Start?

[NoDOHC]

Hey Buggy, I am curious what you get on the dyno with your setup. That will be interesting to contrast the power band of that engine to the one that I posted earlier from mine. You probably have a naturally better intake, but I am mostly interrested in low end, torque curve, etc. Also, what do you get for fuel economy?

To the original poster: Go 4-port FTW! I was worried about losing low-end going from a 6-port to a 4 port, but the 4-port stomps the 6-port above 1800 rpm. Meaning that you get better grunt, even on the interstate in high gear. Idle is good and mileage doesn't suffer much (35mpg 6-port -> 30 mpg 4-port with NA 5-speed, 25 mpg 4-port with turbo 5-speed).

The 4-port is easy to work on (all kinds of space where the turbo is supposed to go), runs cooler (could be from the lower compression ratio) and is much simpler to tune.

The only thing I would do differently if I ever get a chance would be to use NA rotors instead of turbo ones. I don't know if the small weight savings and additional 3 point on the compression ratio makes it worth the expense for RX8 rotors or e-shaft.

[diabolical1]

i realize that this is a year old, but it's the first time i've read this thread, so forgive my late commentary and questions.

as i understand it, the Renesis rotors, on paper, should make slightly more power than the 9.4s and 9.7s given the same setup with only the rotors being different. all the hard facts support it - lighter, higher compression, bevels, etc.

however, most reports from people that have actually put them in older engines have them making the same power at best, and actually making less power in the majority of the time. i've read a couple of theories on why - some sort of make sense to me, some don't, which leads me to believe if anyone actually KNOWS why, they're not talking about it. my guess is greater heads than mine are still working on it.

no doubt some people are not regretful for using them, and make decent power, but with the trouble of the extra machining and balancing, it comes down to personal choice really. i suppose it still carries a coolness coefficient with it as well. however, it doesn't appear that more power has been validated.

as for timing issues with them, i don't know if you'd call it "issues" per se, but they appear to tolerate (even prefer) more aggressive ignition timing when being tuned.

Originally Posted by vex

I don't believe there are any timing issues with the RX8 rotors. Same physical dimensions--just higher compression ratio and that comes in the tub.

more of an addition than a correction, but remember the Renesis rotors are beveled from the factory, so the intake timing for any older engine using them will be slightly different.

Originally Posted by vex

You can search for the exact definition of the half-bridge, but it's basically half the length of a normal bridge; hence why you won't have to cut into the water jacket.

half bridge is when you bridge just a half of the engine - meaning, there's one bridgeport per rotor instead of two (full bridge). convention usually bridges the secondaries only, but i have heard of a handful of people that for whatever reason, bridged only the primaries.

Originally Posted by NoDOHC

... but the 4-port stomps the 6-port above 1800 rpm. Meaning that you get better grunt, even on the interstate in high gear. Idle is good and mileage doesn't suffer much (35mpg 6-port -> 30 mpg 4-port with NA 5-speed, 25 mpg 4-port with turbo 5-speed).

The 4-port is easy to work on (all kinds of space where the turbo is supposed to go), runs cooler (could be from the lower compression ratio) and is much simpler to tune.

this is going to sound way more confrontational than i mean it to be, but where are you getting this from? i'm MOSTLY interested in the parts i bolded, but i'd like to know for the sake of curiosity and/or possible learning, about everything you mentioned.