Bigus Dickus

Yeah, I can see that. Like I said, it's certainly not the most elegant solution. At some point you just don't want to have to go with a larger turbo and such to overcome bad flow characteristics.

I guess I was thinking more specifically for the rotaries. Sounds like they just can't take the high boost levels, so if the turbo can produce a bit more boost than the engine can take, why spend the time and money on expensive port jobs? Wouldn't a restrictive port with higher density air give essentially the same end result?

Dunno... never done a rotary before, much less spent the time on a dyno to get a really good feeling for this stuff.

cach22

anthony: hehe yeah i thought it would of been a nightmare, I think flow benches are a great thing but can also confuse the hell out of you and make you end up chasing your tale, hence why a lot of people haven't really attempted to use it on the rotary. I look forward to seeing your results

Bigus Dickus: the rotary has no trouble with the boost levels its just that the factory intake manifold was never designed to flow the amount of air that is required to make the sort of HP levels Anthony and many others are aiming for.

RICE RACING

catch22, I dunno about not flowing enough ? In drag terms since that is what MANY guys refer too for performance, there are a few cars I have seen personaly that have very high power on the std manifold (series5)

One Pac car I saw "in detail" had no NOS, just single turbo with very agricultural bolt on's, the car ran an 8.8sec @ 154+mph !!!

I make 600bhp with a detailed series 5 intake manifold (cleaned up, slightly ported runners and throttle body) on 1.4bar boost and street porting. Custom designed manifolds "intake" can yield alot more flow than the std stuff you get with an import engine, but it truly is amazing what can be achieved with the std POS

PS ever seen a ford sierra up close? These are the dodgiest POS you have ever seen but make realy high reliable HP 690 from a very GAY manifold and only 2lt capacity and around 2.5bar and only 7000rpm ! I personaly believe there is an amasing amount to be gained in good porting, SP, Partial Bridge or SMPP, case in point SCOOT 13B rx7, secondary PP stock intake manifold 28psi boost 7400rpm and 710RWHP. It is very interesting to get everyones opinion on this subject, the more I look at it over the years the more i lean towards concentrating on porting rather than using a custom intake manifold in general for side port combination engines.

Custom intake will yield more flow for sure, how much and what "order" or mods in slots into is the interesting part?

Anthony Rodrigues

Here,here!!
No one said it was easy, and I believe that I have made something that works better with my combo in my application. What Rice is saying is that OEM's are smart people with alot of money to develop their product. Not many people know more about the rotor than Mazda, I totally agree with him, as I certainly do not! Unless you are confident with the rest of your set-up, and have nowhere else to look for extra power, there are easier places to look. Each manifold can easily absorb 100+ hours, ask me how I know that one!
Regards- Anthony

Lasse wankel

As some of you know i'm gonna build a bridgeported 13B RE motor this winter. I shall swap the stock TB for a custom 65-70 mm TB and cut out the divider between the primary and secondary runners. With that modification i enlarge the plenum chamber volume which i think is good for a BP engine. Any inputs, comments?