Has anybody ever done a 6 port motor that added a peripheral port with ITB's that opened around 6K with extra injectors? I've already got the 5th & 6th ports & VDI working precisley - something like extending the power curve with the extra ports & TB's & injectors? I was thinking of using lightened rotor assembly & oil mods for a high RPM motor. Trying to keep the hp line going diagonal all the way to 10K rpm's instead of flattenning at 6k or so while keeping low rpm power the same. Basically an 8 port motor. All rpm & load dependant. I understand the expense & complexity involved and would be looking to net around 300-350 hp NA. I've seen some semi-Peri-port or cross-port references but haven't seen any street applications. It seems a little hush-hush about this particular setup. Just P.M. me with details if you don't want any pubicity. I know there is alot of added complexity and the mods necessary are expensive for a 10k rpm motor, but it seems like an untapped area for us NA guys.



Ramses666

Ok... never mind!!!



Ramses666

theres really no point, a bp or PP engine makes more low end than the 6 ports, they just dont idle or cruise as well

ok... I guess the point would be to keep my low end performance the same while enabling extreme high end performance. The cost involved with making a high RPM engine diminish the sanity of doing it. It would be nice to just put my foot in it all the way up to 10krpm or so with a straight line power band that just keeps going up to redline. Isn't that what we all want?!? why stop at the 6-port limit of hp vs. rpm? I say add more port area & runner volume for more power at higher rpm while keeping low end power & economy.



Surely someone else has thought of this? I know it's gonna be stupid expensive for a high rpm engine setup, but this is an NA Performance section right? I've read GTORX's posts, but nothing about his semi-PP performance. I've seen what the Drag guys are using with the PP and bridge ports. I'm talking about street performance in a "normal" car. How about a suggested port length, dia. & volume for a semi-ported 6 port motor? Recommended rpm activation? I was thinking about 6k rpm's to open the PP ports with independent TB's & injectors.



Ramses666

The number of ports isnt the problem, and neither is the port flow. Mazdatrix has seen power still climbing through 10k rpm with a streetport on 6 port irons, and proper supporting mods. Their problem was that the ports, even without major porting, close so late into the compression stroke. While its good for high rpm breathing, it kills torque. The ports open too late, and close too late to make really good usable power. Adding more ports is only going to make it worse, unless you are doing something about the port timing. A couple of people have had decent results from bridge porting the 5/6 ports. My experience with that was that the stock ecu was incapable of running it. Nothing I did made it run like it should. I went back to a streetport, and things worked out better, but even still I was really pushing what the stock ecu was capable of. But that streetported engine really came alive with a standalone. Based on my fuel mapping, the torque built up nicely to about 6k rpm, where it leveled off and stayed level through 9700 rpm when I ran out of fuel and leaned out. The car was fun, but had nothing below 4k. Enough to drive in traffic, and thats about it.



Heres that streetported engine



https://www.nopistons.com/forums/gal...239_102509.jpg

one of mazda's early cosmo engines had 2 normal side primary ports, and 2 PP's. they found they didnt need the sideports, and from then on went bp or pp.



a few years ago i had a gsl-se, with the long primary exahaust, working 6 ports, light flywheel etc. driving that back to back with an rx3 with a 13b bp. the bp was into the water jacket, holley carb, dual exhaust. with 3 people in the rx3, the rx3 had more power from idle to 11,000, than the rx7 did. the only thing that wasnt better about the rx3, was that it didnt like to cruise.

ok... I'm talking about a small PP. 1-1.25 in max. through the water jacket plug portion of the housing. The port timing is opening after the secondaries and before the auxillairies and closing after the secondaries & before the auxiliaries. I would not attempt to use the stock ECU for this to ever work. I would be adding 2 ITB's and injectors and another fuel rail and upgrading the fuel pump & regulator. I would also add an x-pipe to my true-dual setup before the pre-silencer for scavenging and better flow velocity. Does that make more sense?



Ramses666

I think you think "VTEC for wankels", but what you should think is "I'll PP it and realise thanks to the modern wonder of gearboxes you don't need a 10k rpm powerband".

If I were trying this and understood you correctly I would close off the 5-6th ports and let the Mini-p-ports do the job of the aux ports. This would make it to where the p-ports would close earlier than the normal aux port timing. Flow and efficiency improve and off to 10K you go.



Just my 2 Iraqi dinars on the subject.

MY idea was simular, to use indy tb's on all ports. 6 tb's and the two for the 5th/6th would be seperate then the other four.

still having them open about 5.5k. still planing rest of mani https://www.nopistons.com/forums/pub...IR#>/smile.gif