So I've been kicking this around lately. I know from reading on here that the 4port when street ported makes more peak power than the 6port but what about low to mid power? Lets say from 3500 rpm on up? Here is the backstory. I built my current engine in 2015 and did a street port. I'm still somewhat kicking myself for staying 6port but it was the cheapest option since I had a set of spare 6port irons. This In retrospect. Could I have went 4 port? - RX7Club.com - Mazda RX7 Forum gives a good backstory and info on why the 6port sucks but doesn't discuss how broad each powerband is. I plan to go turbo and have probably 75% of the parts I need..I also have a standalone I just need to install it and learn to tune. I would just like to get as far as I can n/a first with some limitations like no ITB/ Holley style manifolds as this setup isn't permanent. It's the setup I learn ECU tuning on before I go turbo. I was going to turbo the 6port with hope that the next engine I build would be an 13B-REW and with that goal in mind I recently got an REW LIM and fuel rails. I already had an UIM & TB as I was going to try to fab up something to use them on my N/A like Aaron Cake did. My cars power doesn't really come on good until above 5k or more. So now for what I've been kicking around. Starting to acquire the parts to build an REW block over the next year or two and building it all motor first. The question is how is a street ported REW's powerband compared to a 6port. They(REW ) have made 200 to 230rwhp on the stock manifolds. Do they also make more power at lower rpms than the 6port as well and not just up top?

 

I may have answered my own question. This thread https://www.rx7club.com/naturally-as...t-itb-1103583/ says more power everywhere. OP was talking about ITB's but later talk of other manifolds like 6port intakes on 4 port blocks.

 

https://www.rx7club.com/rotary-car-p...video-1147510/

i think the port timing, and area are pretty straightforward, but the velocity is tricky part. the 6 port flows a lot, but velocity is low, which should, in theory, hurt power everywhere, except maybe at really high rpm

 

I finally got to watch them. Interesting. Since 12A turbo plates are probably unobtanium and probably require a lot of custom fab work, manifolds, engine mounts, etc. if they could be used with GSL-SE housings. Since I have a good set of TII rotor housings, series 6 plates it is. Though it doesn't look like the S5 TII ports are too much worse. I wonder if it is the angled ports combined with the REW LIM that helps them make more N/A than a 13BT. I need to give it another watch to look at the runner shapes again. It's probably a moot point since the rear iron is the only usable TII iron I have I think I'd rather spend the extra $ on REW irons and just sell this TII one to help offset the cost.

Edit to add: I know the REW isn't direct bolt in but there are solutions out there.

 

i've been thinking about an REW swap thread (i've done two FC-REW's). pre-pandemic, the FD swap made sense, because you got more power, while still being emissions legal, and FD stuff was easier to get.
in 2022 availability and price are basically the same between the FC and FD engines, and so its a lot of work for questionable benefit.

the JDM shops would/will do a 13B-T engine, and bolt the FD stuff on that (front cover/CAS, upper intake/tps, sometimes the water pump/alt belts). this way makes the most sense, really because the engine bolts in the car, but you get the upgrades also

anyways, i'm happy to do a thread/pics and stuff, i'm not just sure why :P