Hey this is Logan, I was linked by low impedance. Its always a large debate on 6-port vs. 4-port n/a. I personally feel the 4 port is the way of making power easily, and cheaply. The irons are not expensive, and a used standalone is very cheap as well. Here is my setup of the RE-
Stock upper and lower intake manifold from the 13b-re. Medium sized port, S5 rotors, not ideal header at the time. 1st gen distributer, haltech F10a fuel only computer, 3" k+n filter. MSD box, with second gen coil for leading. Electric fan. 206rwhp with 152rwtq. The power under the curve is great, making more torque at even 1500rpm than a stock GSL-SE. If you guys have any other questions, let me know. I like the forum, so I will be hanging around now :)

^Welcome GTO and thanks for the info.

I'm a little curious about your setup, your running a fuel computer and an MSD ignition, what are your injector/pump sizes? Are you running S5 NA rotors? I ask as I'm curious to know if this is indicitive of the tune or if it's other modifications (including the port job/irons/housings). If it's more indicitive of the tune then that's saying something about the stock NA engines and how much power might be available to them with a standalone.

I am using the 550cc injectors that came with the RE engine. But I dont really count injector size helping with power. Even the 460cc injectors will support enough Hp in n/a form, possibly make more power from the SMALLER injectors, but that is another subject. The fuel pump was upgraded to a msd/walbro style, the stock GSL-SE pump was "almost" there. I did install Series 5 n/a rotors. I would really like to have direct ignition that the FC has stock, as that alone would possibly net 5+ rwhp or more. But I built it on a very tight string budget, and got the old F10a haltech for $100. Its hard for me to plunk down $1k on this car for ignition control :).

I know for a fact that a S5 n/a 6-port will not gain 50-60rwhp from a standalone install. I would love to think so, but its not possible. The AFM is not super restrictive, a loss of 5-10hp is pretty realistic. Tuning and timing will net another 10-20 or so. I would love for someone with a 6-port to prove me wrong, but they require so much work to get there. The 4 port of any type produces 180+rwhp with so little work. And its hard to make less than 170rwhp even with a stock exhaust mani, and 9.0:1 rotors. In my opinion the 6-port just cant do this.

So 4 really is greater than 6, go figure...

4>6 :lol:

It seems a little odd that Mazda would invest time and money into a system that was less capable when a 4-port can make more power and better torque throughout the RPM band. You'd think that they would have had this information upfront and saved time and money with only producing one set of housings. Seems completely counter intuitive. Guess I should pick up an RTek V2 and see what I can get the stock system up to...

on the other hand, auto manufacturers aren't looking at just power output.

Once you start porting engines, playing with tuning etc, the fuel economy, drive-ibility, reliability, etc change. Emissions comes into play. The switch from the 4 port 13b to the 6 port 13b was probably just a function of the above. Plus Mazda seems to enjoy experimenting with new ideas.

That's true, but a street port shouldn't adversly affect those to the point of failure. The regular NA has 3 cats to pass US emission standards. The only difference I can actually see with regards to the engine is the 6pi and their only function is to increase low end torque. I'd like to see a dyno chart of a 4port na compared to a 6 port na and look specifically at their torque curve (below the 3500 rpm mark).

but stock, the ports are rather small as opposed to an a medium to large street port. Porting generally does bad things to most forms of e-check.

Emissions, fuel economy, driveability.

People who race high power turbo hondas dont need vtec either, it's just there for driveability, from the factory.

Couldnt say it better myself. Performance vs. Stock, and the changes needed between the two are so different. Torque between 1000-3000rpms is SO important to mazda in a factory car. If my engine had to have full cats, air pump, etc it would have less torque in this area without a doubt.

so from what i am geting it can be better you just need to be able to tune it right and have the housing ported. it might suffer a little down low but up high it would gain some. Am i correct so it would be almost fesible to do it and see would i would gain or lose. I am just going to be tinkering around with the motors and seeing what would even be able to be reused.

Out of curiosity does anyone have a side by side comparison between the 6 port stock and the 4 port stock (the ports on the irons specifically). I'm curious because I know you can port the 6-port to be much bigger than the 4-port (but you end up killing the intake velocity), but I'm thinking that the 4-port is in a better position for more extreme porting with less negatives associated with it.

i might be able to do so in comparing a 12a four port to a GSLSE, and/or S4 6 port. I only have a turbo center iron.

If you could snap a picture of a direct view of the ports at the same distance that would be great. I'm thinking maybe individually taking the pictures of the ports at 1.5-2ft out on a tripod, then replacing the iron in the same location so we get a little bit of accuracy on the ports (that way one won't appear bigger than the other, etc).

My thinking is that the "no-no" spots or the limits of porting are the same location for the 4 port and 6 port, but I may be mistaken on that.