Hi, I recently got a 89-92 era NA engine and am looking to p port it. I have access to a full machine shop and a dyno when I'm ready. At the moment most if my research is going Into port timing. I would like some help from those who have done NA p ports.
Thanks Jake

 

Mazda has a couple of SAE papers, and just to be simple the later optimized port is like the following

they used a 48mm throttle. the intake port runner is 46mm, timing is 80 BTDC open and 80 ABDC close, the port area is 25cm2

the exhaust is 12.5cm2 opening with timing of 73 open and 55 close, which is close to stock, the big difference is that the MFR runner is 43mm and stock FC is 48mm

the intake manifold is 240mm, with a 130mm air horn, so the total intake length is 370mm from the trochoid surface to the tip of the air horn. longer will lower the rpm at which peak power occurs.

the paper mentions that they tried exhaust header lengths from 500mm to 3700mm (!) but it doesn't say what they picked. having seen the 787, its closer to 500mm (19.8")

 

Thanks, I was very interested in the Mazda lemans design. Due to high output and reliability. Thanks for the info. Hopefully later today I can start to tear down the engine and begin the mods. Additionally I believe they ram a slide type throttle body like a dirtbike carb to eliminate turbulence at wide open. I am going to try and replicate many of their proven ideas in my motor.

 

yeah they did run a slide throttle, and then they added the variable length intake. the two have some obvious gains, but a normal throttle and fixed intake work too

 

Yea I'm not going to take on the variable length intake, I may look into the slide but will probably stay with traditional throttle body's, I'm going to focus on fuel injection as my big hurdle

 

Slide throttles do not help with tip in, transient response, or idle. They are all about top power.

A p-port setup with traditional throttles already has strained grasp on street-ability.

 

yea, the p-port motor has no plans to be in anything remotely streetable. at the moment i dont have a car in mind for it either (another FD would be great). as of now its a project for a Power Mechanics class in college.

 

j9fd3s, how much power could one expect from a 13b setup in the way that you described?

 

The most power you could realisticly see is around 300 at the crank. That however is not very easy to obtain but that's my goal for the project is 300 hp at the crank

 

the 3 rotor engine is up 25kw vs the older style port. the older style port is 450hp@8500, so the new one should be about 480hp. Mazda never built a 3 rotor engine with these ports though, so its hard to say. they went right to the 4 rotor, which is more than 500hp@8500, and then it gets the variable length intakes and ceramic coatings for 650, and then the R26B redesign for 690hp, with restrictors.