This is a junk iron(coolant seal corrosion)



I am in the process of porting my N/A using a Pineapple Racing streetport template.

I am using a dremel for the iron, for precision and what not.



I have some questions on it though:

How do I port the bowl to make it smoother?

How do I make the port more "square" on the edge? But, still keep a beveled edge.

Am I on the right track?

With help from "the other forum", I got this far...



*How's it looking?

No support. Oh well, here is what I got on the intermediate iron.Porting is getting easier. I'm going to clean these up when I port my housing, if I can get the sleeves out(dang pin).

Did you try that method (I think it was) BDC described, where you drive a screw into the pin to pull it out? I have no experience rebuilding, sorry I can't be more helpful.

wouldn't know man, i had my fd ported by a shop. the guys that do stuff like that seem to do hit and runs with posts.

I'm about to do the welder method, the screw method, and something in between. I'm all over that.

The welder method for pulling the pins is as easy as it gets.



I never had good luck with dremels, they always got too hot. I mainly stick to air grinders, and carbide bits. Doublecut for the irons and single cut for the rotor housings. I finish it with mounted stones and a flap wheel.

I've been using both now. I use the air grinder to get close to the scribed line, than I switch to the dremel for precision.

Not many people port the 6 port engines. The rotating sleeve idea was used to have an engine run on the modest port timing and high velocity of the primary ports for better response and fuel mileage, then when needed, a bit more power once the RPM were high enough to be used. Using a rotating sleeve inside the iron, removed the problem of a closed tube connected to the intake and hosing the whole deal with sympathetic harmonics when not in use.



If you disable the sleeve you have the port open all of the time, and that extra volume kills the runner velocity for poor low speed response. Same for removing the sleeve with the added problem that the square ended runner is a disaster for flow. If you choose to suffer the poor low speed performance, you could epoxy the sleeve in place and port from there. You could remove the sleeve and fill the end of the runner with epoxy and port from there.



In later 4 port engines, a similar strategy was used. The engine runs on the center iron ports only. Then if more power in demanded, the TB ports for the end irons is opened and all 4 ports are used.



Keep in mind that the upper ports (with the sleeves) close at 70 degrees ABDC. This is quite late compared to other engines where stock ports close at about 50 degrees, a big street port might be 60 degrees, and my "J" bridge ports at 85 degrees. That angle at the top corner of the port, is the closing line, and probably should not be moved at all. A slight radius and polish job for all closing lines to protect the side seals.



The further past BDC the port closes, the more mixture is push back into the intake runner at low speed.



The 6 port irons are used in all out racing engines where only side ports are allowed. The web between the runners is removed to form one giant runner. The web between the ports is also removed. There is no low speed power at all. The car must be pushed to get it rolling with much engine reving and clutch slipping. Best power is around 9,800 RPM, and the car is shifted well above 10,000 RPM. All of the high rev mods are used, and usually an aftermarket dry sump system.



The top ports can have a small bridge port installed, and the sleeve can be ported to match. This maintains the low speed performance and mileage, but adds quite a bit high end power. If you have a tuneable controller or some cheater gags hooked up you should try for 1600 degrees or a bit less on both EGT gagea, and or, 12.5 to 12.7 Fuel/Air ratio. This is the wide open throttle high RPM tune. The stock tune for anything with the sleeves closed.



Lay out the paths of the leading and trailing ends of the side seals. Keep them supported all across the port opening. There will be no problems if you do this. If your trailing end falls into the port, use the ramp gag to pick it up. Remember to notch the port bottom to pick up that drooping seal should the engine be turned backwards.



Any question. Any time.



Lynn E. Hanover

I'm going to keep the 5th and 6th ports functional, as well as the VDI. The other irons I have to port and use will be put into a1987 RX-7. S4 N/A rotors, S4 irons and housings, and S4 intake/ throttle body. This isn't going to be a full blown race car though. Its plans are daily driver/weekend warrior/rev at stuff; engine wise. I feel like I know half the story. What was the method to figure out why the port is like this? The phrase escapes me. It sounds sort of like, "calculating port timing and degrees" I don't know. Thanks for the explanation. I'm going to make the slope and try to figure this stuff out.