'87 turbo II

iTrader: (1)

When I get a rebuild this winter, this guy I know is offering to port my engine for me for free. He has never ported an Rx-7 but he quote "took a class that taught him how to port/bore metal in college". Should I go for the free streetport or look for some local person who's knowelegable about the FC from this site come over and help out? The guy who wants to port has helped rebuild the engine of and FD with 450 HP that was streetported and he says he knows "how the ports should look" but he didn't do that porting himself. Should I go for that? Would seeing ports on a streetported FD give him enough knowelege? I read up on porting and someone said opening th eports to be lower will increase boost pressure but I'd be scared of exhaust overlap. So you raise the upper part of the port for a minor streetport right? I know not to go into the waterjacket or to cut into the cornerseal or oil seal path too. So what should I do?

Aaron Cake

iTrader: (1)

I don't think there's a school anywhere with a "Porting Rotary: 101" class, but I could be wrong. He probably took a course on porting piston engine heads and such. While the skill set is exactly the same, the principle and practice is NOT. Knowing how they look is great and all, but there are measurements you need to follow so you don't port into the side seal or corner seal track, don't intrude on the oil ring track, and don't port into the water jacket. Get this person a set of porting templates and some old irons and then turn them loose. Then post the results here for reviews.

Icemark

porting should be considered the same as cutting a new cam on a piston motor, as it effects both intake timing and volumn.

Much like a cutting a cam on a piston motor, it is an art to get the proper timing and flow for best power, while maintaining driveability and reliability.

With that said, the simple note of cutting metal is nothing. Anyone can cut metal, you generally don't even need to take a class.

So if you are convinced you want your buddy to cut some biger ports, I too would recommend you get a couple for him to practice on.

But if you are on a budget, and can not afford to have a less than optimal motor until he figures it out, it would probably not even be recommended to port your motor. Stick with the stock port or a professional that has done quite a few.

Samps

mazdatrix used to sell templates!

Icemark

but they only let you set timing, not volumn... volumn of flow is pretty much something that you have to guess at until you know better.

'87 turbo II

iTrader: (1)

You can get a template from RB right? I heard it's pretty small but I just want to see a small upgrade in power maybe 5-15. I'm trying to mod my S4 TII to around 230 flywheel horsepowhorupping the boost any more than 2 psi and I planned on doing most o fhtis during the rebuild. I'll go to my local mazda dealership. they have a rotary specialist working there who dynoed a rotary engine out of car to have 590 hp so I'll trust him to get me the little gain I need, I'll spend the money. Thanks.

Aaron Cake

iTrader: (1)

RB has templates, Mazdatrix has templates, etc. They are fairly common.

If you are looking for a small HP upgrade, don't even bother porting. The stock ports will support 230HP at the flywheel easily. Hell, there are stock port cars dyno'ing at 400HP (check the single turbo forum). Raise the boost a few PSI, upgrade the secondary injectors and get an S-AFC. 230HP at the flywheel is easy.