Porting questions...
 

I'm having my 13b for my 93 rx-7 rebuilt, and while I'm at it I wanted to get some info on Street porting, what are the benefits and drawbacks to a street ported engine? Will it still be streetable? And what kind of added power would I be looking at? Also what about bridge porting or half bridge porting?

Thanks

Richard

A streetport is very streetable (hence the name).
There is no loss in streetability or every day driving.
It will not affect the reliability of your engine or it's lifespan much at all, espeicially compared to more radical forms of porting.

You will lose a slight bit of low end torque power, but the increse in the upper 1/2 of the rev range way more than makes up for it.

Bridgeporting is still streetable, but you will notice much of a difference. It is not as streetable as a strettport. The power loss at low rpms will be much more noticeable but once again, huge increase in top end power. Your idle will be more rough and raspy sounding, maybe even set a bit higher. Your engine won't last quite as long, but still will last a good lifespan. When you get into even more radical porting, engine life is severly affected.

Thanks for the info, Is there a distinct horsepower gain from streetporting, and if so, whats a general idea of how is gained?

I'm not too sure of power gains as I have no personal porting experience. I know that if your engine is modified and you port it, you will see substantial gains, but if your engine is all stock and you port it, your gains will be noticeable but not that great. Even just an intake and exhaust will help your porting gain a lot of power.

Here is just a rough guess:

Stock 3rd gen engine: 20hp streetport / 30hp bridgeport
Modded 3rd gen engine: 35 hp streetport / 50hp bridgeport

those really could be far off though, so don't take them TOO seirously.

Actually, I thought it was more than that.. I heard someone say that a big streetport gave 40hp on a 2nd gen turbo..

-Tesla

Yes, it probably is more,
I just took some wild guess's for power gains.

if your going to the hassle of taking out the engine/taking it apart i think it is worth porting the intake ports. it doesn't cost much. i had it done and as said by Coolidge the power increase was there but the real increase comes from a bigger turbo (bigger turbo=more flow & bigger ports=less restriction).

the 3rd gen has bigger intake ports then the 2nd gen. so if the mazda factory enlarges there ports with almost every engine they bring out, it must mean something.
bigger isn't necessarily better, this is where experience counts, getting the job done correctly first time.

check out:
http://www.k2rd.com/FC3S/MODS/ENGINE...ING/inport.htm

http://www.mazdatrix.com/faq/porting.htm

http://www.rotaryengineillustrated.c...-ports101.html