porting exhaust only
 

As the title says, has anybody experimented with this?
Porting the exhaust, but not the intake.
Does it save fuel? Does it yeild more power?

Maybe it makes your turbo spool quicker good question since Im going to be taking off my turbos soon.

im thinking it might act similar to a renesis.... mazda changed the location of their exhaust ports.... yes?

probably not going to act like a Renesis. the ports will still be peripheral, just larger than stock. i guess you could theoretically gain an MPG (or KPL) or two with it, but that's all i can think of. it will show much more effect if the engine is ported as a whole though.

It'd be the opposite of the "Renesis". The "Renesis" has much less exhaust port timing than a stock peripheral exhaust port, that combined with the effects of moving the exhaust to the side (unburnt end-gases won't get dumped right out the exhaust) is why the engine has much higher efficiency when idling and at low load, which is 90% of an engine's life. Which is the point of the "Renesis" - make it run cleanly and efficiently at idle and putting around town at 30mph. The fact that it makes more power than any N/A previously built (what are they, 200-210hp actual?) is simply due to Mazda not having to crutch the engine as much to make it run acceptably clean.

The exhaust port is the primary choke point in the stock engine, so porting it is an extremely good idea. But while you have it apart why not do a lil' bit to the intake ports as well? :)

The other reason the renesis make more power is the fact that the side exhaust ports allow for larger intake ports and the higher redline due to lighter rotors. But it is certainly not making even the revised 238 Hp.

im going with a blowthrough initially, i want to pair that with a large sp or a half bridge, nothing too extreme

Why would you want to do that?
Everything is apart, so you might as well hit both the intake and exhaust ports.
There's no reason to ignore the intake ports unless you're trying to do something you dunno how...and that's asking for trouble.


-Ted

on stock internals, what would you guys do?

similar question to this one, i have an RE that will be running a T70 at 20psi.. I had seen someone put up a topic that focused on milling out the exhaust port and pressing in a 2 -2 1/2" sleeve.. but I can't seem to find it with the search engine and have come up blank.. I think it was Scalliwag that was presenting this..

Regardless i've got two new TII housings and want to open them up as much as possible without overlapping severly with the intake or expansion stroke.. any sites with timing or topics with previously done full ports like this would be welcome, and I'm sure they'd help the original poster as well ( sorry if this is a hijack )

bump

I think the sleeve idea is on the "other" forum...

that was rotarygod

thread you're thinking of?

I'd just port both. Why not, the more power the better. But u dont have to.

sorry should have explained a little better....
what kind of porting would you guys do (bridge / street / peripheral / other), if you had stock internals and were also doing a blowthrough turbo setup?

I've seen several people only do the exhaust side. Spool is increased and i think you keep a pretty good torque curve. But, i don't know if that is standard or only applicable to specific set ups.