difference betwen porting and not porting
 

yeah what will be the power difference with stock port and street port in a S4 engine with everything stock, even the turbo? 10, 25, 50 hp?

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How much does porting alter the fuel consumption, if any?

Your fuel consumption should go up, your getting more air into the engine and the computer needs to put more fuel in there.

It all depends on the size and shape of the port.

i think for a streetport power gain is generally 10-15% over stock.

lets say u want a port and still stay emission legal whats a reasonable gain?

im not worry about emmision, theres no "stick on the muffler" check in NY. i would like at lease what the average HP of a street port engine.

I have a 6-port s5 engine. Should I rebuild my engine when it dies or should I get a 4 port so I can have a street port?

Oh man. Part of me is surprised that none of the oldies have touched this one.

A port is like adding a cam for a rotary. By enlargening the intake ports on the secondary housings, it allows for more air to flow into the combustion chamber. In a simple streetport, the ports are just massaged to a larger diameter to allow for better/more flow at higher RPM (think like a cam, this shifts the power band right on a dyno sheet, but adds more power). I have seen guys getting 20-30 hp off a mild street port.

No, don't dump for a 4 port engine. It has 2 less ports. Which means that it flows less air. You can port any 13B, not just the 4 port engines.

For daily driven cars, the trade off for power vs. lifespan equates to a streetport to being the best option. A j-port, half/full bridge, or even a perp. port are BAD ideas on daily driven cars IMHO. Do a little research first before making any commitments to port jobs:
http://www.mazdarotary.net/porting.htm

I'm not an old member but it seems that those of us who have done porting and posted about it get tired of answering the same question. But you did well and took care of this week's porting question episode. :bigthumb:

There is no one general answer for such a question.
For every different person you ask this question, you're probably going to get a different answer.

Porting non-turbos is different than porting turbos. People have different views on overlap (I try to minimize overlap).

In general a street port should increase power at least 10% easily.
Due to the increase in power, mileage typically increases.

With my car (1987 Turbo II), porting increased mileage by 1 to 2 mpg. Power increase was about 20hp at the wheels - car produces over 200hp at the wheels.


-Ted

ted...what mods do u have on the car?

http://fc3spro.com/PROJECTS/MYFC/myfc.html


-Ted

More like in the last day or two. When Ifirst started contributing to this board, I was shocked at replys that started with "try searching" or something to that effect. Now 600 posts later I see why. We spend a good amount of time reading the same post over and over.

Anyway to contribute here, Rico has provided solid info and Ted is right. i myself on N/A's try to limit the porting I do unless I see that the exhaust has been upgraded or will be soon. Otherwise, I feel like, why bother.

hey ted.....have any pics of the interior?...im curious as how u relocated everything......thanks

mike

To add-
Porting work won't increase gas consumption unless you are going to be spending a good amount of time with the pedal mashed- using the extra air flow/timing that the porting affords.
Technically, fuel consumption at idle will go up a bit as well, since the engine is drawing slightly less vacuum, and needs a bit more fuel to keep an idle (since the port velocity is decreased). But that's so negligable that it isn't even a factor.

i'm getting 21mpg on the highway on my large as they can get it street port, and 15 in the city, thats a TII with 720 cc secondaries as well

I was regularly seeing 25mpg+ on all freeway trips from Sacramento to Vegas when I moved a few years back.  The actually MPG calculated to just under 28mpg, and a full tank would have easily hit 400 miles!

Ported motor, 4 x 720, Field SFC


-Ted

May I ask why exactly half bridge porting is a BAD idea for a daily driving car? is there a way to get the brap brap brap sound and still keep the car a good car for daily driving car? thank you for your time in advance

btw the car is 1987 turbo stock I think and I'm having the motor rebuild in 2 weeks

holy thread revival.

you were soooo close to finding the right thread.

if you search again there are a billion threads on the advantages/disadvantages of bridge ports and street ports