I havent seen this disscussed before, just warnings against going to wide. But how wide is too wide? the widest safe exhaust port width ive heard to be 2.25 inches +beval, anyone go widder without problems?



forgot to add that when i taked to rotary aviation about there seals i asked how wide of a port they could span reliably and thay said so long as the seal doesnt drop in there seals will be ok, so....

 

the wider u go the less wall the apex seal has room to support itself, at high rpm this is even so important, going wide is not really a good idea.

 

I just went an put the 2.25 up to my ports. I think I am gonna go a bit wider and bevel the closing edge real nice. There still seems to be lots of room with that measurement. I would think the only concern is that the seal will bend in the middle. As long as the bevel is good and your not going too far above 7500 its ok????



Gregory

 

if there is no more room to port up or down only then port to the side. there is no point to compromise apex seal reliaility, even if u port up and down a lot more then there was stock the apex seal spends more time in the air unsupported which is already extra stress for it.

 

I go out to about 1/2" on each edge.

I believe the rotor housing width is 80mm or a little under 3.25".

Take out 1" for the sides, and my exhaust port widths are a little under 2.25", so your 2.25" width sounds just about right.

Funny, most of the pics I've seen in here don't go this wide.

I do use the new Mazda OEM 2-piece 2mm apex seals though.





-Ted

 

Most people on this forum don't port the exhaust enough to make good HP anyway, at leas that is what I am discovering. I see that everyone has these huge *** intake ports and beveled out to the max so the side seals don't break then you look at the exhaust side and its damn near normal..........I don't get it.



Going really wide is a bad idea as has been said, but porting out to the sleeve should be close to the 1/2inch that Ted is talking about. I would say that is definatley in the safe zone.

 

Ive come to the conclusion that North American tuners dont do adequate work with the exhaust ports compared to the intakes on average. Its nothing like the work done in Oz or Japan. It also seems the solution to everything here is a bigger turbo or more boost, not making the most of what you already have.

 

An idea on a mild exhaust port...





-Ted

 

I like your definition of mild

 

Going really big on exhast can really change your low-mid range. I think thats why many people here in the US dont port big and then just add more boost for the big hp numbers. Its all a compromise no matter what you do.