Examining my new exhaust ports, I noticed that I can see past the port inserts on one of the top corners. It's like the insert didn't go deep enough into the rotor housing.

Think this will cause a problem? I'm worried about the insert overheating and collapsing. I really don't want to remove the inserts.

These are GSL-SE rotor housings, and of course it's on my best one.

 

All they are for is to quiet exhaust without restricting flow. And might fall apart if you leave them in. Dont misunderstand the next part, why would you leave them in when now they are restricting flow and might kill your motor if they fall out.

 

You're talking about the exhaust sleeve?

 

Yes the sleves

 

Actually, flow is restricted by removing them. If I really wanted to improve flow, I'd machine inserts that have a much smaller diverging angle. Paul Yaw used to just crush them in a vise and get 30% increase in exhaust port flow with stock port size. The headers he would make had "tongues" in them to fill in the dead area of the port, like MPG Port Plates if you remember those. Incidentally, doing this greatly increased noise by all accounts - Mazda made the large diverging angle in the exhaust port as a way to cut down noise.


Plus, my headers are not large enough to cover a non-sleeved exhaust port, which is the MAIN reason why I want to leave them in. I could just open the exhaust ports even more to fix the angle problem, but I can't do anything about the header size.

 

.. lets quantify increased flow. If by flow you mean volume no. If by flow you mean velocity yes. What i read indicated that the insert changes the direction of the exhaust gas to an angle that reduced the sharp note created by the apex. And we are not comparing stock to no insert. If your issue is port fit to your headder than remove any part of the insert that fails to match the port then reinsert. But if your insert fits like a circle in an egg needs to come out or be converted so it provides a port match to the headder. pics?

 

Top left corner, it's just protruding enough to catch a finger a little.

 

I pulled the offending insert out (6-32 tap and screw method: worked awesome) and WOW. I'd never want to run without inserts, the port shape looks horrible.

I reshaped the insert and slammed it back together.

 

FYI, you can make small diameter inserts by crushing some thickwall (1/8th or so) stainless tube in a vice, some pounding, and welding it into a ring. Maybe too involved, and I can't say for sure what the results are like but...

 

How did you reshape it PJ? Did you weld material behind it and grind away?

 

exactly what i was going to suggest. i have done the same when i overported the exhaust ports.

you really don't want the exhaust getting under an exposed lip, it will crush the sleeve and then you are really boned. granted it's mainly an issue when running well over 300whp but even in lower horsepower n/a applications it will still eventually do the same.