I found out this weekend that the exhaust ports from the heads of a WRX is exactly 1.5" each in diameter (my measurement). The exhaust manifold runners are ~1.6" in diameter. The header-uppipe is ~1 7/8" in inner diameter. My intention was to port-match the OEM header to the heads for flow, but I found out I didn't need to. Yet, I used my trusty Dremel tool and rounded/tapered out the edges anyways. The genuine gaskets that I bought from Morries Subaru were bigger than both the exhaust ports and the header ports, so I didn't need to dremel more then I needed. I noticed a lot of jagged casting inside the pipes which Subaru never smoothed out with max airflow in mind. I got some tough sandpaper and started cleaning up all around the inside (I took the header apart into it's three sections). This process took me at least an hour to smooth out the whole header and costed me a few sheets of sandpaper, because I wanted nothing less than a smooth inner-diameter to maximize the exhaust flow. I'm sure that this procedure helped out with the exhaust flow a lot more than just the tapering of the edges. The cylinders farthest away from the turbo suffered the most from this casting restriction. This job took me about 6 hours of my Sunday: which includes a few runs to the store to pick up an adjustable wrench (22mm) to remove the stubborn O2 sensor on the header. I'm glad I got this done with. I don't need to invest in an aftermarket header, I got all the heat retention I need from the head sheilds and cast iron material the header is made out of, and I don't need to re-drill an EGT sensor for the in-car EGT gauge. I slept like a baby that night. The car is still learning it's Vishnu tuned fuel map, but once it's all set, I'm sure I've gained a few lbs of torque and quicker turbo spool.
<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Mushashi Fong, Great job, now do ya wanna do mine? C <hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote"> Yup, me too....only I'll give you a case of Old Milwaukee, hehehe.
Guys, I still think this is making a difference!!! Feels like the turbo spools a bit sooner than normal. Still learning. )
<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">Originally posted by wall of tvs <blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Mushashi Fong, Great job, now do ya wanna do mine? C <hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote"> Yup, me too....only I'll give you a case of Old Milwaukee, hehehe. <hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote"> 3rd in line!!!!!
Don't make me hurt anybody now... } If you guys are interested in doing this, I can lend a hand and provide the dremel tool with the process though. I will not be spending half a day under the car again. I get headaches when I lay on my back on hard surfaces for a certain period of time. Things needed: Jack & Jackstands (I should have used my ramps!) Wheel stoppers Dremel tool Some attachment bits (I can find out for you) Few sheets of heavy duty sandpaper New gaskets for the whole exhaust system (optional) Monkey wrench 14mm & 12mm sockets A 6" extension (and/or two 3" extensions) 22mm wrench (or an adjustable wrench good for over 22mm) Liquid Wrench or WD40 Rags Spray cleaner to spray out the excess shavings in the header I think that's it. All you do is reset the ECU, take out the header, work on it, and then put it back on. Easy.
Resetting the ECU doesn't make much sense. People reset theirs way too often in my opinion. All you are doing is setting your IAM back to the default and making yourself wait a week or so for it to relearn.
I thought you needed to reset the ECU after anything you do that affects the a/f ratio: spark,fuel,air. :???: I would prefer not to, but I get that "something missing" gut feeling if I don't.
4th in line..i'll give you a thanks since i remembered you complaining about not getting any for helping... when i get my car that is....*sniff*
I would like to bring this thread back from the dead just to say that after a while of the ECU relearning and such, the throttle response is better. I can blip the throttle in second gear and the car would jerk me into my seat. In third, it does it too, but not as hard. IIRC, before the smoothing, it would hesitate for a second and then start spooling. I can't say how much more power my car is producing, but hopefully I can get a dyno chart of how strong my torque curve is at low RPM's.
