RC Car - Can I Port My Header?

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Can I Port My Header?

Comments: I enjoyed your response on the question of porting on the O.S. 12CV. I learned a lot about the engines my son & I are running. With the idea of adding a header pipe and tuned exhaust, I have two questions. Should the header pip be opened up at the flange to match the exhaust opening on the motor to smooth the air flow to the pipe or should the header pipe (HPI) be left with what looks like a small rectangular opening. Also, what about the stinger pipe that comes off the expansion chamber and through the side of the car. What effect does changing the length make.

Sincerely & Thanks

Response: You can smooth out the header port to allow the exhaust to flow smoother. None of the "tuning" of the exhaust is done in the header so it would be a benefit to port the header a bit to match the crankcase. It will not make a large difference though.

I don't really know if the length of the stinger pipe has an effect on performance. I would imagine that all of the back pressure is created before the point in which stinger length would have an effect. I think the stinger is long just to help keep the exhaust away from the body. you could cut it down to free up the flow a bit but again, the performance increase would be minimal (if any at all). It may look ugly to grind it off, especially if your pipe has been anodized.

Let's take off a few tenths per lap,

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