Question regarding head porting

[ikessky]

Okay, so I was looking through the in depth section at the head porting articles. Now, in my thinking, if air flows better unobstructed, why do you not want to touch the short side radius? I mean, if you leveled it out a little bit, wouldn't the port flow better? Or does it have something to do with the velocity the air gets from making the turn............ My head hurts.......

[AaronGTR]

You can smooth the surface of the inside radius, but you don't want to remove a lot of material on that side if you're trying to enlarge the port. The reason being that to make a smooth curve you would have to make a tighter radius, and the tighter the turn is the slower the air moves. Also you have to be very careful working on the inside radius, because if you make any sharp angles or lines across the surface (instead of a smooth arc), it will make the air stream break away from the surface and tumble.

[SappySE107]

Yeah, I just barely touch them to remove any sharp angles. I make sure its rough still though for the intakes because this is a place for the fuel to hit the wall and puddle up.

[ikessky]

I had already known about keeping the areas rough where there is fuel present with the air. How rough do you have to go though? Would hitting them with something like an 80-grit roll be too rough or too smooth? What grit should I use to polish the areas that are just seeing air?

[SappySE107]

I polish the exhaust side with cross buffs after I use sand paper to get it cleaned up. On the intake side, Iuse a grinding stone meant for iron and go really slow. This will leave a nice rough surface.