busychild

Just like the title. Why and how does this add power, or why does it?

Yes, I am a noob.

nickzed20

air flows differently through various port shapes when doing different things. When air is taking a curve it will prefer one port design over another. As to which one is good for what, i forget... its in one of my books and i cant find the info right now

but basically there is square, circlular, and D shaped (hybrid )

If I figure out which book I read it in ill post what I find.

HEAD

I guess the best way I can describe why I might use a square port is if I am looking for alot of volume(air space)

katzenjammer84

D shaped ports are excellent for VE, they make it flow quicker than traditional round ports.

HEAD

I don't know about that, if this was true why would pro stock and almost every other form of racing running or changing to a round port on exhaust and running oval on intake

nickzed20

actually, i believe the D port is the best for curves... which racing and pro series have little of. This is because while the air on the outside of the curve has to have a higher velocity then the air on the inside of the curve in order to complete the turn in the same amount of time, so the configuration helps the two velocities (the round part for one and the straight edge for the other)... again, the only problem is i cant find the info that i wanted to share since i have no clue where i read this all from, therefore the stuff i am telling you is incomplete.

busychild

Is there a better port application when it comes to power adders?(SC, Turbo, Nitrous, NA) On the same note, is this directly related to the type of piping bolted to that port?(turbo manifold, shelf header, custom race header)

HEAD

there is definitly a better port per app. NOS likes really big exhaust ports it will run like poo of the bottle but run like a animal on the juice, Turbo also likes big exhaust but not as big as the NOS stuff, makes turbo lag, I don't have any real blower experience so I won't comment on that.

Nick, I do totally agree with you, I know it makes sense to have the D shape, I use the D on my big block Chevy NOS ports and it absolutly loves it, but I was just saying everyone is getting away from that and going with the oval/round stuff
usually for me if a port is round I will try to keep that shape but if it is square(exhaust) I will make it a D in some cases

nickzed20

yea, all i know about head flow is in theory... ive never ported a head so i trust the experts. Im sure that per application, that you do what will end up flowing the best for what the engine will be doing.

Fkned

This is what Dave means.