cboggs

Hi Gang,

I hope I can help out, ..

Curtis

Mopower71

Hi Curtis
Welcome, and I hope you can help too.

cboggs

Mike,

I think in your case, the best thing to do, .. get a BFH ( big friggin hammer ) and a chissle, .. start bangin away, ...

I'm kidding too, ...

Curtis

onehellofadart

I've been told latley I need my head examined. Where do I start.

Thanks for taking on the task. =D>

DARTSPORT

Welcome aboard!!

cboggs

Thanks for the welcome guys, ..

um Tony, .. I can examine your head, .. but it needs to be done in person so you can lay on the couch, .. and I can make notes, look over the top of my glasses, .. and say, .. uh hu, .. mmmmm, .. interesting, .. and how do feel about small furry animals.

OK, so anyone have a question? home porting, tools to use, .. what's most important in a head ( it's not flow numbers ) etc, ..

Curtis

cboggs

Simple, .. everything.

OK, .. the long answer. several things have to be looked at.
In the order of importance, ..

#1 PORT AREA. You have to measure every section of the port and know the area all the way through the port. Of course this effects velocity but you can have too much speed as well as too little. Area is suggested by the valve size & lift ( curtain area ) as well as the application for the head. Also air speed will have large effects on the wet flow as well as what the port can flow.

#2 WET FLOW. VERY important, .. maybe more important then cfm is what happens to the fuel. Where it goes in the port and more important where it goes in the chamber. Port shape, valve shape & valve seat shapes effect wet flow from the port side but a bigger effect is found in the chamber.

#3 CFM, .. the one thing every one likes to talk about, .. notice it's #3 on my list.
The head must flow enough air to support the HP you are trying to produce. But more important, it's not just a peak flow number, it's good flow through the lift range. If a port flows really well at high lift but is lazy at low lift the engine has to "work" to get the flow started in the port.
A port with good low lift flow allows the atmospheric pressure to do it's job and fill the cylinder with out the engine doing all the work. So not only is it more average flow during the lift cycle but it's also about freeing up hp loss in the engine.

A trend we are seeing these days in race heads is steeper valve seat angles. There's a reason for this. As we get better & better cylinder heads, .. tall ports, nice short turns, and better exhaust ports it has become necessary to kill off some low lift intake flow to keep from pulling the fuel out the exhaust during overlap. The other benefit is steeper angles like a 50º, 52º or even a 55º is they flow better at high numbers, .. it's a big miss-understanding amongst many cylinder head porters that the steep angle are just to gain high lift flow, .. not true, they have other uses.

OK, .. .. enough for now, .. it's past my bed time.

Curtis

mopar12372

hey guys are you talking about heads? hmmmm i do have a hammer, i really didnt think that head porting was that easy!! all joking aside that is some very useful information . all i can say is YURRR RIGHT!!