? about building a 94 RWD 3.4

[ForcedFirebird]

Make them into a shark fin shape.

[3400CaMaRo]

i finished porting mine today no shark fin at all they flowed 127 cfm on the intake and 112cfm on the exhaust at .450" lift then they started to flow less above .450" what do they flow stock i couldnt bench them before hand

[ForcedFirebird]

Does this help?

[taijiguy]

Everything I've read about those heads suggests they flow best with those fins intact.

[ForcedFirebird]

Everything I've read about those heads suggests they flow best with those fins intact.

Exactly. They now flow only as good, or worse, than stock after being ported.

[3400CaMaRo]

well its weight reduction my defense is no flow bench is the same because there is no fin in the exhaust and i opened that up a lot i dont see how they flow the same as stock and im not that smart with flow benches but i do know it pulled 28" of water what ever that means

[3400CaMaRo]

dont hold me to that 28 im not completely sure

[taijiguy]

You can't really compare exhaust flow and intake flow. Remember that exhaust is a pressure, intake is a vacuum. But either way, we aren't just making this up. Every resource, including the 60* V6 Performance book says not to remove the shark fin. And they *did* use a flow bench. Seemingly a little late on the recommendations if you've already removed them, but if you do any amount of research on the subject you'll find the consensus is unanimous. Aerodynamics is a funny thing....

[ForcedFirebird]

Many years ago, it wasn't uncommon to weld a paper clip vertically in the port to do the same thing as the shark fin.

Just to prove it, set your flow bench up and use various shaped clay in the port, and take consecutive tests.

All is not lost, you can have some material welded in there once you are happy with the flow, and shape it similar to the clay.

Supposedly, it also helps atomize the fuel a little better, but that might be more speculation.

[Ortie666]

I could see taking that fin out and hoging the shit outa the port if u were going to be running forced induction, but when it comes to N/A, that fin could be used as a presure drop to increase velocity, in turn making more cfm at lower revs, altho at higher revs with a longer duration camshaft @ mid 400 lift and long tube headers by therory there would be slight presure in the intake port already because of the velocity I would say that fin has then become a restriction.. I beleive it was put in there for driveability because of the short intake runner lenths

[3400CaMaRo]

yeah i think they work with a stock setup but just as fuel mixers and for lower end torque but with the cam im getting it should run good at higher rpms

[Ortie666]

Yeah, kuss honestly the most effective way of truly figuring out is to just try it.. Therory only goes so far..