Has anyone else noticed how the flange where the header blots up to the head has much smaller holes then the exhaust manifold gasket from G.M. ? I'm gasket matching mine with a die grinder has anyone seen what I'm referring to or is it just me?
And if they all have such a smaller port size then how could they be any better then the factory piece ? Anyway I've ported out 2 of them so far and there is a HUGE difference
in the port size which should translate into more horses
Which is a good thing!
Semper Fi SAINT. May you rest in peace.
normally that would make a difference , but look at the ports in the head
they are smaller than the gasket
the port on the header was closer matched to the port in the head , not the gasket
If thats true ( no reason to doubt you i'm just sayin ) Then OH MY GOD !! I am SO getting a head to port cause there is a ton of material that can be taken off to gasket match it. If I were to port out the head too then that should open up all kinds of power!
I'm going junk yard hunting this weekend for sure !!!
Semper Fi SAINT. May you rest in peace.
^^^
its only going to flow as much as it needs to
/\ /\ /\ Have you ever ported a head? ( not being a smart ass just asking ) When you open up the exhaust side the engine can breathe easier and that = more power.
So to port the heads exhaust ports you can increase the h.p.
Semper Fi SAINT. May you rest in peace.
keep in mind GM designed the ports and the flow rates to flow in a certain range
so porting the head , if you go to big will move the power into a non-useable range
i know when bothwell ran the drag team for GM , the port job on the heads they were using on the motor that made 1300-1400 hp was still a small port , compaired to what alot of people would think for that kinda power , and the motor idled at 1500-2000 , and rev'd as high as 10,000 to 11,000
granted they were CNC ported heads
bigger isnt always better , its all about matching parts for the intended usage (rpm range) for the motor
In most cases, you never port match the exhausts. Many stock exhaust manifolds and virtually all tube headers will have larger port sizes than do the heads. You want that "step" from the port to the larger header tube or exhaust manifold because, as pressure pulses flow back and forth in the exhaust system, it acts as a "reversion dam" by resisting back flow of exhaust gases into the port. If you end up with the rare situation where the stock exhaust manifold has ports smaller than those in the head, you will need to port match
http://registry.gmenthusiast.com/images/importkilla32/Bullit.JPG
Not to argue with you Dan but I've always had every hi performance engine I've owned
gasket port matched. Hey if it works for NASCAR & the NHRA then there must be a benifit in there somewhere.
Semper Fi SAINT. May you rest in peace.
/\ /\ /\ Can't link to it just keeps saying can't be found ??? anyway porting the exhaust side shouldn't change the power band to being higher in the rpm band all it should do
is make it freer reving and extend the power band by allowing the exhaust to get out quicker and easier. Porting the intake side as well as the cumbustion chamber are what raise the effective power band up. But I do thank you guys for the warning and since I'm doing this to a spair head and not the one currently on the car if it doesn't work then I'll just switch them back. But I'll keep you guys updated as to how it turned out.
Semper Fi SAINT. May you rest in peace.
