HEAVYBOAT
12-20-2003, 10:38 PM
IÂ’m buying a header kit from hooker (not to be confused with A Hooker) to make some new headers for my new combo and I'm looking for some opinions on the primary size. Last yr my headers were some terrible 2-inch primaries that took an immediate 80-degree bend right after the port.
The motor is a BB 547ci roots blown with 172cc ex port volume and they will flow 310 cfm on ex. Right now I am tossed between 2 3\8 and 2.5 primaryÂ’s. I am shooting for 1100+ hp.
This topic may open a can of worms on whether or not a blown engine still requires some amount of "backpressure". I think we all have heard with a blown engine that backpressure isnÂ’t really needed, but I remember reading a article one time about some testing on a forced engine and finding that that some amount of Backpressure still helped hp in a blown combo because of assisting in scavenging the exhaust out of the port.
Maybe its not backpressure were looking forÂ…. its port velocity for scavenging? Any opinions? Infoegomanic, youÂ’ve been quiet lately... whatÂ’s your opinion on my hookers? :wink:
The motor is a BB 547ci roots blown with 172cc ex port volume and they will flow 310 cfm on ex. Right now I am tossed between 2 3\8 and 2.5 primaryÂ’s. I am shooting for 1100+ hp.
This topic may open a can of worms on whether or not a blown engine still requires some amount of "backpressure". I think we all have heard with a blown engine that backpressure isnÂ’t really needed, but I remember reading a article one time about some testing on a forced engine and finding that that some amount of Backpressure still helped hp in a blown combo because of assisting in scavenging the exhaust out of the port.
Maybe its not backpressure were looking forÂ…. its port velocity for scavenging? Any opinions? Infoegomanic, youÂ’ve been quiet lately... whatÂ’s your opinion on my hookers? :wink: