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Old 01-05-2013, 07:42 AM
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Originally Posted by vinniekq2 View Post
all this porting is a great idea.Remember that almost all the heads need the most work on the exhaust side. Doesnt matter how much air goes in the intake side if it cannot leave
This is 100 percent true. Most factory heads work well because the intake side is under a lot pess pressure to pull the charge in than the exhuast side. The exhuast is going to come out. Because the piston is going to force it out. Most factory heads are very unbalaced because of this fact.

But with heads designed for efi you got to assume it is also built to run with little to no over lap. Now with a poor flowing exhuast port a larger cam with good overlap will not scavange like it is designed to so the exhuast ports always need attention first when starting with an efi head.

Most ford guys are amazed to see the exhuast bump in the 80s and 90s 5.0 engines. It blocks most of the port and by itself its worth 20 hp and will make sure any bolt on you install only works so well. This is also the reason some cars will respond to bolt ons and make 500hp and other will never pass the 300 mark.

On the intake side in this case i would think there isnt much power to be gained past the removing of the ruff casting surface to a smoother sanded surface.

Some none efi heads have the opposite problems. Balance is the key and getting the ports to flow enough to support the rpm the cam is requesting from the engine.

Just some general info to spur discussion.
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