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Optimize Your Air Flow

Port-matching for better performance

A typical automobile engine is an amazing combination of reliability, efficiency and power, especially when you consider that the manufacturer designed it to be as inexpensive and quick to assemble as possible. That doesn't mean you can't optimize its performance with a few race-engine tricks, however. Simple gasket-matching (the first step in a comprehensive porting job) corrects one of the main mass-production flaws, and just might give you that extra airflow you've been looking for! All you'll need are a few new gaskets, a marker and a die-grinder with an appropriately shaped carbide burr. The work can be done anytime, but is most convenient when you already have the engine disassembled to replace a blown head gasket or have valve work performed.

Make Your Mark

Cast aluminum engine components are lightweight and relatively inexpensive to manufacture, but as with any casting, there's a certain amount of deviation from the original design. This is particularly true with hollow parts that use "cores" to displace metal when the casting is poured. If the core is not positioned exactly right within the mold, then the cavity in that part won't be positioned right either. Bolt two of these imperfect parts together (like the intake manifold to the head) and you can see how air flow could be affected at the junction. Here's the fix: use a new gasket as a tool to help identify obstructions and align uneven casting openings. Drop the gasket over the studs that bolt the parts together and mark the areas of aluminum that protrude into the gasket opening. Move the gasket to the mating component and repeat.

Grind To Match

Remove the gasket and block all orifices in the head or manifold with paper towels. You're going to have to remove all the aluminum shavings prior to reassembling the parts, so do a good job. Ideally you'll be doing this work just before having a valve job done on your head, which should clean it even better. Taking great care not to cut too close to water passages or through thin walls, grind away the marked aluminum so that the openings match the gasket (and now each other) perfectly. Blend your work into each opening, striving for smooth transitions and unrestricted air flow. Do the same on the mating part, and repeat the whole process at every junction from the throttle body to the exhaust manifold. Your work will never be seen by anyone but you, but the optimized air flow will be felt by everyone you take for a ride!