Northstar Engines and System Technical Discussion Discussion, Porting the throttlebody in Cadillac Engine Discussion; What may look like an unwanted lump in the airflow may turn out to be a design feature. I remember ...
What may look like an unwanted lump in the airflow may turn out to be a design feature. I remember one guy who tried to clean up the intake ports in his GM engine and killed it. It turns out that what he perceived to be obstructions to air flow were in fact design features engineered to improve cylinder filling. It seems to me the engine was an OLDS 4-4-2.
There is some science and skill involved in head porting. A good set of NASCAR heads goes for $25,000 to $35,000.
He's not porting the heads, he's porting the intake manifold.
Intake is intake. Polishing the intake manifold only is like cleaning only one end of the sewer pipe. The same rules apply to the whole thing. What appears to be lumps and casting flaws to the untrained eye may be design features. The biggest gains may be made in port matching; matching the intake ports at the intake gasket with the ports in the head so there is no step. This can be tough to do without a fiber optics bore scope. Usually the best you can do is make both sides match the intake gasket. Polishing an intake and removing turbulence can kill the lower RPM ranges. A prime example was the early Ford Boss 302. The engine builders had to reduce the size of the intake runners and ports with DevCon plastic to get the thing to run any way but WOT. An amateur should be prepared to throw the whole thing away and start over at any time.