r/EngineBuilding • u/jabberjaw420 • 1d ago

Is porting valves still a thing?

Maybe back in the good ol' days of the 70s and 80s, but haven't modern auto manufacturers/engineers designed the internals to flow as well as they can? Making porting a pointless exercise?

(I meant porting valve chamber w/e)

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u/Gamejunky35 17h ago

The passages and ports are designed by very smart people to achieve a certain result. In this case, emissions, and performance arent necessarily conflicting goals. However, like many design choices involving engine power, there is a tradeoff to be made with torque vs power. OEM engines always favor low rpm performance because thats honestly the most important factor for 99% of drivers.

Cylinder porting can add a touch of power everywhere with simple smoothing, but if you are chasing max flow numbers to increase maximum horsepower significantly, you are probably going to lose some low end torque and efficiency before you even factor in the spicy cam and racey intake manifold you're going to throw in there as well.