Bigger Isn't Always Better
Not the case in every instance, but frequently critical to torque, here's a pretty good rule of thumb. It can apply to just about any major engine component, including intake manifolds, headers, valve timing, intake/exhaust ports, carburetors, and other components that affect airflow into and out of an engine. Don't let an airflow bench fool you. More flow isn't always more power. Perhaps in many cases, but not always. There is not a one-to-one correspondence between increased flow volume and increased flow velocity.
Don't forget the burn Included among the steps to proper parts integration is the need for good combustion efficiency. Even good volumetric efficiency remains dependent upon an engine's ability to combust high percentages of air/fuel mixtures. Once again, Circle Track has previously contained numerous references to methods for accomplishing good combustion efficiency, so you may want to check out stories in earlier issues. In short, "good" combustion efficiency is characterized by low levels of brake specific fuel consumption (b.s.f.c.), crisp throttle response, on-track fuel efficiency, proper parts integration, and races won ... all else being equal.
Jim McFarland is president of Autocom, an Austin, Texas-based company that consults on automotive issues throughout the automotive and motorsports industries.