The restrictor plates used by NASCAR to control speed at its two fastest tracks, Talladega and Daytona, are like a heart monitor or an artificial leg. You hate having to have them, but you can't do without them.
The plate is a thin piece of steel, simple and bulletproof, about five inches square, and with four holes machined precisely so as to fit under the centers of the throttle bores. The holes have varied in size since the introduction of the plates in 1988, and currently are at 0.90625in (29/32nds). The plates are controlled by NASCAR and are installed and removed by NASCAR officials prior to competition events.
The plate is intended to reduce the flow of air/fuel mixture from the carburetor into the intake manifold and hence into the cylinders, the ultimate goal being to reduce horsepower and speed. It is estimated that the restriction knocks about 300hp out of the engine, keeping speeds here and at Daytona in the 185-190 range, safely below the alleged "magic number" of 200mph.
see http://speedtv.com/articles/auto/nascar/10785/ for the whole article
The plate is a thin piece of steel, simple and bulletproof, about five inches square, and with four holes machined precisely so as to fit under the centers of the throttle bores. The holes have varied in size since the introduction of the plates in 1988, and currently are at 0.90625in (29/32nds). The plates are controlled by NASCAR and are installed and removed by NASCAR officials prior to competition events.
The plate is intended to reduce the flow of air/fuel mixture from the carburetor into the intake manifold and hence into the cylinders, the ultimate goal being to reduce horsepower and speed. It is estimated that the restriction knocks about 300hp out of the engine, keeping speeds here and at Daytona in the 185-190 range, safely below the alleged "magic number" of 200mph.
see http://speedtv.com/articles/auto/nascar/10785/ for the whole article
