One Dirt is at the Performance Racing Industry trade show this week. We’re trawling the floor looking for the coolest dirt racing stuff we can find. We’ll share lots more next week (when we finally catch up on our sleep!) but for now we wanted to show you these really trick restrictor plates from Willy’s Carburetor & Dyno Shop which aren’t even for sale yet.
Most of the time when you hear “restrictor plate,” that’s a bad thing. But this isn’t NASCAR, and in dirt racing it is possible to have too much power when the track gets slick. But the typical restrictor plate does a lot more than kill power, it also destroys throttle response. When the race track gets dusty and slick, many racers will try different tricks to dial back some of the power to help make the car easier to drive without spinning the wheels excessively. Some go with a smaller carb, others try to retard the timing a bit–but neither are ideal.
Instead, Willy’s spacer/restrictor plates are designed not only to kill some of the flow from the carburetor but also have anti-reversion measures machined into the underside to keep the accelerated air/fuel flow from bouncing back up into the carb and killing throttle response. We’re told in testing the 1 1/4-inch plate cut 35 horsepower from a dyno test engine with approximately 700 horsepower while the 1-inch restrictor cut a full 100 horsepower.
Look for these new plates to be available from Willy’s sometime in 2016.