NASCAR Tapered Spacer: What Is It? Is It Different From Restrictor Plate?

The word restrictor plate has become quite the common term when describing Superspeedway racing in NASCAR. At these tracks, a restrictor plate is used to limit the amount of power generated by the cars. This is done to reduce the risk of a serious or fatal accident. While this terminology has become a common term, a Tapered Spacer isn’t exactly something that a lot of people would know about it. So what is this exact piece of technology.

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As described by Matt Moeller (engine tuner of the #10 car), a tapered spacer is something that is “mounted on top the intake manifold of the engine and its issued by NASCAR. And it controls the horsepower we have so everyone’s on a level playing field. The biggest difference we have is at Talladega, Atlanta and Daytona we run smaller sizes and actually lower the horsepower to about 510. Everywhere else we run about 670.”

But how does the Tapered Spacer exactly work?

In a video by The Gumout Channel on YouTube, Larry Mac explained, “you can restrict the air by a different amount by the size of these tapered holes.” He also explained that the biggest difference was that the tapered spacer has better throttle response. He also mentioned that the drivers love the tapered spacers for this very reason.

Throttle response is something every NASCAR driver would like to have control over when racing at breakneck speeds around a Superspeedway configuration. Hence, these tapered spacers are used on the race cars instead of the traditional restrictor plates.

Also just like any other performance based part, these are also provided by a single source manufacturer by the promotion. Hence, making sure that while the drivers have better throttle response over the older cars, the playing field still remains relatively the same.