How To Increase Engine RPM - How It Works

Modern race engines turn 9,500-plus rpm with ease, and here’s how they do it

Stephen Kim Sep 23, 2011 0 Comment(s)
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Little Tricks

Judson Massingill: Oftentimes it’s a combination of lots of little tricks that help extend the rpm potential of an engine. For example, longer valves enable using taller valvesprings. Likewise, these days it’s common to run cupped pushrods in race motors. Instead of having a cupped section in the rocker arms, with cupped pushrods the ball portion is on the rocker arm and the end of the pushrod is cupped. This allows running much higher rocker arm ratios and spring pressures before everything binds up. Circle track racers were the first to experiment with cupped pushrods, and now they’re trickling over to drag motors as well. Interestingly, some factory FE Ford and Chrysler motors used cupped pushrods. Another trick we’ve learned from the NASCAR guys is building aluminum tubes with oiling jets into the valve covers that direct oil directly onto the valvesprings. This helps keep them cool and extends durability. Another benefit of this arrangement is that it allows running less oil to the top end of the motor. While we’re on the topic of springs, it’s worth mentioning that we’re no longer setting them up like we used to. In the past, we used to think that running them close to coil bind was a bad thing. Now we’ve learned that in motors that turn 9,300 rpm or more, regardless of what the spring pressure is, we set them up 0.060 inch from coil bind. This helps kill harmful valvetrain harmonics. CHP

Sources

Comp Cams
Memphis, TN 38118
800-999-0853
http://www.compcams.com
T&D Machine Products
Carson City, NV
775-884-2292
http://www.tdmach.com
School of Automotive Machinists
Houston, TX 77055
713-683-3817
samracing
Reher-Morrison
Arlington, TX
817-467-7171
www.rehermorrison.com

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