Crane Cams, Daytona Beach, Florida, had an impressive display at the SEMA show. Chase Knight, valve train product manager, provided some interesting information about their racing cam shaft developments using the Spintron valve train testing machine. A development from special camshaft lift curves and testing is launching the cam lifter off the cam lobe at high engine RPM in a controlled manner for increased lift.
Roller Tappet Trick Camshafts
Valve lift increases of 0.100 inches over the mechanical lift range that now exceeds 1 inch is typical of racing roller cams. Most high output racing engines seem to make more and more power with more and more valve lift. Chase reported that Crane camshafts for the drag racing Pro Stock application make a lot of power with around 270 deg. intake duration. He further advised that the Pro Stock engines make great power with a short intake duration such as that as a result of having a really efficient cylinder head.
Flat Tappet Trick Camshafts
Chase advised that valve lift increases of 0.050 inches over the mechanical lift range are typical of racing flat tappet camshafts in drag racing Stock Eliminator. In these classes of racing, sanctioning organization rules customarily limit camshafts to OEM stock camshaft lift specifications. Launching the lifter off the lobe is one method to get more flow. It should be noted that record setting stock eliminator engines do not have limits to cam shaft duration. Increases in camshaft duration are one of the tuning tricks to building more horsepower in Stock Eliminator racing engines. OEM horsepower ratings in the mid 300 HP range are typically boosted to over 500 HP in these engines with well designed camshaft technology such as reported. It is amazing that HP boost is with a ‘quote’ stock lift camshaft though.
Technology, Technology, Technology
In both applications, the lifter is launched at high RPM in a controlled manner with a carefully designed and tested camshaft lobe profile. High level mathematical calculus is necessary to determine the camshaft lobe profiles to do this feat without destroying the valve train. Chase said the real challenge is the determination of where the lifter comes back to contact the camshaft lobe without damage. That is the technological achievement.
I am now daydreaming about a maximum effort mechanical fuel injection racing engine with a combination of a flatlining fuel curve together with a high lift camshaft that launches off the lobe. Wow, would that be powerful! How about using some nitro!! How about a lot of nitro!!!