Hybrid Racing's Honda K-Series Timing Chain Tensioner - Good Tension, Bad Tension?

All in all, the factory K-Series tensioner is a clever piece of engineering, and to be fair to Honda there is nothing inherently wrong with its design when used as intended on a stock K-Series engine. According to Russ Garehan from Hybrid Racing, "We have not been able to find any cases of chain tensioner failure on a well maintained, unmodified engine. The tensioners are only failing when they are subjected to forces greater than they were designed for, such as those created by the more aggressive profile of aftermarket cams and higher spring rates of aftermarket valve springs. These higher loads wear out the teeth on the ratcheting mechanism used on the tensioner. If the teeth wear out enough, the piston can be pushed into the tensioner far enough to allow slack in the chain, which can result in skipped teeth on the cam gears and potential damage to the motor."

But that's not the only issue Hybrid Racing found with the OEM tensioner. According to Russ, "The only thing that prevents the piston from rotating or spinning in the tensioner is the groove in the chain guide that the tensioner piston fits into."

To address these two main concerns, Hybrid Racing first turned its attention to the design of the tensioner piston and the ratcheting mechanism. The piston was redesigned to make it press into the chain guide in order to minimize any rotation.

This prevents any misalignment of the teeth on the piston and ratcheting mechanism, which in theory should greatly reduce the wear on the teeth themselves. However, to further safeguard against teeth wear given the higher forces the tensioner must endure when aftermarket cams and valve springs are in use, Hybrid Racing added a second ratcheting mechanism to their tensioner, as shown in the design drawing.

Hybrid Racing's tensioner not only looks pretty, it's made with tighter tolerances and from higher-grade materials than the OEM unit, providing the strength and durability required when running aggressive aftermarket camshafts.

Hybrid Racing's tensioner not only looks pretty, it's made with tighter tolerances and fro

The last and arguably most important part of the design stage for Hybrid Racing was the selection of materials for its tensioner and in particular the wear-prone ratcheting mechanism. The body of the tensioner is a special, wear resistant, super-tough stainless steel alloy and without giving away any trade secrets, Hybrid went with an extremely robust alloy for its ratcheting mechanisms, similar to those found in the ratcheting mechanisms on impact wrenches. "Developing this tensioner and sourcing the parts for it has been a tremendous undertaking. Every part has been custom manufactured to our specs. Even the springs it uses had to be custom-wound to suit our application."

After more than a year of rigorous, abusive testing, Hybrid Racing has made its tensioner available to the public. Considering the tensioner's tighter tolerances, higher-grade materials and double ratcheting system, this certainly appears to be a product capable of putting all tensioner concerns to rest for anyone running a modified K-Series under their hood.