Despite being a fairly robust motor, K-Series engines have been found to have weak timing chain tensioners that fall victim to excessive wear when aftermarket cams are installed in the motor (and in some instances with stock cams). The fast ramp rate of aftermarket cams is the main cause of this. Unfortunately, without tearing the motor down after every use, it's almost impossible to detect a worn tensioner before it's too late. While installing a stiffer spring in an OEM tensioner, like other companies do, will slow down the wear of an OEM style tensioner, it will not eliminate it. The use of a stiffer spring will also cause the timing chain to stretch faster. For this reason, we designed our chain tensioner from scratch, ensuring it could take the abuse aftermarket cams cause without causing faster than normal stretching of the chain.
The Hybrid Racing Chain Tensioner is designed to be both stronger and more durable than the OEM Honda chain tensioner found on K Series motors. It is perfect for anyone who wants some added protection for their valuable motor.
The tensioner functions exactly like the OEM unit it replaces while improving upon the flaws of Honda's design. The dual-ratchet design features hardened tool steel teeth that mesh with a heat treated chromoly piston. The teeth are crafted from the same material used for most the ratchets in high-end impact wrenches. The piston is designed to fit into the K series engine's timing chain guide tighter than the OEM unit does; this helps to avoid misalignment of the ratcheting mechanism and the premature wear that often occurs when aftermarket cams are used in conjunction with the OEM K-Series chain tensioner. In addition, the internal oil passageways have been optimized to respond to oil pressure increase faster than the OEM unit; this becomes critical in motors that rev quickly and to high rpms.
Each Hybrid Racing K-Series Chain Tensioner is manufactured from scratch. It is not a rebuilt and rebranded OEM tensioner like those sold by other companies. The Hybrid Racing chain tensioner comes with reliability that has been proven through more than a year of the most abusive testing.
The stock tensioner can allow the teeth to skip.
Timing chain tensioners are simple but important. Take Honda's K-series, for example. As the engine rotates clockwise, the crankshaft keeps the intake side of the chain tight
simply because of the direction the chain's being pulled, but it's the tensioner's job to do so for the exhaust side. Without it, the cams would start spinning but ultimately just sit there doing nothing as the chain slips and bounces around. Spin far enough out of sync and watch expensive pieces like valves and pistons start to touch one another. Ouch.
How They Work : K-series tensioners aren't terribly complex and, simply put, do little more than push a small piston back and forth against the engine's timing chain guide, keeping the chain tight. They do so hydraulically-not unlike older H22A tensioners-which means K-series tensioners operate by way of oil pressure, but they also incorporate a small, internal spring for mechanical purposes. At low engine speeds, when oil pressure is low, the tensioner's internal spring mechanically moves its piston toward the timing chain guide, reducing chain slack on the chain's exhaust side. As engine speed and oil pressure rise, the spring relaxes and oil pressurizes the tensioner's chamber, hydraulically pushing its piston toward the chain's guide. A check valve ensures the oil doesn't escape prematurely and a release valve lets it out when the tensioner's done, well, tensioning things. Additionally, a ratcheting mechanism and teeth built into the piston ensure that it doesn't retract too far back into its housing and loosen up the chain. Sounds like Honda has it all figured out.
The Problem Unfortunately, Honda's internal tensioner spring doesn't always work as you'd expect, and excess tensioner piston travel (more than 0.25-inch) and timing chain slack when oil pressure is low is common-especially while cranking and at low engine speeds when the spring is doing all the work. The results can cause the piston teeth to slam against the tensioner's ratchet, ultimately grinding their tips off, rendering them ineffective. You see, by design, K-series exhaust valves close rapidly. Each time they slam shut, the chain builds slack. And each time they slam shut, the tensioner's piston bashes against its ratcheting mechanism. Aftermarket cams with aggressive profiles and stiffer valve springs only pronounce this. It should be noted that although dealership technicians have reported worn tensioner pistons on otherwise stock engines, it's more likely once camshafts and springs have been swapped. Steeper exhaust closing ramps and stiffer valve springs that close the valves even quicker are to blame. Of course, none of this is good since the ratchet and piston teeth are the only things that prevent the piston from being pushed in too far. All of this can lead to a loose chain, a failed safety mechanism, and engine damage, even on unmodified engines. Worst of all, you'll never know any of this is happening until it's too late since you can't readily monitor the tensioner and, even if you could, all of this happens way to quickly.
The Solution The simplest and least expensive fix is to add a click to the tensioner by manually moving its piston one tooth closer toward the chain. This method reduces how far the piston can retract back into the tensioner housing, but it doesn't solve the overall problem or make the ratchet and piston teeth any stronger. Adding a click is easy but it isn't a permanent solution.
Stiffer tensioner springs have also been experimented with by various companies, but this doesn't address the weak ratchet and piston teeth issue. What it does do is resist
excessive piston movement and bashing at start-up and during low oil pressure situations, though, which is, after all, the reason the ratchet and piston teeth get damaged to begin with.
TODA, Hybrid Racing, and Skunk2 offer more comprehensive solutions. These companies' tensioners are based off of Honda's design but are machined from scratch. All use stiffer internal springs that prevent the exhaust camshaft from slamming shut at low engine speeds by eliminating chain slack, even under low oil pressure conditions where the factory spring is typically compromised. They also address the tensioner's piston and safety mechanism. Hybrid Racing's Timing Chain Tensioner's piston
features teeth on both sides for even load distribution, while TODA and Skunk2's Pro Series Timing Chain Tensioner features taller teeth that, even when filed down or damaged, are deep enough to engage its ratchet. Skunk2's tensioner's piston is also 1.5mm larger than the OEM one and features a larger ratcheting mechanism. Both tensioners also feature provisions to fit tightly against the timing chain guide to ensure against rotational movement, which can exert uneven load against the ratcheting teeth. Even the factory-designed oil passages and check valves are retained, which means both tensioners remain lubricated and pressurized just as Honda intended.
Aftermarket tensioners and heavy duty timing chains are just as important with cams as having the engine properly tuned. Without them engine failure isn't just a possibility...it's just a matter of time. The oil system is also to be looked at especially if you have good springs and retainers meaning your going to be able to run your car at 9000 rpm all year long.
After an install there should be absolutely no noise from the tensioner or the timing chain.