Uncontrolled torsional vibration can accelerate wear of the main bearings, cause inefficient timing, fracture accessory brackets and worst case, cause the crankshaft to snap – Brian LeBarron
We’ve been testing some of the most common changes you can make in common crate engine racing classes by pitting our own CT-350 through a series of tests on our DynoJet chassis dyno. Now, we’re looking to take the engine to the next level and upgrade the engine to the full advantage of the rules. This means valvetrain upgrades, and some new exhaust, but we’re looking to push the engine beyond even that. Chevy Performance strongly suggests to not race the engine above 5,500 RPM – we’ll be looking to rev to somewhere close to 6,500 RPM.
This will require some key upgrades in the top end of the engine, but we wanted to ensure the force from the hundreds of thousands of explosions exerted on the crankshaft would be controlled properly. After talking with our friends Fluidampr about the project idea, we knew having a damper designed to handle the upgrades would be important as well.
Fluidampr’s CT Gold
At first glance, their CT-Gold series viscous damper (part#62260D) would seem like just another damper on the market, but the CT-Gold damper is specifically designed for race engines to control torsional vibrations above 6,000 RPM. “What we’ve found is that as horsepower rises, the need for a Fluidampr CT Gold is even more important,” explained Brian Lebarron of Fluidampr.
Chevy Performance ships the CT-350 with an elastomer style damper. By design, it is tuned for the stock setup and stock peak torsional vibration frequency range. When you start to modify the engine, two scenarios will typically happen:
1) The torsional vibration frequency range still falls within the limits of the stock damper, but now it is being overworked. With this scenario, early warning elastomer failure signs are cracked, bulging or missing rubber between the hub and the outer inertia ring. As it starts to fail it loses its ability to protect the engine and contributes to inefficient timing.
Does Weight Really Matter?
It’s easy to think, that because the damper is rotating mass on the engine, the you would want to seek out the lightest damper that would fit your engine. This is the correct logic for pulleys, and wheels in most cases, but not dampers. A damper needs a given amount of mass to counter the destructive force of torsional vibration. If the damper is too light it does not adequately protect the engine from torsional vibration. Excessive torsional vibration also means lost horsepower and torque.
Size on the other hand does matter, and having a smaller diameter damper usually does translate to quicker throttle response. The stock damper on the 602 is 8-inches in diameter. The Fluidampr CT-Gold on the 602 offers broader torsional vibration protection at only 6-1/4-inches.
None of those choices sounded all that great to us. On the other hand, Fluidampr is a viscous damper designed for performance applications. Fluidampr features a steel housing with an internal inertia ring that shears through highly durable, specialized silicone, and the unique design of it allows it to cover a much broader range of torsional vibration with no setup or maintenance required. With a Fluidampr you can make modifications to the engine and not worry. The only time during the life of the engine a Fluidampr will need to be replaced, is if the housing is damaged or you lose the press fit tolerance from repeated removal/installation.
Why This Matters For Racing
A Fluidampr CT Gold damper helps protect the engine from destructive torsional vibration, which is the twisting & rebounding of the crankshaft generated by internal combustion. “Uncontrolled torsional vibration can accelerate wear of the main bearings, cause inefficient timing, fracture accessory brackets and worst case, cause the crankshaft to snap,” Said LeBarron.
In our class of racing, our engine will see RPM flux between about 3,000 RPM to about 6,500 RPM. The vibration frequency of the engine, even a relativity mild combination like ours, changes throughout the power band. The CT-Gold is designed to work efficiently at any RPM.
Compared to swapping the camshaft, valves, lifters, and valve springs, the install of the CT-Gold is extremely simple. We already had the stock damper off of the engine, to gain access to the timing chain and camshaft so we choose to install the new Fluidampr while reassembling the engine while it was out of the car.
Using an OEM Harmonic Balancer Installer kit, we lubed up the snout on the crankshaft and slid the Fluidampr. With the matching grove machined into the center of the CT-Gold, it’s honesty extremely difficult to mess this install up when it comes to putting it on wrong. Just make sure that the flat side of the damper is facing you. Fluidampr says to continue to press the CT-Gold onto the crankshaft until it is fully seated. If resistance increases dramatically at any time, pull the damper off and try again – something is wrong. It should require a consistent amount of force to install.
Up Next For Our Crate
Now with the added protection of the Fluidampr CT-Gold, we’re ready to hit the Dynojet again with our CT-350 and continue testing some of the most common upgrades for getting the most from your crate engine. Up next, we’ll complete our valvetrain swap testing and dyno results, stay tuned!