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This blue RR Racing Ultimate Damper Pulley replaces the stock Lexus cast iron crank pulley with a much lighter weight pulley that is harmonically dampened to absorb crankshaft vibrations. Not only does our new crank pulley free up power to the wheels through a significant reduction in rotational inertia, but it also fully dampens crankshaft vibrations in order not the compromise engine longevity.
Features of our Ultimate Damper Pulley include:
- Nearly 50% rotational weight savings on the crankshaft (see comparison photo below).
- Over 5X reduction in rotational inertia!
- Fully harmonically dampened using an internal inertia ring and 8 vibration absorbing elastomers.
- Aerospace grade 15-5 stainless steel inner hub capable of withstanding high loads (compatible with our supercharger applications).
- Billet 6061-T6 Aluminum outer shell for high strength and low rotational inertia.
- Less rotational inertial on the crankshaft makes for quicker downshift blips and improved throttle response.
- Approximately 0.2sec improvement in measured 20-68mph acceleration as proven by our in-house testing (see comparison chart below).
- Compatible with RR Racing Supercharger kits, designed to allow "bolt on" of our secondary SC drive pulley.
How much power will this pulley make?
This is a common question asked and the honest answer is that reducing weight on any engine component, brakes, driveshaft, or wheels DOES NOT "make power." Consequently, dyno testing lighter components will generally not yield a power improvement measurable on a dyno. The reason is twofold. First of all, dyno testing is typically conducted in higher gears and over a long segment of time, where the rate of acceleration is low. Reducing weight of rotational components improves acceleration primarily in lower gears, where the rate of acceleration is high. Secondly, most dynos, like our in-house DynoJet 424X utilize rotating drums that weigh over 2500lbs each! Therefore, even significant rotational weight savings at the engine or wheels are dwarfed by the rotational inertia required to spin the dyno drums. To use a similar example, we all know from experience that lightweight race wheels weighing 19lbs each clearly outperform 26lb stock wheels in the real world, however when measuring power on a dyno, wheel weight will not make a difference.
The effectiveness of rotational weight reduction depends on the rate of acceleration of the car. So, in lower gears, where the rate of acceleration is high, rotational weight savings is most effective, with greatest advantage in 1st gear, and progressively less in 2nd, 3rd, and 4th. Rotational weight savings at the engine (crank pulley, flywheel, etc.) is also more effective that weight savings at the wheels due to the fact that the engine rotates faster than wheels. Our acceleration testing results were conducted in 2nd gear, in order to rule out tire slip as a major test variable.
What is a "Harmonic Damper?"
Most modern engines today are internally balanced, but still retain a "harmonic balancer crank pulley." The OEM crank pulley on the ISF/RCF/GSF/IS500/LC500 is made from heavy cast iron and employs a rubber suspended ring. This ring plays an important role in reducing engine vibrations and improving the life of engine components. Rather than make a lightweight pulley that eliminates vibration dampening, our Ultimate Damper incorporates an internal inertia ring. This inertia ring design employs elastomers on the inside AND outside of an inertial ring, allowing for more effective damping of vibrations compared to OEM type crank pulleys with rubber damper only on the inside of an inertia ring. To put our Ultimate Damper to the test, we use it on our shop Supercharged ISF, currently making 730 horsepower at the wheels!
How did you conduct your performance testing to determine a 0.2sec improvement in 20-68mph time?
We conducted all testing in 2nd gear from a 20mph roll. Although the crank pulley will result in greater benefit in 1st gear, we wanted to eliminate tire slip as a variable, as we conducted testing on the street, not a prepped drag strip. Utilizing a Dragy performance meter, we conducted 4-5 warm up passes to warm up the tires and the engine, after which we found times to be very consistent. All testing was conducted on the same day, same ambient temperature of 85F, and on the same 75,000-mile RCF equipped with headers, exhaust, and tune. It took us approximate 45 minutes to install the pulley, so all testing with the upgraded pulley was conducted within 45min of the baseline OEM pulley test. We used the same road and same starting point for all testing.
Compatibility Table
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Make
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Model
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Year Range
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Lexus
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ISF
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ALL
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Lexus
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RCF
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ALL
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Lexus
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GSF
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ALL
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Lexus
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IS500
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ALL
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Lexus
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LC500
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ALL
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Aluminum Pulleys for RCF 
Amazing upgrade