I've heard stories of lighter crank pullies causing issues so be wary of that.Glad you have made some nice small mods they look good :)Only question is on the dyno chart what's the odd looking flat spot at 2500rpm?
Best Lightweight Pulley Kit for VW Golf GTI Mk5 2.0t 04-09: The Go Fast Bits Golf mk5 crank pulley-non underdriveGFB's lightweight non-underdrive crank pulley (part number 2012) is made from anodized aircraft-grade billet 6061-T6 aluminium and offers sharper throttle response and faster acceleration. Kit includes: crank pulley, 6 x bolts, 6 x washers (original factory belt is used).GFB pulleys are designed to improve acceleration by reducing the rotational mass (inertia) on the crankshaft. The effect is similar to a lighter flywheel, and the engine feels more lively and willing to rev. We know that people are sometimes concerned about possible adverse effects of lightweight pulleys, but rest assured we have done our homework! Whilst it is true that some engine types do suffer harmonic issues from lightweight pulleys, we steer clear of those. The kits we release are thoroughly application tested and do NOT cause engine damage in the short or long term.Our products are manufactured in Australia and the company is accredited to ISO 9001, which ensures our products meet stringent quality requirements at all stages of manufacture. GFB have Australia's best performance turbo management solutions. See more of our range at www.gfb.com.au.
There is a common misconception that the factory crank pulley is a harmonic balancer which is not the case. The Volkswagen/Audi TSI engine's rotating section is fully balanced from the factory prior to the accessory drive pulley being installed. Since our Rotamass Lightweight Crank Pulley is precision balanced by both design and manufacturing, it performs nearly identical to the factory part it replaces. With our test engine, we removed the crankshaft prior to the installation of the pulley, measured the bearings and crankshaft journals. During all of our testing there was absolutely zero signs of abnormal engine wear.
WHY NO HARMONIC BALANCER?A better name for a harmonic balancer would be "torsional dampener" since its main task is to absorb the rotational pulses inflicted on the crankshaft by the pistons. Most often it is incorporated into the crank pulley by attaching the outer belt drive ring to the inner by means of vulcanized rubber. At the right RPM, it is possible for a resonant frequency to be set up torsionally on the crankshaft. Resonant frequency occurs when the pulses of the engine correspond with the natural frequency of the crankshaft and it ancillary components. However, since factory pulleys are often comparatively heavy (reasons for this are described later) it is actually the large mass (and therefore inertia) of the factory harmonic balancer and flywheel that will help to excite this natural frequency. So by dramatically reducing the weight and inertia of the crank pulley, the natural frequency of the crankshaft is shifted and its ability to self-excite is greatly reduced. So in fact it is the harmonic balancer's own weight that necessitates the dampening, and since the weight of a GFB crank pulley is typically about 20% of the factory component it cannot supply an exciting force significant enough to damage the crankshaft.An opinion often expressed is "if the manufacturer put it there, it must be there for a reason". However, if you look at it from the car manufacturer's point of view, casting pulleys from steel is very cheap and easy, because they can be produced in large numbers and there is no waste (as opposed to machining them from billet). But because the resulting pulley weighs significantly more than one made from aluminium alloy, it requires dampening.Manufacturers will always build cars (even high performance cars) to suit the widest possible selection of driving scenarios and drivers, which means there are always compromises. The weight of the flywheel and pulley also affect how fast the revs drop between gear shifts, and a production car is designed to only allow the revs to drop fast enough for average shifts. If you hurry the shift the revs will be too high for the next gear, resulting in a sharp jerk as the momentum of the engine transmits through the drivetrain. Reducing the engines' inertia with a lightweight pulley kit allows faster and smoother shifting.When looking at high performance engines such as those found in Honda VTEC equipped cars and the S2000, it is obvious that manufacturers do understand the benefits of reducing engine inertia, and have utilized lightweight pulleys to help the power output and responsiveness without the use of a harmonic balancer.However, this is not the case for all engines, many of them do require the use of the harmonic balancer to prevent failure. Skylines with the RB20, 25 and 26 are a good example of this, which is why we don't make a pulley kit for them. The pulley kits we do make are for engines that do not rely on the balancer to any significant degree.
Nice results!
Good progress, nice upgrades :)I think OEM engine pulley is better TBH. I have read a lot of issues with lightened ones.
Great pics man
