Hol´ dir ein Pulleykit
, da merkt man mehr als ein Kat-Ersatz.
http://www.gofastbits.com.au/pulley.htm
http://www.gofastbits.com.au/amazing.htm
Clubpreise im Members-Bereich.
---- Hier Infos aus der engl. FAQ ----
Pulley Kits - Is there a dyno graph of the Pulley Kit on the WRX?
Yes, we tested an MY97 WRX on the dyno with and without the kit, and you can see that the chart shows large gains at the bottom and the top of the rev range. The reduction in rotating inertia (we've removed about 2kg by using 6061 T6 aluminium) means that the engine can accelerate much quicker during the times it is making very little power before the turbo spools up. The result is better driveability off-boost and better acceleration, which is especially useful for those with large turbos that only make power in the upper rev range. The smaller size of the crank pulley under-drives the power robbing accessories so that the upper end of the rev range is less burdened, while still allowing them to operate properly.
Do I need different belts for the pulley kit?
Yes, however the required belts for the WRX kits are included. All other kits list the correct sizes required.
When using a GFB Power Up Pulley Kit, is there any problem with the removal of the harmonic balancer?
Since the crank pulley in our Power-Up Pulley Kit replaces the factory harmonic balancer, people often express concern for the effect that this will have. It is important to understand the task of a harmonic balancer and why they are fitted to explain the effects of fitting a lightweight pulley.
What is a 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.
Isn't there a loss of torque associated with fitting lightweight pulleys, since the flywheel effect is lost?
Quite the opposite in fact. In early days it was common to fit large heavy flywheels to increase torque, which to a certain extent does work, but it is important to look at the context of the application. A heavy weight acting as a flywheel on the crankshaft has a greater resistance to a change in rotational velocity, which is termed inertia. The term "resitance to change in rotational velocity" applies to both acceleration and deceleration, so a heavy flywheel or pulley does oppose deceleration in situations such as towing caravans up a hill, but it will also oppose fast acceleration.
It is easiest to think of inertia as an energy reservoir, and the laws of physics state that you can only get out the same amount of energy as you put in (actually in the real world it is often less). So an engine needs to put in a significant amount of energy to accelerate a heavy pulley before any useful torque can be extracted from it. Don't forget that when the engine is at low RPM before the turbo spools up, it is only making about 20% of its maximum power, and in this situation the amount of energy required to accelerate the pulley becomes a large percentage of the available power.
Are there any problems associated with under driving the alternator and power steering pump when using a Power-up Pulley Kit?
No, the ratios are only reduced by about 15%, meaning that you get full charge at 1000 RPM instead of 850 RPM which will only cause problems if you plan to drive your car at idle with the fan, high beams, air conditioning, rear demister and stereo full blast.
This is the reason for under driving, since from the factory the accessories (alternator, A/C, power steering) are designed to run 100% at idle, so at high RPM they are causing excessive and unnecessary drag. Reducing the drive ratio by 15% doesn't have a large impact at idle, but at say 6000 RPM, 15% becomes a much larger proportion and the reduction in drag is much more noticeable.
Einbauhilfe und Erfahrungsbericht bald vom GT und WRX !
MfG
2-bias
Dienstag, 7. Mai 2024, 09:48
Zum Seitenanfang
du mit deinem pulley 
