Go Fast Bits - Photos of the pulleys that shed weight for 2013

[Jlin]

In for the review and updates!

[soros151]

There is always one person...

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[Xdragonxb0i]

how hard would this be to install?

[FT-86 SpeedFactory]

Originally Posted by Xdragonxb0i

how hard would this be to install?

Pretty simple really. I wouldn't think more than 60 mins to get these installed.

[FirestormFRS]

Factory crank pulleys are not harmonic balancers. The rubber ring found in them is to quell vibration caused by the Vbelt.

There is no time in a modern factory to balance and engine to a specific crankshaft.

[FT-86 SpeedFactory]

Any other questions let us know. Thanks!

[breezy]

Originally Posted by FirestormFRS

Factory crank pulleys are not harmonic balancers. The rubber ring found in them is to quell vibration caused by the Vbelt.

There is no time in a modern factory to balance and engine to a specific crankshaft.

?? I wonder what these drillings on the stock pulley are then..?

The rubber ring is to absorb torsional vibrations from the crankshaft because your engine fires in a sequence of combustion events that create spikes in torque on the crank. It is not to "quell vibration caused by the Vbelt."

If they don't have time to balance the engine, they shouldn't be building engines. These are balanced at the factory, as evidenced by the drillings.

[FirestormFRS]

Originally Posted by breezy

?? I wonder what these drillings on the stock pulley are then..?

The rubber ring is to absorb torsional vibrations from the crankshaft because your engine fires in a sequence of combustion events that create spikes in torque on the crank. It is not to "quell vibration caused by the Vbelt."

If they don't have time to balance the engine, they shouldn't be building engines. These are balanced at the factory, as evidenced by the drillings.

You're wrong. The drillings are there solely for the purpose of balancing the pulley itself. Same as you would balance a tire on a car to stop vibration.

I've worked in engine manufacturing and assembly for years. You can take any FA20 pulley and stick it on any other FA20 engine. There will be no differance. They will all weigh within a couple of grams of each other. They are not balanced to the crankshaft they go on.

[soros151]

Originally Posted by breezy

?? I wonder what these drillings on the stock pulley are then..?

The rubber ring is to absorb torsional vibrations from the crankshaft because your engine fires in a sequence of combustion events that create spikes in torque on the crank. It is not to "quell vibration caused by the Vbelt."

If they don't have time to balance the engine, they shouldn't be building engines. These are balanced at the factory, as evidenced by the drillings.

Soooo If the pulley is damaged I need a new crank, and vice versa?

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[breezy]

Probably a tolerance on the balancing of each so they can be interchanged.

Am I the only one who sees the drillings? Do you think they're randomly placed?

Edit: Sorry, Firestrom, didn't see your post. I'll agree with you on that one.

[CircuitJerk]

I'm just gonna leave this here...
Should also explain why material has been removed from the stock pulley.
http://ft86speedfactory.com/go-fast-...y-kit-602.html

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.

[breezy]

That's a nice read from the vendor's website, and belongs in a thread that was started by the vendor to promote their product.

The last sentence begs the question: What defines "engines that do not rely on the balancer to any significant degree."? How is this determined? Was this determined for a car and engine that have been on the market for little more than half a year?

These are rhetorical questions. I don't expect an answer because I personally don't believe there is one (vendor can prove me wrong).

I appreciate the vendor developing products for this car. But car enthusiasts should be knowledgeable and need to be aware of the pros and cons. There's a customer for every product - people mod their cars according to what's important to them. For me, there are things I don't want to leave to chance.

[FT-86 SpeedFactory]

It's a great kit. We'll have a review up with video in the next couple weeks. :-)

[ScottDRFT]

Did you guys end up reviewing this? Thanks!