94eg!

The crank pulley (#14) is on the front of your engine (passengers side down low). It turns the belts that drive your alternator, power-steering, and air conditioning. The one that comes on your car has a rubber damper built into it to help control the resonant frequencies of the crankshaft (#8) at certain engine speeds...

fant0m_TL

wow... diagram and everything... thanks a lot! I really appreciate it!


so what good is it to get an aftermarket pulley?

94eg!

A lighter "under-drive" pulley = less rotating mass for slightly faster engine acceleration and deceleration. Also the belt grooves are a smaller diameter which spins the accessories slower resulting in less power loss by driving them. The problem is that the after-market pulley is simply solid aluminum which eliminates the OEM harmonic damper (which apparently is still a point of debate). Some believe removing this damper can lead to premature engine failure, and some don't. I just cannot imagine why the OEM would put it there if they didn't feel it was important. Apparently some people think the damper is simply put there to reduce NVH, but I've NEVER heard that before in my life...

The fact is you could achieve the exact same effects of an under-drive pulley with different parts (light flywheel & larger pulleys on the accessories themselves) without sacrificing the OEM balancer. The problem is this is much more expensive.

Also some aftermarket companies make under-drive crank pulleys WITH a harmonic damper (like Fluidampr), but applications are limited and they are also more expensive (mostly used for high rpm racing engines)...

PS: You can look up any parts diagrams at AcuraOEMParts.com in the "parts" section...

fant0m_TL

thanks again man!

Kennedy

iTrader: (2)

I still fail to see how a lightweight flywheel is any safer. The weighted pulley is design to counteract the harmonics of the engine witht he stock flywheel. Changing that to a light one throws the whole design out of balance.

I still alledge they're safe becasue there's not one 2nd gen on the forums that has had an engine failure due to these...

94eg!

Thats because you keep thinking that the pulley somehow "balances" things. It doesn't BALANCE anything, it simply controls the springing back-n-forth twist of the crank via a weighted ring that is connected by a flexible rubber isolator. The crank is in no way balanced from end to end. If this was necessary, there would be a noticeable difference in engine vibration with the clutch pressed in vs let out. When you engage the clutch, the engines main rotating assembly grows by the length of the transmission's main-shaft. And as you rifle through the gears, the weight of the main-shaft is repeatedly altered (as you go from smaller to larger gears & vice-versa)...

This is why the article I posted previously stated that it is in error to refer to the crank damper a Harmonic Balance since it doesn't actually balance anything at all...

The balancing of the engine is done via the crankshafts counterweights only. And this is set to match the mass of the pistons and rods (not the flywheel)...

blokhead

I had a nice long written response to this, but you seem to have it in your head that it will destroy your engine. I suggest you don't install one.

Excelerate

iTrader: (1)

And yes you feel a small rubber ring will absorb torsional vibrations? There is no provision in the stock crank pulley to dampen crank harmonics.

Here is info from UR's FAQ also:

The pulleys on most of the new import and smaller domestic engines have an elastomer (rubber ring) incorporated into the pulley that makes them look similar to a harmonic damper. The elastomer in the OEM pulley serves as an isolator, which is there to suppress natural vibration and noise from the engine itself, the A/C compressor, P/S pump, and alternator. This is what the manufacturers call NVH (Noise Vibration & Harshness) when referring to noticeable noise and vibration in the passenger compartment. It is important to note in these applications, the elastomer is inadequate in size and durability to act as an effective torsional damper. If you look at the pulleys on some imports there is no rubber to be found at all. We have samples of these, mostly from Acura/Honda, the Nissan Altima, 1.8L Eclipse, 2.3L Fords, Chrysler 2.2L's, and 1.8L VW's, to mention a few. This is not to say with our pulleys you will hear a ton of noise or feel more vibration from your engine compartment. Most owners who have installed our pulleys notice the engine actually feels smoother. This is result of replacing the heavy crank pulley with our crank pulley. NVH is variable and unique to every car. NVH will increase with the installation of an aftermarket intake and/or exhaust, for example. Think of OEM intake systems in newer cars, they use baffles and resonators in the intake to quiet all the intake noise. Aftermarket intakes eliminate these resonators and create dramatic increases in engine noise from the throttle opening and closing. So to most tuners, certain types of NVH can make the driving experience more enjoyable.

The purpose of a traditional harmonic damper is to protect against crank failure from torsional movement. This is not necessary in most modern engines because of the many advances in engine design and materials. Factors such as stroke length, displacement, inline, V configurations, piston dwell time, piston pin off-set, power output, etc., do determine when and how these harmonics and torsional movements occur.

bigmoetl1

I dont have any vibration and I have the stock size ur pulley the car pulls hard too