So let's finally set it straight with aftermarket crank pulleys...
 

OK guys. Ive read and read and read about aftermarket crank pulleys. I need more insight...

I was thinking about replacing my stock crank pulley. I just wanted to replace the CRANK pulley, not the alternator or others. I wanted to replace it with a LIGHTENED AND NOT UNDERDRIVEN PULLEY too. Im not interested in multiple pulley sets or smaller pulleys. JUST a lightened stock-sized pulley.

I know the 4G63 is not the same as my old EJ20. There are plenty the differences. When I replaced the stock crank pulley on the EJ20, I did notice a difference. The car seemed smoother among acceleration and it may have freed up just a few whp. Once again, this was not a pulley set. This was just one pulley. It was the same size as the stock crank pulley but just lighter.

My question: Would a lightened crank pulley (no pulley sets or smaller sized crap) really have negative effects to my engine? Would it only harm it and not provide any positive gains at all? If it does harm it and is strongly not recommended, why is that so and how does it harm it?

Insights from David, Al, and Warr would be appreciated too. Thanks!!!

since you've read and read about them i'm assuming you've read the links that i've posted repeatedly about the crank shaft twang that is not damped by aftermarket crank pullies.

So this damped would not produce results or will it hurt your engine? Expand please. What exactly is it and what will it cause?

What I do know is that OEM Crank pulleys come dampened to absorb vibrations. When you go buy a cheap aluminum pulley with no dampening, where does the motor vibration go at 7000 rpm. You guess it your bearings, therefore cutting the life in half some times less sometimes throwing a rod. If you go buy a aftermarket pulley get one that that has dampening, like Fluidampr or ATI. You will get people on here who say I have had my pulley for this amount of time and no problems. Well some people get lucky.

Ahhh makes sense. Anyone else got insight (Warr/Al/David?)?

These guys aren't feeding you bull. I wouldn't mess with the crank pulley.

Thanks Warr. Always appreciated...

DSM's were the same exact way. Search the dsm forums and you will find out that most of those guys have found out the hard way when using lightened crank pulleys. Considering that it will not make a much a difference in hp I would leave it alone. You will destroy the motor so I recommend not usiing on a stock motor unless it is completely rebuilt including balanced and blueprinted.

Makes sense...

did you even read the link that i posted? it has the exact article in there... it's basically crank shaft twang.

I have had on one for over 2 years, 10WHP across the board and faster spool and more torque.

So people, we know an undriven is bad, but what about a lightened pulley that is the same size as the stocker?

I dont beleive that anthing that is held to the crank with 4 standard bolts is going to absorb enough vibration to make any differance at all. If there is enough force in the engine to twist the crank how the hell is that going to get absorb through the crank pulley? I have a Perrin crank Pulley and have felt a increase in throttle responce and acceleration. I copied this from UR website...they are one of the top producers"

4) "Is my crank pulley a harmonic/torsional/vibration damper or a harmonic balancer?"
People are getting their crank pulleys confused with the harmonic dampers found on some V6 / V8 engines. "Harmonic Balancer" is a term used loosely in the automotive industry. Technically, this type of device does not exist. The "balancer" part comes from engines that are externally balanced and have a counterweight cast into the damper, hence the merging of the two terms. None of the applications we offer use a counterweight as part of the pulley, as these engines are all internally balanced.

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.

Again, there is a lot of internet hearsay about crank pulleys. When engine problems occur, too often people are quick to blame the pulley first, rather than taking the time to look logically into why there was a problem. We hope that after reading this you will understand the crank pulleys better.

6) "Will these pulleys cause premature engine bearing wear?"
This is a fear many prospective owners have and is a valid concern since we are dealing directly with the rotating assembly. Fortunately it is another urban myth with no basis in fact. The fact is our pulleys have the opposite effect on engine bearings. The combination of tight tolerances, precise quality control, perfect balance, and dramatic weight loss versus the stock pulleys reduces stress loads on your engine, extending the service life of your engine. Engine bearing problems are purely associated to poor engine maintenance, use of heavier than factory recommended oils, improper engine building practices (which includes poor balancing), excessively revving of engines when they are cold, and owners expecting their factory oil pumps to handle engine power outputs beyond 3, 4, even 5+ times the stock power levels

Great info. Thx. I may start a new thread with your info soon