whats everyones views on running a lighter crank pulley with FI ive been thinking about this for a while and now with zivmans recent post it really has me scared and im not sure it provides that big of a difference. does it cause more harm then good?

would like some more insight on the subject.

 

If you feel you must run a Fluid Dampner

 

I said it in Zivman's thread, I don't think it is worth the risk of finding out, the stock one is not that heavy and I didn't really notice much when I had it NA or with initial FI install so when I built the engine I used the stock one.

 

said it from the start. the dampeners from the factory are tuned to the harmonics of the motors firing order (at a certain rpm) to dampen the twisting force put onto the crankshaft. everytime a piston fires it creates a huge spike in force on the crank, the crank will twist, thus the snap back into straight is the force that needs to be dampened. imagine having your suspension springs with no shocks. the oscillations are what needs to be dampened. metal has a fatigue life. the oscillations will fatigue the strength on the metal. thats the reason for them.
in my opinion, on a stock motor, you may be able to get away with it, but f/i will give a higher spike when the charge fires, so the oscillation will be amplified. safer ways to gain a few seat of the pants hp than that on a daily driven motor.
that being said, and repeating what miaplaya said, fluid damper should be an upgrade in viscous material to handle the vibration better. but not looked at or tested myself for this motor.

 

^^^
This is very true. The dampener is on the A/C part of the pulley which is in fact floating from my findings after machining a stock pulley apart.

I think it all comes down to how much you want to get out of your engine life wise, what RPM your redline is at and how much power you are going to put to the ground.

There are a number of people such as Going Deep I believe who have put down over 400whp with solid pullies from companies like unorthodox. However, I can't tell you how many miles they drive their car.

I am currently having Unorthodox make me a one-off pulley for my supercharger kit (since I don't have time to finish the one I was making) and since I don't drive my car that much it doesn't really bother me if it never makes it to 20,000 miles because that will take me ten years to drive that much.

 

Everything made it to my shop to finally begin the build next week. I have the UR pulley on my old motor ready to swap over but now I'm not so sure. It doesn't sound like it's worth the risk.

 

I have had the UR Underdrive Lightened Crank pulley for a few months now and no probs at all!!!

 

I talked to couple famous tuner guys and they said it wouldn't be a problem though?

 

The fluidampr crank pulley doesn't look like it's lightened nor underdrives.

It was my thought that since I had no issues, don't worry about it. Now, here I sit, with 13.5K miles on my motor when it was tore down and found a bad crank, among other issues. My engine shop is certain it was the crank pulley that did my crank in.

Let me just say, that if you get to a point that you do have problems, your crank will most likely be in more than one piece, you will spin a bearing, oil pump failure or something fairly severe.

If you are boosted, it isn't worth the risk. Running the motor as hard as it is with the boost and such, a crank pulley isn't really needed.

This experience has opened my eyes in more than one way

 

My bad.. I dont have the Fluidampr.. I have this one..... SGP installed while doing the build....

http://sgpracing-store.stores.yahoo.net/urunpuw35.html

 

that is the exact one I had. definitely not worth the risk. Like I said, my situation it wasn't a huge deal, but imagine if it takes out your oil pump or splits your crank in two under load?!?!?!

 

Well, i dont know what to tell ya.. How long did you have it on?? I couldnt put the stock one on if i wanted to.. Its prob trashed..

 

about 10-12K miles

 

is anyone runnign the fluiddampr pulley?

 

you already drop so much weight off the rotating assembly when you go from a stock clutch and flywheel to a nice twin disk. that weight is also further out and more effective to remove. changing out the crank pulley for a lighter one, when its already so small of diameter to begin with is negligible... waste of money and risk when you wont even see/notice the difference.

 

complete and utter waste of time and money - not even taking into account the possible damage that some people say they may cause. if you want another 2 hp turn your boost up another .1 psi...

 

+1. Not worth it IMHO.

 

Anyone have a OEM crank pulley laying around for me??

 

I ran a UR CP for 30K miles NA no issues. When doing my build I wouldnt risk dammaging my block for a measly few whp, stocker is on and I dont regret it. Its silly to run then on built motors IMO...

 

i cant find mine either.. i wonder how much a new stock one is? and are they different from revup to non revup models? maybe i can find a used one