JoeR

Shoot, Maven, I've got more than 1 post over there!!

And JoeR ain't my screen name there, either!

BTW, folks, this guy knows his stuff and is a valuable contributor to CobaltSS.net.

The Curly 1

Pardon my ignorance but I still do not see where it is dampened. The MRZ site shows the stock one and it appears that it is a steel pulley only. I could not get the picture on here but here is the link.
http://mrzperformance.vstore.ca/prod...roducts_id/144
Am I missing something but it sure looks like an undamened pulley. While I completely agree if the factory uses a damper then definatly do not go with out one.
I also agree that the lighter weight will not make much of a difference in the big picture. Underdrive would only help if there is a lot of accesories on there and overdrive would only help with a Supercharger. For a supercharger I would not change the crank pulley anyway, if you wanted to change it change the one on the SS.

masterchief1112

couldnt you just use the damper off the stock crank on the new crank

tireman1554

Save up your money and buy a flux capacitor instead.

Maven

Thanks. JoeR only has one post over there.

See how the inner portion of the stock pulley looks different than the outer? and theres a line about a half inch in from the outside edge? that line is the damping material, and the smoother looking inner portion is the additional mass that is needed/vibes get transfered to.
The crank pulley IS the damper. cant seperate them

IgottaWoody

If you want to lighten up rotating mass AND gain hp/milage and NOT worry about tearing anything up....just look to the rear of the crank and whats hanging there..Stock overweight clutch or tq converter.There are pieces out there that are lighter/stronger and in the case of converters, much more efficient though costly to install.Plus I'm sure theres a way to do a 2nd thru 4th gear lockup on the converter so it acts more like a clutch.Ever wonder wht the 5spd gets a bit better milage? Direct drive, no slippage.

More_Torque_More_HP

Thanks Maven, Your description is absolutely correct.

It would be less expensive for production if the dampening was not necessary. GM would have eliminated it to same money. The dampening is put there for a reason, Crankshaft life.

-md- HHR

Maven I half agree and disagree. Gm sells an un-damped billet pulley for the ecotecs. Ecotec Billet Crankshaft Pulley GM part number 88958631. That is the pulley that was used on most all of the drag Ecotecs, and is in a lot of the GM build books.


I agree that a lightweight pulley will NOT result in a smoother idle. However, I have not seen a more erratic idle, and never heard of anyone else I have came across.


Lightweight pulleys do help performance. Less rotational mass...is less rotational mass. It takes less energy to move something that is lighter. You can not argue physics. During acceleration less rotational mass helps you get down the track faster. Ever put lightweight racing rims and tires on the car and go down the 1/4 mile compared to heavy 17's or 18's. I guess lightweight flywheels and pressure plates do nothing either. Every little bits helps doesn't it.


Will a un-damped pulley add more stress to the motor. Yes, but I and others believe it is not enough to effect or cause major problems. Our stock crank pulleys are no where close to balanced. Most CNC machined pulleys are VERY balanced, and normally do not require any additional balancing. Have you ever spun a stock crank pulley at 7,000 RPMS it wobbles and vibrates like crazy. Where a balanced CNC pulley doesn't even quiver.


I highly recommend getting a new crank pulley bolt. Since the stock bolt is torqued to yield. Some ecotec owners, while installing new pulleys, are not doing this, and the crank pulleys are working there way loose. Cobalt addition just had this problem with a customer.


Also, the oil pump is driven off the flats on the crank pulley snout. Extreme care needs to be taking to ensure the pulley is properly aligned and seated properly inside the pump gear.


Also, GM wants the motors to be as quite and have the least vibrations so Joe Smo has a nice quite comfy ride. While people doing performance mods normally do not care if comfort is lost in the pursuit of performance.

"Snake oil pulleys."

masterchief1112

very well said MD

More_Torque_More_HP

If you want 5 to 10 HP put the GM Performance Parts neutral balance shafts in. Keep the damper.

Billet dampers are used in some of our higher HP Ecotec engines, however they are almost always steel crank engines. Not a cast crank like in the 2.2L engine.