Underdrive or lightweight crank pulley

[svxash]

So I need to replace the front pulley on my SVX. Motorsport warehouse has both the lightweight stock sized pulley and the under drive pulley. Which is the better way to go or should I just get a stock one?

[fasteract7]

With the stock pulley you keep your drive belt size and have an alternator that still produces the same volts...

[Cotton]

I bought this and intend on putting it in come Spring time. I have new belts that were put on in July.

http://www.ebay.com/itm/152097548233

[svxash]

I did see one that includes an alternator pulley as well. I think it restores the correct rpm's to the alternator. I emailed them to find out for sure.

[Svx95]

I would stick to the lightweight pulley keeping the "normal drive". You have 3 options in the under $140 price range:

PERRIN lightweight pulley

COBB lightweight pulley

GrimmSpeed lightweight pulley


Shop around and you might find them cheaper with Cyber Monday deals!
I really like the PERRIN pulley, but I may be biased (see signature).

[fasteract7]

NASIOC Forum has addressed the pros and cons of a lightweight bearing forever. Below is an example. I myself would put the money towards that really sticky tire set where I can definitely feel the difference. Maybe if my OEM balancer has failed I would go for one...






I recently spun a rod bearing on my Stage 2 WRX - a 2004 with 60,000 miles. I had been running a Perrin lightweight crank pulley nearly the entire time and I had also run a Perrin on a previous, naturally aspirated Subaru.

This blown engine frequently saw high revolutions and redline-shifting and while the pulley may have had nothing to do with the failure, I will not be using a LW crank pulley in the future.

My local tuner has advised me that the heavy, OEM pulley serves to dampen the motion of the crank - preventing resonances and shocks that could beat up the very bearings I destroyed. This argument has been made before - and it makes sense.

Other prominent tuners seem to agree that the lightened pulley is a bad idea for different reasons - see this thread - http://forums.nasioc.com/forums/show...t=crank+pulley and ESPECIALLY this one - http://forums.nasioc.com/forums/show...t=crank+pulley

Here, tuners/vendors like AZScoobie, Kingpin, and Crawford agree that these pulleys are a bad idea. While the pulley is not a "balancer" it does have a "dampening" effect. I believe it has the POTENTIAL to do damage if the motor is spun at high RPM's.

This is a contentious issue, but in looking back at the professional opinions on this board, I note that many respected tuners say "it's not worth it." Support for the pulleys comes mainly from vendors and manufacturers who stand to make money. I'm not the expert, but it is interesting to look around at who is promoting their product and who is offering an unbiased, empirical opinion on this modification.

I will be following the advice of tuners, not retailers this time around.

:

[SoobCrazy]

I'll second the "under-driven/lightweight pulleys are bad," sentiment.

If you're dead set on a pulley upgrade, check out the Fluidamper application for the EJ engine. It is more expensive, but it is one of the few pulleys on the market that won't damage your engine.

[svxash]

I would like to replace the pulley because the previous owner installed an under drive pulley and I noticed at the rear of the pulley the outer lip has some missing material and looks like it broke away.

Originally Posted by Svx95

I would stick to the lightweight pulley keeping the "normal drive". You have 3 options in the under $140 price range:

PERRIN lightweight pulley

COBB lightweight pulley

GrimmSpeed lightweight pulley


Shop around and you might find them cheaper with Cyber Monday deals!
I really like the PERRIN pulley, but I may be biased (see signature).

What about the one from SVX-Motorsport warehouse? http://svx-motorsport-accessories.st...svxlicrpu.html Of the 3 listed when I typed in my vehicle info it said only the Perrin would fit the SVX.

[svxash]

Here's a pic of what's on the car now. If you look at the rear of the pulley you can see the damage I was talking about.

[Cotton]

The one thing I notice with that statement from the guy who had his engine blow up is high RPM and redline shifting. That won't and can't be the case with me with a 4.44 auto.

The OBX one I got is being used by someone on the FB group for a couple years with no issues.

[svxash]

I think I'm going to go back with the stock pulley.