GrimmSpeed crankshaft pulley?

[reberto]

I'm not sure on this one, so someone please clear it up for me.

I read that (at least on the OEM side of things), that the crankshaft pulleys from the EJ's are the same ones fitted to our EG33s. Now GrimmSpeed makes a lightweight pulley that seems reasonably priced to me, and the Impreza/WRX/STi & Legacy owners seem to absolutely love it.

If the EJ cranks fit the EG33s, does anyone see as to why the GrimmSpeed one wouldn't work?

Thanks!

[bishop]

Its correct, ej pulleys from the 2.0, 2.2, and 2.5 liter engines will all bolt up to the eg3.3l no problems at all.

[reberto]

Originally Posted by bishop

Its correct, ej pulleys from the 2.0, 2.2, and 2.5 liter engines will all bolt up to the eg3.3l no problems at all.

Hmm...if that's the case, there are a good number of lightweight replacement options. Not to mention the GrimmSpeed on is a good chunk less expensive than one made by a certain "vendor" (and I use that term loosely) on here.

[Blacky]

I believe this one from Agency Power is the lightest at 1lb. It's $130.00.
It is stock diameter also so no underdrive.

http://www.agency-power.com/catalog/...02-p-5951.html

[Conn SVX]

How much of an advantage is to have these pulleys , my PO installed them on the car I now own. I know rotating weight ( flywheel etc.) increases HP slightly. How much does a small pulley do?

[Crazy_pilot]

A lightweight pulley doesn't increase HP, it just (theoretically) allows the engine to wind up faster because there is less rotational inertia for it to fight against. Exactly how much is open for debate. I'm personally of the opinion that they're more bling than anything.

Underdrive pulleys are slightly different. The smaller diameter effectively decreases the amount of resistance that your engine accessories (P/S, alt and A/C) apply to the crank and frees up some of the power that drives those. It doesn't increase engine HP, it just makes a bit more of what you have available. In terms of numbers I have no idea. If we were making bets I would say 2 or 3 HP. The trade off is that now all your accessories spin at slower speeds. At cruising speed it won't be an issue, but at idle your alternator will be spinning very slowly.

[Lookin4SVX]

I had a Perrin lightweight pulley put in my svx a week ago.
It is the pulley I had bought for my 2.5RS, weighs just 1.2 lbs, the SVX stock one weighs 4lbs.
I went with the Perrin because it doesn't cause a CEL for being too light as far as the posts on NASIOC.
It feels like it revs and pulls faster, says my butt dyno.
I bought mine from these guys, shipping was quick and free: PSP-ENG-100 $116.99 shipped

Just don't buy an underdriven pulley, get one that is lightweight but the same size.
SVX alternator is poor enough, I don't want to short my power steering pump on power when going slow, and don't want to have to use different belt.

[LetItSnow]

Originally Posted by Crazy_pilot

I'm personally of the opinion that they're more bling than anything.

This.

Considering the amount of mass involved through the rest of the drivetrain including everything to the tires (and everything after the center diff being even more "heavy") and that the moment of inertia of the pulley is very small, any sensation of it improving things is strictly placebo. Physics beats butt dynos, hands down.

If you like shiny, it's a great way to go, as it's right in front where everyone can see it.

[Lookin4SVX]

I swear it feels like it revs faster while in neutral..
But yeah, on the road it isn't much of a difference, just 3lb lighter in the front.
Like I said, my butt dyno approves of it.

[reberto]

Originally Posted by LetItSnow

This.

Considering the amount of mass involved through the rest of the drivetrain including everything to the tires (and everything after the center diff being even more "heavy") and that the moment of inertia of the pulley is very small, any sensation of it improving things is strictly placebo. Physics beats butt dynos, hands down.

If you like shiny, it's a great way to go, as it's right in front where everyone can see it.

Seems to get 500rpm above what the stock pulley does in the same amount of time. When the stock pulley equipped engine gets to 3500RPM, the lightweight one is just a hair above 4000RPM. Can't argue that


https://www.youtube.com/watch?v=-f-xt_kfaXc
Also can't argue that the OEM two piece design is more durable/reliable than the lightweight one piece design.

[1986nate]

Originally Posted by reberto

Seems to get 500rpm above what the stock pulley does in the same amount of time. When the stock pulley equipped engine gets to 3500RPM, the lightweight one is just a hair above 4000RPM. Can't argue that


https://www.youtube.com/watch?v=-f-xt_kfaXc
Also can't argue that the OEM two piece design is more durable/reliable than the lightweight one piece design.

that's also in neutral... When you're in gear, aka-when it matters, you have about 700 lbs worth of inertia forces from teh internals of the transmission,to differentials to driveshaft/axles and finally to the wheels. A neutral rev means nothing other than in a M/t car making it more of a ***** to drive.

[kinz]

Doesn't the stock two piece act as a harmonic balancer?
I remember looking in to this a while ago. General consensus was that there was no ill effects from not using stock pulley. Just making it aware that there is a function lost with the lightweight pulleys.

[Lookin4SVX]

Originally Posted by kinz

Doesn't the stock two piece act as a harmonic balancer?
I remember looking in to this a while ago. General consensus was that there was no ill effects from not using stock pulley. Just making it aware that there is a function lost with the lightweight pulleys.

Yeah the guys over on NASIOC fought about this until they contacted subaru directly.

From the info section on the grimspeed pulley page:
http://www.grimmspeed.com/catalog/pr...roducts_id=230

Here is a note directly from SOA:

"Thank you for your patience as I checked with our Technical Services Department regarding your message below. They advised that the crank pulley is a pulley and nothing else. It is not used as a harmonic damper/balancer. Thanks for the opportunity to be of assistance. If you need any future assistance, please feel free to contact us again."

Best wishes, John J. Mergen

Customer Service Department Subaru of America, Inc."

Just thought I throw that out there..

The 2 piece pulley on the SVX has been known to split and fall apart, at least you know that won't happen with the 1 piece.

[92 SVX]

As far as harmonic balancer, From my reading the flat 6 is fairly balanced as is and I expect there is some internal balancing so there is no need of external balancing.

Some engines, the chevy v8 comes to mind DOES need external balancer and so the crank pully on that acts as a balancer.

[oab_au]

Originally Posted by Lookin4SVX

Yeah the guys over on NASIOC fought about this until they contacted subaru directly.

From the info section on the grimspeed pulley page:
http://www.grimmspeed.com/catalog/pr...roducts_id=230

Here is a note directly from SOA:

"Thank you for your patience as I checked with our Technical Services Department regarding your message below. They advised that the crank pulley is a pulley and nothing else. It is not used as a harmonic damper/balancer. Thanks for the opportunity to be of assistance. If you need any future assistance, please feel free to contact us again."

Best wishes, John J. Mergen

Customer Service Department Subaru of America, Inc."

Just thought I throw that out there..

The 2 piece pulley on the SVX has been known to split and fall apart, at least you know that won't happen with the 1 piece.

Just shows that the "Customer Service Department Subaru of America, Inc.", have no idea of Automotive Engineering principals. Must have asked the cleaner. If it was just a pulley, why was it designed that heavy and two piece?
It is a balancer to damp out the harmonics that run up and down the crank. fitting a lightweight, plain pulley, can distort the signals from the crank position sensors.This is why the EZ engines have the crank sensor at the flywheel end of the crank.

This is from a long time ago.

http://www.subaru-svx.net/forum/show...monic+balancer

Harvey.