Underdrive vs lightweight crank pulleys

[subie/legacy]

What are the differences between the two?
Pros/Cons of each?

should I stay away from cheap Ebay pulleys
Also can I use a Wrx lightweight or underdrivin pulley on my N/A ej22? why or why not?

-Kyle

[rougeben83]

underdrive reduce the amount of parasitic loss that each component its tied gets from the engine. This means lower power steering assist, lower alternator speed, a/c doesn't cool as quick, etc, depending on the severity of the underdrive.

Lightweight just reduces the mass of the pulley itself while still keeping the right diameter to not affect the drive of each component.

Underdriving is not really worth the tradeoff on a street car. On a race car, you just take the accessories off unless its specified in the rule book that you have to run one.

[subie/legacy]

Thank you for clearing that up for me.
do all subarus share the same size crank pulley?

[mike-tracy]

They've been making subarus for a few decades now, I'm pretty sure there are several different sizes.

If you are talking about EJ series engines exclusively, then yes they are interchangeable.

[subie/legacy]

haha. yea exclusively EJ series engines. probably should have mentioned that part.
thanks for the quick responses fellas.

If anyone has/had lightweight or underdrive pulley on your EJ enigine, I would like to hear your experiance
such as likes, dislikes, and ill affects.
seat of the pants gains or dyno charts if you know of any.
Im just trying to gather as much info as possible about the two.
This may become a good reference for other noobs such as my self concerning this topic.
Thanks
-Kyle

[legacy98gt]

i have light weight underdrivin pulley from ebay, i noticed alot better acceleration, i can really feel the difference, i think this is the best mod ive done and it only cost 40 bucks plus the new belts so its not bad, best bang for the buck in my opinion but i dont now much about just light weight, i havnt had any problems with chagrging or anything but i have a home made grounding kit im not sure if that matters, and i live where it gets 110 and my ac is still ice cold and it takes about 3 minutes to get cold witch isnt bad, and my steering is the same i cant tell

[green97gt]

i have light weight underdrivin pulley from ebay, i noticed alot better acceleration, i can really feel the difference, i think this is the best mod ive done and it only cost 40 bucks plus the new belts so its not bad

link to seller/product? thanks.

[legacy98gt]

i bought it from eautotuning and when i got it it was like 40 bucks but im not sure he has any left, im sure you can just get the other ones on ebay that are 40 bucks they all look the same

[slaytalera]

I have the Perrin Lightweight crank pulley and i love it. Its not so much a "rise in power" but it smoothes everything out a lot. the engine revs quicker and will hold RPM better compared to the stock one(my experiences of course, on a motor with 240k miles on it)

[Grafton]

i have the group a pulley, and have the same experience as ^

[subie/legacy]

The group A pulley is lightweight NOT an underdriven. is this correct?
Was your group A pulley installed during your dyno pulls?

[ouch1011]

I have the Worx Tuning low-mass crank pulley. Got it as a gift. Probably wouldn't have bought it for myself, but it is pretty and it is a lot lighter.

Someone did a video a while back using that same pulley vs stock... kind of interesting.
http://www.youtube.com/watch?v=e5VPh9LqjaI

[subie/legacy]

that video was pretty cool... thank you for your input.
Anyone else with any comments? post 'em up

[Grafton]

The group A pulley is lightweight NOT an underdriven. is this correct?
Was your group A pulley installed during your dyno pulls?

group a pulley is not under-driven just light weight, and it was installed for my dyno pulls

[subie/legacy]

great thank you. I thought group A pulley was lightweight, but wasn't sure.

[Reason]

You are over thinking this, it's just a pulley, there are no negatives of a lightweight pulley. It's one of the best mods I did and everyone that has one would agree. I had one on a 5 spd and a auto, I felt it more on the 5 spd, couldnt tell on the auto. It makes driving a 5 spd "easier" and smoother like said above.

[slaytalera]

i can feel the difference on an auto, but im sure 5 speed would be an even bigger improvement

[LegacyDeluxe]

I'm no Sub expert, but I've spent alot of time and money in muscle cars in general, as well as alot of shade-tree mechanic work for others. I've got say I really don't like the idea of underdrive pulleys. I don't think it's good for the battery (spinning the alternator fast enough), or for the alternator itself. I honestly think it's pre-maturely killed a couple alternators on some Mustangs I've seen. In addition, if your water pump is in the mix, I don't like the idea of a water pump spinning slower than intended......especially on something that's meant to be driven fast, or as a "performance vehicle".

That's just my 2 cents.

I'd go with the lightweight (only) pulley. I'm thinking about the Perrin myself.

[jey]

Water pump is on the timing belt in Subarus so that shouldn't be an issue.

[1-3-2-4]

all the lightweight pulleys I've seen are over $100?