Effectiveness of a Lightweight pulley
 

So I've been reviewing parts regarding a lightweight pulley for the crankshaft and I've seen a few reviews saying that it seems to be pretty amazing. But I have two questions, first off have we had any dyno results indicate an appreciable gain in WHP/WTQ? (I'm not even sure it would show up on the Dyno but I would think anything that facilitates faster revs and acceleration should also show up on a Dyno)

And secondly, I've read a lot about harmonic balancers and how going with a lightweight crankshaft pulley can destroy your crankshaft bearings... Is this the case on our car? (I would imagine it would be somewhat different since it is an H4 instead of an I4)

Sorry if this question was already asked and thanks for all your help!

It has been asked, but there is never really a clear cut 'yes' or 'no' (Unless there is, and I just get bored reading through several dozen conflicting posts).

It's a mod I wouldn't mind doing, so I'm really interested in a definitive answer. I plan on having my FR-S a long time (When the damn thing finally shows up that is), and while I want to mod and have fun with it, I'm not interested in destroying my motor from the inside, just for a little quicker spin up ;)

Here you go...enjoy!

http://www.ft86club.com/forums/showthread.php?t=12450

No, it is not a problem on the Subaru engine and No it won't give you a lot of HP or Torque on the dyno BUT it does help free up rotational restriction so the engine revs easier and and therefore builds energy faster...and better gas mileage although YMMV.

No offense, but I'm four pages in, and still reading an awful lot of speculation >.<

Edit: Just found Jeff's post on page 5, and yes, that does make me feel better ;)

AP's pulley shows a significant increase in hp and tq on their dyno.
http://www.ft86club.com/forums/showthread.php?t=13011

Not sure why this is the case.

That dyno is the pulley, header and crosspipe all together....

Post #3 shows pulley only...

Holy crap... if I am reading that right though, they are putting down almost 170 max HP at 'stock' and then the pulley is boosting it to 186~ !?

Everything I've seen of stock Dynos are seeing about 160 stock... But that pulley seemed to give more power than the whole exhaust system.

170whp is not that odd, I have seen a few read that high. I do find the numbers on the pulley a little strange however...

Everyone seems to say that you can't see the pulley on a Dyno... But that makes almost no sense. Anytime you lower the weight of your drive train you improve WHP right? And more over, with something like a pulley that is on the other side of your engine, it would improve crank power as well?

Because magic.


I can't wait until Perrin dynos their pulley.

It won't make the engine produce more power, but can show a little on a chassis dyno. However, the weight if VERY close to the centerline of rotating mass, and we aren't talking about a lot of weight so I do find a ~50% reduction in driveline loss under acceleration to be a bit unbelievable still from just a pulley. There are so many other components involved that I just find it very hard to believe.

I've seen lightweight pullies dynoed before, and have never seen any sort of WHP increase like Vivids.

Vivid's #s have been in question since their first pull. It's not a good idea to use their dyno results as a benchmark for anything.

That said the link above with the Perrin post on pg. 5 helps clear up most questions.