Pulley change?

[jsteve1109]

Are there any benefits in going to a lightweight crank pulley. I'm coming
up for the 75000kms inspection on my 03 WRX and figure when have belt
changed can change pulley at same time. Any drawbacks to having lighter
pulley as well? Any makers better than others?

 

[Edward Hayes]

I think your timing belt change is due at 105,000 miles so check your
manual. As to a lighter pulley I feel it's a waste of money except for
a drag-strip where you value a few hundreds of a second. ed

 

[Rick Courtright]

Are there any benefits in going to a lightweight crank pulley. I'm coming

Hi,

I'm with Ed...

Or, as they say in the sporting good stores, fishing lures catch more
fishermen than fish!

Lightweight alloy pulleys were all the rage back in my air-cooled VW
days and I'm sure still are with the afficianados. They looked nicer
than the stock stamped pulleys, but nobody could put many real numbers
(other than the usual "100% increase in horsepower, gas mileage and sex
appeal" advertising hype) on their performance beyond sales figures
showing how much the buyers' wallets had been lightened!

Rick

 

[ismlv]

Hi,

I'm with Ed...

Or, as they say in the sporting good stores, fishing lures catch more
fishermen than fish!

Lightweight alloy pulleys were all the rage back in my air-cooled VW
days and I'm sure still are with the afficianados. They looked nicer
than the stock stamped pulleys, but nobody could put many real numbers
(other than the usual "100% increase in horsepower, gas mileage and sex
appeal" advertising hype) on their performance beyond sales figures
showing how much the buyers' wallets had been lightened!

Rick

Agreed - I have 2 air cooled Bugs (or Beetles if you will) and they're all about the light weight pulleys but I've never seen anyone get
hyped up about them elsewhere.

 

[CompUser]

Are there any benefits in going to a lightweight crank pulley. I'm coming
up for the 75000kms inspection on my 03 WRX and figure when have belt
changed can change pulley at same time. Any drawbacks to having lighter
pulley as well? Any makers better than others?

There's aspects to the construction of the OEM
crank pulley that allow it to function "like" a
harmonic balancer. There's some fine points to
it, so I'm phrasing it *that way*. I looked into
it and concluded a lightweight pulley wasn't an
advantageous mod for a WRX, and promptly
dismissed the details. ;-)

If you spend some time looking thru the mod
commentary over on Mike Shield's site,

http://www.spdusa.com

I believe you'll find the info there...along with
a lot of other well thought-thru philosopy and
information on modding WRXs.

 

[Ragnar]

There's aspects to the construction of the OEM
crank pulley that allow it to function "like" a
harmonic balancer. There's some fine points to
it, so I'm phrasing it *that way*. I looked into
it and concluded a lightweight pulley wasn't an
advantageous mod for a WRX, and promptly
dismissed the details. ;-)

And I've seen a Subaru Tech memo that says the pulley was not designed
and does not act *as* or *like* a harmonic balancer.

I'll try to find it and then post the link.

If you spend some time looking thru the mod
commentary over on Mike Shield's site,

http://www.spdusa.com

I believe you'll find the info there...along with
a lot of other well thought-thru philosopy and
information on modding WRXs.

I've read his site and generally agree with most of his points.
However, some of his stuff is at direct odds with other tuners who also
know their stuff.

 

[Ragnar]

Found the link to the pulley stuff on NASIOC.

http://forums.nasioc.com/forums/showthread.php?s=&postid=4835269#post4835269

 

[CompUser]

Found the link to the pulley stuff on NASIOC.

http://forums.nasioc.com/forums/showthread.php?s=&postid=4835269#post4835269

Stick around on NASIOC, and you will be AMAZED
at what people report SOA as saying.

You can eyeball the *construction* of the OEM
pulley and see there's more to it than a pulley;
like I said, I've already "discarded the data",
but when it comes to saving money & simplifying
design, all auto makers are there...have fun, get
a CAI and a BOV too.

 

[Ragnar]

Stick around on NASIOC, and you will be AMAZED
at what people report SOA as saying.

You can eyeball the *construction* of the OEM
pulley and see there's more to it than a pulley;
like I said, I've already "discarded the data",
but when it comes to saving money & simplifying
design, all auto makers are there...have fun, get
a CAI and a BOV too.

Whatever. I guess some people just won't believe data published by the
carmaker.

 

[CompUser]

And I've seen a Subaru Tech memo that says the pulley was not designed
and does not act *as* or *like* a harmonic balancer.

I'll try to find it and then post the link.

Yes, I saw the link...someone posted that he
asked SOA, and SOA replied that it was not...no
"Subaru Tech memo".

 

[Ragnar]

Yes, I saw the link...someone posted that he
asked SOA, and SOA replied that it was not...no
"Subaru Tech memo".

Actually, I couldn't find the original memo so I linked to the
conversation that referenced it.

In any event, the little piece of rubber between the two halves of the
crank pulley isn't a harmonic balancer.

 

[Michael]

I had a af/x underdrive pully on my NT Eclipse. The stock pully on an
eclipse does work as a harmonic balancer. I never had an issue having it on
there, i put it on at 70k with a timing belt change and the car ran fine. I
traded it in on the WRX at 135k. I noticed a little improvment in power.

 

[james]

i switched out my "03 wrx wagon pulley for a vishnu
alloy crank pulley myself-----relatively easy job.


yes it's much lighter, however the main advantage is
diameter (underdrive means easier to drive
compressor, alt, p/steering, --less effort but they do not
spin as fast either.
first question, will this affect p/steering, a/c, & alt
operation???
answer---no noticeable change, except more
power. after 2 years, i have had plenty of juice even at
idle, to operate all i need, however i've never been
the type to run stuff at idle that i do not need to be on.
the beauty of this is that power gain is at
ALL rpms, so driveabilty is better especially at lower
rpms where turbo is lagging. vishnu claims 5-10HP
which sounds about right.

jellymax

 

[Mike]

What do y'all think of this in comparison?

http://www.spdusa.com/pulley_kit.htm

 

[Ragnar]

What do y'all think of this in comparison?

http://www.spdusa.com/pulley_kit.htm

I note that he doesn't address the issue that Subaru itself says the
crank pulley is not a harmonic balancer.

 

[Philip Procter]

There are light weight pulleys and underdrive pulleys.

The light weight pulley is used to reduce the rotating mass or inertia
of the motor so there is less resistance to rapid speed changes. That
can help race motors to respond faster. How much benefit there might
be on the street is questionable IMO.

The underdrive pulley reduces the speed that belt driven accessories
run. Alternators, AC compressors, etc use engine power and the slower
they run, the less power is lost driving them. The power increases are
smal;l but measurable, but there is a direct price to be paid. Your
accessories will not run as designed, eg: your alternator will put out
less amps and batteries will charge slower or you will have to turn
down your 3000watt stereo.

Philip

 

[Edward Hayes]

Biggest advantage for a daily driver is looks and your quarter mile
time may improve .003 seconds.