Contour Enthusiasts Group Archives Forums Modifications Duratec Performance pulley

well i just got my UR ultra street pulley from CTA Motorsports. Great service as always and it gets installed on friday. what should i be expecting from this? revs up faster? remember i have an auto
but that will change once it goes south. then perhaps level ten will be getting my business....

so what should i expect from this pulley?

Not much, I've got ASP and could hardly tell after instal

You might expect a shorter engine life, as well as more vibration into the vehicle...and you will defiantely notice alot more vibration at high RPM's...good choice on a waiste of cash.....

AAAAAAAAAGGGGGGHHHHHHHHH!!!!!!!!!!!!!..'again'........

When you spin a bearing, let me know. I could use a set of new heads.

Doesn't anyone research these things before they spend their money?

Here it is again, in its entirety:

Underdrive Pulleys ? Our Testing
by James Walker, Jr. of scR motorsports

A few comments from our dyno experiences at Team scR. Since we are allowed to change accessory
drive components, we have looked into issue this on more than one occasion. With all of the wild
horsepower gains advertised, we figured that it was at least worth a solid investigation. Here?s what
we found.

Alternate ?Crank Pulleys?

At first glance, the most obvious change to make to your accessory drive system would be to
change the biggest part in the system ? the crankshaft pulley. If you go to the Saturn factory parts
book, however, you will see that the crankshaft pulley is not referred to as a pulley ? it is known as
the crankshaft harmonic balancer assembly. Here's why:

During the hectic life of a crankshaft, it is subjected to numerous loading conditions and
consequently will 'flex' or 'bend' at very high frequencies. If this 'flexing' is severe enough, the
crankshaft will fatigue and break into lots of small pieces. In general, this is not viewed as a
performance enhancing modification.

Now, in order to reduce some of the more severe vibrations, the Saturn Powertrain designers elected
to hang a big old hunk of metal on the end of the crankshaft to damp out (absorb) those frequencies
which occur at the natural frequency (or resonant frequency) of the crankshaft assembly. By
reducing these frequencies, the life of the crankshaft would be extended, and during its life, the
noise and vibration levels from the engine would be reduced.

To make sure that the big old hunk of metal damped the right frequency range, calculations were
performed to determine the exact weight required to attack the most severe frequencies. Math, I
know, but don?t run away just yet.

From this, you now realize that the weight (or mass, as the engineer would say) of the balancer is
CRITICAL to the happiness of the crankshaft. Vary from this weight, and best case you will get
more vibration in the passenger compartment. Worst case results in spewed parts under your
car?and money spewing from your wallet.

Case in point: last season our engine builder was experimenting with alternate crank pulleys on
BMW engines. Like the other BMW teams (6 or so) in the series, they all elected to run these
pulleys on a given race weekend. Anyway, 4 of the 6 cars went home that weekend on the trailer
with broken cranks. Tell you something?

This does not mean that alternate Saturn crankshaft pulleys will cause your crank to snap in two
instantly, but that pulley is big and heavy for a reason. A very good reason. If nothing else, it?s
something to think about.

Other Pulleys

In general, the other pulleys in the system are not sensitive to weight like the crankshaft pulley, so
harmonic imbalance is not a concern here. If you do decide to underdrive, though, be aware that
while there may be a slight horsepower gain (read more on this below), your components will not be
operating in the ranges determined by the factory. If you are on a race track at constant high RPM,
this may actually prolong the life of these components, but on the street, it could go either way ? a
water pump or power steering pump which is designed to operate at a given speed may not be as
efficient as necessary when underdriven.

Another perspective is that auto manufacturers such as Saturn are always trying to squeeze the last
1/10 of a MPG from their vehicle?s fuel economy estimates. Big dollars and big engineering budgets
are dedicated to this task, and you can bet that if any component could be underdriven further (a
potential plus for fuel economy) and still meet its performance and durability bogeys, it would have
been already.

The Horsepower Story

With various aftermarket manufacturers claiming up to 15 horsepower gains with their underdrive
pulleys, we set out to the dyno to find out how much power WE could expect on our 1999
ITA-prepped Saturn twin-cam powerplant. The results might surprise you, but here they are.

Because there were no pulleys available at the time, we went to the extreme and actually REMOVED
the accessory drive belt (only for one run, of course) to see what the impact would be to ZERO drag
due to the accessory drive ? sort of pulleys with infinitely small diameters. We figured that if we
saw a big gain without a belt, that the pulley gains would be somewhere inbetween, right?

We fired up the dyno and low and behold, removing the belt netted a whopping 3 HP (and we?re
rounding UP). That's it. The number was repeatable, and even correlated to data run earlier on the
doomed BMW motors - they saw similar results in their application.

So, in light of the fact that 3 HP was completely without a belt, we estimated that the best we could
do was to underdrive a few components by 20% - or a theoretical 0.6 HP gain (3 HP x 0.2). After that,
it hardly seemed worth it to try to custom fabricate pulleys for less than a 1 HP gain.

I know, I know ? stock pulleys, like stock suspension bushings, aren?t sexy, and you can?t brag
about them in the pits?but in racing horsepower talks and marketing BS walks. We chalked up this
exercise as yet another learning experience in the quest for REAL horsepower. Maybe someday
we?ll find some.

All I'm going to say: 46,000 miles with pulley (~67,000 miles on engine), hardly any noticeable increase in vibes, definite increase in engine spool up speed (UR is lightest pulley out there though).

Like always - I'll be sure to tell everyone when my engine explodes in a flaming ball of vibrationally induced death :rolleyes:

Seriously - everyone should know there is a potential for decreased crank and bearing life - but even Judge and Terry will tell you (after they roll there eyes at your stupidity) that they can not predict just what that shortened life will be.

ack, everything seemed to make so much sense. less weight makes more power as it takes less to move everything. seems logical. everything that was on the sites i looked at praised them, guess I should have looked into it more. on other cars I've only heard good things about pulleys. and i figured this one would be good as it doesn't underdrive that much. well i guess we'll see how things go with it.

Yeh...thats why I have 4 SVT's in the shop, all with bottom end 'knocks', one with a 'pulley' and no damper,two other had pulleys but were removed, one has been stock for life..all need new bottom ends!!!!!...

Hmm I don't think Ford would've redesigned the part if there wasn't a problem. Get a dual mode damper.