Lightweight crank pulley vs OEM vs Fluidampr by MotoIQ

[CSG Mike]

http://www.motoiq.com/MagazineArticl...dent-Test.aspx

So now we come down to the numbers game, the bottom line of this test.

Perrin - the Flyweight = 177.82 peak WHP with 138.29 ft. lbs max torque
OEM Subaru - the Light Heavyweight = 179.19 peak WHP with 139.81 ft. lbs max torque
Fluidampr - the reigning Heavyweight = 179.05 peak WHP with 139.03 ft. lbs max torque
What this does show it that a roughly 1 pound heavier Fluidampr crank pulley can make the same wheel horsepower and torque as the OEM Subaru unit but with an even smoother more balanced crank. It also shows that what should be the lighter and faster Perrin pulley did not translate into more horsepower or torque. Is it just this simple? Nope, it isn’t.

During the test we noticed how smooth the car ran when it was equipped with the Fluidampr. We even further noticed when the car was on the dyno how the engine sounded smoother as it made its runs. Again this could be us being crazy but the four of us there were all in agreement, Fluidampr allowed the Subaru Boxer engine to run out the smoothest out of the 3.

It was also decided that the Fluidampr would remain on our test car for the next couple weeks to have the daily driver test done on it. Over those 2 weeks our test car owner comments were: “It feels smooth,” “ Toned down the exhaust rasp a little” and “it shifts way smoother”. His comments are again just his opinion.

I understand all that I have done here just shows some numbers, weights, video and data that some may chalk up one way or the other. What we can’t really show here though is the long term benefits of the dampened pulley on the engine. I know it now becomes a subjective thing and everyone may see or feel things differently, but with that said the numbers don’t lie. We feel that the benefits and claims of the Fluidampr are very valid for your car and ours.

[cruizin01]

Had a Fluidampr in my 500hp GTI. Will definitely consider one for this platform. Good to know all these lightweight pulleys are a waste of cash.

[celek]

Thanks @CSG Mike I need a Fluidampr to add to the build list.

[raven1231]

But what about my butt dyno

[stugray]

One thing I like to point out in these discussions about "Can a lightened pulley provide more HP":


Can HP be measured at a constant RPM? - YES.
In fact the original term "Brake Horse Power" was used because the oldest method of measuring HP was to hold the engine/motor at constant RPM and apply the "Brake" (yes an actual BRAKE).
When the engine begins to drop RPM (and the throttle cannot be opened any further), the power applied to the brake was determined and that was the 'BHP' for that particular RPM.
Repeat the test at all RPMs and you get the typical curves that we are used to seeing from Dyno runs.


SO IF classical Horsepower is measured at constant RPM, then WHAT does rotational mass have to do with HP?
Answer - NOTHING.


(Since rotational mass only resists CHANGES in RPM.)

[STV3]

@WhiteFRS69

[mrk1]

Never been a fan of solid pulleys, I've had my eye on this for a bit now. I think solid pulleys are one of those mods people convince them self there is an improvement since they just shelled out cash for it, "wallet dyno" even more unreliable then the "butt dyno"

[industrial]

Nice test but doesn't prove anything. Stu and I have gone round and round on this and I agree with his analysis here. (see #3)


1. The lack of difference on the dyno is obvious. You can get a 2whp delta by changing your shoes between runs.
2. Confirmation bias. Testing 101. "Hey look at this awesome pulley, it's supposed to make the car run smoother!" -> "The awesome pulley makes the car run smoother!" For the same reason everyone thinks a lightened pulley "makes the car pull harder!"
3. What should've been measured is the delta in time vs. power. Lightened drivetrain components do not make more power on the dyno, they reduce the amount of energy necessary to load the components to put the car in motion. This can't be measured on a dyno.
4. A heavier flywheel makes a car smoother to launch and smoother to drive. Is that good for performance too?


All that said, I sent an email to fluidampr about a year ago asking them to make a pulley after messing with the ATI offering (which sucks). Back when I was going to do a high RPM NA engine build, this was absolutely on my list of things that HAD to be addressed. It's a safety of engine thing. Then I got lazy and added FI.

[Sleepless]

Interesting info.

This comment from the above is also enlightening (pun intended?):

Scooby921 Thursday, September 03, 2015 5:13 PM
As a former design engineer for crankshaft dampers I just wanted to point out a couple important items.

The crankshaft damper has nothing to do with engine balance and vibrations. Motion and oscillation of the powertrain, as an assembly, is addressed by your engine mounts, transmission mounts, and potentially roll restrictors.

The purpose of a crankshaft damper is to reduce the angular twist / deflection of the crankshaft. Combustion creates pressure. Pressure becomes load into the connecting rod which creates torque on the crankshaft. That torque creates deflection of the shaft as it's not infinitely stiff. Depending on the material, journal offset, length of the shaft, and loads created in the cylinders you can see several degrees of angular deflection in the crankshaft. I've seen an OEM crankshaft which displayed 7° of deflection without a damper. With the damper it was under 2°.

The mass of the crank damper and the stiffness of the spring element (the rubber part) are vital to the effectiveness of the damper. They control the resonant frequency of the damper and impact the effective damping. If you change the mass or change the spring stiffness you change the frequency at which it operates. If you don't have enough mass, even at the correct frequency, you don't provide sufficient damping. An incorrectly tuned damper could actually make things worse.

[Captain Snooze]

Originally Posted by industrial

3. What should've been measured is the delta in time vs. power. Lightened drivetrain components do not make more power on the dyno, they reduce the amount of energy necessary to load the components to put the car in motion. This can't be measured on a dyno.

I beg to differ here.
It depends on the type of dyno being used. If it is a brake dyno then no, it can't be measured but if it is an inertia dyno then yes, it can be measured.

[NyC Zn6]

So people that want to make power should just stay with the factory crank pulley.

[stugray]

Originally Posted by NyC Zn6

So people that want to make power should just stay with the factory crank pulley.

WAIT!! What is this sorcery?!!?

YOU are NOT allowed to state the obvious or use common sense on the internet!
Off with his head!

Summit has the fluidampr for ~$390 Hmm.....

[CSG David]

Originally Posted by celek

Thanks @CSG Mike I need a Fluidampr to add to the build list.

Very important for a built motor.

[JohnJuan]

Well, I may actually go back to stock from NST now.