Lightweight crank pulley vs OEM vs Fluidampr by MotoIQ

[churchx]

I wonder though, if it's known that lighter pulleys/flywheel and other similar components won't change HP measurable on dyno, but will affect rpm changes over time / acceleration .. why were dyno runs performed at all instead of several drag race runs? Sure, those will be way more imprecise and with higher margin of error .. but if done many enough times, shouldn't it somewhat average/smooth out results? This particular test looks to me like choice to use scales for measuring distance or clock to measure volume.

[Captain Snooze]

Originally Posted by churchx

but if done many enough times, shouldn't it somewhat average/smooth out results?

I am hypothesizing that the margin of error is just part of the noise. That is, because the difference between oem and aftermarket is so small any variation will be just part of experimental error.

[churchx]

Hmm, then i guess it needs to add something more for change to be bigger then experimental error. For example to not change just CP, but also lighter driveshaft/flywheel. Won't suggest lightened wheels/brake kits, as they will change not just rotational weight but also unsprung weight and thus very possibly grip. Though still, things like how good shifting was and how good start from stationary was and such will affect 0-60 times a lot. I'd rather see performed on dyno (to lessen changes by differences in grip when driven on normal road with varying surface quality) chart with rpms over time with chart segments per each gear starting/ending at specific rpm ranges to take out any gear switch variables.

[Captain Snooze]

Originally Posted by churchx

For example to not change just CP, but also lighter driveshaft/flywheel.

But then there is more than one variable so the test is no longer valid.

Given the small diameter,small width and small mass I am suggesting there is negligible benefit in a lighter crankshaft pulley. The greatest angular inertia items in the drive train (to the best of my understanding) are the flywheel and wheels. The wheels are tricky because the tyres have the greatest diameter so probably contribute most to the angular momentum.

In the test from Motoriq, who I respect but take issue with on this occasion, they are claiming a 1.37 hp difference between the Perrin and oem. This is less than 1% difference!! I am suggesting it is possible to get more than this sort of error even on exactly the same car at different times of the day due to variations in temperature, pressure and humidity.

[churchx]

Spinning up (or slowing down with breaking) heavier wheels+tyres and larger diameter at that needs more energy, sure. Crank pulley/flywheel turn at higher rpms then wheels though.

[raven1231]

Regardless of if they work or not the potential gain is negligible, especially for the cost.

[stugray]

Originally Posted by churchx

Spinning up (or slowing down with breaking) heavier wheels+tyres and larger diameter at that needs more energy, sure. Crank pulley/flywheel turn at higher rpms then wheels though.

On another thread I calculated that reducing the driveshaft weight from 30 pounds to ZERO pounds made a difference of .032 seconds in a 0-100 MPH run.
Based on the rotational energy of the shaft only.
So reducing to rotating mass of the pulley by 4 pounds would make ev en less of a difference.

[celek]

Originally Posted by raven1231

Regardless of if they work or not the potential gain is negligible, especially for the cost.

Except when you have a $2400 crank shaft and you want to protect the investment from harmonics and premature bearing wear.

[raven1231]

Originally Posted by celek

Except when you have a $2400 crank shaft and you want to protect the investment from harmonics and premature bearing wear.

I was talking about whether or not they're harmful, just the potential or lack of potential performance gains.

[why?]

Originally Posted by Captain Snooze

I am hypothesizing that the margin of error is just part of the noise. That is, because the difference between oem and aftermarket is so small any variation will be just part of experimental error.

This is the biggest problem with this "test". They admitted they did one dyno run for each, and have almost no variation and did no other real testing. No one I have ever talked to would even try to say such a variation was due to aftermarket parts, because you could probably test all 3 pulleys all day and they each would take a turn getting the highest hp.

This is not real data, this is a paid fluff piece and nothing more.

[uspspro]

To me you buy one of these for peace-of-mind, if you are going to push a lot of power, rpm, or abuse the motor frequently.

It's not about making power. It's about using a high quality component as one of those little things than cumulatively add up to a less problematic setup.

[Slowmotion]

Originally Posted by why?

This is the biggest problem with this "test". They admitted they did one dyno run for each, and have almost no variation and did no other real testing. No one I have ever talked to would even try to say such a variation was due to aftermarket parts, because you could probably test all 3 pulleys all day and they each would take a turn getting the highest hp.

This is not real data, this is a paid fluff piece and nothing more.

Even if they only did 1 run a piece, it still is real data, they were probably just being cheap and getting the standard 3 dyno pulls for $125. They put the car on a dyno and measured it. Is it accurate real data? No.

Though, no matter how many dyno runs they do, on a rolls, your inputs to the engine are never the same so whatever average you get is a fluctuating average where this data will just wash out. Unless you can control the intake air temperature, barometric pressure, oil temperature, coolant temperature and cell temperature (there are probably a few more I'm missing) to about +/-1 deg/in-Hg of nominal and do it say, 10-20 times, The actual benefit or detriment will never be known.

[stugray]

Originally Posted by why?

This is not real data, this is a paid fluff piece and nothing more.

Actually it is a test that provides real data that agrees 100% with the predictions made by sound PHYSICS.

I dont care if you remove a 30 pound pulley and replace it with a ZERO pound magic pulley.
You still will not see a difference in horsepower on a dyno.

So I dont know what you were expecting to see.

[why?]

Originally Posted by stugray

Actually it is a test that provides real data that agrees 100% with the predictions made by sound PHYSICS.

I dont care if you remove a 30 pound pulley and replace it with a ZERO pound magic pulley.
You still will not see a difference in horsepower on a dyno.

So I dont know what you were expecting to see.

I wasn't expecting to see anything. I was pointing out the reality that there are no people on the planet that I've ever talked to or read that would take 1 dyno run and even think about reporting what it said as fact.

I was also pointing out this paid review cannot be used as evidence of anything at all, because there was no real test, and there was no real comparison.

It is disingenuous at best to try and use it as proof of anything at all. It does nothing to further our knowledge base about anything.

Originally Posted by Slowmotion

Even if they only did 1 run a piece, it still is real data, they were probably just being cheap and getting the standard 3 dyno pulls for $125. They put the car on a dyno and measured it. Is it accurate real data? No.

Though, no matter how many dyno runs they do, on a rolls, your inputs to the engine are never the same so whatever average you get is a fluctuating average where this data will just wash out. Unless you can control the intake air temperature, barometric pressure, oil temperature, coolant temperature and cell temperature (there are probably a few more I'm missing) to about +/-1 deg/in-
Hg of nominal and do it say, 10-20 times, The actual benefit or detriment will never be known.

It is real data that says there is no statistical difference whatsoever between the three pulleys and nothing more. Not data you can draw any conclusions from.

And if a person can get consistent repeatable runs on a dyno then the data can be considered valid. No one will ever be able to perfectly repeat everything, which is why 2 or 3 hp is usually considered to be no gain at all.