Perrin Crank Pulley now available

[brichard0625]

question to the people that have the pulley installed...i noticed the stock pulley makes alot of noise in then engine, seems a little shakes alot. Does the after market pulley fix this problem.

[ame="http://www.youtube.com/watch?v=5ZC_XsJuZ20&feature=player_embedded"]http://www.youtube.com/watch?v=5ZC_XsJuZ20&feature=player_embedded[/ame]

I know its not the pulley thats being changed but wondering if the crack pulley helped with the noise

[nubbster927]

Originally Posted by lancie

is there a dyno run with only perrin crank pulley ?

i just asked someone on the perrin website and they said they hadn't dyno'd their crank pulley. but maybe someone on the forum has and would care to share

[Opposed]

Originally Posted by nubbster927

i just asked someone on the perrin website and they said they hadn't dyno'd their crank pulley. but maybe someone on the forum has and would care to share

Check out Vivid's dyno of their pulley. Take it with a grain of salt, but theirs showed a substantial gain...

[wu_dot_com]

Originally Posted by nubbster927

i just asked someone on the perrin website and they said they hadn't dyno'd their crank pulley. but maybe someone on the forum has and would care to share

vivid have post their dyno findings. however their data interpretation method is questionable.

meanwhile. Perrin have posted that the advantage of the pulley will not show in a dyno test. since the change for the pully is faster engine RPM acceleration not HP. as a result, a traditional RPM vs HP or torque curve will not depict the RPM rate of change vs time.

[serialk11r]

Originally Posted by wu_dot_com

vivid have post their dyno findings. however their data interpretation method is questionable.

meanwhile. Perrin have posted that the advantage of the pulley will not show in a dyno test. since the change for the pully is faster engine RPM acceleration not HP. as a result, a traditional RPM vs HP or torque curve will not depict the RPM rate of change vs time.

No, the way almost all cars are dynoed is they do "pulls" where the car accelerates in 1 gear. Removing rotating mass will show up in such a test, because the whole driveline is accelerating. If they plotted an hp chart keeping the speed constant and incrementally increasing speed, then a lightened pulley would not show.

[nubbster927]

Originally Posted by wu_dot_com

vivid have post their dyno findings. however their data interpretation method is questionable.

meanwhile. Perrin have posted that the advantage of the pulley will not show in a dyno test. since the change for the pully is faster engine RPM acceleration not HP. as a result, a traditional RPM vs HP or torque curve will not depict the RPM rate of change vs time.

Yep that's exactly what the Perrin rep said. I won't say i'm very mechanically inclined- could you explain why Vivid's dyno showed such a big increase?

[wu_dot_com]

Originally Posted by serialk11r

No, the way almost all cars are dynoed is they do "pulls" where the car accelerates in 1 gear. Removing rotating mass will show up in such a test, because the whole driveline is accelerating. If they plotted an hp chart keeping the speed constant and incrementally increasing speed, then a lightened pulley would not show.

i still failed to see your logic.

a typical dyno chart is RPM on X axis, and torque and hp on the Y axis. the HP and TQ data was taken at individual RPM range and a polynomial line is connecting all the data point.

the pulley by it self does not increase power, and it does a minimal job in removing drive tran losses because the relative weight saving comparing to the transmission system is small.

therefor, even for a back to back dyno test between stock and perrin pulley, you will not be able to find that at X RPM perrin pulley is producing Y HP or torque more than stock pulley. the possible gain will be scatter in the noise of the data.

yes you are right, in a dyno test, the car does accelerate in first gear. however, that acceleration is actually just taking wheel HP / TQ data from 0 RPM to redline. this is why you usually will see a dyno is done on all the gears from 0-redline for a more detail dyno run.

form what you are saying about moving the drive line, in a traditional dyno chart, the HP and TQ line can move up, down, left, and right.

if it moves up, it means the engine gain power, i.e. at the same RPM, the engine make X HP or TQ more over stock. this is not what the pulley can do.

if it moves down, it means the engine lost power, i.e. at the same RPM, the engine make X HP or TQ less over stock. this is not what the pulley will do.

if it moves left, it means the engine makes more power at lower RPM. this is usually done through altering the gears of the car, making it closer ratio. not something the pulley would do.

if it moves right, it means the engine makes more power at higher RPM. this is usually done through altering the gears of the car, making it taller. not something the pulley would do.

so back to the original topic, the pulley advantage will not show the gain in a traditional dyno chart.

Think back to high school physics. There are distance, velocity, and acceleration. Your speedometer readout is velocity i.e. rate of change, not acceleration; acceleration is in the second order or in simple English the changes to the rate of change. In our case, we are talking about angular acceleration, not angular velocity. In angular terms, revolution is equivalent to distance, RPM is like velocity, and how fast the RPM needle jump is angular acceleration. Perrin pulley, and light flywheel changes the angular acceleration.

[wu_dot_com]

Originally Posted by nubbster927

Yep that's exactly what the Perrin rep said. I won't say i'm very mechanically inclined- could you explain why Vivid's dyno showed such a big increase?

i tend to agreed that vivid's data is interesting, yet irrelevant and not comparable.

this is because the test they run is not in a control environment.

each run was conducted at a different time, rather than back to back. there are many other factors that can skew the test results like this which i dont want to speculate. but for example, ambient temperature, pressure, engine oil, dyno calibration, etc.

i have a disagreement with their test methodology rather than the test itself. with the wrong testing method, the conclusion they drawn can be misleading.

as a result, though i appreciate they spent the time and money on the dyno test, i just think their test conclusion were inconclusive.

[_F-R-S_]

i will have to order it this weekend. seems like no problems with it so far..

[mrnurse]

Has anyone noticed increase in vibration or any troubles with the lighter pulleys?

[SkAsphalt]

Originally Posted by mrnurse

Has anyone noticed increase in vibration or any troubles with the lighter pulleys?

None so far. Only 8000km on mine though

[rikixass]

Anyone had any issues? Ordered, but heard bearing could get messed up. Anyone can confirm it deny? Please advise.

[xwd]

Not a Perrin one but I think I've had a lightweight pulley on the car for 45k miles without issue. I've never really heard of a lightweight pulley causing issues on a Subaru motor.

Here is an odd question, but I don't suppose someone can measure the width and depth of the portion of the pulley the bolt goes in? I went to determine if it's exactly the same size as the stock one or not.