Lightweight crank pulley

[Captain Snooze]

Originally Posted by tennisfreak

If my engine blows up on me then I will gladly come on here and admit to being a dumbass and advocate not putting them on your car.

Only if you can attribute the engine blowing up to the pulley and not by it being struck by a meteorite.

[wootwoot]

Originally Posted by tennisfreak

I think that until I go forced induction I will be more than happy, and feel safe, with my lightweight pulley install.

I dont care if its placebo or not, I like the way my car feels with a full pulley kit on it.

If my engine blows up on me then I will gladly come on here and admit to being a dumbass and advocate not putting them on your car.

I like your style

[wootwoot]

From Cobb:

Hello!

The real question here is whether or not a harmonic balancer/dampener is necessary on a a Subaru engine, and the answer is no.

The fact is that some engines are more balanced than other simply by design. The Subaru boxer engine is inherently more balanced than say an inline 4 or V8, both of which typically require some sort of added dampener, typically in the form a heavy rubber insulated crank pulley.

It is absolutely fine to run an aftermarket pulley on a boxer engine, we have had them installed on our shop cars and employee cars for 100k+ hard miles without issue.

The only downside would potentially be the lightened rotating assembly making it harder to start out from 1st gear, as with any lightweight flywheel. However, you really will not have any noticeable increase in difficulty with just a pulley.

From Wikipedia:

"The boxer configuration is the only configuration in common use that does not have unbalanced forces with a four-stroke cycle regardless of the number of cylinders, as long as both banks have the same number of cylinders. They do not require a balance shaft or counterweights on the crankshaft to balance the weight of the reciprocating parts, which are required in most other engine configurations"

Thank you,
Aaron
ph: 866-922-3059

[OICU812]

There you go, a lightweight pulley on "our engine" has zero negative effects. Thx all for your independant research.

[Captain Snooze]

One thing I notice that is totally absent from this discussion is the possibility of creating a black hole that will devour our galaxy after fitting a lightweight pulley. I read about it some where and will post the link if I find it again.

[wootwoot]

Originally Posted by Captain Snooze

One thing I notice that is totally absent from this discussion is the possibility of creating a black hole that will devour our galaxy after fitting a lightweight pulley. I read about it some where and will post the link if I find it again.

This made me spit out my breakfast I laughed so hard.

[stugray]

Originally Posted by Apoc

I would like to see some evidence of a heavy pulley providing more stored energy and acceleration at higher RPM as this seems to defy any physics I know.

What the hell are you talking about?
It is perfectly understood physics that the heavier pulley stores more energy than a light pulley.

E = I*w^2 where E is the kinetic energy, I is the rotational inertia of the rotating mass, and w is the angular velocity (RPM).
Light pulley, I is small, Heavy Pulley I is big.

[stugray]

One question I keep asking is: "Are the rotating masses of our engines dynamically balanced at the factory?".
If the answer is YES then changing any piece of the rotating mass without rebalancing is not smart.

If the answer is NO, then go for it!
My factory pulley has a hole drilled into it near the perimeter in the front.
This leads me to believe that the rotating assembly IS balanced at the factory.

I have my racing 4-cylinder boxer engines dynamically balanced by a pro before I assemble the engine.
If I change ANY part of the rotating mass after that, I need to have the entire assembly rebalanced.

[pseudo]

Originally Posted by stugray

What the hell are you talking about?
It is perfectly understood physics that the heavier pulley stores more energy than a light pulley.

E = I*w^2 where E is the kinetic energy, I is the rotational inertia of the rotating mass, and w is the angular velocity (RPM).
Light pulley, I is small, Heavy Pulley I is big.

It takes energy to create that angular velocity, though. The effort needed to rotate the mass of the pulley will leach energy from the torque being applied to the transmission. The only time you will see that force is when δω is negative, in which case the stored energy of the pulley will counteract the negative torque being applied to the crankshaft. This means that a big pulley will simply rev slower in both directions.

[stugray]

You are correct. What some on here fail to understand is that you have more energy stored to use when you shift with the heavier components.
Same thing applies to lightened flywheels.
If you lighten your flywheel & pulley (all rotating mass) and try to "peel out" from a stop, you will have a much harder time than if you had the heavier rotating mass.

[jonbonazza]

Originally Posted by pseudo

It takes energy to create that angular velocity, though. The effort needed to rotate the mass of the pulley will leach energy from the torque being applied to the transmission. The only time you will see that force is when δω is negative, in which case the stored energy of the pulley will counteract the negative torque being applied to the crankshaft. This means that a big pulley will simply rev slower in both directions.

Therefore:

[effty_ac]

Originally Posted by Captain Snooze

I have a challenge for everyone. Read the following story then answer the question.

"Yesterday was a beautiful,sunny day. It was about 26 deg Celsius. My wife and I went for a drive about some twisty roads close to but out of town. I had my window down with the air-con on. (Yeah, weird huh?). I wasn't going fast, just enjoying the day, the car, the company. I was thinking it doesn't get much better than this."

Did I have a lightweight pulley fitted?

Sometimes I like to drive with the windows down and the heat on. Wanna be friends?

[Captain Snooze]

Originally Posted by effty_ac

Sometimes I like to drive with the windows down and the heat on. Wanna be friends?

lol

[Mtlrick]

Originally Posted by effty_ac

Sometimes I like to drive with the windows down and the heat on. Wanna be friends?

[ame="http://www.youtube.com/watch?v=XRGd0gD0QNE"]Why Can't We Be Friends- War LYRICS - YouTube[/ame]



By the way , I ordered my Perrin Pulley yesterday !!