Lightweight pulley wow

[karma003]

Originally Posted by Captain Snooze

http://www.zhome.com/ZCMnL/tech/harmonics.htm
http://what-when-how.com/automobile/...ce-automobile/

"Vibrations not normally included in either primary or secondary balance include the uneven firing patterns inherent in some configurations.
The above definitions exclude the dynamic effects due to flexure of the crankshaft and block and other force induced deformations."
https://en.wikipedia.org/wiki/Engine_balance

All I see that telling me is the info I already know. The need for counter weights & balancing the motor. I don't see y any configuration would be different from the other. All motors where ment to fire in sequence, otherwise they'd be more prone to self-destruct. Maybe uneven firing orders like 3cyls & 5cyls I could understand the uneven forces & the loss of balance. But in even number motors I don't see that happening.

[atledreier]

So this makes the motor rev faster? Noticeably?

[Captain Snooze]

Originally Posted by karma003

All I see that telling me is the info I already know.

Pardon me but did you read the articles? It states "inline six, flat six, and V-12 engines have no net shaking force when they are spinning but not actually firing".

From http://www.autozine.org/technical_sc...ne/smooth3.htm
"What about vertical / transverse forces? like 3-cylinder engines, the vertical and transverse forces generated by individual cylinders, no matter first order or second order, are completely balanced by one another. The resultant vibration is nearly zero, thus inline-6 is virtually a perfect configuration."

From http://www.caranddriver.com/features...angles-feature
"The first two of these forces—rotational and reciprocating—can often be balanced through engine configuration, as in, for example, a 90-degree V-2"

From https://en.wikipedia.org/wiki/Straight-six_engine
"An inline six engine is in perfect primary and secondary mechanical balance, without the use of a balance shaft. The engine is in primary couple balance because the front and rear trio of cylinders are mirror images, and the pistons move in pairs. That is, piston #1 mirrors #6, #2 mirrors #5, and #3 mirrors #4, largely eliminating the polar rocking motion that would otherwise result. Secondary imbalance is avoided because the crankshaft has six crank throws arranged in three planes offset at 120°. The result is that the secondary forces that are caused by differences from purely sinusoidal motion sum to zero."

I assume you mean

Originally Posted by karma003

All motors were meant to fire in sequence

What do you actually mean by that?

[karma003]

Originally Posted by Captain Snooze

Pardon me but did you read the articles? It states "inline six, flat six, and V-12 engines have no net shaking force when they are spinning but not actually firing".

From http://www.autozine.org/technical_sc...ne/smooth3.htm
"What about vertical / transverse forces? like 3-cylinder engines, the vertical and transverse forces generated by individual cylinders, no matter first order or second order, are completely balanced by one another. The resultant vibration is nearly zero, thus inline-6 is virtually a perfect configuration."

From http://www.caranddriver.com/features...angles-feature
"The first two of these forces—rotational and reciprocating—can often be balanced through engine configuration, as in, for example, a 90-degree V-2"

From https://en.wikipedia.org/wiki/Straight-six_engine
"An inline six engine is in perfect primary and secondary mechanical balance, without the use of a balance shaft. The engine is in primary couple balance because the front and rear trio of cylinders are mirror images, and the pistons move in pairs. That is, piston #1 mirrors #6, #2 mirrors #5, and #3 mirrors #4, largely eliminating the polar rocking motion that would otherwise result. Secondary imbalance is avoided because the crankshaft has six crank throws arranged in three planes offset at 120°. The result is that the secondary forces that are caused by differences from purely sinusoidal motion sum to zero."

I assume you mean

What do you actually mean by that?

Meaning one after another. Each helping the other push out using the opposing forces to benefit each other. "meant" was meaning if off timing, it would do more harm then good especially when it comes to balance. If off time, it'd make sence any motor would be off balance, but when on time. Each piston. Moves in sync. & I'm sorry, to be honest I didn't read those, there was way to much to read lol. Sorry. But in theory, logically it doesn't make sense to me, even if they say they've proved it. Im quite enjoying this debate to be honest. Lol. Havent had a debate like this in a while. But perhaps ur right, & all those articules prove accurate, but like I said, it doesn't make sense to me

[noAE86]

Originally Posted by karma003

Meaning one after another. Each helping the other push out using the opposing forces to benefit each other. "meant" was meaning if off timing, it would do more harm then good especially when it comes to balance. If off time, it'd make sence any motor would be off balance, but when on time. Each piston. Moves in sync. & I'm sorry, to be honest I didn't read those, there was way to much to read lol. Sorry. But in theory, logically it doesn't make sense to me, even if they say they've proved it. Im quite enjoying this debate to be honest. Lol. Havent had a debate like this in a while. But perhaps ur right, & all those articules prove accurate, but like I said, it doesn't make sense to me

are you thinking of a two stroke engine?

because in a 4 only one piston firing is moving the rest of the pistons through there respective cycle, thus it is inherently unbalanced no matter if its inline4 flat4 or v4

[karma003]

Originally Posted by noAE86

are you thinking of a two stroke engine?

because in a 4 only one piston firing is moving the rest of the pistons through there respective cycle, thus it is inherently unbalanced no matter if its inline4 flat4 or v4

Hmph, if this is correct then I guess im wrong. Even thou the video on scion & Subaru show the motor & my theory working

[Tainen]

Hmm. I'd love to see some dyno results of just the pulley, I know Perrin said they were going to do this sooner or later. Since AP is saying they get what 27whp from the pulley/flywheel, I'm wondering if just the pulley alone gets some amazing amount of power. Probably not, as those numbers are pretty suspect it seems, but... it'd be an incredibly useful data point. Maybe this motor/drivetrain just responds crazy well to lightening the rotating mass. I'm very curious.

[serialk11r]

Originally Posted by karma003

Hmph, if this is correct then I guess im wrong. Even thou the video on scion & Subaru show the motor & my theory working

Well, power strokes never give you even pulses of torque anyways, that's not called balance though IIRC.

[PERRIN_Jeff]

Lots of questions to answer here. Keep in mind that the Subaru engine is a very well proven engine to be ok with a lightweight solid type aluminum pulley. We sell thousands of these a year and if you skip over to the Subaru forums, you will find these kind of discussions happened years ago then stopped. Its because there are no issues that come up, and its so proven that there are no more concerns. I knew this same kind of thing would happen with the FR-S/BRZ as most everyone is a completely new customer and may not be aware of all the non-issues with these parts. In fact this happens anytime a new car comes out. People somewhat freak out at first, then over time settle down after a couple years.

The stock pulley has the small dimples in it only because its balanced by it self before it goes on the motor. The part is a cast iron part with a the rubber band between the outer and inner pieces. This by nature, isn't accurate and forces the manufacturer to balance the part.

Yes the stock part is a Harmonic Dampener, not balancer. These are installed on every car now a days, but the real question is, does the engine NEED this. There are tons of articles describing why, and how they work, but some of this doesn't matter. Typically, long cranks are the cause of the problems, where there is twisting happening adding to the harmonics of the engine and pulley. In these cases dampeners help keep parts from failing form these harmonics. I have "Heard" BWM 6 cylinders are not a good Idea to do this on, as well as Chevy V8's. I still see tons and tons of them out there with them, and almost never see forum posts about them failing in some weird way.

Dyno will happen soon. Every moment on the dyno has been spent doing other things lately. But this will happen soon. As I have said on the other crank pulley thread, I don't expect it to show up on the dyno. The weight of the drivetrain doesn't really effect HP readings on our dyno. We also haven't put this on as its a variable to HP gained on other parts.

Originally Posted by sportsguy83

The downside is the potential for vibrations in your motor internals, especially at high RPM.

Since this isn't a balancer, its not going to cause an imbalance as though a rod was 15g heavier than another.

Originally Posted by sportsguy83

I read countless of threads, and people swear by this mod. Lots and lots of positive reviews, not really anyone reporting any issues with a regular LW pulley. People have issues with Underdriven pulleys but this Perrin Pulley is not underdriven. NOW I am a bit concerned, as pointed out by @Nezz, that the stock pulley is balanced.

My question to anyone with way more knowledge than me is: are those balance marks of just the pulley being balanced, or are those marks of the pulley being balanced together with the crank, rods, pistons, flywheel?

I think this was answered before, but just to make sure. All the parts during manufacturing are balanced individually. From what I have seen on most all mass produced engines ,is that the cranks are balanced by them selves with weights representing the rods and pistons. The manufacture simply uses the fact that all the rods/pistons are made with-in say .001" tolerance making the weights all the same. Is this perfect? No, but its good enough. Just like the last 3 Subaru engines I built, I didn't balance them at all, i just tossed in the rods and pistons and called it good (there way more to it than that of course)

Originally Posted by 86drift

I'd like an answer to this before I install a LW pulley. When I have an engine built it is balanced together.

One of the things I first noticed driving this car was the slow reactions of the engine due to flywheel (and pulley) weight. I find my gear changes are faster with lightened flywheels.

There are a handfull of customers that have reported how this helps reduce this slow feel. I can also tell you that a full exhaust system also makes it feel much snappier!

Originally Posted by karma003

Taking another look at it, I figured it out. I think those dimples on the edge for the static timing. Advancing or retarding the time & those stand for the degrees & limits of advancing & retarding I believe. They used to put little notches on the lip, I'm going to throw out a random guess & say that's what I think it is

There are timing marks and have been for years on Subarus. We always laugh because there is nothing to adjust visually to change timing. Spending time hooking up a timing light is a waste of time as its breaks up at higher RPM. While its funny to us, we do get asked that question a lot. We do not include the timing mark as its not worth the added time ($$$) to do this as there is no reason to. If you want to adjust timing, that is what a reflash is for.

Its great that these threads exist as it does nothing but help everyone out with making good decisions about buying new part. I suspect in a year, or so, there will be lots of happy customers and the concerns will go away.

[Philly]

Hey guys,
Let me add my review. I just installed the Perrin pulley today. For the most part 1st and 2nd gears feel slightly quicker, and throttle response from stop feels better also. Also, I think I hear a bit more noise from the engine, which I don't mind. After weighing the stock pulley and the new one, I don't doubt there has to be some gain from this upgrade.

The pulley itself looks and feels very high quality - I got the red one. Although I'm no professional in the matter, if I were to quantify if there's any gain in HP I would say it feels like 5 hp. Again, I'm no expert just trying to share my experience.

Overall not a night and day difference, but makes the car even more fun. In fact, I think I'll go for drive right now

[Sportsguy83]

Originally Posted by PERRIN_Jeff

Lots of questions to answer here. ...

Thank you so much Jeff. This is EXACTLY what I wanted, knowledgeable input from an educated and experienced individual. It was a LOT of questions, and you got to them. Now I can rest this topic in peace. My Pulley will not be coming out anytime soon.

[Bonburner]

Originally Posted by PERRIN_Jeff

Lots of questions to answer here.

Thanks Jeff!

I'm a little curious if you've tried replacing all the pulleys. I'm sure you could shave a lot of weight and I've seen some modified blocks from japan where they've all been replaced.
Any lights saying there's a problem or anything?
Also have you tried tossing a lightweight flywheel with the pulley/pulleys?

Thanks!

[PERRIN_Jeff]

We have not replaced the crank pulley yet. We have a customer who has and should be testing a crank pulley along with it in the next couple of weeks. That will be a good test! Some customers are concerned about misfires (mainly old WRX customers) and we should be able to put that to rest as well.

[OrbitalEllipses]

Originally Posted by PERRIN_Jeff

We have not replaced the crank pulley yet. We have a customer who has and should be testing a crank pulley along with it in the next couple of weeks. That will be a good test! Some customers are concerned about misfires (mainly old WRX customers) and we should be able to put that to rest as well.

Weren't misfires caused by lightweight flyhweels used in conjunction with lightweight pulleys?