Fluidampr Pully

[Johnybeas]

http://www.fluidampr.com/SUBARU.html

Thoughts or feedback???

[icingdeath88]

It was covered many, many times on nasioc and other places as well that the crank pulley serves no damping purpose. Some rep from subaru confirmed it. Just get the cheapest lightweight pulley you like. I just got the kartboy one in the mail this morning. Good price, not bad looking at all (black), and like 2.4 lbs.

[LetItSnow]

Some rep from subaru confirmed it.
"Some rep from Subaru" was quoted as having said that Australia will importing 700 BRZs each month. Subaru of Australia (who allegedly immediately declined interest in the BRZ) shows on their website that the decision won't be made until later this year. Reps don't hold a lot of credibility in many cases, especially in the department of engineering.

I suppose you could argue til you're blue in the face why Subaru shouldn't use the stock pulley they place on the faces of all their engines because they're eleventy billion pounds and fall to pieces, but I'd search for a better answer than some rep saying so. Look for an answer that makes sense.

I wouldn't buy a Fluidampr pulley for a stock or slightly modified Subaru, but for something that'll receive much more punishment, it would definitely be in consideration.

The same, I wouldn't buy a lightweight pulley for any car for performance purposes. They look purdy, sure, but the low mass lost at such a tiny moment of inertia doesn't offer much along the lines of rotational benefit. They're easy bolt-ons if you dig the placebo effect, but they quickly become inconsequential as they drown in the rest of the drivetrain. You can tell me I'm wrong and that you felt a difference, and I'll tell you you're imagining things and can prove it by showing some well-established physics-based math.

[sicksubie]

You can get stock sized pulleys that weight around 18 oz. I had one a while back, but obviously not any more.


Oh and for what it is worth, the only difference I noticed with one installed is that the engine rev'd quicker in neutral. Beyond that no difference really...

[Crazy_pilot]

I bought a lightweight pulley becuase my stocker separated. My engine grenaded a few years after that. *shrug* I'll still put it on the new engine.

[icingdeath88]

Reps don't hold a lot of credibility in many cases, especially in the department of engineering.

True, but I read the thing and it seemed to come from a somewhat reliable source. Too long ago to remember exactly though.

I wouldn't buy a Fluidampr pulley for a stock or slightly modified Subaru, but for something that'll receive much more punishment, it would definitely be in consideration.

Yea after reading about them some more I'd consider one for an engine that was going to rev super high or something. But it would be pretty far down the list. They're expensive too.

The same, I wouldn't buy a lightweight pulley for any car for performance purposes. They look purdy, sure, but the low mass lost at such a tiny moment of inertia doesn't offer much along the lines of rotational benefit. They're easy bolt-ons if you dig the placebo effect, but they quickly become inconsequential as they drown in the rest of the drivetrain. You can tell me I'm wrong and that you felt a difference, and I'll tell you you're imagining things and can prove it by showing some well-established physics-based math.

Yea, I bought it for the looks mostly. The stockers I have are all rusty/nasty looking and I would rather not have to worry about it separating. I figure if it does anything, great, and if not, then at least it looks good.

[Johnybeas]

looking at parts for my build... sorry for all of you that just wanted to make things pretty, no it's not a gutted pully it's an actual stock style pully however much stronger, and if I ever plan to make 640whp I'd like to know my parts are hardcore ;)

I plan to replace my rusty gross ones with OEM parts either brand spankin new or used in good condition have them sand blasted and powdered :) if there were underdrive pullies that were light weight I might look into it, however it's not a priority, there is much more power to be made in other ways.

[svxfiles]

and if I ever plan to make 640whp I'd like to know my parts are hardcore ;)



Schwing!!!!!!!!:eek:

[XT6Wagon]

It was covered many, many times on nasioc and other places as well that the crank pulley serves no damping purpose. Some rep from subaru confirmed it. Just get the cheapest lightweight pulley you like. I just got the kartboy one in the mail this morning. Good price, not bad looking at all (black), and like 2.4 lbs.

Quite... totaly... WRONG.

The EJ motor suffers from very low rotating mass. Put on a exedy twinplate clutch with its lightwieght flywheel and a WRX crankpully and you will suddenly start having nasty misfire issues around and off idle as the engine will start seeing far too large a change in rotation speed with each firing pulse. Smoothing these pulses is critical and keeping enough rotating mass is key.

The SVX will have less issues given more firing pulses, more mass, etc. but you still need to keep the engine management happy.

[Lookin4SVX]

I thought the general consensus on NASIOC was:
Lightweight pulley = OK
Extreme Lightweight Flywheel = OK
Extreme Light Flywheel + Lightweight pulley = BAD

[icingdeath88]

I thought the general consensus on NASIOC was:
Lightweight pulley = OK
Extreme Lightweight Flywheel = OK
Extreme Light Flywheel + Lightweight pulley = BAD

That's how I feel about it too. Compared to the flywheel the small change in mass of the crank pulley is pretty minor. But I wouldn't do both and expect it to work well. The stock pulley is like 5 lbs and the one I got is 2.4, not a pound like some out there. Not a big enough difference for any of the downsides to manifest, hopefully.

The EJ guys have issues with just a lightweight flywheel though it seems like.

[XT6Wagon]

Back when I played with them the STi was more sensitve than the WRX to lightwieght flywheels/pullies. Which is in part why its crank pulley was heavier on the STi. It would also affect performance well before you hit the point where it would start actualy misfiring and/or stalling. In many respects the STi engine management was TOO good for proper performance. Awesome for not blowing motors across the parkinglot, but really happy to yank too much timing, dump too much fuel, etc to false readings.

For a street car, I'd keep some kind of isolation to the accessories.
For a race car, I'd go with either SFI rated awesomesauce like the fluiddamper, or reliable solid metal... And worry about rotating mass on the flywheel side if I have to.

Anyhoo, Nasioc as a souce is often wrong. Lol hundreds (thousands?) of people who were lead down the path to ruin thier turbos by porting the wastegate thanks to mob mentality, bad tuners, and a total lack of understanding about how anything at all works. Things like people pulling more and more timing trying to *LOWER* boost. Yah, you know that wastegate isn't going to do anything when you've spooled the turbo up like a jet engine and feed it huge amounts of air and fuel still burning like a blowtorch when the exhaust valves open.

[icingdeath88]

For a street car, I'd keep some kind of isolation to the accessories.
For a race car, I'd go with either SFI rated awesomesauce like the fluiddamper, or reliable solid metal... And worry about rotating mass on the flywheel side if I have to.

The fluidampr seems pretty heavy, even heavier than the stock ones. Might make it easier to deal with a lightweight flywheel?

What does the isolation between the crank and accessories help with? Protect the crank or the accessories?

Anyhoo, Nasioc as a souce is often wrong.


This is very true. There is a lot of weird stuff going on over there. It's not like here where more experienced members can constantly verify/rectify information - there's just too much traffic. But, there is a lot of information there, and a lot of useful stuff.

[Johnybeas]

^ rocking a lightweight flywheel since day 1

[svxfiles]

^ rocking a lightweight flywheel since day 1

Our TQ weighs about 35#s, plus flexplate.
I just ordered a cromoly 12.5# flywheel for a customer from Colorado, and a Spec Stage 4 clutch.
I will get an actual weight in a couple of days.

That, compared to a 5.4# to 1.4# crankshaft pully seems like like a bigger deal.
Especialy concidering the DIAMETERS of said mass.

[LetItSnow]

Mass (weight is great for static stuff) in rotational bits really isn't a great raw measurement. You can consider that, as a component of the car, you'll be using energy to change its linear direction just like any given fixed part of the car (headlight, battery, spare tire, door, Little Tree (R) ), but that's the limit that any two flywheels, pulleys, wheels/tires, etc. can be compared when using a scale.

You've got to account for the moment of inertia. How far is the average mass from the center of its rotation? Take a given mass on a piece of string and spin it around, and again on a longer piece of string. The further from the axis, the more energy it takes to change the speed it spins.

Two flywheels that read 13 lbs on a scale will not necessarily perform identically in rotational acceleration.

This is also the reason that lightweight pulleys are bling; a crank pulley's moment of inertia is dwarfed by those of the flywheel, the wheels and other bits that make those 2.6 lbs. at a 1.5" radius almost inconsequential and certainly not something that you would notice in straight line acceleration.

Wheels are a different story; they're plenty larger than pulleys in diameter, making changes in their raw mass typically much more influential. Moving the moment of inertia further from the center with a larger diameter wheel fights speed changes substantially, and gyroscopic properties make more effort in steering.

So, unless you're down to the ragged edge or being very cruel to the hardware, g'won and choose your pulley by its appeal to the eye. Don't spend too much time going on about how it took .3 sec off your quarter mile, though? ;)

[Johnybeas]

Our TQ weighs about 35#s, plus flexplate.
I just ordered a cromoly 12.5# flywheel for a customer from Colorado, and a Spec Stage 4 clutch.
I will get an actual weight in a couple of days.

That, compared to a 5.4# to 1.4# crankshaft pully seems like like a bigger deal.
Especialy concidering the DIAMETERS of said mass.

Just curious why spec not exedy?