Effectiveness of a Lightweight pulley

[Ravenlokk]

Considering this costs not much more then a tank of gas, its a pretty good gain for the money spent.

[DEnd]

Originally Posted by Dimman

Part of gains showing on a dyno depend on how the dyno is operated.

On a Dynojet you pretty much just do acceleration pulls, so you will a gain from ANY rotating mass reduction. They measure power based on the time it takes to accelerate a drum of known mass.

However on resistance or brake types that make the motor fight a resistance and hold rpms, you generally won't see rotating mass gains unless they are doing acceleration type pulls.

People should understand why this is as well. It all boils down to Newtons laws of motion.

1st law states an object at rest will stay at rest unless and outside force acts apon it, and an object in motion will stay in motion unless an outside force act apon it.

So it takes force not just to move an object but also to slow it down. In an engine this means it takes more power to accelerate than it does to hold at a steady RPM. This is because the engine has to not only overcome it's internal friction but force is also "absorbed" by the mass of the rotating assembly. At a steady RPM basically the only thing that is requiring power (ie trying to slow the engine down) within the engine (to hold that RPM) is the internal friction of the engine.

This also explains why a lighter rotating assembly slows down a lot quicker than a heavier one. Since heavier rotating assembly has more "absorbed" force (energy) the amount of internal friction is smaller in relationship to the absorbed energy in the parts.

lets look at it like this: a heavy rotating assembly requires 50 lb/ft of force to reach 100 rpms. a Lightweight one requires 25 lb/ft to reach 100 rpms. If the drag caused by the internal friction in the engine is say 1 lb/ft then you can clearly see that the lightweight assembly will slowdown about twice as fast as the heavier one, and likewise accelerate faster with the same power applied. However once it reaches it's destination RPM, since the only power it requires to stay at that RPM is to overcome the internal friction both engines will output the same power (all else being equal).

So real world what does this mean for us? It means that with lighter rotating componets you will see quicker acceleration for the power applied, and likely better gas mileage while accelerating (especially if you accelerate at the same rate). However, you will not see a higher top speed, nor increased fuel economy at a steady state.

[FrsSwag]

Originally Posted by Celica00

decreasing rotational mass and increasing throttle response.

cheap and easy upgrade. I want one

[wlfpck]

Please read the last two pages of this thread. (Pages 10 - 11)

http://www.ft86club.com/forums/showt...=12450&page=11


Also... We are talking about a dampener on the pulley. Not a balancer. They are two different things.

If you go to the thread above and read pages 10 - 11, it contains a lot of things that I've posted about the lightweight pulley.

At the same time, I have linked a thread on yoursciontc.com.

This thread contains A LOT of information about undampened crank pulleys.

It also contains a reason that people in Supra world no longer run undampened pulleys.

Also... If these pulleys were so safe and such...

The NHRA requires a dampened pulley.

ATI and other companies make dampened pulleys that cost almost 3 times the cost of these aluminum pulleys.


However... there are some people that have ran a undampened pulley on the scion tc for 50k miles. If you think that it is enough evidence for you that the pulley is ok for the car, then go for it.


P.S....

You'll see more improvement from a lightened flywheel and you can see the exact same results by getting lighter wheels.


http://www.suprasonic.org/public_htm...atedamper.html


As for seeing the gain on a dyno... you'll see a gain if it is an inertia based dyno. Which again, you will see a gain on these dynos if you use lighter wheels.

[mike2100]

Originally Posted by wlfpck

Please read the last two pages of this thread. (Pages 10 - 11)

http://www.ft86club.com/forums/showt...=12450&page=11


Also... We are talking about a dampener on the pulley. Not a balancer. They are two different things.

If you go to the thread above and read pages 10 - 11, it contains a lot of things that I've posted about the lightweight pulley.

At the same time, I have linked a thread on yoursciontc.com.

This thread contains A LOT of information about undampened crank pulleys.

It also contains a reason that people in Supra world no longer run undampened pulleys.

Also... If these pulleys were so safe and such...

The NHRA requires a dampened pulley.

ATI and other companies make dampened pulleys that cost almost 3 times the cost of these aluminum pulleys.


However... there are some people that have ran a undampened pulley on the scion tc for 50k miles. If you think that it is enough evidence for you that the pulley is ok for the car, then go for it.

Just FYI, for me this thread only has 6 pages. Depends on how many posts per page you set in your options.
Also, remember that references to TC and Supra engines do not completely apply. Different animals with very different damping needs.
And... NHRA requires dampened pullies... for what engines? Hot Rod engines?

[wlfpck]

Originally Posted by mike2100

Just FYI, for me this thread only has 6 pages. Depends on how many posts per page you set in your options.
Also, remember that references to TC and Supra engines do not completely apply. Different animals with very different damping needs.
And... NHRA requires dampened pullies... for what engines? Hot Rod engines?

That's why I put page 10 - 11 in (). The sentence reads Read the last two pages...


As for the different animals thing....

Yes, you are correct. The supra and tC engines are not the same. Keep in mind that the the scion tc thread and the other thread in ft86club also reference Dinan as well.

As for the NHRA, if I am not mistaken, that is for any of their track events.

---------

Do I advocate people using undampened pulleys or for using dampened pulleys? No. I could care less what people buy. It does NOTHING for me. I am simply sharing the research that I have done.

On that note, there are some things to think about...

Is the factory pulley dampened?

If it is dampened, why would subaru/toyota spend more money on using a dampened pulley as opposed to just making a steel undampened pulley? The manufacturing process is a lot easier for an undampened.

What are the research hours/process that these companies used to make the lightened crank pulleys? Taking a stock pulley, then creating it in CAD so that it can be CNC'd out of Aluminum is not research. No company that has undampened pulleys has provided any sort of documented testing for their pulleys either (to my knowledge).

Why do people purchase lightened pulleys from ATI and Fluidampr for 3x the cost of the lightened undampened ones?



In conclusion...

Maybe running an undampened pulley will have no negative effect what so ever on the 86. Maybe the damper is actually not needed because the engine doesn't rev high enough to achieve the disastorous frequency that causes issues. The point is that it is untested for an extended amount of time. There needs to be controlled testing that takes place.

Look at the Air Raid Intake thread. Just look at the testing that went on to provide people with an intake. I have yet to see any sort of "research and development" thread that was created for these lightened crank pulley.


Again... this is NOT my car. I simply share information that I came across in my research. I can lead a horse to the water, but I can't make it drink. If people CHOSE to run an undampened pulley, go for it. It doesn't make me a millionaire and it doesn't make me lose any sleep either. It has ZERO effects on me.

[showbe]

What are some cons from doing these mods? Like Lightweight pulley and the Carbon Fiber DRIVEshaft? Long term downsides to these mods? Reduced engine life?

[Ranatsu]

Originally Posted by showbe

What are some cons from doing these mods? Like Lightweight pulley and the Carbon Fiber Crankshaft? Long term downsides to these mods? Reduced engine life?

You mean drive shaft.

[showbe]

Originally Posted by Ranatsu

You mean drive shaft.

ya thanks hey i was close. was too lazy to check to see if i was right

[OrbitalEllipses]

Originally Posted by Ranatsu

You mean drive shaft.

CF crankshaft WOULD be cool.

[MSTiFK8R]

has anyone seen negative effects on Subaru engines, caused by undampened pulleys?

I personally heard of ZERO issues

Having swapped my pulley for PERRIN's one, I am really cautious about risk I may carry from now on

[wlfpck]

It's too soon to tell. After a lot of hard driving (track driving) and higher mileage, then it will be possible to determine the reliability.

It's the same with any experiment, you need to data to create a conclusion. That why I only provided background information from research. Actual data is not available as of this time for the 86.

[Celica00]

Originally Posted by MSTiFK8R

has anyone seen negative effects on Subaru engines, caused by undampened pulleys?

I personally heard of ZERO issues

Having swapped my pulley for PERRIN's one, I am really cautious about risk I may carry from now on

perrin has said they've been using LW pulleys on boxer engines for years w/ no issues. so i'd assume its the same for the FA20

[OrbitalEllipses]

Originally Posted by Celica00

perrin has said they've been using LW pulleys on boxer engines for years w/ no issues. so i'd assume its the same for the FA20

As has been said numerous times: it's because the boxer is naturally balanced (moreso than inline and vee engines) and doesn't use the pulley as a harmonic damper.