lightwieght pulleys, pistons, flywheels, driveshafts

[AeRoKaBn]

Been on google searching through other forums and manufacturers sites for awhile now but havent really been able to tell if they make much difference. Heres what ive read

pistons/rods- accelerate quicker, increase rev limit, decrease bearing loads

pulleys- takes less power to run them, decreased engine load

flywheel- improved acceleration in lower gears, revs drop quicker, easier to stall

1 piece alloy driveshaft- gets more hp to the wheels, some notice increased vibration

None of these things will give a higher peak HP as is, but all claim to improve acceleration, some say theyve noticed a difference same say they havent but if u were to install all of the above do u think you would notice much difference in acceleration/lag? are they any other pros/cons?

Ofcourse alot will say money ($5K?) will be best spent elsewhere and u would be right but i just want to know if ud be able to notice the difference if u had everything above not just one or two items

also these things are all hidden from sight (apart from pulleys and driveshaft which would only get seen on super close/hoist inspection)

[Kyosho]

flywheel makes a HUGE difference in how the car drives.

[brett_celicacoupe]

pulleys- takes less power to run them, decreased engine load

pulleys dont take 'power to run' if rpm is constant. well they do but only through air resistance(minimal). they do affect things if the RPM is changing. if the angular velocity (RPM) is decreasing then energy will be introduced to the system (lost from the rotating mass). this will decrease the rate at which everything slows down.

probably best to read through wikipedia articles on torque, power, angular acceleration, angular velocity, moment of interia


by removing weight from rotating parts you lower the moment of inertia. its most beneficial to remove weight from the outer sections.

[AeRoKaBn]

pulleys dont take 'power to run' if rpm is constant. well they do but only through air resistance(minimal). they do affect things if the RPM is changing. if the angular velocity (RPM) is decreasing then energy will be introduced to the system (lost from the rotating mass). this will decrease the rate at which everything slows down.

probably best to read through wikipedia articles on torque, power, angular acceleration, angular velocity, moment of interia


by removing weight from rotating parts you lower the moment of inertia. its most beneficial to remove weight from the outer sections.

yeah i get what u mean cos they are just a pulley but what they are connected to is what takes power to run at all rpm constant/accelerated but im talking about under acceration

flywheel makes a HUGE difference in how the car drives.

(edit: with the whole "less stored energy" thing) whats it like launching? i read u get like a "virtual?" 30hp increase in first (depending on hp u started with), 20 in second, 10 in third and decreasing in every gear after that etc

[Sam_Q]

the general concencus is that flywheel weight makes a big difference, as for the others I cant say much about the power increase.

I will say though be very carefull of aluminium crank pulleys. I think almost all pulleys have a rubber isolator thats there for a reason. Now I am not going to pretend to know much about it other than I think you should be carefull.

[Kyosho]

(edit: with the whole "less stored energy" thing) whats it like launching? i read u get like a "virtual?" 30hp increase in first (depending on hp u started with), 20 in second, 10 in third and decreasing in every gear after that etc

With the whole launching, you REALLY have to slip the clutch a fair bit more. They do drop RPMs rather quickly as you let the clutch out, so you have to learn to use the throttle more.
BUT, if you break traction, they near on instantly snap to redline in wheelspin, as the motor can accelerate alot quicker.

Unsure on this "hp" shit you're on about. Just make the engine more responsive, even in 5th

[Macross]

I will say though be very carefull of aluminium crank pulleys. I think almost all pulleys have a rubber isolator thats there for a reason. Now I am not going to pretend to know much about it other than I think you should be carefull.

The reason for this is that the vibration of the crankshaft is not dampened with an all-alloy pulley, so the crank can literally shake itself to pieces given the chance.

For the O.P. I run a complete set of lightened pullies and flywheel on my 2jz and I have to say that the difference is massive, though most noticible is that lightening the pullies and changing to an aftermarket crank damper is that driveline vibration has decreased tremendously as well as the revs rising much quicker. Haven't had any problems with having to slip the clutch more, drives like any stock car with upgraded clutch (but with more power )

[Draven]

I've got a twin plate clutch (which has a lightened flywheel)... stock assembly weight was ~25kgs, twin plate assembly was ~13kgs.

you'll stall a bit to begin with, and then get used to it

[AeRoKaBn]

sounds good, whats this aftermarket crank dampener? what brand is it

think ill definately be going with a lightened flywheel when i need a new clutch

Kyosho ill try and find the website i got it off was a good read, they said the light flywheel basically makes the "virtual weight" of ur car less

[Draven]

It makes the actual weight of your car less too.. by 10kgs in my case. the difference is that in lower gears, the rotational mass of the engine/driveline has a much greater impact on acceleration, so that 10kg difference will be effectively much more. As you go higher up in the gears, the difference drops back closer to to just being 10kgs.

The lightened flywheel makes the car feel a lot revvier and more responsive, but depending on your current mods I daresay leave the lightened pulleys until you've done plenty of other mods, because the benefits are simply not worth the cost.

[Talasas]

Has anybody ever had trouble with non-damped alloy pullies before? I understand that they pose more of a problem on 4 cylinder cars due to the lack of overlap in power strokes but so many people use the on 4AGZEs and I've only seen them crack along the spokes due to twisting.

[Kyosho]

Draven: From what I've been told, any form of rotational mass, is also equivalent to 10 times the static mass.

And I also agree 100% with the having to get used to it when taking off, due to how quickly they will change revs, with a lower momentum

[brett_celicacoupe]

Draven: From what I've been told, any form of rotational mass, is also equivalent to 10 times the static mass.

thats bit of a broad statement.

it depends on the amount of mass and more importantly, how far it is from the axis

look up the moment of inertia formulas on wikipedia

edit:

for a solid cylinder

I = (Mass*radius^2)/2

[psychofox]

Has anybody ever had trouble with non-damped alloy pullies before? I understand that they pose more of a problem on 4 cylinder cars due to the lack of overlap in power strokes but so many people use the on 4AGZEs and I've only seen them crack along the spokes due to twisting.

There have been many documented cases of 4AGZE Alloy Pullies (ie NEVO, etc.) failing around the keyways due to stress cracks. Many theories about why this is the case, but a lack of dampening could be a cause.

[jeffro ra28]

thats bit of a broad statement.

it depends on the amount of mass and more importantly, how far it is from the axis

look up the moment of inertia formulas on wikipedia

edit:

for a solid cylinder

I = (Mass*radius^2)/2

Agreed. it all depends on how much and how far the weight is from the center. Eg. A 4 inch flywheel will have less inertia of a 12 inch flywheel of the same mass.