Flywheel Characteristics?

[i<3mycb7coupe]

as soon as i got the car i installed street act flywheel not even the race one, n it dropped the torque bad...
my other mods - exedy stg 1 clutch, + greddy evo2 exhaust n left it there...
my question is, does this really drop the low end torque, cuz it feels weak even for a honda XD, any replies are appreciated

[wed3k]

it's called loss of inertia. you have to rev it higher in order to get the car moving to the same speed.

unless your timing is off from not puting it back in the same spot when you did the flywheel job.

[Leung]

is that even possible? when Customchord put my F1 flywheel on, he could only install it one way because of this peg that was sticking it. So he naturally just lined it up to fit that peg.

[i<3mycb7coupe]

yeah it pops on one way, n the timing was good before n is afterwards,
it kinda blows cuz i do have to rev it higher n if i dont it jerks like a mofo, shakes the whole car

[Leung]

yeah i've got an 11.5 pound F1 fw. i figured i'd have to turn up my RPMs because i'm also using metal/poly engine mounts otherwise my dash is going to rattle like a mofo.

[do2mind]

yeah it pops on one way, n the timing was good before n is afterwards,
it kinda blows cuz i do have to rev it higher n if i dont it jerks like a mofo, shakes the whole car

Okay, here's the deal...

The flywheel is on the engine side of the clutch... and it's basically a weight that spins with the motor.

There are three basic purposes of a flywheel... and all are related to Newton's First Law of Motion... i.e. a weight in motion will remain in motion unless acted on by a force.

The first purpose is when you're idling (i.e. spinning the shaft at low rpm)... the cylinders power the shaft in a jerky way... bang, bang, bang, bang... and in between the bangs nothing is turning the shaft... but if you attach a weight that spins with the shaft... it keeps the shaft spinning more smoothly at low rpm than it would without. A drag racing car with a super light flywheel may have trouble idling.

The second purpose is that when you're shifting between gears... let's say from second to third... because you let off the gas and momentarily drop your horsepower to near zero, the engine would naturally tend to wind down because an engine that's supplying less power than it takes to maintain steady state actually acts as a brake... but the flywheel... a spinning weight... will tend to keep spinning, and make it easier to synchronize the motor shaft to the the transmission / drive train to get into third gear... and off you go.

[do2mind]

The third purpose is starting from a standstill... this purpose is the purpose that requires the flywheel to be heaviest in an OEM car... and this is going to be where you see the most difference when you get an aftermarket light flywheel... a car is a heavy thing... and starting something heavy moving from a standstill takes a lot of energy... more energy than your little F22A four banger has at 2000 rpm... BUT... if you take that little F22A four banger and attach an 18 pound weight and spin THAT at 2000 rpm... now you have some stored kinetic energy. When you pop the clutch and the standing still car wants to kill the engine... that extra stored kinetic energy helps get the car moving without killing or dragging down the motor.

BUT... when you go with a light flywheel... you don't have as much extra stored kinetic energy, and are more likely to bog down or kill the engine unless you rev it up.

The other half of Newton's First Law of Motion is why we go with light flywheels when we want performance... a weight at rest will remain at rest unless acted on by a force... a heavier flywheel is harder to accelerate.

And that's that.

So that's why it's easier to stall from a standstill with a light flywheel... simple physics... not necessarily a bad flywheel.

[ibr_adam09]

mmm, good read. a flywheel could do so much

[wed3k]

a good clutch (like an ACT 4 puck) + heavy flywheel = good for launching

[robert@bisimoto]

The third purpose is starting from a standstill... this purpose is the purpose that requires the flywheel to be heaviest in an OEM car... and this is going to be where you see the most difference when you get an aftermarket light flywheel... a car is a heavy thing... and starting something heavy moving from a standstill takes a lot of energy... more energy than your little F22A four banger has at 2000 rpm... BUT... if you take that little F22A four banger and attach an 18 pound weight and spin THAT at 2000 rpm... now you have some stored kinetic energy. When you pop the clutch and the standing still car wants to kill the engine... that extra stored kinetic energy helps get the car moving without killing or dragging down the motor.

BUT... when you go with a light flywheel... you don't have as much extra stored kinetic energy, and are more likely to bog down or kill the engine unless you rev it up.

The other half of Newton's First Law of Motion is why we go with light flywheels when we want performance... a weight at rest will remain at rest unless acted on by a force... a heavier flywheel is harder to accelerate.

And that's that.

So that's why it's easier to stall from a standstill with a light flywheel... simple physics... not necessarily a bad flywheel.

This is true. We at Bisimoto on use and sell aluminum flywheels.

[HondaFan81]

do2mind, very nice explanation, very nice.