Hi everyone, so I installed an ACT light weight flywheel on my Ap1 and I noticed a difference in power/torque. When I first purchased my s2k It seemed much faster in both aspects. The tires used to screech from the power transfer of the engine to the wheels after down shifting from mid to high revs and punching down on the accelerator. Overall the car seemed much faster with the OEM flywheel. As with the ACT light weight flywheel, the engine revs alot sooner (faster) but seems sluggish when you accelerate from a stop and also makes the exhaust sound louder but doesnt feel like it's moving for the sound it's making. I also have a stage 2 spec clutch installed. Has anyone else experienced this? Will going back to an OEM flywheel get rid of this. I understand light weight flywheels reduce rotational mass and create an imbalance in crankshaft rotation as well as these flywheels are usually used for track, drifting, or drag where quicker revs are needed for a better power response.

 

I went from an AP2 flywheel to an AP1 flywheel and finally to an ACT pro lite flywheel recently. In each case the engine got peppier and easier to rev which feels great on the heel-toe downshifts. It takes a little bit of technique when pulling away from a dead stop but I don't feel that it's any more sluggish than the heavier flywheels in the low RPM. On the contrary, the car as a whole felt faster with each change to a lighter flywheel. It might be in my head but I don't notice what you seem to be describing. It also doesn't seem any louder than before.

 

Lighter flywheel anecdotally shifts the powerband more towards the higher rpm. The heavier flywheel is Capable of storing more energy as rotational inertia which gets transferred to the wheels when the transmission is engaged. This provides a feeling of torque like you used to have but at the expense of a slower revving engine since the heavier flywheel requires more energy to spin it faster.

 

A lightweight flywheel does absolutly nothing to the powerband of the motor. A lighter flywheel wont make more horsepower. It will allow the motor to rev faster and access the available hp sooner.

 

You seem to have skipped an entire word in my post. I stated it Anecdotally shifts the power band. I didn't say it did it physically. I phrased it in a way the op could understand not knowing his background in physics but I did follow that up with a simple explanation of why it would feel as if the powerband is shifted.

 

Except 'anectodal' doesnt mean 'perceived'. But yeah, you are right. To some it can 'feel' like that, the perceived effect of lighter flywheel...

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It frees up HP, it doesn't make hp. Its removing rotational mass. Removing weight anywhere from the drive train frees up hp, such as wheel weight, driveline etc, but the flywheel has the most effect on this, coupled with engine response when out of gear. I run the 8.3LB Act pro light flywheel with my F22 and would never go back to the stock boat anchor. It also removes duty from your clutch, if thats a concern/factor for you.

 

Think we are talking about inertia. Inertia of an object is the energy needed to change its motion. Whether at rest or moving. In this case, the angular momentum of the engine. More mass of flywheel (greater inertia) = greater energy needed to change the RPMS of the engine. Too much inertia = very sluggish engine response to throttle.

Too little inertia = an engine that does not rotate smoothly. Subject to unwanted pulsing because the source of energy is pulsing and not constant (pistons are firing in pulses).

Think of the flywheel as an object that stores rotational energy from the pulsating engine. Then, releases this stored energy, when the pistons aren't firing, back to the engine's rotation to help smooth out the ebb-&-flow of combustion, to make the engine run more smooth.

Like smoothing out a sine wave curve. Trying to make it more straight or linear. And not undulating.

So, what you need is a balance between responsiveness and smooth performance.

The absolute amount of HP or torque produced by the engine does not change, with flywheel changes. The transient time to get to max HP or torque (or any point on the powerband) and stay there, does.

 

...which means not everything that improves performance shows up on a dyno. This is one reason the butt dyno and real dyno dont always jive (other big reason is of course placebo effects, etc).

Sometimes you make a chance you really can feel, but naysayers claim its not real since dyno doesnt show it. Both are right. Yes, it didnt improve hp, yes, it did improve performance.

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If you have an AP2, its flywheel should be significantly heavier than an AP1 or an aftermarket flywheel.
I hear it makes a big difference.
Enjoy it