So i am a kid now... should I be calling you old fart? this is lame. before my lighter flywheel, i can do perfect Heel-toe, rev match and not jerk one bit in my integra. since driving the TC, i jerk even when i force myself to gas earlier. I never had a jerking problem driving my friend's civic, g20, rx7, mr2, and another integra either.

my other buddies mercedes has worse throttle delay than the TC. it's an auto. no flywheel here.

draxcaliber:
thanks for your reply.
I am also knowledgeable about cars and very often, I diagnose and fix my own problems. however, to say i don't respect his knowledgeable about the electrical system would be a lie.

 

I know this will no doubt make someone crazy, but I have to ask. Is there a difference between a lightweight crank pulley and a flywheel, or are they one in the same?

 

yes, they are two different parts at opposide sides of your engine.

the crank pulley turns your serpentine belt that powers your alternator, water pump, and a/c condensor.

the flywheel is a wheel that your engine spins, and then the clutch holds a friction plate to it to spin gears in the transmission and move the car.

they are both part of rotational mass.

 

So, would a flywheel generate more HP then a crank pulley? What is the better mod here?

 

neither one generates more whp. as part of rotation mass, the heavier they weight, the more power they require, and the less power that gets from the engine to the wheels.

so replacing these with lighterweight components means less energy used to spin them and more energy that gets to the wheels.

 

they do not add hp, but lighter one reduces rotational mass thus making the car increase/decrease rpm faster.

 

there are pro's and cons to each of them.

the crank pulley is way cheaper, and easier to swap and you can do a full set of nst lightweight pulleys for the crank, alternator, and water pump, and even the supercharger pulley.

all you need to is take off the passengerside tire, take off the inner fender, loosen the serpentine belt to swap the pulleys, and replace the belt if you change sizes.

the flywheel is more expensive, and takes alot more labor since the transmission and clutch have to be dropped out to get to it.

also, the flywheel makes the car alittle harder to drive from a stop in first gear because it has less stored energy and can make it easier to stall out. i'm still getting the hang of it after about a week, but it is just a matter of adjusting my timing with the clutch and throttle input.

 

The light weight flywheel reduces the load on the engine. Wich is why the RPMS increase and decrease faster.

Superchargers and Turbo chargers work differently. But both are still dependent on RPMS.

Superchargers build boost as RPM increase.

Turbochargers do not start at full boost. Most turbo chargers reach full boost from 2.5k to 3k rpms. So the faster you can build RPM, the faster you can reach full boost.

My post had nothing to do with adding load on an engine to build boost.

 

turbo build boost by the amount of flow of your exhaust gas. saying it is dependent on RPM might be misleading because when u are deccelerating, you do not boost because you are not on the gas, thus the amount of exhaust gas is similar to being on idle. i am pretty sure about this, but i may be wrong.

 

yes, and same with the supercharger, when you are decelerating, you are not in boost either, because the throttle is closed and it isn't sucking in air.

 

hmm talking about rotational mass and flywheel, it pops out in my mind that also when you are upgrading to a bigger or heavier wheel, you are also increasing the rotational mass thus your car feels a lil heavy when you accelerate from a stop. My question is

1.how do you think would getting a lighter flywheel compensate the slower acceleration brought by the heavier wheel (added rotational mass)
2. Would launching and stalling still be a concern with a lighter flywheel if you have a heavier wheel adding to your rotational mass
3. Would a rapid increase/decrease of rpm brought by lighter flywheel still be there if your rotational mass (brought by heavier wheel) has also increased? my guess is that it wont affect each other that much since its FLYwheel which functions differently with the true wheels.. still not sure...

most likely difference would be felt (if there is any) when comparing from a stop, but im not sure.. any input guys?

 

well, lightweight flywheel with heavier wheels sounds like a car that would be a pain in the @$$ to move from a stop because making the flywheel lighter alone makes it harder to launch the car, so making the wheels heavier too would make it even more difficult.

 

^^ I prolly got it know, lighter flywheel has less stored energy potential.. from a stop, less energy needed to move it but at the same time less energy needed to stop/slow it = faster rise/fall of rpm..
With heavier wheels+ lighter flywheel (less potential to keep the energy) = harder to launch..

 

The thread is about light weight flywheel pros and cons. Not the workings of turbos adn superchargers. My post was expressing the benefit a light weight flywheel would have on those applications. Stay on topic.

 

To clarify (most has been said here and there but to put it all together...)

reducing rotational mass does not add or free up power. On many dynos will look that way, but dynos are also inherently inaccurate to a point, so you hvae to take the numbers with a grain of salt. Inertial dynos are the worst and will also say you gained power by putting on lighter wheels.

Reducing rotational mass means the engine will change rpm faster. This is good for acceleration and rev matching, but you also have the downside of it being easier to slow down the engine, so not only will this affect launch, it will to some small degree affect how smoothly the engine feels. Engines dont run smooth, they run on a series of pulses. One reason for a flywheel is to smooth out this effect and make it feel smoother. With a change like this, that effect should be small to un-noticeable, but still there.

A lighter flywheel would help you a little bit on building boost since you can spin the engine up faster, but really, load plays a very large role. The engine can spin as fast as it wants, but if the throttle is not open far enough then you arent moving as much air.

As far as pullies vs flywheels, the flywheel removes its weight from a much larger diameter, thus making it a MUCH larger impact on things (pulley is near negligible). And since the pullies remove the damper (NOT BALANCER) I would never put one on my car. There are plenty of threads with plenty of links to people talking about this, so I will leave that argument there.

So really, I would not expect the flywheel to improve boost performance much other than in neutral. When pulling, the car isnt going to spin up that much faster since the flywheel is a smaller part of the drivetrain mass and torque needs. A light flywheel is best for helping out on rev matching and a little bit on acceleration.

 

Nicely put.