thread ressurection..

noticed people comparing lightened flywheels to lightened main pulley..

so would it be a good idea to get a lightened main pulley with a lightened flywheel? i have a 9.5lb flywheel with auto-counterweight but i don't think it's as balanced/smooth as i would like it. could a aluminum main pulley help balance it out end-to-end? just a crazy idea i had..

edit: doesn't seem like it would matter at all just throwing it out for discussion.. lol

 

What exactly isn't balanced/smooth? You'd most likely have to balance your entire rotating assembly imo.

I don't run any kind of aftermarket main crank pulley, but after I deleted my p/s and a/c I just got rid of one of the two main crank pulleys. Boom, free mod

 

the engine seems to wobble slightly maybe every 5 seconds when idling. and when revving up seems to do the same. but it does smooth out/become less noticable as rpms increase.

the first time i considered there there being a problem was after test driving a rx8 and noticing its perfect idle.. no wobble at all. then i tore down my engine due to blown coolant seals, and noticed the front and rear main bearings were both showing uneven wear. talked to racing beat and they said it might indicate a imbalance with the rotating assembly or over-revving. jim told me not to worry about it on a street car, so im looking for minor things that may help the situation- even if only partially.

 

You're not actually gaining power. just re-assigning it from moving higher ratio/heavier pulleys. Thus more power to the wheels. the engine is always making the same amount of power, it is just how efficient you can make the overall operation. I understand that this is not directly on topic, but my next sentence will tie it in:

using underdrive pulleys will make a difference. if you didn't notice much of a difference, you probably didn't install the main pulley. it will also improve your overall water pump performance, since it will cavitate at high rpm. if you autocross in the summer, underdrives are your friend in EVERY WAY! (except maybe your alternator... )

 

Well, your flywheel itself should not have any effect on rotational vibration because it should be balanced within itself. The auto counterweight that you added was not originally matched with your rotors and front counterweight. This is what will introduce an imbalance. Your original flywheel had an integral counterweight that was matched to your original rotating assembly.

A pulley isn't going to make a bit of difference.

In a nutshell, you could have a 1lb flywheel and a 20lb front pulley. As long as you have the right counterweights, your rotating assembly will still be balanced.

 

yeah.. bummer. i will have to get it all rebalanced, thats too bad shops just slap on a auto counterweight with a lightened flywheel and figure it is good enough

 

It's weird, I read alot of people saying it doesn't matter, some saying it only matters on a track car, and still others saying that you definitely need to have it all re-balanced. I guess sometimes it is good enough, it just depends on how lucky you are.

I wonder if you couldn't send out your original f-wheel and the new f-wheel and counterweight and have them matched. That way you wouldn't have to pull apart the engine to get a good balance. It would be worth asking around about it.