DigitalSynthesis

Okay. The stock flywheel HAS a counterweight built into it. This is critical to vibration reduction. If you go aftermarket on the flywheel, then you MUST use an automatic tranny counterweight which is designed to go with the rotors you use. Search on this, you'll find a lot of info. Rotors and counterweights go together. The front counterweight is just a small one, its not sufficient to balance against the rotors. I think perhaps the front counterweight balances the e-shaft but I'm not 100% sure on this. I do know for a fact that the rear counterweight balances the rotors and is therefore critical that it be matched to the set of rotors you are running, such that with the weight but w/o the flywheel, the engine is perfectly balanced. Then, once you add the balanced aftermarket flywheel, you still have a perfectly balanced engine. Got it?

zjbarra

iTrader: (2)

That makes sense. I can't use the automatic counterbalance though since it's not going to be matched for turbo 2 rotors though am I right? So I need to buy a counterweight from racing beat or someone along those lines?

I was thinking from the begining that the rotors were out of phase at the correct angle to not require any counter weight but I guess this would be in the ideal rotary engine where the rotors would only spin and not move beyond that? We're gong to go with a s5 counter weight for now and see what I can do about getting a s4 one. Thanks for the info.

GUITARJUNKIE28

using an s5 counterweight with s4 rotors will blow it up!!!

DigitalSynthesis

Yep. You MUST match the counterweight with the rotors, as I said. MUST. MUST. MUST. And I have an auto counterweight from an S4 TII on mine. So I know they exist. :-P

zjbarra

iTrader: (2)

Oh I know I must have it, I'm just trying to figure out what I need to get. An auto counterweight as in for an automatic turbo 2? Did they make them in japan or something?

DigitalSynthesis

Yes, an auto counterweight as in from whatever model your rotors came out of. If you have S4 TII rotors, then you need an auto from the S4 TII. If you have S5 TII rotors ... you got it.

Mine came with my engine when I imported it from Japan. I thought they made automatic TIIs in the US as well, though.

zjbarra

iTrader: (2)

I'm almost 100% sure they didn't actually. That is why I asked a couple times to make sure. I looked at a webpage that said the weight of the rotors out of the NA is the same as that of the turbo for both s4 and s5's I'd assume that the mass of the rotor is balanced so would I be able to use ANY s4 counterweight?

DigitalSynthesis

I could be wrong but I believe that the CR being different requires you to use a different counterweight as the weight of the rotors might be equal but the center of gravity for each might not be. I cannot state whether it would work or not, but something in me suspects you would run into problems.

zjbarra

iTrader: (2)

I would figure the rotors to be balanced thus making the center of mass right smack in the center. Beyond that, if the essentric shaft did not change weight, it would make sense that be universal from NA to turbo. Just an idea, not something I want to roll the dice on though.

DigitalSynthesis

You are right about the center of mass, I think I meant polar moment, which affects rotational inertia. But my main point was the same as yours: its not something to gamble on.

GUITARJUNKIE28

i have always wondered if the n/a and turbo rear counterweights were the same.
for my personal preference, i don't like really lightweight flywheels--the 3rd gen stock flywheel is just fine for me.

zjbarra

iTrader: (2)

I'm sure too light can be a pain. The steel I put in is something like 18 with counterweight so it shaves a bit.

Some has to have tried this out. I think the only problem would be that without a machine to balance it with, you're going to be shooting blindy because even if the polar moment was really close, it would probably be hard on the engine as well. I do think that the polar moment about the center axis of the essentric shaft is going to only be effected by the location of the center of mass of the rotor which would be a single point location dead center of the rotor. It's instantanious "lever arm" is going to be the same distance regardless of the rotor used and the center of mass should never be changing unless my physics is more wishful than accurate :-P

RETed

Counterweights are dependent on rotor weights.
Since the turbo versus non-turbo rotor weights were identical for matching years...yes, the counterweights are identical.



-Ted

DigitalSynthesis

Well then. There it is. Go for your NA auto tranny counterweight from that year.

GUITARJUNKIE28

ted's the man