Lightweight flywheels For NA: Pros and Cons

[Phoenix7]

I have the NA's motor out and I'm starting to put the replacement together and I think this is the best time to upgrade the flywheel...I'm looking to get input from those with lightweight flywheels and how light I should go.

The NA will not be daily driven but it will see some mild traffic once in a while.

[infernosg]

Sub for info.

I had one of Fidanza's 7.5 lb flywheels on my old turbo Protege (with an Exedy clutch) and I hardly noticed a difference. I had to give it a little more throttle to get it going and shift a tad faster but it wasn't anything inconvenient. I daily drove the thing too. I don't have any experience with them in a rotary though.

[Kentetsu]

I installed the Racing Beat lightweight steel flywheel on my 12a this spring. Feels okay, but I should've gone lighter. If I had it to do again, I'd take a look at the Fidanza Infernosg mentioned.








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[diabolical1]

i've heard all sorts of stories from one extreme to the other, but my experiences have not uncovered any drivability issues. on my MR2 Turbo, i never found myself having to slip the clutch any more than with the stock. on my Rx-7, i never detected any need to slip it more either. the only difference i detected there was engine deceleration between shifts, but it was only slight. admittedly, it could have been my mind's expectations manifesting itself.

i must add though, that i lived in Florida, so it's pretty flat. i see you live in the Bay, i've been San Francisco (spent a few hours in Oakland, too) and i know it's hilly, so that may affect your experience if you decide to do it. however, as long as you can adjust yourself easily, it shouldn't be a problem even then.

Originally Posted by Kentetsu

I installed the Racing Beat lightweight steel flywheel on my 12a this spring. Feels okay, but I should've gone lighter. If I had it to do again, I'd take a look at the Fidanza Infernosg mentioned.

this was the experience i had with the lightweight steel on my old 12A. i plan to move to aluminum for my next engine.

[jtbshaw]

Keep in mind that if you go lightweight FW, you will lose torque.

[diabolical1]

Originally Posted by jtbshaw

Keep in mind that if you go lightweight FW, you will lose inertia.

though i think i know what you meant with your original statement, i also think this is more correct.

[IH8DSM]

It's a rotary what torque

[NoDOHC]

Keep in mind that if you go lightweight FW, you will lose torque.

Although the launch is a little weaker becuae you lose engine inertia relative to vehicle inertia (which barely changes with the little bit of weight you save) if you look at the engine and drivetrain as a whole, where would the lighter flywheel put the torque - if it were causing you to lose it?

Anyway, I went from a stock flywheel to the Fidanza, I picked up 0.2 seconds in the 1/4 mile. (13.4 to 13.2) with a completely stock RX7.

I didn't notice that the launch was that difficult with a stock-type clutch in the car.

I now have a RB 12 lb turbo flywheel in the car with a spec stage 3+ clutch and it is a bit challenging to get it moving without a smoky burnout, but I don't blame the flywheel.

Your idle may not be as smooth.

[Phoenix7]

yeah, the reading I've done says that they're not ideal for drag-racing so I am not too concerned about that.

How much does the Fidanza Aluminum flywheel weigh?

http://www.good-win-racing.com/Mazda...R-1003RX7.html

I found that one but there is no info on the weight...

DO you have any good places where I can pick them up at a good price?

[diabolical1]

Originally Posted by Phoenix7

How much does the Fidanza Aluminum flywheel weigh?

http://www.good-win-racing.com/Mazda...R-1003RX7.html

I found that one but there is no info on the weight...

DO you have any good places where I can pick them up at a good price?

if i am not mistaken, i think RB subcontracts Fidanza for their aluminum flywheels, which i think they advertise as 12 pounds, but i don't remember if that's with or without the counterweight.

[Phoenix7]

I found an Exedy unit for less than the Fidanza too....But I can't find the weight even on the Exedy site.

I'm still doing some searching so I hope to find the info soon.

Question: can I use a TII lightweight flywheel with the NA counterbalance?

[diabolical1]

as long as the rear counterweight is correct for your rotors and front weight, then i think you can use virtually any aftermarket flywheel that will bolt to it.

[TitaniumTT]

Yup, you match the counterweight to the engine, and the flywheel to the trans.....

I had the lightest offering from SR motorsports, something like 9.5lbs, I had to rev slightly higher to get going in 1st, took a few minutes to get used to but nothing to bad. Reved faster, quicker shifting, but yeah the idle was messed up a bit.

All in all I'd do it again without hesitation.

[RotorDad]

I use the Exedy lightweight chromoly flywheel, not too sure of the weight. The car does rev faster & has quicker shifts. Never noticed the idle because mine was off anyways

[infernosg]

What happens to the idle? I never noticed anything on my other car so I guess this is something unique to the rotary? Are we talking "car will randomly stall" idle effect or something like "idle is more erratic"? I suppose nothing bumping up the idle 100 RPM or so wouldn't fix?