Question about flywheel diameter change

[nwcubsman]

Can anyone out there answer my question? I am planning to install a F54 engine from an '82 ZX 2+2. I know the flywheel diameter is larger in the 2+2 than the coupe. What difference would I find in running the larger flywheel vs the smaller stock flywheel from the 280 coupe? My understanding is the weight is equal, but the larger diameter may not spin up as quickly. What are your thoughts?

Thx, Bryan

[Arne]

Bryan, while they are the same weight, the weight is carried farther from the centerline of the crank. So you are right, the throttle response may not feel as snappy. More inertia.

It would seem to me that the only advantage to the 240mm flywheel would be on an engine that makes more torque than the smaller 225mm clutch can handle. At one point (when I was thinking more towards a high performance engine for my car), I figured I'd look for the lighter 810 flywheel. I think you'd be happier with either that or the stock 225mm over the 240mm.

[zguitar71]

Even though they weigh the same having weight farther out from the center with the bigger flywheel should in theory make the revving slower but I bet you might not notice that much difference from the small one. If you want to get the motor to rev quicker you need to buy a light weight flywheel. Going from the heavy stock one to a 10 or 11 pound wheel makes a huge difference.

[sblake01]

The 2+2/Turbo flywheel is not larger in diameter than the coupe flywheel. They are the same weight and diameter. You'll also need the 2+2/Turbo clutch disc and pressure plate to make the change over. It's the clutch surface that is larger.

[Arne]

The 2+2/Turbo flywheel is not larger in diameter than the coupe flywheel. They are the same weight and diameter. You'll also need the 2+2/Turbo clutch disc and pressure plate to make the change over. It's the clutch surface that is larger.

Ahh! That makes sense, since I didn't see how you could fit much larger a flywheel in the bellhousing anyway. And now that I think about it, a larger overall diameter would require a different starter, since the ring gear would be farther from the centerline.

So the flywheel isn't an issue, Bryan. But you'll want to make sure that the larger pressure plate isn't a whole lot heavier than the normal one. But I'm betting that if it is heavier, it'd only be by a couple of pounds or so. Probably not all that significant.

[nwcubsman]

Thanks all for the response. Stephen, you do make sense. Thanks for bringing that to light.