Just found and read this thread, wasn't really thinking towards flywheels. No wonder I never have any money in my bank account
http://zclub.net/community/index.php?threads/pros-and-cons-of-a-lightened-flywheel.20455/
Well Mr Woody, I really waxed and waned on this one and geeked out reading everything I could find. I also spoke to quite a few members with the lighter flywheels. Base on all this my humble opinion is:
People I spoke with who have the lighter flywheels didn't suffer drivability issues and found their engines to be, in the words of one member "less like it's constantly towing a boat anchor", read much keener to rev. But also read revs will drop equally as quickly when changing gear so you have to modify your driving style a tiny bit to suit.
One school of thought advises against lightening an existing flywheel for a number of reasons: 1. The energy in a flywheel is HUGE and if you introduce stress fractures during the lightening process it may choose to come apart at high revs - which will rip through your bell housing, legs etc like an extra hot Fal curry through your intestines. 2. If your flywheel also needs resurfacing due to 40years of abuse, or because you want a new clutch plate to go on a new flywheel surface then the costs aren't far off getting a new one. (Having said all that, I never came across a case where a lightened flywheel has come apart.)
One member who runs an L28, runs this one and is WAY happy with it ...
https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.co.uk/ulk/itm/222862718485
I bought the Fidanza as it came highly recommended by people who build high end engines, had great reviews and has a replaceable surface should it ever need changing. It is a bit lighter than the one above - not been put it on the car yet, so time will tell when I get my engine back in.
https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.co.uk/ulk/itm/122458092672
Don't believe the hype about releasing horse power - a fly on it's own is not consuming or dissipating power, it is merely storing and returning it; and slowing down the rev-ability for smoothness.
The sports stage 2 and 3 clutches have fewer "pucks" to increase pressure per point of contact (P= Force / Area) for high load applications but that also makes them less smooth and more "grabby".
This is a truly annoying review of a 240z, but if you can ignore that bit, the owner is running a centre force and the reviewer is constantly speaking of how grabby or heavy it is:
While most stage 2 are advertised as close to stock feel, they run pressure plates with more pressure and one member (I think it was Jonbills-could be wrong) said theirs was advertised so and it certainly is a lot heavier.
240v225mm: again, I would beckon to the experts to jump in - it will help with longevity and smoothness on application of the clutch pedal; the additional friction surface is not necessarily going to give you greater Torque handling (remember P=F/A). That is very much a function of the pressure plate springs. If you plan to have an L28 one day, then 240mm would be a future proofing option IMHO.
If you go stock Nissan clutch then Mr F is your man - in fact, like John Shaft, he is THE man, period!
Disclaimer:
All views expressed are that of a keyboard warrior/geek who has to do a lot of research and collect data before doing anything. It does not in any way represent the views of the club. No animals or members were harmed during the research.