240mm Lightweight flywheel options | The Z Club of Great Britain
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240mm Lightweight flywheel options

Discussion in 'S30 (240Z,260Z,280Z) Engine' started by Woody928, Mar 30, 2018.

  1. Woody928

    Z Club Member

    Hi All,

    I decided to start another thread so that there was a place to more specifically discuss this topic having divulged slightly away on my clutch thread as linked below (Great info though).


    I've decided that while I am replacing the the gearbox that a new clutch will be going in and I'm being swayed towards going up to 240mm to future proof against planned modifications to come. With that in mind I'm now also thinking to put in a light weight flywheel to help things out as well. Given I'm looking at 240mm clutches I'm going to have to increase the flywheel size to 240mm to match.

    What have people fitted to their cars and are able to recommend?

    I've already been given the below linked options however I'd be really grateful of all feedback and recommendations given I'm still completely new to this area.


  2. franky

    Z Club Member

    So, a 240mm jobbie, is only 6.25% larger, so it can handle 6.25% more power? Is that how it works?
  3. franky

    Z Club Member

  4. AliK

    Z Club Committee
    Committee Member

    I doubt it's a linear equation ;)
  5. franky

    Z Club Member

    Agree, however its going to have more mass to rotate, all of that further away from the centrepoint so carrying more inertia? Higher gyroscopic effect sort of thing?

    How much more will it take? I've struggled to find(in the past 30mins) may threads of a 225mm jobbie imploding while a 240 has been fine?
    Last edited: Mar 30, 2018
  6. Bobafett

    Bobafett Forum User

    Would a lightweight flywheel on a Nissan 6 cylinder engine, not compromise on 'real world' useable low bottom end torque/rev range?
  7. jonbills

    ZClub Administrator
    Staff Member Committee Member

    240 & 225 mm flywheels are same size and weight, they just have a different friction area diameters (225 & 240mm).
    FWIW, my flywheel is lightened - I had a few lb removed from the outer half of the standard 240mm wheel.
    It hasn't disintegrated yet and it's had some abuse.
    I think the data shows that:
    flywheels store energy from the system when they're being accelerated and supply energy back to the system when the system tries to slow the engine (like when you change up)
    when it's storing energy, that energy isn't available to move the car.
    the amount of energy it stores is a function of it's weight, speed and how far out from the centre the weight is.
    so all things being equal, a lighter flywheel leaves more power available to do work when the engine is accelerating.
    But then you get the power back when you change up a gear.
    If you compare power available to do work in a given gear (I.e. no change up) then the engine with the lighter flywheel has a couple more horsepower available.
    The difference is hard to detect on the road or track.

    the main things you can notice is:
    Lightened flywheels make the engine spin up and slow down quicker when the engine is unloaded, so that feels cool while you're revving at the lights.
    you can stall it a bit easier at those same lights
    Woody928 and AliK like this.
  8. AliK

    Z Club Committee
    Committee Member

    You know, I can't see how it can't affect some low end smoothness while pulling off etc. But most people I spoke with said it brought their L6 engines to life without issues low down or in traffic. I guess it depends how light you go too.

    I'll report back when mine's up and running.

    Also given the car is an ecosystem it depends what you are doing. If you just change the flywheel then sure you will notice a difference directly related to the weight saving and may need to dial in a few hundred more revs pulling off.

    But if at the same time you have (like in my case) increased displacement, compression, added a beefier damper, got slightly heavier flat top / oversized pistons but then on the opposite side of the equation running a wilder than stock cam, larger valves, lighter flywheel etc it's difficult to know exactly how any one of those things on its own can be directly attributed to any difference in drivability. Food for thought!
    Woody928 likes this.
  9. Woody928

    Z Club Member

    It's always the way unless you do one mod/change at a time. Very difficult to attribute the changes directly to one item. In my situation changing as much as I will be it will be hard to say what has had the most positive effect come the finished project.

    Thank you all for the links and info everyone, lots of food for thought right now. Having thought 240mm was the way to go I'm now thinking it's not as big a deal as I imagined given the relatively small changes. I'll let you know what route I finally decide on.

    For reference does anyone have the weight of the stock 240Z flywheel and clutch?
  10. SeanDezart

    Z Club Member
    Official Trader

    Been running my stroker on a 225 ally lightwork flywheel - no issues, no stalling. Sometimes all this cautious theory is a waste of time - just do it !:cheers:

    Seriously, I'd choose also by pricing, maybe a 240mm clutch is cheaper, maybe a combination price of flywheel and clutch is cheaper yet.
    AliK likes this.
  11. Woody928

    Z Club Member

    Thanks, I'm convinced I might as well fit one at this point. Also now quite happy to go either way clutch wise. Getting quite tempted to bit the bullet with this setup, just trying to do the man maths in my head.

  12. franky

    Z Club Member

    I’ve £40 worth of ‘points’ that are about to expire. You can have them if you let me ship an oer fuel rail with it
  13. Woody928

    Z Club Member

    You Sir have a deal! Drop me a PM or email so we can work out the details :cheers:
  14. franky

    Z Club Member

    All done.

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