Should i use a lightened flywheel

[iruvyouskyrine]

Hey all,

RB20DET looking at around 230ish kw. I have in my posession a normal RB flywheel and an Exedy lightened flywheel. I don't know the weight difference between them but its reasonable.

What are the advantages/disadvantages to using one in my car? Seems to be lots of conflicting info on this so hopefully someone can shime in with some real world data.

Thanks

[GTSBoy]

Doesn't really make any difference to throttle response under load, and in fact a torqueless lump like an RB20 could benefit from the extra inertia under quite a few circumstances.  But where you do really notice it is in heel-toe throttle blips.

I've never had a manual Skyline without a lightened flywheel.  When I converted from auto I went straight to a lighter one.  But it was only ~1kg less than stock (which is ~9kg), so not so different really.  The really light ones are much lighter and probably not the wisest for the street, but great for a race car.

[Dobz]

I'll second that gtsboy. Extra inertia is exactly what you don't want on the track. Hill starts yes, high speed driving no. Years ago I had an r31 I put an rb20 in, drove it a while with stock clutch and then swapped to light flywheel (6.5kg) and button clutch. One hell of a difference for smoother shifting at speed but a nightmare for hill starts though the terrible gt2876r wouldn't have helped either.

[r33cruiser]

The only thing I noticed is that with a stock flywheel I could putt around town at 60kmh in 5th gear (RB25DET). Now I have to keep it in 4th- that is the only thing I've noticed.

[mikel]

I was very dubious of any benefit of a lightened flywheel when I replaced my clutch a while ago - after all you have the rest of the drive train hanging off it, what difference can a few kg's in the flywheel make?

Well to my surprise it certainly made a difference in 1st and 2nd to how quick the car would rev out - I'd not understood the effect of reducing rotational inertia on the front side of the gearbox in low gears .

Street cars need mass in their flywheels for drivability  but IMHO some mas reduction is a good thing

cheers

 mike

 

 

[simpletool]

Had a lot of experience with RB25 between stock and exedy.   I'd go Exedy everytime unless you do nothing but cruise.  Exedy is 6.7 and stock is 9.8 or some such.  Most of that difference is rotational inertia (ie. depends on distribution of mass from centre).  Anyway it will make the car more responsive and the lower the gear the bigger the difference.  There is a small reduction in inertia when taking off and hill starts but nothing you won't learn to ignore.  My exedy has the spiral centre for cooling the clutch so with those you also notice a turbine type air sound while revving. 

[iruvyouskyrine]

Thanks all for the replies. I went with the Exedy lightened flywheel and NPC organic clutch so will report back as to how it feels.