MR2 Roadster Owners Club

The Workshop => Performance Related => Topic started by: ptennisnet on July 17, 2017, 22:49

Title: stock engine / lightened flywheel worth doing?
Post by: ptennisnet on July 17, 2017, 22:49
Hi,
I am getting a new gearbox fitted next week.  I will probably get the clutch done (40K on it) and was wondering whether getting a competition clutch lightened flywheel was worth doing on a stock engine.  The only mod I have, other than dents (my car isn't a polisher) is Matt's brace.  My car is a daily driver that takes me on a 35 mile cross country daily commute.
Thanks

Nick
Title: Re: stock engine / lightened flywheel worth doing?
Post by: shnazzle on July 18, 2017, 08:51
I found the lightened flywheel a bit odd and it would seem a bit of a chore in traffic.

It's not night and day from stock but you definitely need to rev it a bit more to get going

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Title: Re: stock engine / lightened flywheel worth doing?
Post by: ptennisnet on July 18, 2017, 10:57
Thanks for the reply.  I guess I'll leave it as it is then - it's primarily a commuting car and ease of use is a consideration.
Title: Re: stock engine / lightened flywheel worth doing?
Post by: shnazzle on July 18, 2017, 11:12
Any chance you can try a car with one? Don't know where you are but there are definitely a few fidanza flywheels about in the country

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Title: Re: stock engine / lightened flywheel worth doing?
Post by: lamcote on July 18, 2017, 11:35
Shnazzle, what weight was the lightened flywheel you used? Recent research suggests that the standard 1zz is about 15lbs and most lighter ones are about 9lbs, BUT the standard 2zz flywheel seems to be about 12lbs. That might be the sweet spot? Presumably the standard 2zz is perfectly OK for driveability?
Title: Re: stock engine / lightened flywheel worth doing?
Post by: Bernie on July 18, 2017, 11:56
The Fidanza is 9lbs I have one in mine, takes some getting used to and does pick up well but maybe for stock set up not necessary

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Title: Re: RE: Re: stock engine / lightened flywheel worth doing?
Post by: shnazzle on July 18, 2017, 11:59
Quote from: "lamcote"Shnazzle, what weight was the lightened flywheel you used? Recent research suggests that the standard 1zz is about 15lbs and most lighter ones are about 9lbs, BUT the standard 2zz flywheel seems to be about 12lbs. That might be the sweet spot? Presumably the standard 2zz is perfectly OK for driveability?
I was referring to Bernie's. The only lightened flywheel I've driven.
But his car is not quite stock  s:) :) s:)
Title: Re: stock engine / lightened flywheel worth doing?
Post by: Bernie on July 18, 2017, 12:02
Quote from: "shnazzle"
Quote from: "lamcote"Shnazzle, what weight was the lightened flywheel you used? Recent research suggests that the standard 1zz is about 15lbs and most lighter ones are about 9lbs, BUT the standard 2zz flywheel seems to be about 12lbs. That might be the sweet spot? Presumably the standard 2zz is perfectly OK for driveability?
I was referring to Bernie's. The only lightened flywheel I've driven.
But his car is not quite stock  s:) :) s:)

You would need more than a one off blat to acclimatise to it  :-) :-) :-)
Title: Re: stock engine / lightened flywheel worth doing?
Post by: ad_car_08 on July 18, 2017, 13:21
I managed to pick up a second hand TRD lightened flywheel and didn't regret it.
It's true that there's no night and day miracle changes going on, but it revs up so much easier to make better use of the engine.
And as for having to rev more to pull away...yes you do but only minutely. People seem to make mountains out of mole hills with regards to that  s:lol: :lol: s:lol:
Title: Re: RE: Re: stock engine / lightened flywheel worth doing?
Post by: shnazzle on July 18, 2017, 13:53
Quote from: "bernie11a"
Quote from: "shnazzle"
Quote from: "lamcote"Shnazzle, what weight was the lightened flywheel you used? Recent research suggests that the standard 1zz is about 15lbs and most lighter ones are about 9lbs, BUT the standard 2zz flywheel seems to be about 12lbs. That might be the sweet spot? Presumably the standard 2zz is perfectly OK for driveability?
I was referring to Bernie's. The only lightened flywheel I've driven.
But his car is not quite stock  s:) :) s:)

You would need more than a one off blat to acclimatise to it  :-) :-) :-)
Absolutely!
As with everything you get used to it.
It maybe sounded a bit more dramatic than I intended.

Coincidentally I thought about it a few days ago when I was in very slow start-stop traffic and I thought I'd be revving it a bit higher every time I pulled away a few feet.

No biggie. Definitely a huge bonus on fast road and coming out of corners.
Title: Re: stock engine / lightened flywheel worth doing?
Post by: jonbill on July 18, 2017, 22:47
Although lightened flywheels do have a pleasant blippy effect when not in gear, they have next to no impact on the actual peformance of the car in gear.  
How much power does it take to accelerate 10lbs to 5000rpm? I can't do the maths, but it's a tiny fraction of what's required to accelerate a 2500lbs car from 0 to 50 mph.
Title: Re: stock engine / lightened flywheel worth doing?
Post by: lamcote on July 18, 2017, 23:11
I've found some information about lighter flywheels for the Miata and they reckon a 5lb lighter flywheel is equivalent to reducing the weight of the car by over 90lbs, for 1st gear. It reduces from this in each higher gear.
That should be easily noticeable.
Title: Re: stock engine / lightened flywheel worth doing?
Post by: Bernie on July 18, 2017, 23:14
Worth a read the point is it builds the revs quicker on acceleration so you are in to the sweet spot range quicker as less mass to turn

 m http://www.torquecars.co.uk/tuning/flywheel-lightening (http://www.torquecars.co.uk/tuning/flywheel-lightening) m
Title: Re: stock engine / lightened flywheel worth doing?
Post by: SteveMK3 on July 19, 2017, 20:48
Quote from: "ad_car_08"I managed to pick up a second hand TRD lightened flywheel and didn't regret it.
It's true that there's no night and day miracle changes going on, but it revs up so much easier to make better use of the engine.
And as for having to rev more to pull away...yes you do but only minutely. People seem to make mountains out of mole hills with regards to that  s:lol: :lol: s:lol:

Mine's a Fidanza not a TRD but  I'd totally agree with the above, it revs so much better and takes hardly any getting used IMHO.
Title: Re: stock engine / lightened flywheel worth doing?
Post by: weeJohn on July 19, 2017, 22:24
Its not just the overall weight that matters, taking more weight off the outside diameter makes more difference than taking it off at the center.

It can be a bit of a pain when town driving, takes you to be a bit more aggressive pulling off.
Title: Re: stock engine / lightened flywheel worth doing?
Post by: jonbill on July 19, 2017, 23:03
This site I think is very good and has the maths in it  m http://www.w8ji.com/rotating_mass_acceleration.htm (http://www.w8ji.com/rotating_mass_acceleration.htm) m
It shows I think that taking 10lbs off your flywheel is equivalent to maybe 5 bhp extra during a 1/4 mile drag for a 15 second car.
So not nothing, but given the effort required to fit one, it'd be quite a way down my list of things to so.
Title: Re: stock engine / lightened flywheel worth doing?
Post by: dan_daran on July 25, 2017, 10:33
hi ive got the cc ultra light weight fitted and the maf mod i would say yes worth doing when clutch goes , car is more driveable it gets to the power quicker would be great to have the 2zz close ratio box someone said on spyderchat it feels like 30bhp!
Title: Re: stock engine / lightened flywheel worth doing?
Post by: desmondo on August 3, 2017, 18:16
Hi, I too got the CC Ultra Light FW fitted (bought from Steve at GT4-Play) - i think it weights just over 4Kgs - and I'd agree with Dan - it definitely feels just that little bit more nimble and lively. The downside was that I stalled a lot in the first few weeks after getting it fitted (not helped by the new clutch), but you soon adapt and it rarely happens now.
Title: Re: stock engine / lightened flywheel worth doing?
Post by: Gaz mr-s on August 3, 2017, 18:53
It seems to me that a standard 2 takes a long time to slow down/lose rpm when the throttle is lifted-off at high rpm....seems like very little engine braking.  Is this down to the flywheel or something else?
Title: Re: stock engine / lightened flywheel worth doing?
Post by: JoeCool on August 3, 2017, 23:34
If you're talking about just the car rolling down from speed, that's just the way the car is.

If you're talking about the time taken for the engine to lose revs whilst the clutch is disengaged during an upshift,  then that's flywheel mass and possibly gear changing technique. It's most noticeable on some diesels - the lack of a throttle plate combined with a very heavy flywheel means that the engine will really tame tome to slow down.

Personally I love my lightened flywheel - the responsiveness of the engine during gearshift is hugely improved, and it makes nailing gearshifts all the more sweet. But then I do have a zingy engine and gearshifting needs to be precise, I'd imagine much of the benefit would be lost on a 1zz with longer ratios.

As a single upgrade I wouldn't bother, if you're doing a clutch or even an engine swap anyway I'd consider it a very worthwhile additional upgrade for keen drivers.