For the love of a tractor engine: The life and times of the 18R-G

[JustenGT8]

Bollock yet again

Yes a mass of flywheel helps with the initial torque input into a launch, but a 4.5 kg will only be a good thing for drag racing. A few practise launches and you'll have the launch just as dialled in as with a 20kg flyhweel

My flywheel weighs 1.5kg....i have no problem launching the 3S alloy flywheel would have been sub 4kg, again no issue at all.

just get one ordered already....and who the hell is your behind the scenes flywheel advisor? sack them

[The Witzl]

JMR.

He previously had a 4kg frywheel on his KE20, and struggled with consistent launching.
If he struggled, i would struggle substantially more.


Drag racing is likely the only racing this car will see.

[JustenGT8]

Jase should know better but also a totally different kettle of fish. You will have torque for starters. You also have high comp ratio pistons, if i recall correctly, so good off boost response.

And as you say, you will struggle much more than Jase Jase was chasing 0.1 sec consistency, with a known setup, that was dialled in pretty well to perfection. My guess is you will get to WSID every now and then? there will be more issues in consistency with track conditions, tyre condition, ambient temps, tyre pressures, your period....probably 5 other things at least you will need to worry about before choosing between a 6 or 4.5 kg flyhweel.

The start line is also 0.0001% of the driving you will do. Does it make sense to trade off the benefits one of those readily available flywheels will give you 99.999% of the time? i think not

The horse has been lead, if it don't wanna drink.......

[o_man_ra23]

You will gain more from a lighter flywheel along the track than you will lose in consistency at launch from not having a heavy flywheel. There was a calculator somewhere which worked out the equivalent power increase based on drive ratio and flywheel mass difference. It worked out some pretty massive gains in the first couple of gears.

[The Witzl]

Well the thing is I've got options available.... either chromo or fidanza at 4.4-4.5kg.... or billet steel to whatever I specify (with Direct Clutch that RA35GT linked to).
The billet steel works out cheaper than the chromo options as well.

So i'll just get what's good enough. I have the choice so why not make the choice that is best balance for what i want.

[Zammo]

BAH you dont know what you want we do



jk

[JustenGT8]

Well the thing is I've got options available.... either chromo or fidanza at 4.4-4.5kg.... or billet steel to whatever I specify (with Direct Clutch that RA35GT linked to).
The billet steel works out cheaper than the chromo options as well.

So i'll just get what's good enough. I have the choice so why not make the choice that is best balance for what i want.

That's fair enough. Anything 4-6kg will be a noticeable difference for the positive

[The Witzl]

so.... can someone please weigh a stock 18RG flywheel for me, and advise the weight?

Thanks

[RA35GT]

Woops, I'll try to remember to bring the flywheel with me to work tomorrow and weigh it. Might also have a standard flywheel around home somewhere too I can bring.

[The Witzl]

yeah just measure the standard one for me if you can.
The guys where you got your billet one made are going to make up one to whatever I specify.... so just want to know weight of the stock unit as my starting point.

[Zammo]

yeah just measure the standard one for me if you can.
The guys where you got your billet one made are going to make up one to whatever I specify.... so just want to know weight of the stock unit as my starting point.

Not trying to be intensionally rude

but have you tried searching both RG threads cause im sure its in one of them already ??? ive got a feeling ive read all this before

[RA35GT]

yeah just measure the standard one for me if you can.
The guys where you got your billet one made are going to make up one to whatever I specify.... so just want to know weight of the stock unit as my starting point.

Sorry dood, mate borrowed the flywheel a while back and I think he still has it. Might be a little while until I can get it on the scales.

[MorGo]

Just get the lightest one you can get!!
THE LIGHTEST!
Then you don't talk anymore "tractor engine"..
Everything would be better with light flywheel/clutch.
Light clutchplate and the transmission will praise you! (less inertia on plate,the easier synchros workload)

There is no downsides in having lightest possible flywheel/clutch setup.Easier to drive,revs better,generally feels lighter engine and trans shift quicker.

[The Witzl]

Just get the lightest one you can get!!
THE LIGHTEST!
Then you don't talk anymore "tractor engine"..
Everything would be better with light flywheel/clutch.
Light clutchplate and the transmission will praise you! (less inertia on plate,the easier synchros workload)

There is no downsides in having lightest possible flywheel/clutch setup.Easier to drive,revs better,generally feels lighter engine and trans shift quicker.

Anyone seriously into 4 cylinder turbo drag racing would argue otherwise.
I've talked now to two separate companies who do a lot of work in drag racing and street cars, and JMR, and they all say the same thing.

In drag racing - Lightest flywheel = NO GOOD.


It's more about WHERE the weight is distributed on the flywheel, as opposed to all out lowest mass.
In circuit racing, yes you want minimum mass, as the mass centred to the crankshaft as much as possible to aid in quick changes in RPM that are highly desirable in circuit racing.
In drag racing however, especially smaller 4-cylinder big turbo drag racing, you want more mass at the periphery of the flywheel, in order to keep some interia to avoid losing RPM on launch and thus losing boost.

More rotational interia = less loss of RPM during launch = more boost on launch = out of the trap much faster = WIN.

From what I am hearing from those with a lot of expertise is - YES, it is beneficial to reduce flywheel weight.... but for a 4cyl big turbo doing drag racing, you dont want too light and you want to keep more mass towards the circumfrence of the flywheel to keep some rotational inertia.


Im going to listen to those with experience in the thing i want to do.
Thanks for the input guys.



EDIT - some internet sluething has told me stock flywheel = 10kg.
That sounds about right.

[S. Lowlux]

Just weighed 2 stock flywheels & 10 kg is correct.
Owen.