Chop chop!!

I wanna know lol :D

Thanks everybody for all your input.

I have read it all and took it all in, i think for my standard Type-R i have more to loose with a lightened flywheel.
Gonna have mine skimmed and balanced slightly and leave it at that.

The only way I can see that anyone could come to the conclusion that the granny spec OE flywheels are they way forward on a performance car is that they have mis-read some of the information, read to much into the information from people who haven't really tried it or confusing the views between lightened OE flywheels and uprated forged lightweight flywheels.

My gran doesn't drive my car, and therefore I benefit from the joys of a superlight flywheel. ;)

I speak from first hand experience and having had the benefit of customer feedback. I think you would be missing out on a great chance to upgrade.

You can lead a horse to water.... :D

Don't get it balanced SLIGHTLY. :) Get it done fully. ;)

Lightening the flywheel can have limitted benefits but you have to decide if these benefits are worth the cost of the replacement flywheel plus possibly the cost of removing and refitting the gearbox unless you have a clutch or gearbox replacement at the same time.

Do the measurable benefits outweigh the downsides and cost?

With a lighter flywheel and the engine in neutral it will rev slightly faster when the throttle is blipped because of the reduced rotational mass. Now if that floats your boat for that level of expenditure......fine.
If you claim that acceleration is NOTICABLY improved, think about it. You remove 4-7 kg perhaps nearly 8 kg in an extreme case and at a radius of around .08m. Removing any weight will improve acceleration. That is physics. Removing rotating mass at maximum radius is obviously preferable. The rotational mass consists of pistons, rods, crank, clutch, flywheel, gears and shafts, propshaft, diff, driveshafts, wheels and tyres. (To name a few)

Does removing 4 to nearly 8kg from the flywheel, have a measurable difference on the drivetrain performance? I think not.
Do you measure the acceleration improvements from fitting a lighter set of wheels which probably has an even greater effect than a lightweight flywheel????
You probably get the same benefit from running on a light fuel load or ditching the spare wheel and jack and that costs nothing!!!

Now if anyone wants to continue insisting that a lightweight flywheel makes a measurable improvement to acceleration, let us devise an agreed, objective test regime, measure the vehicle accelaeration, fit a lightweight flywheel and remeasure the difference.
A test car will not be a problem, I can remove and refit the gearbox and we will have defined and quantified, agreed, factual information. If the test proves that a lightweight flywheel makes a measurable difference I will do the gearbox swap for free.

Can't be fairer than that.

Harvey: If you were anywhere nearby, I would happily let you swap out the flywheels. I would be very confident of improved acceleration on a 4.3kg flywheel vs a stock 12kg one, particularly in low gears.

I will happily take the car to somewhere local like MocomRacing or Zen and have the losing party pick up the bill for the fitting and re-fitting (because I simply could not live with a sluggish OE weight fly). I would also allow someone like Zak/Paul to test the car independently on several 0-60/100mph runs, with both weight flywheels.

Or to make it easier, point me in the direction of a car in the region of 340bhp that can run 11s 1/4 miles on a OE flywheel.

Simple physics, it will accelerate like a lighter car, far beyond the actual KGs saving.

I know we've disagreed on this topic for years, and iirc you were one of the people who advised me it would be a pig on the 1/4mile.

Far from it. I believe I proved otherwise by breaking the very well respected time of AndyF's STiRA 440bhp 20g a while back with my 340bhp, with several runs in the 11s on the same day. I find the cars launching to be very consistent as shown by the time slips posted previously.

We come from different camps, I have no interest in the RR figures, but am interested in making the car as fast as possible with mods within most peoples reach. I have no intention of making my car a 500bhp monster as it nice to know it can hold its own and that I can give it death all day on the strip against 450-500bhp Impreazs and still drive it home.

Subaru choose the flywheel weight based on what will suit the mass market, and that includes granny driving to the shops. I have a flywheel weight to suit me and which will give greatest gains.

What weight flywheel do the likes of Exedy choose on their twin plate clutches etc and why? By using far superior materials these aftermarket flywheels can select the best weight from scratch. This is why we need to take off the blinkers that the OE weight must be the right one and just select a weight which is most suitable for our needs whic the box is off

I haven't had any customer feedback saying they wished they stayed with the OE weight, on the contrary, I often follow up on sales to see how customers are getting on and the feedback to date has always been positive.

I strongly believe it is a very good upgrade to do whilst the box is off and at under £200 (without exchange), is great value.

It's nice to know that we can debate this things nowadays without resorting to having pops at one another ;) :D

BOB5... all this time youre typing this you could be weighing an OE setup for me to compare with ha ha :lol1:

Right Bob. You have an offer from Harvey. You supply the flywheel and put your money where your mouth is. It could be of great benefit to the Subaru community and settle the conflicting claims once and for all.

Mick

Harvey & Bob's you both have very intresting points

I am undecided now

I think i have about 2 weeks to decide what i am going to

Bob : With respect, you are missing some important points that need to be clarified and resolved so that what we do is objective and defined. Once that is done we can proceed with the actual testing.

FIRSTLY. What you are trying to measure is so small that we need to define the test method. What you are trying to measure could be greatly distorted by climatic conditions, wind, gradient or the vehicle weight itself other than the flywheel weight loss. Any small gain could be wiped out, reversed or compounded by a change in any of these perameters.
0-60 or 0-100 times lack consistency and rely on human input and are therefore by their very nature, inconsistent.
We need to measure acceleration where there are as few variables as possible so the results are meaningful. Hence the need to devise a precise testing method that will achieve the objective ie to prove or disprove your claim that a lightened flywheel makes a noticable difference to the acceleration of a car.

SECONDLY. When the test method is agreed we need to define "a noticable difference" so there are no subsequent arguements because one person has a more sensative ar5e than an other. :)

Then we can agree on how to proceed.

See below for some further input.

Classic cars have 12.2 or 10.4 kg flywheels or thereabouts. It makes no difference what weight of flywheel the car has before the test. The car can be selected randomly and the actual flywheel weight recorded publicly at the time the lightweight flywheel is fitted after the test figures are obtained for the car in standard test format.

What weight of flywheels do you sell?
I think you said the most popular was 6kg or therabouts?

0-60 runs or 0-100 are not consistent and rely on human input and are therefore not an accurate test of whether any performance difference is signifigant enough to be felt.
Running a random test car with an O/E flywheel and then rerunning it with a lightweight flywheel from yourself obviates the need for two fitting and removal operations.............unless of course the owner is not happy with the lightweight flywheel.
I thought you lived in Lutterworth and therefore Roger Clark Motorsport are a lot closer if you are saving expense.
Once the test proceedure and "noticable difference" are clearly defined we can go where ever makes economic sense to the parties involved.

Bob. I assume you refer to your own car which has outstanding results. All credit to your quarter mile achievements but this comment is not really meaningful. Do any of the other people you have sold a lightweight flywheel to, with around that power level, do quarter times in the 11 second bracket?
Surely you are not pinning your success on the flywheel alone. What about your own obvious ability in this area? You are being too modest.

Would you like to expand on this? I think it is a topic on its own and very interesting.

SORRY, YOU ARE ATTEMPTING TO ATTRIBUTE COMMENTS TO ME I HAVE NOT MADE.


My position, based on my own considerable experience, is farly straight forward. With an O/E flywheel you can come off the line for a drag start with as little as 4,000 rpm and the actual revs required are not critical. With a flywheel in the 4-5 kg bracket you have to be very precise with your launch to within perhaps a couple of hundred RPM. Too few revs and you easily bog down, too many revs and you get time sapping, excess wheel spin.
I have also found that once you come below the 7-8 kg bracket then the launch control becomes that much more difficult and the downsides outweigh the possible benefits. Purely my own observations but in line with those of others that have discussed this with me.
Again, surely you are not telling us that you broke some Andy F performance figures because you had a particular lightweight flywheel?
Out of interest, what weight of flywheel was he running?


[quote]We come from different camps, I have no interest in the RR figures, but am interested in making the car as fast as possible with mods within most peoples reach. I have no intention of making my car a 500bhp monster as it nice to know it can hold its own and that I can give it death all day on the strip against 450-500bhp Impreazs and still drive it home.[quote]

What has 500 bhp or rolling road figures got to do with anything?
If what you say is correct, there will be a noticable performance difference on any Subaru, regardless of power when fitted with one of your flywheels.

What suits you may not suit most other people in the same way that what suits me may not be the choice of others. However, I would suggest that your choice of extremely light flywheel would not be the advisable choice, for the majority of people as evidenced by the fact that your 6.?kg flywheel is apparently the most popular.

Please stick to the facts and what is relevant. Not many people run twin plate clutches and I assume a twin plate clutch assembly is heavier than an organic clutch assembly, hence there is more scope for reducing inertia. However, what Exedy fit on a twin plate clutch has nothing to do with your claim that there is a noticable performance difference from a lightweight clutch, which most people fit in 6.?kg format. (according to you)

This is not and never has been my position. Please read what I and others are saying on this and many other threads. Where we differ is that you say that the difference in acceleration with a lightweight flywheel is noticable. I dispute that it is noticable and indeed it would be very difficult to measure accurately because the difference is so small.
Of my four Subarus, I have 7-8 kg flywheels on three of them, simply because the gearboxes has been out for other reasons and I have plenty of experience with 4-6 kg flywheels too. Even with the lightest flywheels I cannot say I ever felt any quantifiable difference in acceleration which is what you claim.

I also believe that the choice of a flywheel of 4.3kg for the vast majority of Scoobynet members where their car is their daily driver would be a very unwise decision and this is based on my own experiences with comments from many other people.
I agree there is scope for lightening the O/E flywheel.
I do not agree you can feel the improved acceleration.
Going to a very low weight for most drivers, especially those that do not have previous experience of lightweight flywheels is a costly and retrograde step in my experience.

By the way I also sell lightened flywheels. ;)



I saw a recent post, (no idea if it was one of your flywheels) but the owner who may have been Ian Jones, not sure, had fitted a lightweight flywheel, around 6 kg I think and was regretting the decision because of the hassle he was experiencing in traffic. I paid little attention as it was not signifigant at the time.

Very keen price I agree. Have your prices come down and what is the price delivered?
As with blow off valves, suppliers will claim all sorts of performance benefits but have great difficulty substantiating them.
Even with the gearbox already out, there are many things a long way up the list before a reduced weight flywheel would even come on the radar.

Don't get me wrong, if you drop something between four and nearly eight kg, it must make a difference and if it is a rotational loss so much the better but is it enough to feel? I think not but I look forward to devising a test method that will provide an objective and accurate conclusion.

Why use one word when a million will suffice :D

My offer is there for everything to be tested independently.

I've been around here long enough to know that these things rarely come good due to defining test parameters, conditions etc etc.

Even if I proved that the car was 0.2 secs (for example) quicker 0-60mph, there could be a whole heap of counter arguments about air temps, density, road temps, tyre temps. :D

The physics are quite clear, and I drive the proof everyday so you'll not convince me that a granny weight OE flywheel is the way forward in a car tuned for optimum performance.

Likewise, Harvey will say he has tried light flywheels and not thought much of them, so you'll not convince him.

I can only recommend and share my experiences of what I have seen first hand myself. I know what works well to make a quick car and I'm not about to change it.

Harvey and I just come from different schools of though....

I like to make a fast car with the least amount of effort and bhp vs Harvey likes mahoosive bhp figures whilst not going any quicker. ;)

Also worth thinking about what the likes of Exedy choose as decent flywheel weight vs the cost cutting cast OE ones that Subaru spec'd for Grannies to be able to drive around in.

My personal advice and recommendation is to fit a lightweight flywheel if doing a clutch change. The benefits are worthwhile IHMO and the feedback from customers has been nothing but good. :thumb:

Harvey: You beat me to it! :D

wow....I will respond when I get a spare minute or two......ok maybe an hour or two ;) :D

So, on a dailt drive running 350bhp what weight flywheel would you guys recommend? 4.3kg?

That would be the lightest weight to go for, which would also make the biggest difference.

However it does make medium speed take off trickier and can take a little while to get used to.

6kgs is the most popular with our customers and is a good all rounder. :thumb:

i have a lightened 6kg flywheel with an ap racing clutch
is the lightened flywheel why the clutch judders on pull away unless i use more revs..if it is i would rather have a standard flywheel and to hell with rotational mass:eek2:

Mines fantastic along with my light weight pullies.
My mate and I have identical spec cars apart from I have the lightweight bits and mine is much quicker off the line to make boost and get away.

Scoobynet is full of anecdotal statements like this, some of which compound the Scooby myths.
Let us deal in facts and deterimine whether the improvements from a lightweight flywheel are such that they noticably improve accelleration as claimed.
Think about it. The best way to get a turbo working is to apply load so a turbo will always spool earlier in a higher gear than a lower gear. A turbo will spool earlier running up a hill than it will on a level surface or down a hill. Taking this to an extreme, apply your left foot on the brake and your right foot WOT and you can have your turbo spooled at ridiculously low revs.
Removing weight from a flywheel marginally reduces load on the engine so it follows that you have not made boost quicker because of the reduced load/lighter flywheel. Do you accept that?

Frayz : I would like to get factual information as opposed to illogical claims or those used as spurious comparisons. This will be of great benefit and interest to a large proportion of the Subaru community. It is therefore necessary to be very precise and cover all points.
At post 39 I have set out the need for a test procedure that will be meaningful and worthwhile and I have also answered point by point the issues raised by Bob's previous post extolling the virtues of a very light flywheel. Now as I have already explained, I believe there is a place for a lighter flywheel if you happen to be changing the clutch or gearbox and you are prepared to spend a lot of money for a gain that is almost intangible but what I object to is people being led to believe that the effects of this modification are such that they will feel the improved accelleration.
There are numerous far more important mods that will have a greater beneficial effect than £200 odd spent on a flywheel. As far as I am concerned the flywheel is not cost effective in terms of gains and comes towards the very bottom of the to do list.
Surely there is enough brain power on Scoobynet to devise a meaningful test procedure that can give repeatable results to measure any differences brought about by a lightweight flywheel and put this subjective argument to bed once and for all.
In the same way that I have answered the claims and statements extolling the virtues of lightweight flywheels then my post 39 should be answered paragraph by paragraph if there are any answers but let us keep it objective.
Comments have already been attributed to me that I have not made.

Frayz: Like you, I too am very interested to know the clutch assembly weight for both twin plate clutches, organic clutches and the relevant flywheel options and it would be useful if Bob could provide this information which should be readily to hand.

Bob :

Good. We are agreed on that. So let us put our efforts in to devising an objective test procedure that is repeatable and can stand scrutiny. There are loads of guys on this board that should be able to contribute to that.

With a little bit of effort and a contribution from other members we should be able to devise an objective test procedure that will stand scrutiny. There must be tremendous range of experience and knowledge within this BBS.

I have no idea what we are going to prove and the results will be interesting. The reason we need a defined test method is to take care of the variables you raise above and others.
Personally, I don't think a .2 second difference in a 0-60 sprint is noticable to almost any driver, F1 included but if we work on devising a test procedure we will resolve "a noticable difference"

The first paragraph is subjective in that just because your car has a lightened flywheel is proof of nothing.

I am sure the physics are quite clear and no doubt one of our members with a good knowledge of physics can calculate the benefit from a flywheel lightened by 6kg at .08 metres or whatever the correct measurements are and it maybe that they or someone else can actually relate that to the effect on road performance on the overall car.

You are missing the point and making statements that are totally contrary to what I believe.
I have tried numerous lightened flywheels on numerous makes of vehicles, not just Subaru and I have an indepth knowledge from my past experience. As I have said above, I run flywheels of around 8kg on 3 out of 4 of the Subarus currently registered for the road.
It cost me a lot less than the average person to fit a lightweight flywheel even when I already have to have the gearbox out.
What I am saying is that you cannot feel the difference in accelleration from a lightweight flywheel which is where this debate started.

I know what is required to make big numbers but that is not the only thing I do. I also know how to get massive gains in performance, on the road or on the strip for minimal expenditure. My STi 3 Wagon was/is a good example of that.
I would say that maximum gains for minimal expenditure is very high on the prioriity list for many of our users.

OK so let us have weights for clutch assemblies like Frayz has been asking for plus flywheels and do you know the flywheel material ?

Fine. What I object to is the claim that the accelleration performance is noticable which it is not IMHO but if it is noticable it is certainly measurable and I for one would very much like to know what it is to the point that I am prepared to put a bit of effort in to it.

As an aside there are other items to consider with lightweight clutches or when the clutch material is changed. I don't have adequate indepth knowledge to know if a lightweight flywheel, particularly a very lightweight flywheel is likely to reduce crank or bearing life and there are issues relating to heat sink ability and dissipation but that is for another topic. :)
__________________

Pros: as already mentioned; real world gains are not going to be measurable by any large degree, but it makes the engine feel more racey in neutral.


Cons: Inadvertantly buying junk:

https://www.scoobynet.com/drivetrain...d-you-fit.html

I just prefer the feel of the lightweight flywheel, and 5kg is 5kg, a carbon prop offers a silimiar weight saving for 4 times the price!

BOB5Personally, I prefer to buy from suppliers with technical knowledge, that know what they are doing and preferably with more in depth knowledge than me. :)

At Time Attack level, losing 5kg along with every other little mod you can find on the basis that many a mickel macks a muckel is certainly worthwhile which is the very reason for running an £850 retail price prop shaft. What akes sense on a Time Attack car can make no sense whatsoever on a road car or even occasional weekend racer where prioritising modifications relate gains to exenditure.
However, on a road car, IMHO, the loss of 5kg or even nearly 8kg is so small that bearing in mind the down sides and expense it is hardly worthwhile.
Running on half a tank of fuel will save 22kg, removing the spare wheel, jack, mats, junk, ICE will remove substantially more and cost nothing.

If a lightened flywheel makes a noticable improvement to accelleration, then it must be fairly straight forward to quantify it so let us come up with a defined test regime and quanitfy it.

That's an unnecessary and unquantified dig Harvey.

Read the quote and context. It was on a thread about someone who had brought a LIGHTENED (ie drilled out and machined OE cast item) which was done dangerously.

https://www.scoobynet.com/drivetrain...d-you-fit.html

These drilled/machined items are more your field than mine.

We sell high quality, purpose made, forged lightweight flywheels at great prices.


If you want to keep this thread civilised and beneficial to the Subaru community I suggest we keep it clean.

Just due to the length of your posts it is difficult to respond without spending vasts amounts of time (which I just don't have at the moment).

If you make your posts clearer and concise you will receive faster replies.

Cheers,

Bob

Had a medium weight 6kg ish if i remember right from zen when i had a new clutch fitted-would never go bk to a std flywheel now,car accelerates noticeably quicker and none of the stalling an revs related problems mentioned earlier in this thread-ticks over like any other uk turbo-you`d never know any different-imo as much difference to drive as decatting one even without going really light.

When this clutch is nackered will definately be bk to paul for another exedy organic/medium weight flywheel.

Yes, very true. But my 1/8mile times are consistanly 0.4ish seconds quicker that his. He actually has more power and torque than me to. Again not proof just personal exp to act on.

some very very very intresting points

Hey mate. Chill. I quoted exactly what you said and commented tongue in cheek hence the smily. I fully agree the flywheel in question was dangerous and clearly done by someone with no idea what they were doing. An accident waiting to happen.

In view of your previous comment above, your dig is a bit like the pot calling the kettle black.
I did not get shirty when you wrongly attributed comments to me.
Don't let the heat get to you. ;)

I assume they are a high quality item but I have not seen one yet. I have asked you what material they are made from, weights and already agreed they are at a great price. I also asked you about the price, none of which you have done. I am only asking for resonable information I would expect you to have at your fingertips.

I most certainly want to keep the thread civilised and the whole purpose of asking the questions and making the suggestions I have already made is so that we have more factual and accurate knowledge and as a result of the thread.

I like to be clear and precise and if the points I raised had been answered in my first post I would probably have had nothing else to say but despite your six further posts we have not really moved forward. I have made five posts in total, this one included. I think you have made around 15 posts.
Frayz who is a customer or a prospective customer is also waiting for answers.
I am happy to wait for your information and I am not pressing you but I do think I have a right to respond to some of what you say.



Sorry but I had thought my posts were very precise and clear. If anything is uncelar just copy it and I will happily try to explain it more clearly. As regards the length of my posts or the number I have made, just let us move on from here and concentrate of the core issue and not muddy the water.

Very interesting and useful information Carl.
Where are Puma Race Engines located?
It would be interesting to rework the figures to a specific Subaru example that would be typical of our cars. There will be signifigant differences in gearing and as the flywheel diameter is 290mm or thereabouts the radius figure would be neare half of the figure used in the example.
Once we had reasonably specific figures for a typical Subaru, I am sure we can find someone to do the calculations as to the differences for in gear acceleration, gear on gear based on a typical car weight plus driver.
Other people may have better suggestions.

I don't know where they are. Contact details give his bank details, but no company adress. There's some good tech articles on that site.

Puma Race Engines - Contact Details

How about emailing them?