Flywheel Advantages?

[MR R34]

What are the major draw backs???

[mattymagoo22]

djr81 you're a tool mate. I have clearly explained the ideas behind removing rotating mass from anypart of the drivetrain and simply used Gran Turismo as an example. You clearly have no experience or knowledge on the subject so kindly shut your pie hole champ.

If you were to compare a stock car and one with a lightened flywheel over a 1/4 mile or around a track the one with lighter flywheel would clearly out accelerate the stock vehicle however this is beyond your comprehension and you've obviously never been in a car before and after this mod has been carried out. Do me a favour and grab a rock and put it in your sock and swing it around in a circle take the rock out and put in a bigger rock swing it in the same fashion it will take more to get the bigger rock going that it will for the smaller rock.

MR R34

Only that you'll feel like you'll have less torque down low due to the loss of momentum due to the removal of mass from the flywheel, however once on boost you'll barely notice it. your engine will rev out a lot quicker though and acceleration particularly in lower gears will improve. oh yeah and it costs money.

Cheers Matt.

Edited August 27, 2007 by mattymagoo22

[Eug]

one with a lightened flywheel over a 1/4 mile or around a track the one with lighter flywheel would clearly out accelerate the stock vehicle

there have been instances where a lightened flywheel made you slower in drag racing, revs drop too quickly between gear shifts. it's a compromise and depending on the application, some pluses outweigh some negatives

[djr81]

djr81 you're a tool mate. I have clearly explained the ideas behind removing rotating mass from anypart of the drivetrain and simply used Gran Turismo as an example. You clearly have no experience or knowledge on the subject so kindly shut your pie hole champ.

If you were to compare a stock car and one with a lightened flywheel over a 1/4 mile or around a track the one with lighter flywheel would clearly out accelerate the stock vehicle however this is beyond your comprehension and you've obviously never been in a car before and after this mod has been carried out. Do me a favour and grab a rock and put it in your sock and swing it around in a circle take the rock out and put in a bigger rock swing it in the same fashion it will take more to get the bigger rock going that it will for the smaller rock.

Cheers Matt.

Well first things first, Matt. Be nice. There is no need to resort to vitriol to try & make a point. In fact it is usually indicative of someone who has run out of logical argument.

I did not say that the lower mass/lighter flywheel car would be slower. So maybe read what I posted again. What I said was it would be marginally quicker, but that in gear you CANNOT feel the difference by the seat of your pants. For the record you can barely detect it with good data logging equipment (which I have). See the attached plot of lateral versus longitudunal gees for my two gtr's. Once has 435rwhp, lightened flywheel etc etc, the other 305rwhp & stock pretty much everything. See how inconsequential the differences are in longitudinal gees? Given that, what chance do you think you would have of detecting a 2 kg difference???

I do in fact have an understanding of polar moments of inertia - certainly beyond the rock swinging, rock ape stage which you have attained. It is high school physics level stuff, after all. My car has a lightened flywheel. Amongst a heap of other components to bring the weight down. But according to your expertise I have never been in my own car, so maybe I just don't know.

Maybe next time you decide to hang shit on someone you could consider using more substantial examples than what you managed to do on some lame arsed computer game. You could even try quantifying it with some numbers. That is what people who are professional engineers (like me) do for a living. Lastly try not to make wrong assumptions about what others may know or for that matter do.

Champ.

Edited August 28, 2007 by djr81

[MR R34]

lol ok then... seeing as though I am removing the gearbox to change my clutch and the nismo lightweight flywheel will cost an extra $350-$400 it is worth getting it on my car that will only be used for street purposes??? Yes or No?

Feedback is great...

[PX29]

What are the major draw backs???

You may need to adjust your idle rpm alittle higher or atleast when taking off you need to increase your rpm or you may stall.

Driving at low speeds around the city may be uncomfortable, as taking off and changing gears will not be as smooth. You will need to get used to providing the extra revs just before engaging the clutch to give the now lighter flywheel the extra momentum. Basically the loads transfered between the drive-train and engine would not be "smoothed out" as much since a heavier flywheel can maintain the momuntum longer.

You need to compromise between the driveability and performance. On the other hand, too light a flywheel will be a disadvantage. Engines are designed a way for a reason, the engineers decide on a suitable geometrical size and weight of a flywheel to optimise performance, driveability and cost. If you want to pay more and sacrifice alittle driveability for the increaced performance then all I can say is go for it..!

This is just my opinion.....and not everyone is always right (inc Me), so do your research and make a decision..........after all it is YOUR car.

Cheers,

[GTS4WD]

Only "advantage" you will see on a dyno is that the engine will rev out quicker

Advantage or disadvantage?

Depends what your doing..

If your dragging.. disadvantage.. you want a stock/same weight fly wheel as momentum will keep the flywheel spinning during gear changes and you wont loose rpm when changing up..

If your circuit racing.. advantage.. revs will increase and decline faster.. this will mean your car will accelerate quicker.. and brake in shoter distances..

[GTS4WD]

What are the major draw backs???

Its harder to get cars with a light flywheel off the line..

and..

because its a thinner flywheel heat will be transfered to clutch and clutch preasure plate..

[PX29]

djr81, are you implying that from your datalogging the 435rwhp gtr has similar acceleration to the 305rwhp gtr and hence suggesting that the lightweight flywheel is insignificant..??...I must be missing something here..

Curious about your findings..?

Edited August 28, 2007 by PX29

[mattymagoo22]

I guess that means I'm wrong.

I apologise.

Cheers Matt.

[MR R34]

my car is not going to be used for drag or circuit purely street crusing with the occasional squirt? Is it beneficial???

[Robo's]

Only "advantage" you will see on a dyno is that the engine will rev out quicker

Advantage or disadvantage?

Depends what your doing..

If your dragging.. disadvantage.. you want a stock/same weight fly wheel as momentum will keep the flywheel spinning during gear changes and you wont loose rpm when changing up..

If your circuit racing.. advantage.. revs will increase and decline faster.. this will mean your car will accelerate quicker.. and brake in shoter distances..

That doesnt make sense. If your car accelerates quicker, it will be quicker down the 1/4.

[Gts-t]

On a circuit car you want the lightest flywheel possible, from the man himself SK

enjoy

[MR R34]

That doesnt make sense. If your car accelerates quicker, it will be quicker down the 1/4.

Yeh that's what I dont understand either? What about for street what do you guys think???

[cosworth1971]

this is what people dont tell you!!!!!

some cars use the weight of a flywheel to propell the car...these cars are usually big bodied v8s like american muscle.

lightening some can make a car slower.

the theory i have is.

1 is the engine big for the body?if so u can lighten the flywheel

2 if the engine is small for the body dont do it

3 with a lightend flywheel u need to keep you shifts quick to keep momentum(this is race knowledge) to slow and the advantages are lost

4 there is a perfect point eg, not too light not too heavy

my escort runs 27 lb flywheel thats from about 35lb STD any lighter and it would go worse..

but thats a 2 litre in 1000 kg(big motor for wieght)

also some drag racers keep heavy flywheel for launch! and many circuit racers use light for the cars stay at high rmp eg 7000-9000

[djr81]

djr81, are you implying that from your datalogging the 435rwhp gtr has similar acceleration to the 305rwhp gtr and hence suggesting that the lightweight flywheel is insignificant..??...I must be missing something here..

Curious about your findings..?

Yes. That is what I am saying.

If you have a look at the two plots (blue is more rwhp) the difference in acceleration (measured in gees) is not massive. Certainly not different by the close on 50% increase in hp.

I am using that to try & demonstrate that when the clutch is engaged the small change in flywheel weight would be much smaller & hence undetectable to the driver & difficult to detect by a data logging system. I suppose the analogy would be demonstrated by asking does your car feel substantially different on the way back from buying 2 litres of milk at the corner shop? Sure rotating components are more influencial, but only by degrees.

For what its worth the peak terminal velocity on my old car was 204km/h st the end of the main straight at Wanneroo.

The 435rwhp version gives 211km/h.

Now there is a little extra braking for the second case, but you can see that all that horsepower really makes a relatively small difference to terminal speeds.

Basically when finding speed for a car there is no silver bullet. If you need say 0.5 seconds around a circuit chances are you need to find four or five things to get it....

[PX29]

Yes. That is what I am saying.

If you have a look at the two plots (blue is more rwhp) the difference in acceleration (measured in gees) is not massive. Certainly not different by the close on 50% increase in hp.

I am using that to try & demonstrate that when the clutch is engaged the small change in flywheel weight would be much smaller & hence undetectable to the driver & difficult to detect by a data logging system. I suppose the analogy would be demonstrated by asking does your car feel substantially different on the way back from buying 2 litres of milk at the corner shop? Sure rotating components are more influencial, but only by degrees.

For what its worth the peak terminal velocity on my old car was 204km/h st the end of the main straight at Wanneroo.

The 435rwhp version gives 211km/h.

Now there is a little extra braking for the second case, but you can see that all that horsepower really makes a relatively small difference to terminal speeds.

Basically when finding speed for a car there is no silver bullet. If you need say 0.5 seconds around a circuit chances are you need to find four or five things to get it....

Mate, I dont know how else to explain the effect a lightweight flywheel has on acceleration.....I'm not saying that your plots are wrong, but looking at it diagramatically the difference in acceleration may "seem" insignificant between the two cars, but you cant possibly try and tell me that you cant "feel" the difference in Gee's between the two cars....especially when one has 130rwhp more...? Also the fact that the data-logging was carried out around a track makes it abit more complicated to compare, since your not in first gear much(when light FWheel is most effective) and other factors.

I dont agree on your 2Litre milk bottle analogy as explained in earlier posts.

Terminal velocity comparisons are completely useless when trying to quantify lightweight flywheel influences. I understand that the difference in speeds at the end of the track is minimal (7km/hr) for the extra 130rwhp, but this is due to many other factors such as engine efficiency, increaced mechanical losses and the extra energy to get 1400kg from 204km/hr to 211km/hr is ALOT considering the high areodynamic drag experienced at these speeds...!!

I think we are going of the topic here. If its for the street, then in my opinion you will feel the difference in acceleration, but if for the track and your trying to cut 0.5 sec/lap then yes the flywheel makes a very small impact on times.!

If you want, I'll take you for a spin in my GTR and then you can pay for a lightweight flywheel to be put in and if you cant "feel" the difference, I'll give you your money back..!!

Cheers.

Edited August 29, 2007 by PX29

[djr81]

Mate, I dont know how else to explain the effect a lightweight flywheel has on acceleration.....I'm not saying that your plots are wrong, but looking at it diagramatically the difference in acceleration may "seem" insignificant between the two cars, but you cant possibly try and tell me that you cant "feel" the difference in Gee's between the two cars....especially when one has 130rwhp more...? Also the fact that the data-logging was carried out around a track makes it abit more complicated to compare, since your not in first gear much(when light FWheel is most effective) and other factors.

Well try this plot then. What I am saying is that a near on 45% gain in rwhp doesn't produce anything like that difference in acceleration. A change in mass (yes rotating mass) that is much less than one percent of the total will have a proportionally smaller affect on the acceleration. My point is that I characterise that change as being negligible. But you are right, ofcourse you can feel the difference of much more powerful engine - although you do get used to it really quickly.

You are correct in saying it is more significant in lower gears at lower speeds (less aero drag for one & more rpm per km/h), but this is fairly unimportant because you are invariably traction limited.

I dont agree on your 2Litre milk bottle analogy as explained in earlier posts.

Well up to you, but I was trying to quantify the change & give people an idea of what sort of order of magnitude to expect. Make 5kg if you like, but you don't chuck 5kg worth of gear on your car and suddenly turn it into a slug.

Terminal velocity comparisons are completely useless when trying to quantify lightweight flywheel influences. I understand that the difference in speeds at the end of the track is minimal (7km/hr) for the extra 130rwhp, but this is due to many other factors such as engine efficiency, increaced mechanical losses and the extra energy to get 1400kg from 204km/hr to 211km/hr is ALOT considering the high areodynamic drag experienced at these speeds...!!

All of which goes to show the minor influence the flywheel has on proceedings. Which is my point.

I think we are going of the topic here. If its for the street, then in my opinion you will feel the difference in acceleration, but if for the track and your trying to cut 0.5 sec/lap then yes the flywheel makes a very small impact on times.!

If you want, I'll take you for a spin in my GTR and then you can pay for a lightweight flywheel to be put in and if you cant "feel" the difference, I'll give you your money back..!!

Thanks for theo offer, but budget is a bit tight this month. Anyway I already have a lightened flywheel, so to a degree you are preaching to the converted.

Edited August 29, 2007 by djr81

[MR R34]

If you want, I'll take you for a spin in my GTR and then you can pay for a lightweight flywheel to be put in and if you cant "feel" the difference, I'll give you your money back..!!

Cheers.

I like statements like this, finally I'm getting an answer saying that you would recommend it for the street lol

I spoke to a few mechanics today and the majority said the same thing to me, if I'm making the power which I am looking to get 220-230rwkw, then lightweight is generally benefitical in all areas for me, especially the street due to the acceleration advantages it brings about.

Majority also said lightweight flywheel is worthless on a bone stock car, where acceleration may be increased but in the long run the times on track will be reduced, due to the fact that the car is not producing enough to meet the minimum standards required to achieve maximum advantage of a lightweight flywheel (half decent power is required).

I don't know if it's just because they are all trying to sell one to me or not, but they said at the 220rwkw power range there are no real major drawbacks and would recommend I put one in 110% if the gearbox is coming out.

Do you agree with this???

[PX29]

Well try this plot then. What I am saying is that a near on 45% gain in rwhp doesn't produce anything like that difference in acceleration. A change in mass (yes rotating mass) that is much less than one percent of the total will have a proportionally smaller affect on the acceleration. My point is that I characterise that change as being negligible. But you are right, ofcourse you can feel the difference of much more powerful engine - although you do get used to it really quickly.

You are correct in saying it is more significant in lower gears at lower speeds (less aero drag for one & more rpm per km/h), but this is fairly unimportant because you are invariably traction limited.

Well up to you, but I was trying to quantify the change & give people an idea of what sort of order of magnitude to expect. Make 5kg if you like, but you don't chuck 5kg worth of gear on your car and suddenly turn it into a slug.

All of which goes to show the minor influence the flywheel has on proceedings. Which is my point.

Thanks for theo offer, but budget is a bit tight this month. Anyway I already have a lightened flywheel, so to a degree you are preaching to the converted.

hahaha.....We still see things differently and it seems like my explanations are not good enough to make you agree. Fair enough, when I got time I'll hit you up with a more detailed explanation.

P.S. Some "converted" ones dont know why they converted.

Cheers,

Edited August 29, 2007 by PX29