i heard you can lose top speed (15kph or more) when you go with ligther flywheel, true or some joe-bloe-talk

I know that unorthodox racing make some 10lbs flywheel, and fidanza 8lbs for a H series, and after reading I would think that going with the 10lbs would be the best since it's a streetable, but still a question, up here we have some hard winter, so wonder if aluminium would hold up, if not wich company could make lightweight flywheel in other material than aluminium?

 

i just thought i would show u guys the spoon sports flywheel, this is what im going with, as well as a exedy clutch...




"The Spoon lightweight flywheel weighs in at 4.2kg compared to the factory 6.9kg. This flywheel is not too light, so you won't loose off the line torque. Help your engine spin freely. Pre-balanced and comes with a new pilot bearing and flywheel bolts. "


sorry i was just wondering also, how to determine weight.. from Kg, i suck at math.. haha

 

I personally have not heard anything like that before.

I have not noticed it either, but I do still have a speed limiter :-(

 

So why don't you guys make a poll out of this? that way you can just vote?

 

Spoon Sports FW is 4.1kg About 9 pound and some change (9.04)

Excellent Choice. Again, anytime you go lighter the effects will be the SAME just than depending on how much less it weighs the differences are going to be more or less noticable.

I think I too will switch to the Spoon FW because I find that although LIVABLE, the 8.6 pound J's Racing FW is just a bit too much for street use.

NO ONE is Fighting here I think this is a good debate and both sides come out to express their Opinions and add a little tech as well. Someone who reads this will be better able to select a FW for their needs.

 

Man there are some retarded people in this thread.

I run a 7.5lb Fidanza flywheel on my ITR. It is extremely daily driven, I average over 30,000mi a year, about 25,000mi have been with my flywheel. If this flywheel came with the car stock I don't think anyone would notice, yes it is THAT streetable. Of course you have to rev it a tad higher than stock or ride the clutch a touch longer on normal take offs, but it is absolutely nothing to think about.

There is no torque loss with the flywheel. This is only precieved when coming off a dead stop because the car requires a tad bit more rpm. The flywheel is lighter and doesn't have as much inertia to get the wheels rolling, BUT this is only as you are in the process of engaging the clutch. Once the clutch is fully engaged it is just that, engaged, as in directly contected to the flywheel, as in you now have alot less rotational mass on the crank = faster.

Once my clutch is engaged my car is faster from idle to redline. Especially in the first two gears, which due to gearing and some physics is where the majority of the gains are felt (in first gear the car equates to be roughly 200lbs lighter if I'm not mistaken). If anything my car feels as if it has noticeably MORE torque from this effect. Don't believe me? Put two exactly equal cars against one another the only difference being one having a lightweight flywheel from a very low rpm first gear roll. Now watch as the car with the lighter flywheel pulls ahead, then come tell me about torque loss.

 

well theres all that physics stuff and such. so i'll just speak from experience. i have an 89 4wd wagovan, cruisin' on the highway at 70(which is about 3500rpm) im at about 5% throttle and my variance is very little with the rpms and i have incedible mileage at this throttle% and rpm 30+ while in 4wd, which means i've got the tranny spinning half of a drive shaft assuming my wheels aren't slipping. If i go to about 15% throttle i get upto about 85 mph in no time, if i had to estimate i'd say between 10 and 20 seconds. City driving isn't hard, no problems there i can shift at 2500 and still get upto speed within reason. If i happen to be going up a hill and im under 2500 rpms i have to downshift but past 3000 rpms i can consistantly accelerate at 30%-50% throttle. Now i tried to teach my bud stick while i've got this 8.8 ACT flywheel in my car, he couldn't control it worth a damn. Its easy for me and my rpms don't drop much since i probably shift fast enough, and i simply listen for the engine when at stop to start going, and my throttle is 1%-3% (thats about 3000 rpms when the clutch is disenagaged from the flywheel)when i go from a stop in normal stop&go traffic. So indeed you need a nimble foot to manipulate a light flywheel but by no means does it kill gas mileage in any setting or kill the little lowend torque (0-4k) i do have. Im also sporting a d15b sohc vtec with currently no vtec hooked up. btw i hope this makes sense if not read it again im tired and have no ambition to make this coherent

ohh btw when racing my friend, while in 4wd mind you i peeled in 1st all the way to redline and chirped second so i suppose i can say more power does make it to the wheels thats for sure

 

having a lighter flywheel makes the engine have less rotational mass. Less rotational mass = faster accelerating car, because the car does not have to waste energy by spinning the heavy mass.

it's like putting lightweight rims on your car.

here is a good page for some more information.

http://www.siscom.net/~welter/racing/rotation.html

 

the less rotational mass theroy is true.

But just a thought, if it does spin that fast it would create more wear/tear on the crankshaft, and rods/bearings etc.?

correct?


Though I still will be going with my Spoon FW, because of the weight, and I trust spoon with honda made parts.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Soon2B18Boost &raquo;</TD></TR><TR><TD CLASS="quote">So why don't you guys make a poll out of this? that way you can just vote?</TD></TR></TABLE>

DONE!

https://honda-tech.com/zerothread?id=597275

 

Okay I want to say this at no offense... Though the concepts are the same you are taking this discussion into a different areane with 4wd.

Let me say this. Like you say it take a different foot to drive a lighter FW than what people are used to. Not to say that we can't teach ourselves to drive a Lighter FW.

I did myself, but I think I went a bit too far when I went woth the 8.6 pound FW so I may go back up but only to a 9 not back to the 12.
Gas mileage: Think of this.... WHY does a car get better MGP on the Highway than in the City? ONE WORD= Consistency. Speaking from personal Experience I lost a few MGP when I wen lighter. This is not an imagined thing. This is not cause I feel the desire to drive fast. It is SIMPLE. You have to rev higher and what happens when you do that? You use more GAS. Having said that. the lighter you go the more evident these tendencies will be. You will notice less difference between a 12 pound and 16 pound than you would with a 7 pound and a 16 pound.
Like I was saying in the Integra Forum and lets not get into reading too deeply into what I am saying... Some people Like the 7 pound FW and feel that it is totally streetable, but doen't change the FACT that there are some of us out here that feel 7 pounds is too light. It's not hard Just accept it.
One example I made about the 4.9 ATS FD... There are people on this MB that say it is totally streetable. Moderator of the Civic forum for one. Well I am sorry but not for me. I drove in a car for about 20 mins and wanted to get out. I am not saying that you should not get a 7 pound if you think you can deal with it then go for it. FACT IS it is not for everyone and that has been my whole point in this whole thing. I want to provide the other side of the story so to speak.
An engine with a lighter FW will not last as long as the an engine built to specs with a heavier FW. TRUE Why? Well the Heavier FW stores energy and naturally wants to remain in motion. A lighter FW stored less energy so the crank has to be taxed more to keep the FW in motion. With the Heavier FW the stored energy can be transfered to the clutch on engagement without taxing the energy in the crank. The Lighter FW as less mass therefore less Stored Energy so when the clutch is engaged what ever energy it can't get from the FW it will get from the crank.

Lol think of this: Two people go to work everyday and make $$$ One person puts most of his money in the bank to save for a rainy day. The other Spends most of his money and has FUN FUN FUN. All is good in either place until the clutch is dropped... Then WHO HAS TO STRESS OUT to get that $$$ so they won't Starve (Stall)
No one is arguing that Lighter FW don't have less rotational mass and therfore less work for the engine INITIALLY....

But I think there is a trade off. I think the engine has to work harder to maintain.
Another thing you have to consider when comparing a FW... All FW were not creasted equal. You may be running a 7 pound FW but depending where the weight is taken off it may be just as effective a 12 pound FW. Though it may weigh 7 pounds if that wight is towards the rim then it is not working for you the way a 7 pound FW with the weight towards the center would.
Look at my FW that weight is taken from the edges of the FW. it weighs in at 8.6 pounds and it is a big difference from my 12 pound FW Just something to think about...

 

its all about inertia so its easy to get it in motion and since its lighter it takes less energy to keep it in motion. ts that whole e=1/2mv^2 deal. assuming you've got a 14lb flywheel and you goto a 7 lbs your flywheel will store 1/2 the energy as teh original 14lb one so it takes 1/2 the energy to move it and it takes 1/2 the energy to get it to the speed of the 14lbs flywheel

 

Since we're going to be talking about rotational movement, why don't we start using rotational kinetic energy?

KE(Rot) = 1/2 I w^2, I = 1/2 M r^2 so...

KE(Rot) = 1/4 M r^2 w^2 where M is mass, w is angular accel., and r is the radius.

There's not really a difference, but if we're talking about flywheels, we shouldn't be using linear formulas.

The torque at the seen at the wheels is going to be better at every rpm seen at the engine. Why? The flywheel is not producing a positive torque (positive meaning turning the wheels the direction we want), but is actually producing a negative torque hindering the crankshaft's effort. This is because the engine has to push it's fat flywheel *** around =&gt; rotational inertia (it has mass).

KE(engine) = KE(flywheel) + KE(remaining components)

Any KE that the flywheel has, is KE that the remaining components will not receive.

Edit:

The flywheel produces a negative torque. I define a negative torque as in the oppostie direction of the engine's acceleration. This negative torque occurs because the flywheel is being propelled by the engine (it is not propelling itself) and it has mass. The engine must overcome this negative torque at every engine speed. This negative torque isn't applied at constant velocity, but the flywheel is still directly attached to the engine. So when the engine stops accelerating (even though it doesn't) it doesn't allow the heavier flywheel to use it's larger momentum to propell the rest of the drivetrain. =&gt; The flywheel moves when the engine says it can.


Modified by GSpeedR at 3:38 PM 8/20/2003

 

genius absolute genius.

just to clarify and be absolutely 100% sure. you're saying if it takes 1 ft/lb to rotate the flywheel thats 1 ft/lb less the wheels will see, correct?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by altoid &raquo;</TD></TR><TR><TD CLASS="quote">its all about inertia so its easy to get it in motion and since its lighter it takes less energy to keep it in motion. ts that whole e=1/2mv^2 deal. assuming you've got a 14lb flywheel and you goto a 7 lbs your flywheel will store 1/2 the energy as teh original 14lb one so it takes 1/2 the energy to move it and it takes 1/2 the energy to get it to the speed of the 14lbs flywheel</TD></TR></TABLE>

You're off on that one. True it take less effort to get it moving and it will accelerate faster, BUT keeping it in motion is a different story. The heavier has more stored energy and it wants to stay in motion. A greater force will have to act on it to stop it from rotating.
This is the reason that it is easier to stall the car with the lighter FW. Instead of storing the energy the lighter FW applys the energy to the wheels and that is why you accelerate faster. The Law of inertia applies here. Forget the laws and formulas. THINK about it... Given two wheels spinning at a certain speed one is 20 pounds and the other is 10 pounds which would take the greater amount of energy to stop it from spinning? Which one would take less amount of work to get it to spin at that certain speed? Now take two Spinning tops One weighs twice as much as the other. Spinn them and tell me which one will stop spinning FIRST. True it takes less to get it going but it also takes less to get it to stop meaning it takes more to keep it going at a constant ans smoothe speed. How man times can you spin the lighter one before the heavier one stops??If you want the lighter one to keep going for as long as the heavier one you will have to keep sninning it from time to time so essentially you are expending more effort to keep it going.
Another way to look at it. Take a motorcycle traveling at 100 MPH and run it into a brick wall Now take a train and get it to 100 and run it into the same wall. What happens? Sure it too more to get that train going but it kept going through that wall whereas the Motorcyle hit the wall and bounced off. ( okay maybe that was a little off but you get the point. It's almost 4am and I'm sleepy :-)

 

God damn you guys are still discussing this crap? so after 3 pages does everyone know the differences between flywheel weights and its effects? or maybe we need another 3 pages!! lol

 

I really don't think anyone is arguing that a lighter FW doesn't allow the car to acce=lerate faster. No one is denying the facts

Plain and Simple: if you a used to driving with a say, 16 pound FW and you go to an 8 pound you will have to change the way you drive. If you could chirp the tires on take off at say 2500 rpms if you try the same thing with a lighter FW you will not chirp the tires at 2500 rpms
You have to apply more rpms to get the same effect. So when people say that the car feels like it lost some torque at the bottom this is what they are experiencing. The torque necessary to chirp the tires with the 16 pound FW has moved up to a higher RPM
In my case I had to rethink my driving practices to compensate. Some people are willing to adjust to a point.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Spoond TEG &raquo;</TD></TR><TR><TD CLASS="quote">

You're off on that one. True it take less effort to get it moving and it will accelerate faster, BUT keeping it in motion is a different story. The heavier has more stored energy and it wants to stay in motion. A greater force will have to act on it to stop it from rotating.
This is the reason that it is easier to stall the car with the lighter FW. Instead of storing the energy the lighter FW applys the energy to the wheels and that is why you accelerate faster. The Law of inertia applies here. Forget the laws and formulas. THINK about it... Given two wheels spinning at a certain speed one is 20 pounds and the other is 10 pounds which would take the greater amount of energy to stop it from spinning? Which one would take less amount of work to get it to spin at that certain speed? Now take two Spinning tops One weighs twice as much as the other. Spinn them and tell me which one will stop spinning FIRST. True it takes less to get it going but it also takes less to get it to stop meaning it takes more to keep it going at a constant ans smoothe speed. How man times can you spin the lighter one before the heavier one stops??If you want the lighter one to keep going for as long as the heavier one you will have to keep sninning it from time to time so essentially you are expending more effort to keep it going.
Another way to look at it. Take a motorcycle traveling at 100 MPH and run it into a brick wall Now take a train and get it to 100 and run it into the same wall. What happens? Sure it too more to get that train going but it kept going through that wall whereas the Motorcyle hit the wall and bounced off. ( okay maybe that was a little off but you get the point. It's almost 4am and I'm sleepy :-)</TD></TR></TABLE>

Exactly. Many people don't get the point. Although it takes a little more work to start off, once it keeps going it will be more efficient on gas.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Beave0101 &raquo;</TD></TR><TR><TD CLASS="quote">it also depends on the motor.

Running an ITR motor i would go 9-10 lbs
running an LS/Vtec I wouldnt go lighter than 12lbs, not a great offset for a light crank and a light flywheel</TD></TR></TABLE>

i have an ls/tec and i have a fidanza 7.4lb flywheel and i love it. i have no problems with it at all. i love it

Ryan

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Spoond TEG &raquo;</TD></TR><TR><TD CLASS="quote">You're off on that one. True it take less effort to get it moving and it will accelerate faster, BUT keeping it in motion is a different story. The heavier has more stored energy and it wants to stay in motion. A greater force will have to act on it to stop it from rotating.</TD></TR></TABLE>

This only matters when the rest of the drivetrain is not attached to the engine (clutch is out). The flywheel is directly connected to the engine. So the only benefit of a heavier flywheel is at the launch. The clucth is not attached so the flywheel's larger inertia provides more potential energy at every engine RPM. So when the clutch is engaged, the drivetrain sees more kinetic energy from the flywheel (at that instant). As soon as the flywheel and clutch are moving at the same speed, there is more torque transmitted to the wheels, because the engine doesn't waste as much kinetic energy spinning the flywheel.

As soon as the clutch is engaged, the car with the lighter flywheel will make more torque at the wheels (less driveline loss) at every engine speed.

Here is a quote from allenp from https://honda-tech.com/zerothread?id=114022:

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by allenp &raquo;</TD></TR><TR><TD CLASS="quote">"Flywheels cause you to lose torque and gain HP."
This is such a widely held misconception that no matter how many times I try to explain it, it never reaches anyone it seems. I'll try to dissolve this idea here.

Your engine produces torque. The rate at which the torque is produced is power. It's a simple formula: Power=Torque*engine speed, with some other numbers in there to make the units work... ANYWAY. When you put a lightened flywheel in, you make NO CHANGES to the torque produced by the engine. So, therefore, you make NO CHANGES to the power put to your wheels. However, it SEEMS like you lose some low-end torque, for this reason:

When the flywheel is spinning, it stores energy. The faster it's spinning, and the larger it's mass moment of inertia (related to the weight), the more energy it stores. Therefore, when you launch the vehicle, the energy stored in the spinning flywheel is transmitted through the clutch, transmission, and to the wheels, helping you accelerate. Let's say, for example, you launch your car at 1000 RPM. If you lighten the flywheel, there will be less energy stored by the flywheel at that engine speed. SO, it will FEEL like there's less torque available because of the reduced energy storage. And as a result, you have to put your foot into it harder. Theoretically, if you put a big enough flywheel in, you could simply let go of the clutch and the car would launch, because the flywheel had enough energy to perform that launch.

Once you've launched the car and are accelerating, there is no advantage to a heavier flywheel. The lighter flywheel will allow the torque produced by the engine to accelerate the vehicle instead of accelerating the flywheel inertia.</TD></TR></TABLE>

The only benefit of the heavy flywheel occurs at the launch/idle.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">Quote, originally posted by altoid »
just to clarify and be absolutely 100% sure. you're saying if it takes 1 ft/lb to rotate the flywheel thats 1 ft/lb less the wheels will see, correct?
</TD></TR></TABLE>
That's the concept.



Modified by GSpeedR at 5:57 PM 8/20/2003

 

I missed the post here from ActiveAlero, but he is correct.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Soon2B18Boost &raquo;</TD></TR><TR><TD CLASS="quote">the less rotational mass theroy is true.

But just a thought, if it does spin that fast it would create more wear/tear on the crankshaft, and rods/bearings etc.?</TD></TR></TABLE>

Yes. Here is some excellent information from allenp once again:

From https://honda-tech.com/zero...age=1 (a good thread if you want to read the entire thing).
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by allenp &raquo;</TD></TR><TR><TD CLASS="quote">The internal combusion engine fires 1 cylinder at a time. Each time the cylinder fires, all rotating components in and around the engine (balance shafts, valve timing drives, front end accessories) as well as connected to the crankshaft (flywheel, clutch, transmission, etc) accelerate and decelerate with each combustion/compression cycle. If you look at a graph of speed over time of the engine, it will have a sinusoidal waveform. The more powerful the engine, the more severe the amplitude of the waveform. Additionally, the fewer the cylinders (and hence the lower firing frequency of the engine) the more severe the vibration. THIS is the reason the clutch disc has springs in it -- to absorb/dampen those vibrations before they get to the transmission. But that is another issue.

So where does the flywheel fit in? As an energy storage device, it stores rotational kinetic energy produced by the engine with each firing, and thus when the engine is in the compression cycle (the valley of that speed/time curve) it releases energy, bringing the valley up. Conversely, when the engine fires, it brings the peak of the acceleration down by soaking up some of the energy. The net result? A smoother waveform (lower peak-to-valley difference.)

As those rotating components accelerate and decelerate, they experience stresses. When load fluctuates like that, fatigue failures become a problem. Timing belts have broken as a result of engine torsional (rotational) accelerations. As have accessory belts. So, the engine designer needs to consider this.

The solution? A flywheel that smoothes out those accelerations as much as necessary.

Usually the flywheel is conservatively designed, so some lightening will likely have little long-term effects. However, severe lightening can.</TD></TR></TABLE>

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by GSpeedR &raquo;</TD></TR><TR><TD CLASS="quote">I missed the post here from ActiveAlero, but he is correct.

Yes. Here is some excellent information from allenp once again:

From https://honda-tech.com/zero...age=1 (a good thread if you want to read the entire thing).


</TD></TR></TABLE>

Great thread.

 

YES and No

The main difference at launch but keeping the FW rotating is nolonger helped from the rotating mass.
Another Down Fall I experience is that the REVs dropped quicker as a result of less stored energy. The Lighter FW will just not want to stay in motion like the heavier one.
I am not saying that Lighter is BAD I am just saying that there are other issues to consider other than Acceleration. I don't disagree that the Lighter FW will accelerate faster and I don't think anyone else is disagreeing on that.

I went from Stock to 12 pounds and I liked it. There was a difference in driving the car but I got used to it. I could live with the change. I had to RELEARN how to drive my car. I though I liked the 12 so much maybe I should go lower. I got a great deal on the J's FW and I took it. I was really looking for a 9 but the 8.6 was better priced. Same thing... better Acceleration, but the other effects it had were also more pronounced. So I will probably go back up to a 9 pound.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Spoond TEG &raquo;</TD></TR><TR><TD CLASS="quote">YES and No
The main difference at launch but keeping the FW rotating is nolonger helped from the rotating mass.</TD></TR></TABLE>

The heavier flywheel will resist acclereation and "do a better job" at keeping the engine at a constant velocity. The misconception here is that because it is attempting to stay at a constant velocity, it will be easier to accelerate it (which is untrue). Even at a constant velocity, the heavy flywheel requires more energy/torque to spin than a lighter flywheel. This is energy/torque that is no longer transmitted to the wheels. I'm not sure if this is what you're trying to say, however.

Edit: The increased momentum/stored energy/potential energy of the heavier flywheel resists changes. So if suddenly, your car approached a steep hill, the increased momentum of the heavy flywheel would resist the deceleration that the drivetrain experiences. This is the only way I can see that more inertia "helps". The rotational inertia produces a negative torque opposing the acceleration from the engine pushing it, and the decelration from the hill slowing it.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">Another Down Fall I experience is that the REVs dropped quicker as a result of less stored energy. The Lighter FW will just not want to stay in motion like the heavier one. </TD></TR></TABLE>

The lighter flywheel does what the engine does, which is essentially what you are telling them both to do. The light flywheel does everything faster and with less energy.


Modified by GSpeedR at 1:06 AM 8/21/2003

 

Right but you are loosing some cinsistency in your engine and making more into surges.

If you put the rpms on a line graph the Heavier FW will have a Smooth Hilly graph where in the Lighter one will have more peaks and valleys.

When the clutch is engaged it is more like connecting the crank directly to the transmission .... Bare with me a bit here.
I made a statement that a Lighter FW was harder (not meaning energy wise)on the Crank and Trans. (Meaning wear and tear) We can agree that an engine with more cinsistency will last longer than one with Spikes pos and NEG...
The energy that is nolonget stored in the FW is distributed to the drive train and to the wheels. EXACTLY where you want it on a race car. It is safe ot say and through my observations and others that the energy nolonger stored will add extra stress to the other componets...