Flywheel Advantage
08-02-2004, 02:04 PM
#31
Originally Posted by SLO-S2000,Aug 2 2004, 12:12 PM
nice post slipstream
Also, something I might add. Now "we" know the car with the heavier flywheel is easier to get started because of more stored energy/torque. Now what if car A is stock, and car B is stock apart from Lightweight Flywheel, and stronger/heavier pressure plate. That heavier pressure plate should help the car get started faster because it engages the clutch quicker and with more force, right? So by having the Pressure plate, it helps to get rid of the "hard to get startedness" of the lighter flywheel, right?
All that might be needed is a few more revs (couple hundred) while engaging the clutch which will be come second nature in the first 10minutes.
As you, I actually found my S2000 was easier to drive with the lighter FW/Higher force PP. And as you - I nearly stalled the car (once) right after having the lighter FW installed, but completely adjusted within a few minutes of driving. I have not an ounce regret - the car is much better.
My friend has a stock clutch on his S2000, and I can't stand to drive it. I like the higher pedal effort because it makes it easier to control the clutch engagement - even with my chicken legs!
08-02-2004, 02:18 PM
#32
I find it easier to control and modulate a clutch with a moderate effort PP - that has higher than stock clamping force.
The friction or 'bite' of the disc is more a function of the friction material of the disc. Since I'm using an OEM Honda disc in my setup, the actual bite of the disc didn't change.
However I find it easier to modulate a heavier pedal because you have to concentrate a just a little harder and the heavier pedal provides more feedback. There's obviously a point where a heavier pedal effort begins to detract from the operating ease of the clutch, but the ACT is right on!
The stock pedal effort is too light and doesn't provide as much feedback as the ACT. It's like having too much boost in a power steering system, you get to the point where the steering feels numb. Conversely, if you've driven a 1965 Mustang that was equipped with an un-boosted reciprocating ball steering system, it gets to the point you have to work too hard to steer with any finesse. The same can be said with the clutch.
The friction or 'bite' of the disc is more a function of the friction material of the disc. Since I'm using an OEM Honda disc in my setup, the actual bite of the disc didn't change.
However I find it easier to modulate a heavier pedal because you have to concentrate a just a little harder and the heavier pedal provides more feedback. There's obviously a point where a heavier pedal effort begins to detract from the operating ease of the clutch, but the ACT is right on!
The stock pedal effort is too light and doesn't provide as much feedback as the ACT. It's like having too much boost in a power steering system, you get to the point where the steering feels numb. Conversely, if you've driven a 1965 Mustang that was equipped with an un-boosted reciprocating ball steering system, it gets to the point you have to work too hard to steer with any finesse. The same can be said with the clutch.
08-02-2004, 02:23 PM
#33
Originally Posted by Elistan,Aug 2 2004, 03:53 PM
Since its on/off character gives you less opportunity to modulate the friction by slipping the clutch, you're more likely to fully engage the clutch before the engine can get above its stall speed. Therefore it's much easier to stall the engine. Even with giving the car extra revs, it's easy to dump the clutch without intending to, and while the car will lurch forward for a little bit, it'll likely stall.
08-02-2004, 05:22 PM
#34
Registered User
Thread Starter
Join Date: Sep 2001
Location: Guaynabo
Posts: 105
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by xviper,Aug 2 2004, 05:38 PM
The easiest way to explain this is it would be "like" adding another slightly bigger sprocket to the set on the back wheel of your bicycle.
08-02-2004, 06:14 PM
#35
Originally Posted by Alfredo,Aug 2 2004, 07:22 PM
So one could say that the loss of torque you loose at low end (with the lighter FW)will be compensated with a higher final gear and still have the benefit the lighter flywheel gives at the high end?
I don't look at it in a way that there is a "loss of torque". It's just that a lighter flywheel doesn't hold as much of the torque (in the form of inertia). The torque doesn't go anywhere. You just don't have the same inertia in the lighter flywheel to get the car going.
08-02-2004, 06:38 PM
#36
Originally Posted by xviper,Aug 2 2004, 08:14 PM
That's a very simplistic way of putting it, but yeah.
I don't look at it in a way that there is a "loss of torque". It's just that a lighter flywheel doesn't hold as much of the torque (in the form of inertia). The torque doesn't go anywhere. You just don't have the same inertia in the lighter flywheel to get the car going.
I don't look at it in a way that there is a "loss of torque". It's just that a lighter flywheel doesn't hold as much of the torque (in the form of inertia). The torque doesn't go anywhere. You just don't have the same inertia in the lighter flywheel to get the car going.
So true.
This site (same as I posted before) also puts some of the gear thing in perspective ...
http://www-unix.oit.umass.edu/~tcroy/artic...gineinertia.htm
08-02-2004, 09:50 PM
#37
Originally Posted by Elistan,Aug 2 2004, 01:53 PM
No, a stronger pressure plate that grabs quicker/harder will make a car with a lightweight flywheel even harder to get started. Since its on/off character gives you less opportunity to modulate the friction by slipping the clutch, you're more likely to fully engage the clutch before the engine can get above its stall speed. Therefore it's much easier to stall the engine. Even with giving the car extra revs, it's easy to dump the clutch without intending to, and while the car will lurch forward for a little bit, it'll likely stall.
08-02-2004, 11:21 PM
#38
Join Date: Sep 2003
Location: las vegas
Posts: 3,361
Likes: 0
Received 0 Likes
on
0 Posts
[QUOTE=slipstream444,Aug 1 2004, 11:59 PM] 
Looks like you quoted a text book my friend. You need to get back in that text book, read it fully, get someone to help you better understand it, move onto statics, thermo, dynamics (all while getting help), and then post.
For the record, I have a very strong background in calculus-based physics (straight 'A's back in my college days) and understand the principles of kinetic energy very well. Additionally, the principles involved with describing the properties associated with a flywheel are covered throughout the physics continuum from Physics 1 through advanced and applied Dynamics (and on). I
Looks like you quoted a text book my friend. You need to get back in that text book, read it fully, get someone to help you better understand it, move onto statics, thermo, dynamics (all while getting help), and then post.
For the record, I have a very strong background in calculus-based physics (straight 'A's back in my college days) and understand the principles of kinetic energy very well. Additionally, the principles involved with describing the properties associated with a flywheel are covered throughout the physics continuum from Physics 1 through advanced and applied Dynamics (and on). I
08-03-2004, 01:08 AM
#39
Originally Posted by S2oooNvegas,Aug 3 2004, 01:21 AM
well, lets see. its obvious at this point that slipstream is a bookworm, lets see what he actually know about whats inside an engine. tell me some stuff about hydrodynamics, tell me some stuff about spark energy and its relation to torque production concommetent to thermodynamics. lets hear it book boy, how long have you been building engines. yeah, thought not. lets see, what happens when an engine is desgned with a specific horsepower output in mind, the flywheel is then designed to absorb harmonic vibrations from the crankshaft at a broad band of RPM. why is this done, so that the crank can spin freely on a film of oil, the study of hydrodynamics. if you then increase the horsepower, you narrow the range in which the flywheel is able to reduce transitive vibrations.many other factors are involved of course, but this is for the sake of someones high horse being toppled. so now you add horsepower, even lets say FI, and the lighten the flywheel. i hope you plan on adding 70 wt oil, because your poor crank is not going to enjoy the rough ride it gets as it trys to handle the vibes that the flywheel once helped to smooth out. take a look sometime at the studies of gene berg. on an engine as small and fragile as an aircooled vw, he would take weight from the flywheel end, and then end up with massive bearing failures, lack of oil pressure, and out of line bearing tunnels. so then where did he end up making the difference, for the sake of hydrodynamics, so he wouldnt loose oil shear, he added weight on the pulley end. i know, most of you are lookin to lower rotating mass, in order to pick up some gain. well, if this was so easy to do, and weight has no effect then why dont more manufacturers do so, all im tryin to say is this.
experience proves, lighter flywheels are great on the track. not for daily use, an engine that sees that many heat cycles will wear much faster with a light wheel.
the s2k wheel is already at 15 lbs. that is damn light for a factory car. if you feel the need, go ahead so far no one has attributed an s2k engine failure to a lighter wheel, i was just stating some tech jargon when i said this. now i am replying to a mole who has trenched in my grass. feel free to attack as you may, getting the best of me, doubt it. laters folks, enjoy life. dave
experience proves, lighter flywheels are great on the track. not for daily use, an engine that sees that many heat cycles will wear much faster with a light wheel.
the s2k wheel is already at 15 lbs. that is damn light for a factory car. if you feel the need, go ahead so far no one has attributed an s2k engine failure to a lighter wheel, i was just stating some tech jargon when i said this. now i am replying to a mole who has trenched in my grass. feel free to attack as you may, getting the best of me, doubt it. laters folks, enjoy life. dave
Oh dear, I think I hurt your feelings.
And look at the big brain on Brad ... we're all so proud!
You have humbled me in the ways of the Bookworm, oh learned one.
While I never studied fluid dynamics (directly), I believe I have a relatively good handle on the subject. Perhaps maybe - a little edge on you ... perhaps.
Let me give you a little advice: before you drop a barb, Mr. S2000 in Vegas ("Dave"), prepare to receive the same in kind (and have a thick enough hide to deal with it). And when you make a poorly developed assumption - expect to hear about it ... even more so (especially on this site).
You made a snide comment implying I needed to study up on kinetics. Vegas Baby, that's my line of work - I'm a pilot in the U.S. Navy - I do nothing all day but 'manage energy" (if you need an explanation on that ... for the sake of the other folks here, please PM me).
BTW (Mr. Harmonic vibration hydrodynamic bearing tunnel transitive spark energy oil film boy) your basis for your original assumptions were two dimensional, poorly conceived (or at least poorly communicated), ... and, uh uhhhmmm ... used a fixed reference frame (geek ... I know).
"My" S2000, however, operates in three dimensions, is defined by a moving reference frame, and - oh by the way - doesn't exist in a test-tube environment. The S2000, while a finely tuned machine, does not require the tolerances of the space shuttle (or "... a small and fragile" air-cooled VW ... ? ... whaaaatt? ... that was your example dude? ... ... can't help you there).
You need to get your nose out of your collection of books (and at least attempt to come up with your own material - i.e. stop plagiarizing your used text books) and get a sniff of the real world my friend - it's much more interesting.
While it's obvious you do in fact have a lot of valuable knowledge - you need to learn how to apply it and effectively communicate it. Do me a favor - put down the fluid dynamics text and pick up the "Communication Skills for Dummies" book ... Gooood ... now read it.
(Good God man ... you quoted the studies of ... ... Gene Berg ...)
One last thing - go out and get laid dude, it might help out a little.
Cheers
For note ... I've been working on cars since 1981 (or thereabouts) - not necessarily building engines at that time ... but I've had my hand in an engine or two ...
08-03-2004, 01:34 AM
#40
Registered User
Join Date: Apr 2003
Location: Hawaii
Posts: 1,987
Likes: 0
Received 0 Likes
on
0 Posts
I'm no engineer but perhaps someone can explain my dilema. I don't understand why a heavier flywheel would be easier to spin than a lighter one. From what I gather, a lighter flywheel should be easier to get moving than a heavier flywheel wouldn't it? (don't flame me yet, please read my examples below to understand why I'm thinking this)
The way I picture it in my head is imagine a benchpress bar (representing the crank) with a 45 pound weight on one end (representing the flywheel). If I were to try and rotate the bar (not at the weight), it'd be difficult at first since I have to overcome the inertia of moving an object with a larger mass. However once I get the bar spinning, and stop spinning it by hand, it won't be quick to slow down and it'd keep rotating longer. Now in a car, I'd imagine that revs wouldn't drop quickly and it'd be easier for the driver to take his/her sweet time to shift between gears since the revs will remain steady. This would be nice for a nice long cruise.
Now if the 45 pound weight were to be substituted with a 10 pound weight, if you try and rotate the bar, it'd be easier since there's less mass to move, meaning it'd take less effort to move something lighter. However once the bar is spinning, once I stop spinning it by hand, it'd slow down at a much higher rate than the 45 pound weight as it can't store nearly as much energy causing a more rapid decline in rotational speed. In a car, I'd imagine it'd allow for a quicker pickup for acceleration, but revs may drop quicker between shifts since it can't maintain the momentum (forgive me if I'm using the wrong terms) of the spinning motion. This would be helpful where throttle response and acceleration become a major priority.
Another way I see it is with a bowling ball versus a plastic ball. It'd be easier for an infant to push the plastic ball but it'll slow down quickly since it can't store enough energy, however if the infant were to manage to move the bowling ball (which requires more effort), it'd take a lot longer for it to slow down since it can store more energy.
The way I picture it in my head is imagine a benchpress bar (representing the crank) with a 45 pound weight on one end (representing the flywheel). If I were to try and rotate the bar (not at the weight), it'd be difficult at first since I have to overcome the inertia of moving an object with a larger mass. However once I get the bar spinning, and stop spinning it by hand, it won't be quick to slow down and it'd keep rotating longer. Now in a car, I'd imagine that revs wouldn't drop quickly and it'd be easier for the driver to take his/her sweet time to shift between gears since the revs will remain steady. This would be nice for a nice long cruise.
Now if the 45 pound weight were to be substituted with a 10 pound weight, if you try and rotate the bar, it'd be easier since there's less mass to move, meaning it'd take less effort to move something lighter. However once the bar is spinning, once I stop spinning it by hand, it'd slow down at a much higher rate than the 45 pound weight as it can't store nearly as much energy causing a more rapid decline in rotational speed. In a car, I'd imagine it'd allow for a quicker pickup for acceleration, but revs may drop quicker between shifts since it can't maintain the momentum (forgive me if I'm using the wrong terms) of the spinning motion. This would be helpful where throttle response and acceleration become a major priority.
Another way I see it is with a bowling ball versus a plastic ball. It'd be easier for an infant to push the plastic ball but it'll slow down quickly since it can't store enough energy, however if the infant were to manage to move the bowling ball (which requires more effort), it'd take a lot longer for it to slow down since it can store more energy.