233 rwhp dyno sheet
07-05-2011, 08:29 AM
#101
you know --i was wondering if a lighten flywheel was a good mod or not?
I know it is not that simple--but hear my crazy thinking. The rotory engine really doesnt like accelerating and decellerating but its great for constant rpm running ( one reason airplane guys get better life out of it). Now a lighten flywheel magnifies the acceraltion and especially the decel part--right? I do wonder if a lighten flywheel causes more of a particular type of stress on this engine than the oem one?
Mazda went to great lenghts to squeeze out the most power to the wheels from the engine in this platform. I mean --a carbonfiber driveshaft in a production car? If they where that intent--then why did they stick with such a heavy flywheel?
In driving the same model of car-- one with a light flywheel and one that has the oem--i have to admit the oem one is noticeably smoother.
A lighten flywheel does help with rev matching but for anything else--i am not so sure?
When my present clutch goes-- i do believe i will go back to the oem one.
lol Team you hitting that Crown Royal?
I know it is not that simple--but hear my crazy thinking. The rotory engine really doesnt like accelerating and decellerating but its great for constant rpm running ( one reason airplane guys get better life out of it). Now a lighten flywheel magnifies the acceraltion and especially the decel part--right? I do wonder if a lighten flywheel causes more of a particular type of stress on this engine than the oem one?
Mazda went to great lenghts to squeeze out the most power to the wheels from the engine in this platform. I mean --a carbonfiber driveshaft in a production car? If they where that intent--then why did they stick with such a heavy flywheel?
In driving the same model of car-- one with a light flywheel and one that has the oem--i have to admit the oem one is noticeably smoother.
A lighten flywheel does help with rev matching but for anything else--i am not so sure?
When my present clutch goes-- i do believe i will go back to the oem one.
lol Team you hitting that Crown Royal?
07-05-2011, 08:46 AM
#104
Soju @ Korean BBQ joint
He was referring to Moment Of Inertia vs. static weight. Discussing the weight of a flywheel without knowing the MOI values is a bit pointless. For all you know your lighter flywheel/clutch combo has the same or higher MOI than the factory setup. The static weight is not that relevant, MOI is what counts for rotating mass ...
He was referring to Moment Of Inertia vs. static weight. Discussing the weight of a flywheel without knowing the MOI values is a bit pointless. For all you know your lighter flywheel/clutch combo has the same or higher MOI than the factory setup. The static weight is not that relevant, MOI is what counts for rotating mass ...
07-05-2011, 06:10 PM
#106
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Thread Starter
Soju @ Korean BBQ joint
He was referring to Moment Of Inertia vs. static weight. Discussing the weight of a flywheel without knowing the MOI values is a bit pointless. For all you know your lighter flywheel/clutch combo has the same or higher MOI than the factory setup. The static weight is not that relevant, MOI is what counts for rotating mass ...
He was referring to Moment Of Inertia vs. static weight. Discussing the weight of a flywheel without knowing the MOI values is a bit pointless. For all you know your lighter flywheel/clutch combo has the same or higher MOI than the factory setup. The static weight is not that relevant, MOI is what counts for rotating mass ...
Happy Rotoring,
Eric
BTW, the MOI concepts are not "street" or "race" oriented. Just like the guy in the video doesn't have to be either a college physics professor or an elementary school teacher.
07-05-2011, 07:24 PM
#107
Or not.
Since no one here is redesigning the clutch/pressure plate/flywheel/starter ring for the RX-8 and since there is essentially only one practical way to effectively reduce the mass of those components, not only will all available assemblies have roughly the same moment of inertia but knowing that value is almost completely useless since you cannot apply that value to a compensation anywhere else in the system.
When not engaged, the MOI change, as it correlates directly to mass, only ends up amounting to a somewhat trivial change in "feel" and possibly an adjustment to the engine management to compensate for overrun and idle return.
When it is engaged, the effect of the MOI of the total rotating mass of the motor is entirely trivialized by the effects of effective gearing and its synthesis of angular momentum.
Since no one here is redesigning the clutch/pressure plate/flywheel/starter ring for the RX-8 and since there is essentially only one practical way to effectively reduce the mass of those components, not only will all available assemblies have roughly the same moment of inertia but knowing that value is almost completely useless since you cannot apply that value to a compensation anywhere else in the system.
When not engaged, the MOI change, as it correlates directly to mass, only ends up amounting to a somewhat trivial change in "feel" and possibly an adjustment to the engine management to compensate for overrun and idle return.
When it is engaged, the effect of the MOI of the total rotating mass of the motor is entirely trivialized by the effects of effective gearing and its synthesis of angular momentum.
07-05-2011, 09:52 PM
#109
Most people would see/feel more from a balanced rotating assembly than changing the flywheel. The lighted flywheel will drop rpm faster and rev faster, however the heavier flywheel will retain its momentum during shifts. There is a very delicate balance here you must find/know for your particular set up.
Good read.
Good read.
07-05-2011, 11:13 PM
#110
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Thread Starter
Or not.
Since no one here is redesigning the clutch/pressure plate/flywheel/starter ring for the RX-8 and since there is essentially only one practical way to effectively reduce the mass of those components, not only will all available assemblies have roughly the same moment of inertia but knowing that value is almost completely useless since you cannot apply that value to a compensation anywhere else in the system.
When not engaged, the MOI change, as it correlates directly to mass, only ends up amounting to a somewhat trivial change in "feel" and possibly an adjustment to the engine management to compensate for overrun and idle return.
When it is engaged, the effect of the MOI of the total rotating mass of the motor is entirely trivialized by the effects of effective gearing and its synthesis of angular momentum.
Since no one here is redesigning the clutch/pressure plate/flywheel/starter ring for the RX-8 and since there is essentially only one practical way to effectively reduce the mass of those components, not only will all available assemblies have roughly the same moment of inertia but knowing that value is almost completely useless since you cannot apply that value to a compensation anywhere else in the system.
When not engaged, the MOI change, as it correlates directly to mass, only ends up amounting to a somewhat trivial change in "feel" and possibly an adjustment to the engine management to compensate for overrun and idle return.
When it is engaged, the effect of the MOI of the total rotating mass of the motor is entirely trivialized by the effects of effective gearing and its synthesis of angular momentum.
07-05-2011, 11:57 PM
#112
"Too"? Who else is included in that invite?
Meh. Since I don't really drink much and I'm pretty sure you don't mean nitrous, I'm going to have to just scratch my head on that one.
OK. Edumakate me.
I already know about MOI. A LOT about MOI.
So, what is "new" here?
So far, all you did was point to Team's post and say "hit Google".
So, I hit Google. I looked at all the usual stuff, like the Wikipedia entries on angular momentum, inertia and polar moment of inertia (an article that I contributed to editing, BTW).
I followed the links about flywheels. I read some interesting stuff on the various manufacturer sites. Etc.
So far, I haven't found anything to send me in the right, new and "enlightened" direction.
Since flywheels operate at engine RPM, their effect is direct, so the kinetic energy is what it is. (Part of the reason why the "I gained HP by installing a lightened flywheel!" threads are so entertaining.) Since you can only "lighten" anything one way - by removing mass - you are limited to altering the angular momentum by removing mass in places that it possesses mass that is not structural. On a flywheel, there is only a limited radius where this material exists and the MOI isn't affected much until you remove a fair amount of that material, so the entire radius that can be altered must be altered to have an effect on MOI.
Even the "stupid pet tricks" like an aluminum starter ring or aluminum dowels have a limited effect (even though they exist at the furthest reaches of the "r" in L=r*mv).
So, I most humbly ask again - elucidate us. Google doesn't have your experience in this new and exciting realm, apparently.
Meh. Since I don't really drink much and I'm pretty sure you don't mean nitrous, I'm going to have to just scratch my head on that one.
I already know about MOI. A LOT about MOI.
So, what is "new" here?
So far, all you did was point to Team's post and say "hit Google".
So, I hit Google. I looked at all the usual stuff, like the Wikipedia entries on angular momentum, inertia and polar moment of inertia (an article that I contributed to editing, BTW).
I followed the links about flywheels. I read some interesting stuff on the various manufacturer sites. Etc.
So far, I haven't found anything to send me in the right, new and "enlightened" direction.
Since flywheels operate at engine RPM, their effect is direct, so the kinetic energy is what it is. (Part of the reason why the "I gained HP by installing a lightened flywheel!" threads are so entertaining.) Since you can only "lighten" anything one way - by removing mass - you are limited to altering the angular momentum by removing mass in places that it possesses mass that is not structural. On a flywheel, there is only a limited radius where this material exists and the MOI isn't affected much until you remove a fair amount of that material, so the entire radius that can be altered must be altered to have an effect on MOI.
Even the "stupid pet tricks" like an aluminum starter ring or aluminum dowels have a limited effect (even though they exist at the furthest reaches of the "r" in L=r*mv).
So, I most humbly ask again - elucidate us. Google doesn't have your experience in this new and exciting realm, apparently.
07-06-2011, 12:44 AM
#113
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Thread Starter
^2 Questions:
1. Let's pretend someone on these forums wants to make their RX-8 street car faster and asks you to chose which was more important: Weight or Moment of Inertia for measuring the benefits of a higher performing Flywheel and pressure plate/clutch assembly. They want their car to accelerate more quickly. That is their question. You can only chose one. Weight or MOI. What do you tell them?
2. Why?
1. Let's pretend someone on these forums wants to make their RX-8 street car faster and asks you to chose which was more important: Weight or Moment of Inertia for measuring the benefits of a higher performing Flywheel and pressure plate/clutch assembly. They want their car to accelerate more quickly. That is their question. You can only chose one. Weight or MOI. What do you tell them?
2. Why?
07-06-2011, 12:56 AM
#114
Weight
Because they wont have an f-ing clue what I'm on about if I say "MOI".
And, more importantly, weight and MOI are directly and inextricably tied in this particular part on this particular application, so you aren't imparting any useful information when you try to impress them with your brandishing of an engineering term like "MOI".
Because they wont have an f-ing clue what I'm on about if I say "MOI".
And, more importantly, weight and MOI are directly and inextricably tied in this particular part on this particular application, so you aren't imparting any useful information when you try to impress them with your brandishing of an engineering term like "MOI".
07-06-2011, 08:03 AM
#115
You're not fooling anyone
Are you saying that all the different flywheels have more or less the same momentum? I think that I misunderstand you, english is not my mother language, but just wanna check. Cause from a theoretical view, as mine is, you're gonna store less energy in a wheel that has the same shape, but is made from a lighter material. And of course you will have the same effect if you remove mass from the original wheel.
What leads me to say that you're gonna increase whp because you're "filling" less energy into the flywheel when increasing RPM, and instead puts it out to the back wheels.
Or have I forgot something?
@eric:
When you say that lighter isn't always better, you're point is that two axles with same mass and diameter, but where one is hollow and the other massive, the massive will have less MOI than the hollow since the hollow necessarily have more mass further away from rotation center? Pew! - that was a long sentence...
Are you saying that all the different flywheels have more or less the same momentum? I think that I misunderstand you, english is not my mother language, but just wanna check. Cause from a theoretical view, as mine is, you're gonna store less energy in a wheel that has the same shape, but is made from a lighter material. And of course you will have the same effect if you remove mass from the original wheel.
What leads me to say that you're gonna increase whp because you're "filling" less energy into the flywheel when increasing RPM, and instead puts it out to the back wheels.
Or have I forgot something?
@eric:
When you say that lighter isn't always better, you're point is that two axles with same mass and diameter, but where one is hollow and the other massive, the massive will have less MOI than the hollow since the hollow necessarily have more mass further away from rotation center? Pew! - that was a long sentence...
07-06-2011, 08:26 AM
#116
^2 Questions:
1. Let's pretend someone on these forums wants to make their RX-8 street car faster and asks you to chose which was more important: Weight or Moment of Inertia for measuring the benefits of a higher performing Flywheel and pressure plate/clutch assembly. They want their car to accelerate more quickly. That is their question. You can only chose one. Weight or MOI. What do you tell them?
1. Let's pretend someone on these forums wants to make their RX-8 street car faster and asks you to chose which was more important: Weight or Moment of Inertia for measuring the benefits of a higher performing Flywheel and pressure plate/clutch assembly. They want their car to accelerate more quickly. That is their question. You can only chose one. Weight or MOI. What do you tell them?
Because they wont have an f-ing clue what I'm on about if I say "MOI".
And, more importantly, weight and MOI are directly and inextricably tied in this particular part on this particular application, so you aren't imparting any useful information when you try to impress them with your brandishing of an engineering term like "MOI".
And, more importantly, weight and MOI are directly and inextricably tied in this particular part on this particular application, so you aren't imparting any useful information when you try to impress them with your brandishing of an engineering term like "MOI".
07-06-2011, 08:44 AM
#117
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The location of the weight it what is important.
Lets say there were two fly wheel and clutch/pressure plate assemblies of the same or similar weight.
Assembly A has a higher concentration of mass towards the center of the plate.
Assembly B has slightly less weight near the center but more closer to the edge.
Even though the weights of the assemblies are the same Assembly B would have a higher MOI because its extra weight is being applied at a large distance from the center.
Lets say there were two fly wheel and clutch/pressure plate assemblies of the same or similar weight.
Assembly A has a higher concentration of mass towards the center of the plate.
Assembly B has slightly less weight near the center but more closer to the edge.
Even though the weights of the assemblies are the same Assembly B would have a higher MOI because its extra weight is being applied at a large distance from the center.
07-06-2011, 08:55 AM
#118
The location of the weight it what is important.
Lets say there were two fly wheel and clutch/pressure plate assemblies of the same or similar weight.
Assembly A has a higher concentration of mass towards the center of the plate.
Assembly B has slightly less weight near the center but more closer to the edge.
Even though the weights of the assemblies are the same Assembly B would have a higher MOI because its extra weight is being applied at a large distance from the center.
Lets say there were two fly wheel and clutch/pressure plate assemblies of the same or similar weight.
Assembly A has a higher concentration of mass towards the center of the plate.
Assembly B has slightly less weight near the center but more closer to the edge.
Even though the weights of the assemblies are the same Assembly B would have a higher MOI because its extra weight is being applied at a large distance from the center.
That's part of the reason why race cars have 4.5 or 5.5" flywheels and clutch combos
MOI is an interesting subject but real world results may be disappointing for the aforementioned reason. Now swap for a smaller diameter flywheel\clutch combo and that argument becomes relevant again
07-06-2011, 09:04 AM
#119
being a pragmatic man i will follow the results.
Results being subjective, i probably need to better define my meaning.
Street driven performance? This includes longetivity as most street driven cars are in for the long haul. The way I understand this is the MOI will only be of any measureable benefit in 1st and 2nd gears. All street driven drag racers will tell you this and show you their 60ft times to prove it. They also have to balance the driveability of the car on the street with performance.
It is impractical to go with a flywheel that would interfere with idling with the a/c on and difficulty to start off on a hill for example. So with the amount of total practical weight reduction limited it can be very important to get the MOI of the wheel as good as you can.
Road Track monsters? 1st and 2nd gears are usually not used? But also the overall diameter/weight of the clutch/pressureplate is not as critical. The weight of the flywheel is also not as critical. So road guys go with a smaller in diameter pp/clutch with a much lower moi than the larger ones like oem. They then mate it to the lightest flywheel with the best MOI that they can get. The combo of the smaller in diameter PP/clutch with the decreased moi flywheel is what keeps most of the weight in the same area of the total assembley. The overall significant reduction of weight from the smaller in diameter pp/clutch plus its decreased moi plus a lighten flywheel with its decreased moi is what helps with the overall race cars performance? Tracks change the leverage/weight and the moi?
Am I in the ballpark? If not I will just shut up and eat my ball park frank.
Results being subjective, i probably need to better define my meaning.
Street driven performance? This includes longetivity as most street driven cars are in for the long haul. The way I understand this is the MOI will only be of any measureable benefit in 1st and 2nd gears. All street driven drag racers will tell you this and show you their 60ft times to prove it. They also have to balance the driveability of the car on the street with performance.
It is impractical to go with a flywheel that would interfere with idling with the a/c on and difficulty to start off on a hill for example. So with the amount of total practical weight reduction limited it can be very important to get the MOI of the wheel as good as you can.
Road Track monsters? 1st and 2nd gears are usually not used? But also the overall diameter/weight of the clutch/pressureplate is not as critical. The weight of the flywheel is also not as critical. So road guys go with a smaller in diameter pp/clutch with a much lower moi than the larger ones like oem. They then mate it to the lightest flywheel with the best MOI that they can get. The combo of the smaller in diameter PP/clutch with the decreased moi flywheel is what keeps most of the weight in the same area of the total assembley. The overall significant reduction of weight from the smaller in diameter pp/clutch plus its decreased moi plus a lighten flywheel with its decreased moi is what helps with the overall race cars performance? Tracks change the leverage/weight and the moi?
Am I in the ballpark? If not I will just shut up and eat my ball park frank.
Last edited by olddragger; 07-06-2011 at 09:08 AM.
07-06-2011, 02:16 PM
#120
Unfortunately, the day-to-day reality is quite the opposite.
I realize that there are people that will take the initiative. However, they usually aren't the individuals asking the questions.
One of the traits of autodidactism is "saving" of questions for the time in which they are most valuable.
No. I am saying that different RX-8 flywheels of the same net weight have more or less the same MOI because of the way they must be assembled and that fractional differences in mass distribution over the range where milling can be done have little or no effect of MOI because the effective "r" is the same.
Last edited by MazdaManiac; 07-06-2011 at 02:19 PM.
07-06-2011, 02:37 PM
#121
SPOOLN8
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What MM is saying is that all flywheels need to be the same size for our car and minor manufacturing difference such as weight distribution have miniscule effects on Moment of Inertia.... realistically meaning static weight has the greatest effect on MOI (because all of the flywheels must have relatively the same dimensions for the same application) and the lighter the flywheel the less MOI the flywheel will have meaning faster RPM change and less HP needed by the engine to spin the flywheel
Last edited by RotaryMachineRx; 07-06-2011 at 02:40 PM.
07-06-2011, 03:06 PM
#123
I have to agree that it is the entire assembly instead of one part. I should have stated my sentence better earlier in the thread.
07-06-2011, 03:14 PM
#125
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The Socratic method is a negative method of hypothesis elimination, in that better hypotheses are found by steadily identifying and eliminating those that lead to contradictions. The Socratic method searches for general, commonly held truths that shape opinion, and scrutinizes them to determine their consistency with other beliefs.
I think that plenty of the people that aren't scared of learning that are on the boards have no problem with this method at all, but when we only have part of the possible factors identified, then it can mean an incorrect conclusion.
Perhaps we should start with a basic question, then identify every single possible factor, and then we can apply this method.
Of course, the niggling thought that it wouldn't matter crosses my mind. Since we can get all the way to a 'confirmed' solution to this, and all it takes is someone coming along and saying "talking about it doesn't prove anything. Take it to the race track and see if you win"