Custom 8.5" Clutch shenanigans
04-23-2014, 06:02 PM
#41
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Yes, but the difference made by the flywheel isn't chassis weight; it's drivetrain inertia. The flywheel is effectively a container that stores energy. Making it smaller means that you don't have to feed it as much energy as you accelerate, meaning more power reaches the wheels.
I think this is where our disagreement starts from: you guys seem to think that the loaded acceleration benefit of a light flywheel isn't measurable, but I know that it is, and I know how small that measurement actually is.
I think this is where our disagreement starts from: you guys seem to think that the loaded acceleration benefit of a light flywheel isn't measurable, but I know that it is, and I know how small that measurement actually is.
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04-23-2014, 06:05 PM
#42
I'm not sure why people try to save mass on the clutch. I mean, even with the lightest flywheel and the heaviest clutch available for our car, the clutch still weighs about 1/3 as much as the flywheel. Stock it's less than 1/10.
Reducing flywheel weight is what gives you that quick revving in neutral. When you're in gear, there's no difference between a 7 lb flywheel and a 20 lb one. I guess a light clutch would make you rev faster when you're out of gear with the clutch engaged, so I suppose it would help if you double clutch your downshifts. Otherwise I see no benefit. No real disadvantages either, though.
Did you get a part number for the new clutch?
Reducing flywheel weight is what gives you that quick revving in neutral. When you're in gear, there's no difference between a 7 lb flywheel and a 20 lb one. I guess a light clutch would make you rev faster when you're out of gear with the clutch engaged, so I suppose it would help if you double clutch your downshifts. Otherwise I see no benefit. No real disadvantages either, though.
Did you get a part number for the new clutch?
Yes, but the difference made by the flywheel isn't chassis weight; it's drivetrain inertia. The flywheel is effectively a container that stores energy. Making it smaller means that you don't have to feed it as much energy as you accelerate, meaning more power reaches the wheels.
I think this is where our disagreement starts from: you guys seem to think that the loaded acceleration benefit of a light flywheel isn't measurable, but I know that it is, and I know how small that measurement actually is.
I think this is where our disagreement starts from: you guys seem to think that the loaded acceleration benefit of a light flywheel isn't measurable, but I know that it is, and I know how small that measurement actually is.
U SRS right now?
But yes, it certainly is measurable. I don't think you have any idea what the measurement is, though.
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04-23-2014, 06:08 PM
#43
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Omg a DYNOJET is not REAL LIFE.
It shows a change in output from a change in flywheel mass because it is not a real dyno and the change is small because the drum is heavy as ****.
Inertia dyno's are a cheap substitution for a real load holding dyno, which would show no gains from a flywheel.
It shows a change in output from a change in flywheel mass because it is not a real dyno and the change is small because the drum is heavy as ****.
Inertia dyno's are a cheap substitution for a real load holding dyno, which would show no gains from a flywheel.
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04-23-2014, 06:21 PM
#44
Man I wish I wasnt so busy at work to miss this.
What you're missing is the fact that yes, the inertia of the car is a couple orders of magnitude larger than that of the flywheel, the speed at which the flywheel is rotating and the rate of acceleration of the flywheel are multiple orders of magnitude beyond what the car as a whole are attempting to do. Which is where the difference in the acceleration of the whole car comes from when reducing the rotational inertia of the car.
I want to know how much the OP paid for this custom clutch and flywheel setup and if it was even worth it. I hope it was under $600.
And some other things to clear up. The stock flywheel weighs ~20 pounds, the stock and most other pressure plates weigh ~9 pounds and the stock friction disk weighs about 3 pounds. So the weight of the clutch does matter and it makes up ~1/3 of the weight of the clutch and flywheel setup.
And did you know I can make a 10 hp swing on a stock miata engine on a dyno jet just by switching between BALLER 45 pound 18" wheels and silly 7 pound 13" wheels?
What you're missing is the fact that yes, the inertia of the car is a couple orders of magnitude larger than that of the flywheel, the speed at which the flywheel is rotating and the rate of acceleration of the flywheel are multiple orders of magnitude beyond what the car as a whole are attempting to do. Which is where the difference in the acceleration of the whole car comes from when reducing the rotational inertia of the car.
I want to know how much the OP paid for this custom clutch and flywheel setup and if it was even worth it. I hope it was under $600.
And some other things to clear up. The stock flywheel weighs ~20 pounds, the stock and most other pressure plates weigh ~9 pounds and the stock friction disk weighs about 3 pounds. So the weight of the clutch does matter and it makes up ~1/3 of the weight of the clutch and flywheel setup.
And did you know I can make a 10 hp swing on a stock miata engine on a dyno jet just by switching between BALLER 45 pound 18" wheels and silly 7 pound 13" wheels?
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04-23-2014, 07:23 PM
#45
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Hey Failure, I'm sure it is you alone who are right and all the rest of us are wrong. But since you decided to ignore my earlier warning and now we have 3 pages of stupidity, let me throw this in the works. Ignore acceleration for a minute so you can stop talking about drivetrain losses and horsepower gains. a lighter flywheel will decelerate the car quicker as well, creating yet another performance advantage. But what do I know. What do we know. What do all of the car builders all over the world from history know. I guess nothing, so we should all put big lead flywheels in our rides since it makes almost no difference at all according to you.
Last edited by guttedmiata; 04-23-2014 at 08:06 PM.
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04-23-2014, 11:13 PM
#48
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Man I wish I wasnt so busy at work to miss this.
What you're missing is the fact that yes, the inertia of the car is a couple orders of magnitude larger than that of the flywheel, the speed at which the flywheel is rotating and the rate of acceleration of the flywheel are multiple orders of magnitude beyond what the car as a whole are attempting to do. Which is where the difference in the acceleration of the whole car comes from when reducing the rotational inertia of the car.
I want to know how much the OP paid for this custom clutch and flywheel setup and if it was even worth it. I hope it was under $600.
And some other things to clear up. The stock flywheel weighs ~20 pounds, the stock and most other pressure plates weigh ~9 pounds and the stock friction disk weighs about 3 pounds. So the weight of the clutch does matter and it makes up ~1/3 of the weight of the clutch and flywheel setup.
And did you know I can make a 10 hp swing on a stock miata engine on a dyno jet just by switching between BALLER 45 pound 18" wheels and silly 7 pound 13" wheels?
What you're missing is the fact that yes, the inertia of the car is a couple orders of magnitude larger than that of the flywheel, the speed at which the flywheel is rotating and the rate of acceleration of the flywheel are multiple orders of magnitude beyond what the car as a whole are attempting to do. Which is where the difference in the acceleration of the whole car comes from when reducing the rotational inertia of the car.
I want to know how much the OP paid for this custom clutch and flywheel setup and if it was even worth it. I hope it was under $600.
And some other things to clear up. The stock flywheel weighs ~20 pounds, the stock and most other pressure plates weigh ~9 pounds and the stock friction disk weighs about 3 pounds. So the weight of the clutch does matter and it makes up ~1/3 of the weight of the clutch and flywheel setup.
And did you know I can make a 10 hp swing on a stock miata engine on a dyno jet just by switching between BALLER 45 pound 18" wheels and silly 7 pound 13" wheels?
Paid 120 for the clutch, 90 for the resurfacing. PP and fly came with the motor I bought so I don't have a price for those. Thanks for your input, I was hoping someone would touch on this..
Pretty funny because that exaclty what i was thinking when titling it. I almost went with "evil shenanigans"
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04-25-2014, 11:45 AM
#53
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Motor is going in on the 14th of May. After break in, I'll post my findings
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04-25-2014, 05:41 PM
#54
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I just don’t get why anyone would stick with the 1.8l size clutch and flywheel if they are worried about rotational inertia. A stock size 1.6l clutch disk is only 200mm ~7.9” diameter. And weighs about a 1 lb less than a 1.8l. The pressure plate in an ACT clutch is about 1.5 lbs lighter for the 1.6l version and a Fadanza 1.6l flywheel is just over 7 lbs instead of something like 9 or 10 for many of the light weight 1.8L flywheels.
The 1.6l ACT MZ1-XTR4 on a Fidanza flywheel comes out something like 18 lbs for total rotating assembly. It is rated to hold 350 ft-lbs. I’ve broken 3 six speed transmissions with too much torque and haven’t changed the clutch or flywheel so I can vouch for its torque capacity. The car is plenty drivable on the street once you get use to it as well.
The 1.6l ACT MZ1-XTR4 on a Fidanza flywheel comes out something like 18 lbs for total rotating assembly. It is rated to hold 350 ft-lbs. I’ve broken 3 six speed transmissions with too much torque and haven’t changed the clutch or flywheel so I can vouch for its torque capacity. The car is plenty drivable on the street once you get use to it as well.
Last edited by bbundy; 04-25-2014 at 05:51 PM.
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04-25-2014, 05:46 PM
#55
I just don’t get why anyone would stick with the 1.8l size clutch and flywheel if they are worried about rotational inertia. A stock size 1.6l clutch disk is only 200mm ~7.9” diameter. And weighs about a 1 lb less than a 1.8l. The pressure plate in an ACT clutch is about 1.5 lbs lighter for the 1.6l version and a Fadanza 1.6l flywheel is just over 7 lbs instead of something like 9 or 10 for many of the light weight 1.8L flywheels.
The 1.6l ACT MZ1-XTR4 on a Fidanza flywheel comes out something like 18 lbs for total rotating assembly. It is rated to hold 350 ft-lbs. I’ve broken 3 six speed transmissions with too much torque and haven’t changed the clutch or flywheel. The car is plenty drivable on the street once you get use to it as well.
The 1.6l ACT MZ1-XTR4 on a Fidanza flywheel comes out something like 18 lbs for total rotating assembly. It is rated to hold 350 ft-lbs. I’ve broken 3 six speed transmissions with too much torque and haven’t changed the clutch or flywheel. The car is plenty drivable on the street once you get use to it as well.
LA LA LA LA LAAAAAAAAAAAAAAAAAAAA I CAN'T HEAR YOU
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04-25-2014, 07:16 PM
#56
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Oh its because the mass taken off the flywheel and cliutch is only about 4 times as effective at improving acceleration as if you took it off the weight of one of your wheels. assuming you are in a 1:1 gear and even more in lower gears.
Another little secret. Taking the rotating weight off at your alternator is about 8 times as effective it's got to spin up at ~2.5X engine RPM.
The rate at which things have to spin at has a big effect on the impact of their rotationl intertia.
Another little secret. Taking the rotating weight off at your alternator is about 8 times as effective it's got to spin up at ~2.5X engine RPM.
The rate at which things have to spin at has a big effect on the impact of their rotationl intertia.
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04-25-2014, 08:08 PM
#57
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Fairly educational with math and science and physics and stuff. note in second gear flywheel/clutch weight has a huge effect on acceleration.
The Effects of Rotational Inertia on Automotive Acceleration
The Effects of Rotational Inertia on Automotive Acceleration
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04-26-2014, 11:19 AM
#59
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Yep, if I were to choose, I would go with the 1.6 Fadanza flywheel. However, (other than the clutch) this package came with the motor , so I'm going to stick with it.
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