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Suspension, Brakes, Drivetrain discuss the wondrous effects of boost and your miata...

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Old 04-23-2014, 05:28 PM   #21
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Originally Posted by thenuge26 View Post
That's almost 7 stickers worth.


If anybody wants a good read, check out this old thread I participated in:
tungsten crankshaft - D-series.org

This guy was even dumber than "failure", he wanted to make a super heavy crankshaft out of tungsten because he thought that the crank carrying more inertia would equate to a faster car... somehow.
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Old 04-23-2014, 05:29 PM   #22
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Its not just the reduction of weight. Say you have a car with a 20lb flywheel and an identical car with a 10lb flywheel and a 10 lb weight sitting in the car. Both cars would have the exact same curb weight, the second car (with the light flywheel) would be measurably faster.
The car is faster because its not having to spin that added weight at 7000 rpm.
Yes, I agree. Nothing I've said is incompatible with this.


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Originally Posted by Full_Tilt_Boogie View Post
In Herb Adams book "Chassis Engineering" he says:


He goes on to create an example in which a car minus 15 pounds off the driveline at crank speed (e.g. flywheel, crank, etc.) creates an improvement in acceleration equivalent to 32 horsepower.
I don't doubt that this is possible, but this example car certainly isn't a Miata. Also, this is only true for a single gear, and it assumes the flywheel wasn't spun up before engaging the clutch.
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Old 04-23-2014, 05:32 PM   #23
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Dude have you ever played Gran Turismo 3? The first mods you always do to a car are LWFW, stage 3 clutch, and carbon driveshaft. They are the cheapest and drop your lap time significantly.

Vidya games don't lie

The Miata is a front engine rear wheel drive car, hardly unique in the automotive world. What makes you think that it would be different?
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Old 04-23-2014, 05:34 PM   #24
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Originally Posted by Failure View Post
Yes, I agree. Nothing I've said is incompatible with this.
O RLY!?
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Originally Posted by Failure View Post
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.

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Originally Posted by Failure View Post
I don't doubt that this is possible, but this example car certainly isn't a Miata.
It doesnt matter what car it is. It doesnt matter how much the car weighs. All that matters is the difference in rotating mass and the rpm. If anything it may have a greater affect on a miata because we would be spinning to higher speeds than the big V8s that Herb Adams worked with for Trans Am racing.
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Originally Posted by Failure View Post
Also, this is only true for a single gear, and it assumes the flywheel wasn't spun up before engaging the clutch.
Yeah, I set my rev limit at 10k rpm, so when I slowly flat shift at 8k I get a clutch raping boost in acceleration. That makes more sense than shifting fast.
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Old 04-23-2014, 05:39 PM   #25
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Originally Posted by Failure View Post
Yes, I agree. Nothing I've said is incompatible with this.



I don't doubt that this is possible, but this example car certainly isn't a Miata. Also, this is only true for a single gear, and it assumes the flywheel wasn't spun up before engaging the clutch.

Everything you've said is incompatible with that. It's almost like you don't even know what you're saying, yourself.
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Old 04-23-2014, 05:43 PM   #26
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Quote:
Originally Posted by Full_Tilt_Boogie View Post
O RLY!?
I never denied that reducing the weight of the flywheel freed up power. Only that it did so by a relevant amount.

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Originally Posted by Full_Tilt_Boogie View Post
It doesnt matter what car it is. It doesnt matter how much it weighs. All that matters is the difference in rotating mass and the rpm. If anything it may have a greater affect on a miata because we would be spinning to higher speeds than the big V8s that Herb Adams worked with for Trans Am racing.
You're not trying to imply that 1 lb of flywheel mass = 2 HP, regardless of anything else about the car, are you? I can assure you, my 7 lb flywheel didn't give me 30 HP. How much gain did yours net you on the butt dyno?
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Old 04-23-2014, 05:53 PM   #27
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Quote:
Originally Posted by Failure View Post
I never denied that reducing the weight of the flywheel freed up power. Only that it did so by a relevant amount.
...

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Originally Posted by Failure View Post
When you're in gear, there's no difference between a 7 lb flywheel and a 20 lb one.
Glad we're on the same page now. I guess 32hp isn't relevant to you though, seems like quite a bit to me when you start from ~140hp. Though I guess it would be a bit less than 32hp since you're only talking about a 13lbs difference rather than a 15lbs difference like in the example.
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Old 04-23-2014, 05:54 PM   #28
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Quote:
Originally Posted by Failure View Post
I never denied that reducing the weight of the flywheel freed up power. Only that it did so by a relevant amount.
Well yeah. It's relevant. That's why we're talking about it.


Quote:
You're not trying to imply that 1 lb of flywheel mass = 2 HP, regardless of anything else about the car, are you? I can assure you, my 7 lb flywheel didn't give me 30 HP. How much gain did yours net you on the butt dyno?


There's a very important qualifier that you're leaving out.
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Old 04-23-2014, 05:58 PM   #29
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Glad we're on the same page now. I guess 32hp isn't relevant to you though, seems like quite a bit to me when you start from ~140hp.
Yeah, it sure feels awesome putting down 115 + 32 = 147 HP from my 1.6. Apparently I have more horsepower than the 1.8 guys now.
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Old 04-23-2014, 06:01 PM   #30
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Originally Posted by Failure View Post
Yeah, it sure feels awesome putting down 115 + 32 = 147 HP from my 1.6. Apparently I have more horsepower than the 1.8 guys now.


Tell me more about how the MOI differs between 1st and the rest of the gears, I'm almost pissing myself I'm laughing so hard.

Where is this whacky theoretical knowledge of yours coming from? You're not a freshman mechanical engineering student are you?
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Old 04-23-2014, 06:04 PM   #31
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Yeah, it sure feels awesome putting down 115 + 32 = 147 HP from my 1.6. Apparently I have more horsepower than the 1.8 guys now.
You are so unbelievably short-sighted it's a wonder you can put on matching shoes every day.


Of course, that's an assumption on my part.
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Old 04-23-2014, 06:05 PM   #32
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Tell me more about how the MOI differs between 1st and the rest of the gears, I'm almost pissing myself I'm laughing so hard.
I wonder if someone else will point out that you don't know what you're talking about or if they're too busy shitting all over me.
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Old 04-23-2014, 06:13 PM   #33
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We've got the 'shipped artwork hall of fame' thread and the 'Joe Perez Epic Rants' thread, we need a collection of 'Epic Failures in Physics/Engineering' thread to compile these. I remember the guy who vehemently argued that the most important part of the suspension was the amount of suspension travel, which is why his stock suspension setup was better than everyone who 'ruined their handling' when lowering their cars with coilovers.
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Old 04-23-2014, 06:14 PM   #34
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Originally Posted by Failure View Post
I wonder if someone else will point out that you don't know what you're talking about or if they're too busy shitting all over me.
Unlikely, as he's not the one that's wrong.

Nobody is saying that a flywheel adds power. There's your hint of the day.
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Old 04-23-2014, 06:22 PM   #35
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Nobody is saying that a flywheel adds power. There's your hint of the day.
No, they're just claiming that reducing flywheel weight reduces drivetrain losses well into the negatives.

As to why the flywheel has less effect in higher gears, it's not because the MOI of the flywheel changes. In high gear, much more load is placed on the engine from the road, while the load from the flywheel stays constant.
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Old 04-23-2014, 06:24 PM   #36
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Quote:
Originally Posted by Failure View Post
No, they're just claiming that reducing flywheel weight reduces drivetrain losses well into the negatives.

As to why the flywheel has less effect in higher gears, it's not because the MOI of the flywheel changes. In high gear, much more load is placed on the engine from the road, while the load from the flywheel stays constant.
No... nobody is saying it reduces losses into the negatives. I don't know where the hell you got that.

I don't even have a degree and sucked at math past trig, and even i understand what's going on here. Let's keep up, shall we?
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Old 04-23-2014, 06:44 PM   #37
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The difference made by the flywheel isn't just weight. It will show a change in power on an inertial dyno. The obvious implication of the "1 lb = 2 HP" crowd is that if you removed the flywheel, clutch, and pressure plate and linked the crank directly to the input shaft of the transmission, you would see a change of about 50 HP vs stock. This is manifestly untrue, because where the **** is that 50 HP going to come from?
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Old 04-23-2014, 06:46 PM   #38
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It's not "drivetrain losses", losses come from friction.

It's just like weight reduction only the affect is amplified because of the high speed things like the flywheel are accelerated to.
Taking 200 lbs out of a miata might make it accelerate like it has another 20 HP. That doesn't mean if gained 20 HP. Taking this same weight out of the wheels, driveshaft, crank, flywheel, etc. Would have an even greater affect.

We're talking about a measured difference in acceleration of the car here. It is true that an inertia dyno will show small differences in power from drivetrain inertia, but that is just because inertia dyno are retarded. Plus, this discrepancy is relative to the mass of the inertia dyno's drum which is easily 1000 lbs. That is why a flywheel would only have a small affect on its reading.
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Old 04-23-2014, 06:52 PM   #39
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Quote:
Originally Posted by Failure View Post
The difference made by the flywheel isn't just weight. It will show a change in power on an inertial dyno. The obvious implication of the "1 lb = 2 HP" crowd is that if you removed the flywheel, clutch, and pressure plate and linked the crank directly to the input shaft of the transmission, you would see a change of about 50 HP vs stock. This is manifestly untrue, because where the **** is that 50 HP going to come from?
I'd count the number of times you've contradicted yourself, but i'm too dumb to count that high and suck at math.
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Old 04-23-2014, 06:54 PM   #40
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