Originally Posted by thenuge26
(Post 1124632)
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. |
Originally Posted by Full_Tilt_Boogie
(Post 1124628)
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.
Originally Posted by Full_Tilt_Boogie
(Post 1124628)
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. |
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? |
Originally Posted by Failure
(Post 1124639)
Yes, I agree. Nothing I've said is incompatible with this.
Originally Posted by Failure
(Post 1124460)
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.
Originally Posted by Failure
(Post 1124639)
I don't doubt that this is possible, but this example car certainly isn't a Miata.
Originally Posted by Failure
(Post 1124639)
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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Originally Posted by Failure
(Post 1124639)
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. |
Originally Posted by Full_Tilt_Boogie
(Post 1124645)
O RLY!?
Originally Posted by Full_Tilt_Boogie
(Post 1124645)
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.
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Originally Posted by Failure
(Post 1124650)
I never denied that reducing the weight of the flywheel freed up power. Only that it did so by a relevant amount.
Originally Posted by Failure
(Post 1124460)
When you're in gear, there's no difference between a 7 lb flywheel and a 20 lb one.
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Originally Posted by Failure
(Post 1124650)
I never denied that reducing the weight of the flywheel freed up power. Only that it did so by a relevant amount.
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. |
Originally Posted by thenuge26
(Post 1124654)
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.
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Originally Posted by Failure
(Post 1124656)
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? |
Originally Posted by Failure
(Post 1124656)
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.
Of course, that's an assumption on my part. |
Originally Posted by thenuge26
(Post 1124658)
:bowrofl:
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. |
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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Originally Posted by Failure
(Post 1124661)
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.
Nobody is saying that a flywheel adds power. There's your hint of the day. |
Originally Posted by concealer404
(Post 1124663)
Nobody is saying that a flywheel adds power. There's your hint of the day.
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. |
Originally Posted by Failure
(Post 1124667)
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. 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? |
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 fuck is that 50 HP going to come from?
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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. |
Originally Posted by Failure
(Post 1124675)
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 fuck is that 50 HP going to come from?
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