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Old 10-25-2017, 07:21 PM   #31 (permalink)
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I've heard the wheel weight thing thrown around: yes, fractionally beneficial fo FE, but much less appreciated are the benefits to cutting unsprung weight: much crisper turn-in, better braking, and better suspension control once you eliminate deadweight. It's the only reason I'd consider some rims on my Civic instead of the steelies with what look like nice, aerodynamic factory wheel covers.

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Old 10-28-2017, 01:33 PM   #32 (permalink)
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wheels

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I've heard the wheel weight thing thrown around: yes, fractionally beneficial fo FE, but much less appreciated are the benefits to cutting unsprung weight: much crisper turn-in, better braking, and better suspension control once you eliminate deadweight. It's the only reason I'd consider some rims on my Civic instead of the steelies with what look like nice, aerodynamic factory wheel covers.
You need to be acquainted with the concept of polar moment of inertia.In order to determine if lighter wheels will pay you back in savings,you need to know how the mass of the lighter wheel is distributed dynamically,compared to the existing wheel/tire combination.
There may be a You-Tube video out there somewhere,which will show you how to analyze this.Without the procedure,you'll never know beforehand if the wheels are a good investment.They're not all created equal,and some alloy wheels offer no weight reduction at all.
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Old 10-28-2017, 08:39 PM   #33 (permalink)
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You need to be acquainted with the concept of polar moment of inertia.In order to determine if lighter wheels will pay you back in savings,you need to know how the mass of the lighter wheel is distributed dynamically,compared to the existing wheel/tire combination.
There may be a You-Tube video out there somewhere,which will show you how to analyze this.Without the procedure,you'll never know beforehand if the wheels are a good investment.They're not all created equal,and some alloy wheels offer no weight reduction at all.
If I ever get serious about it, I'll do that. For the moment the only reason would be if I moved to the snowbelt and wanted an extra set of wheels. Use the stockers for winter tires and an extra set with summer rubber.
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Old 10-28-2017, 09:59 PM   #34 (permalink)
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You need to be acquainted with the concept of polar moment of inertia.In order to determine if lighter wheels will pay you back in savings,you need to know how the mass of the lighter wheel is distributed dynamically,compared to the existing wheel/tire combination.
There may be a You-Tube video out there somewhere,which will show you how to analyze this.Without the procedure,you'll never know beforehand if the wheels are a good investment.They're not all created equal,and some alloy wheels offer no weight reduction at all.
A wheels weight distribution is a good point; one that is rarely mentioned. It will determine the torque required to achieve a particular rotational acceleration. However it is calculated using the Moment of Inertia - no need to go polar for this Weight closer to the axis of rotation will have less impact on rotational momentum than the same weight further out.
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Old 10-29-2017, 06:40 AM   #35 (permalink)
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I boosted the tires to 38 psi. The car either handles better or I'm more careful (it does seem to make less noise). I can't tell if the mileage is better, though the weather has been colder and I've had to turn on the air conditioning to deal with rain moisture and use the brights more.

Someone mentioned Atkinson cycling... ballpark estimate, how much would a conversion cost?
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Old 10-29-2017, 08:58 AM   #36 (permalink)
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Someone mentioned Atkinson cycling... ballpark estimate, how much would a conversion cost?
More than you would ever save in fuel.
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Old 10-29-2017, 09:26 AM   #37 (permalink)
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Minimum, you're pulling the head of the motor and putting in a new set of custom cams, plus an aftermarket computer and a tune, so lots of man hours and probably several thousand.
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Old 11-04-2017, 01:22 PM   #38 (permalink)
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polar

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A wheels weight distribution is a good point; one that is rarely mentioned. It will determine the torque required to achieve a particular rotational acceleration. However it is calculated using the Moment of Inertia - no need to go polar for this Weight closer to the axis of rotation will have less impact on rotational momentum than the same weight further out.
Polar Moment of Inertia is a metric used by the Society of Automotive Engineers in their standard practice for all components of rotational mass.
Coastdown testing of vehicles cannot be accomplished without a full accounting of polar moment of inertia for all rotating components of the drivetrain.
It's just an engineering convention.

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