Unsprung Mass? (wheels and tires)
#41
Originally Posted by d00df00d
I guess this is a question for the autocrossers around here, but any input would be appreciated.
I have some random no-name aftermarket rims that my car's previous owner put on before I got it. Those rims with my 205/65/15 Continental tires weigh 42lbs total. I can get Kazera 16" wheels with 225/55/16 Pirelli P-Zero Nero tires, which will weigh about 36 lbs total per wheel/tire.
So, 6 lbs less per corner, 24lbs less unsprung rolling mass in total. Anyone think that'll be noticeable?
I have some random no-name aftermarket rims that my car's previous owner put on before I got it. Those rims with my 205/65/15 Continental tires weigh 42lbs total. I can get Kazera 16" wheels with 225/55/16 Pirelli P-Zero Nero tires, which will weigh about 36 lbs total per wheel/tire.
So, 6 lbs less per corner, 24lbs less unsprung rolling mass in total. Anyone think that'll be noticeable?
Which makes me chuckle when someone puts 17s or 18s on and a y-pipe when the first get the car and marvel at how much 'faster' it feels. hahaha
Dave
#42
Originally Posted by PTownMax
good info, but i love how my car looks with my 18"s, do you think a flywheel and performance axles would make that much of a diff?
I'm not sure if performance axles are any lighter than stock. Even if they are, though, they probably wouldn't make very much of a difference because all the mass is in the center of their rotation.
A flywheel would certainly help your acceleration somewhat. In terms of acceleration in first gear, every pound you remove from the flywheel is worth about 10 pounds of dead weight on your car. It will also make the engine rev quicker, improve throttle response, and take some stress off the clutch and other transmission bits.
#43
Originally Posted by d00df00d
A flywheel would certainly help your acceleration somewhat. In terms of acceleration in first gear, every pound you remove from the flywheel is worth about 10 pounds of dead weight on your car.
Unfortunately, I'm not aware of any easy way to measure the rotational inertia of a flywheel or wheel/tire combo. You'd either have to calculate it, or do testing to figure which one is best. It would be very cool if someone had (or made) such a tool and tested stuff.
Dave
#44
Originally Posted by dgeesaman
Stock flywheels tend to be very rim heavy from driveability, and aftermarket flywheels are not only lighter, but more hub-heavy. So losing 4lb going from a stock flywheel to performance flywheel is greater than losing another 4lb going to an even lighter performance flywheel. (I'm making up numbers with 4lb, but the point is the same). I'll bet that rule is based on going from a stock setup to an aftermarket setup.
Aren't some stock parts near the outside of the flywheel also transferred over to the new flywheel in most cases? For example, I understand that the Unorthodox Racing flywheel, which claims to be the lightest, is only the hub, and that all the other bits have to be reused from the stock flywheel.
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