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991 weight distribtion vs. 997 ?

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Old Dec 8, 2011 | 01:55 PM
  #16  
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Originally Posted by djantlive
there is a difference between mid engine and rear engine even if the weight distribution is the same.

i dont understand why porsched didn't lighten the rear with alum to balance the car further. if anything, i would lighten the rear and make the front heavy.

one of the best $5 mods you can do to a C2 is put a 20 lb kitty litter in the front trunk. you'll notice the car handles so much better.

but according to C. Harris (and other experienced drivers) the 991 handling is now near perfect.
almost no understeer, no light front end, no off throttle snap oversteer, very balanced chassis, very agile, very forgiving & easy to control.
With PSM on, even for Newbies.
 

Last edited by catchmyshadow; Dec 8, 2011 at 02:02 PM.
Old Dec 8, 2011 | 02:08 PM
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I'm no expert, but my sense is that some rear weight bias may be preferable over perfect "balance", especially with RWD. As already noted, it improves traction under acceleration, and it better balances braking demand between the front and rear (otherwise the front tires get overloaded too soon). And it doesn't necessarily compromise cornering, since the extra mass at the rear increases lateral g force but it also increases grip.

The bottom line is that track times show that the 911 can hang with pretty much any car with comparable power/weight ratio, so this recipe does work.
 
Old Dec 9, 2011 | 12:44 AM
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Originally Posted by Manifold
I'm no expert, but my sense is that some rear weight bias may be preferable over perfect "balance", especially with RWD. As already noted, it improves traction under acceleration, and it better balances braking demand between the front and rear (otherwise the front tires get overloaded too soon). And it doesn't necessarily compromise cornering, since the extra mass at the rear increases lateral g force but it also increases grip.

The bottom line is that track times show that the 911 can hang with pretty much any car with comparable power/weight ratio, so this recipe does work.
Fully agree with above
 
Old Dec 9, 2011 | 10:17 PM
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Originally Posted by heavychevy
That could be as simple as how much gas is in the car. I would be willing to bet Porsche gives the weight on empty but the balance on full. If Sport auto didn't have a full tank it could have affected Porsche's claimed numbers.



Yes, between the 997 and cayman, but don't forget, the 997 C4 has a 50+ lb front differential in it to affect balance so the 991 C4 should be even better balanced and create more of a gap.

People cry about balance all day, but the fact is that it's a benefit. Yes F1 cars are mid engine, but there is NO weight on the front of the car. Only CF and suspension and some of the driver. Open wheel cars (including F1) have similar balance to 911's and even most mid engine cars have weight shaded to the rear, because it adds grip and makes the car more predictable.
sport auto always weighs its test cars with a full tank.
 
Old Dec 9, 2011 | 10:22 PM
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Originally Posted by djantlive
there is a difference between mid engine and rear engine even if the weight distribution is the same.

i dont understand why porsched didn't lighten the rear with alum to balance the car further. if anything, i would lighten the rear and make the front heavy.

one of the best $5 mods you can do to a C2 is put a 20 lb kitty litter in the front trunk. you'll notice the car handles so much better.
My guess why Porsche didn't go to aluminum fenders in the rear is that they needed the strength of steel. I think the rear fenders play a much more important structural role (they are welded in -- front fenders are bolted on) than the front fenders. There is that engine and drive train and to hold in place and torque loads to manage.
 
Old Dec 10, 2011 | 07:44 AM
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Originally Posted by m5_2010
Not sure what this means? Weight distribution is just that? Can you elaborate?
Center of gravity. The closer the bulk of the weight is to the center of gravity, the easier it is to control. The difference is minimal, but present.
 
Old Dec 10, 2011 | 11:45 PM
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brief video explanation from motor trend

This topic gets a nice overview from motor trend via youtube:

 
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