weight distribution vs center of gravity , speak geek to me
11-10-2008 | 06:29 AM
#1
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weight distribution vs center of gravity , speak geek to me
Just some 5 am half asleep thoughts.. I was wondering if you experts can explain to me , the difference in theories , philosophies between bmw and porsches....
1)
its well agreed upon, that in order achieve good handling you need to have a close to perfect 50/50 weight distribution,
why is it then that porsches 911 have 40/60 biases, but are nearly ranked in top 1 or 2 in ever handling contests from top magazines? BMW 330 is nearly 50/50. I guess to get the rear to be that heavy you need to have the engine in the back .
2)
another debate, the inline 6 versus the flat 4: the reason porsche uses flat 4 configuration also known as box layout is to get the cars center of gravity as low to the ground as possible but bmw uses inline 6 offers because they offer better balance, so why doesn't bmw just place the engines as low to the ground as possible? it would be the best of both worlds..better balance and lower center of gravity.
3)
The bmw 3 series tops out at 50~ for the m3. whereas just to get into a 911 costs minumum 76k+. I dont get why do you have to pay a 25K price difference enough though it has the similiar engine out put, options, features etc.
Any thoughts?
1)
its well agreed upon, that in order achieve good handling you need to have a close to perfect 50/50 weight distribution,
why is it then that porsches 911 have 40/60 biases, but are nearly ranked in top 1 or 2 in ever handling contests from top magazines? BMW 330 is nearly 50/50. I guess to get the rear to be that heavy you need to have the engine in the back .
2)
another debate, the inline 6 versus the flat 4: the reason porsche uses flat 4 configuration also known as box layout is to get the cars center of gravity as low to the ground as possible but bmw uses inline 6 offers because they offer better balance, so why doesn't bmw just place the engines as low to the ground as possible? it would be the best of both worlds..better balance and lower center of gravity.
3)
The bmw 3 series tops out at 50~ for the m3. whereas just to get into a 911 costs minumum 76k+. I dont get why do you have to pay a 25K price difference enough though it has the similiar engine out put, options, features etc.
Any thoughts?
11-10-2008 | 06:47 AM
#2
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I don't want to comment on the BMW to Porsche comparison but one more point for handling is that the centre of gravity should not only be as low as possible but also, not only the centre of gravity but as much of the total mass as possible should be at centre of the car to make the turning inertia as low as possible.
The fact that the engine is not at the front allow the horizontal rotation inertia being minimised and this may be more important than the 50/50 front/rear wieght balance.
For the weight balance anyway the drive wheels should have most of the weight to increase grip for acceleration (this takes dynamic weight distribution into account), so the 50/50 isn't ideal in all aspects (perhaps unless the car is a 4WD).
The fact that the engine is not at the front allow the horizontal rotation inertia being minimised and this may be more important than the 50/50 front/rear wieght balance.
For the weight balance anyway the drive wheels should have most of the weight to increase grip for acceleration (this takes dynamic weight distribution into account), so the 50/50 isn't ideal in all aspects (perhaps unless the car is a 4WD).
11-10-2008 | 03:20 PM
#3
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I don't want to comment on the BMW to Porsche comparison but one more point for handling is that the centre of gravity should not only be as low as possible but also, not only the centre of gravity but as much of the total mass as possible should be at centre of the car to make the turning inertia as low as possible.
The fact that the engine is not at the front allow the horizontal rotation inertia being minimised and this may be more important than the 50/50 front/rear wieght balance.
For the weight balance anyway the drive wheels should have most of the weight to increase grip for acceleration (this takes dynamic weight distribution into account), so the 50/50 isn't ideal in all aspects (perhaps unless the car is a 4WD).
The fact that the engine is not at the front allow the horizontal rotation inertia being minimised and this may be more important than the 50/50 front/rear wieght balance.
For the weight balance anyway the drive wheels should have most of the weight to increase grip for acceleration (this takes dynamic weight distribution into account), so the 50/50 isn't ideal in all aspects (perhaps unless the car is a 4WD).
good point i guess having an engine in the front for a bmw would just be un-practical as its usually a daily driver around here anyway
