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      10-18-2010, 05:49 PM   #89
therealm3
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Quote:
Originally Posted by niuniu View Post
Moving 500lbs (engine weight) or so 1/4 of an inch is a big deal! How can you compare that to removing 8lbs I have no idea.
Because the engine is much closer to the center of gravity and the roll center of the car than the roof. So with the roof being further from that point is has a much bigger "lever" effect where by less weight can have the same effective change.

Think about it. put a 6" ratchet on a lug bolt and try to loosen it with your hand; most people cant’ do this. Now use a 24” breaker bar and wow it takes very little force to move that lug. Now think of the weight that is pushing from the height of roof being the breaker bar example and you can see how small amounts of weight far away from the centers can and do make a difference.
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      10-18-2010, 07:07 PM   #90
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Quote:
Originally Posted by therealm3 View Post
Because the engine is much closer to the center of gravity and the roll center of the car than the roof. So with the roof being further from that point is has a much bigger "lever" effect where by less weight can have the same effective change.

Think about it. put a 6" ratchet on a lug bolt and try to loosen it with your hand; most people cant’ do this. Now use a 24” breaker bar and wow it takes very little force to move that lug. Now think of the weight that is pushing from the height of roof being the breaker bar example and you can see how small amounts of weight far away from the centers can and do make a difference.
I honestly don't believe EITHER example makes enough difference to affect performance in any detectable (by butt dyno or track times) way.

But I still say, it's ALL conjecture until documented. Can ANYONE here post a legit link to a performance test involving the same car but one with CF and the other steel? I'll grant it makes a MINOR, THEORETICAL difference. The questions are:

1. How much is the CALCULATED difference,
and - even MORE importantly
2. What is the MEASURED performance difference?

? ? ?
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      10-18-2010, 09:54 PM   #91
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Kurt – I don’t know what more anyone can say seeing you “just don’t believe it.” I’ll give you that most will not feel the 8lb loss if the cars are driven back to back and honestly given where most 1M’s will spend the majority of their lives (the street), the cf roof is a moot point and more for looks. BUT, there is definitely a reason for using it and there would be quantifiable data if someone put the test together. It may be only a few tenths a lap on a given short distance track, but that’s still a few tenths. And there is no auto engineer in the world that wont’ view that as better performance. Now the improvement may not be directly felt as a “handling” improvement per say, but it could help in a more indirect way. For example, slightly less weight transfer in a corner means less work the tires have to do cornering, which means power can be put down sooner, and they run cooler. Which intern means they will go longer before getting greasy, allow more braking force, and work more consistently. Again all things that are positive. Now if we go to the approx 44 lbs lost with no sunroof and then a CF roof, well that is something that I honestly think you would feel just on a 270 onramp with the sales rep riding shotgun.

In the end, I don’t’ really care if it has a CF roof or not. All I really want is Lemans or Interlagos Blue.
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      10-18-2010, 10:46 PM   #92
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WE NEED A BLUE CAN YOU TELL US ANYTHING SCOTTT!!!!
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Last edited by Cameraeye; 10-18-2010 at 10:48 PM.. Reason: adding a video
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      10-19-2010, 05:32 AM   #93
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Quote:
Originally Posted by formula M View Post
Lulz..


Being able to "feel" it, is vastly different than being able to measure it...

But I see what you did there.. your argument is no longer factual, it's subjective to your own pseudo-engineering principles of "feeling". Oddly, one cannot feel many things, such as lighter structural steel in certain areas of the car either, or the battery in the trunk. But, they are there and help performance/handling... and you pay more for such engineering.

But, obviously since these principles are not understood by you, then "it doesn't matter" either, right?


Kurt.. it sounds to me, like YOU don't care, therefore it doesn't matter to YOU. But please, your ignorance isn't fact, lets not dismiss the fact that a lighter top aids in handling. It's provable physics. You clearly know very little about engineering, or even manufacturing, as engineers spend millions on these exact principles that YOU arbitrarily dismiss because YOU'RE butt dyno doesn't feel it..?

Coincidentally, YOUR inability to admit, that lowering the center of gravity of a vehicle, aids in performance, is absurd!
1. Could you PLEASE keep the discussion about the topic, which is the CF roof, not your ridiculous ad hominem that proves nothing?

2. I DID say measure it, but I ADDED you won't feel it. I still say BACK IT UP! Show some measurements or even calculations! Oh yea, that's right, you already know that but chose to attack ME instead of prove your speculation. Hmmm, I wonder why . . . ?


As I said before, I completely agree there is SOME difference. My opinion is that it is insignificant - a shorter or lighter driver makes more difference (my example was a 5'6" driver vs. one whose head touches the headliner).
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      10-19-2010, 07:04 AM   #94
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Quote:
Originally Posted by Kurt_OH View Post
As I said before, I completely agree there is SOME difference. My opinion is that it is insignificant - a shorter or lighter driver makes more difference (my example was a 5'6" driver vs. one whose head touches the headliner).
Remember that your butt is planted to lowest part of the car, making the least amount of effect to weight distribution. Lessening weight that is fastened to the highest part of the car would have a more significant impact.

I agree that it is minimal, but I disagree that it is insignificant. Your car is more tossable/maneuverable with a lower center of gravity, versus a higher center of gravity. I don't think you'd need me to cite a source for that one. It's about as basic as you can get.
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      10-19-2010, 07:35 AM   #95
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Quote:
Originally Posted by Kurt_OH View Post
1. Could you PLEASE keep the discussion about the topic, which is the CF roof, not your ridiculous ad hominem that proves nothing?
.
I was exactly thinking the same thing. It is quite pointless at this point to dicuss further with this person.

Quote:
Originally Posted by larryn View Post
Remember that your butt is planted to lowest part of the car, making the least amount of effect to weight distribution. Lessening weight that is fastened to the highest part of the car would have a more significant impact.

I agree that it is minimal, but I disagree that it is insignificant. Your car is more tossable/maneuverable with a lower center of gravity, versus a higher center of gravity. I don't think you'd need me to cite a source for that one. It's about as basic as you can get.
Since I do not exactly know the exact point of CG, I can not exactly calculate. However, with rough napkin math, I can say that CG will not move more than 1/16 of an inch by 8 lbs reduction from the tallest point on the car, which is overall a 3300lbs car.

I think you guys are totally missing the fact that is the weight of this car here. If car was 300 lbs, yes. 8 lbs is huge at the rooftop. Current condition, This reduction is still calculatable, but small enough that it is negligible considering the price you want to pay for it. If you have endless money, if you want the ultimate best performance from this 1M, yes CF. But if you are NOT like that, put that money into suspension, you will end up better handling car overall.
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      10-19-2010, 08:53 AM   #96
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Quote:
Originally Posted by larryn View Post
Remember that your butt is planted to lowest part of the car, making the least amount of effect to weight distribution. Lessening weight that is fastened to the highest part of the car would have a more significant impact.

I agree that it is minimal, but I disagree that it is insignificant. Your car is more tossable/maneuverable with a lower center of gravity, versus a higher center of gravity. I don't think you'd need me to cite a source for that one. It's about as basic as you can get.
I do need you to cite a source for the hard to believe claim that 8lb off the roof of a car with these specs/dimensions makes a measurable difference in performance. As of right now no one here has even come p with the MUCH easier to provide calculation of the actual change in forces.

So YES I need you to cite it, quantify it via legit calculation or stop claiming that your GUESS is any more legit than mine.
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      10-19-2010, 10:27 AM   #97
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It's pretty easy to test raising or lowering 200lbs if you raise and lower your seat.

Testing a weight change near the roof is a little harder but consider that the average head plus helmet is about 14 pounds.
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      10-19-2010, 02:05 PM   #98
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Look, I cited a real world example of how a change in center of gravity makes a noticeable difference. This is based on street driving and on track experiences from 10+ years of pounding BMWS around different tracks. This was blown out of proportion claiming an S14 weighs 500lbs and dismissed my comments as not REAL proof.

Quote:
Originally Posted by Kurt_OH View Post
Time to put up or shut up. Cite proof of the difference it makes.
And to this quote I say you prove to us with hard evidence/calculations that the weight loss does not matter. It goes both ways.

Now lets get back to the real tragedy at hand... no blue.

Last edited by therealm3; 10-19-2010 at 02:12 PM..
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      10-19-2010, 02:41 PM   #99
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Quote:
Originally Posted by therealm3 View Post
Look, I cited a real world example of how a change in center of gravity makes a noticeable difference. This is based on street driving and on track experiences from 10+ years of pounding BMWS around different tracks. This was blown out of proportion claiming an S14 weighs 500lbs and dismissed my comments as not REAL proof.



And to this quote I say you prove to us with hard evidence/calculations that the weight loss does not matter. It goes both ways.

Now lets get back to the real tragedy at hand... no blue.
Your "butt dyno" claim ain't gonna do it.

As for me proving your claim, no thanks.

Re: blue . . . Eh, doesn't bug me. I do like blue but orange will be ok.

Last edited by Kurt_OH; 10-19-2010 at 02:54 PM.. Reason: typo
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      10-19-2010, 03:29 PM   #100
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Quote:
Originally Posted by Kurt_OH View Post
Your "butt dyno" claim ain't gonna do it.

As for me proving your claim, no thanks.

Re: blue . . . Eh, doesn't bug me. I do like blue but orange will be ok.
hahaha, i didn't ask you to prove mine, I asked you to prove your statement that it doesn't make a difference. ;-) And i'll have you know my butt dyno is a very well calibrated device.


Yeah, i am hopig that in the next 6 months or so Orange will grow on me. Doubt it.
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      10-19-2010, 04:39 PM   #101
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Quote:
Originally Posted by therealm3 View Post
hahaha, i didn't ask you to prove mine, I asked you to prove your statement that it doesn't make a difference. ;-) And i'll have you know my butt dyno is a very well calibrated device.


Yeah, i am hopig that in the next 6 months or so Orange will grow on me. Doubt it.

I suspect that if there IS any measurable difference in favor of CF, it may be due to stiffness (of the car!)?!
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      10-19-2010, 05:09 PM   #102
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lol

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Originally Posted by Cameraeye View Post
WE NEED A BLUE CAN YOU TELL US ANYTHING SCOTTT!!!!
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      10-20-2010, 06:48 AM   #103
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Quote:
Originally Posted by Kurt_OH View Post

2. You STILL have offered ZERO evidence that a CF roof makes any difference. Because you don't have any. It's likely so infinitesimal that it can't even be detected in performance testing. If it CAN BE, then it HAS BEEN. Prove it. Stop whining about how "YOU know" and expecting folks to believe you. Prove it. Find some tests showing it makes a measurable difference. I've even asked that you simply show the calculations regarding how it would dynamically change the center of gravity for the vehicle. At least then we could quantify it.
It is fairly elementary to see that it makes a difference. If we start at 0 (CF roof) and record data around a lap and then add balast of 50+lbs on the roof of the car, and then do the lap again, what the hell do you think is going to happen? Especially under the dynamic G loads of changing directions quickly.

T
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      10-20-2010, 08:51 AM   #104
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Quote:
Originally Posted by ///Mangler View Post
It is fairly elementary to see that it makes a difference. If we start at 0 (CF roof) and record data around a lap and then add balast of 50+lbs on the roof of the car, and then do the lap again, what the hell do you think is going to happen? Especially under the dynamic G loads of changing directions quickly.

T
Yeah but what happens if you add a bag of sugar to the roof (5lb to 10lbs depending what size). Do really thing a bag of sugar will change your lap time?

I have the BMW base support, BMW snowboard rack and then two snowboards with bindings on there. I can't feel any difference on the corners or performance and I've been driving longer than most guys in the 1er forum I'd bet.
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      10-20-2010, 10:41 AM   #105
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I guess ya'll will have to agree to disagree. LOL! I think the truth of the matter is that yes, empirically any weight reduction will help performance. I think everyone can agree that if there was a machine that was able to measure to a very exact, minute, degree and that if the car was able to be driven around a test track or skid pad exactly the same over and over to erase driver error that you would be able to see a difference that could be measured.

I don't dispute the fact that lowering a cars center of gravity is a good thing, that making it lighter is a good thing, even if it's only one pound. BUT I'd bet that for 99% of the population (including pro drivers) that the 8lbs savings from the roof would be irrelevant to the performance of the car - i.e. driver error, lack of skill, tire temp, track condition, wind speed, how much gas is in the tank, etc would all make more difference than the 8 pounds not on the roof.

Now I agree that I love the look of the CF roof and I would definitely check the box if I got one, but since a 1M is not in the stars for me, I'll have to live with my 135i. :-)
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      10-20-2010, 11:03 AM   #106
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Don't want to add anymore fuel to the fire, but you need to argue the point about the weight. It's not just 8lbs, it's about 45lbs. less when you take OFF the sunroof. This does have a significant difference on the center of gravity.

But, as I posted an article from Top Gear, it would have to be added to other parts being substituted such as hood, trunk, etc.

Kurt, I hear your argument about not having proof, but I think you're not being realistic. Every car high-performance manufacturer is looking to reduce weight and will use lighter materials as CF and other metals. You can't say that an all steel Corvette will be the same on a track as a fiberglass version? It's just common sense.
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      10-20-2010, 11:04 AM   #107
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Quote:
Originally Posted by james33 View Post
I guess ya'll will have to agree to disagree. LOL! I think the truth of the matter is that yes, empirically any weight reduction will help performance. I think everyone can agree that if there was a machine that was able to measure to a very exact, minute, degree and that if the car was able to be driven around a test track or skid pad exactly the same over and over to erase driver error that you would be able to see a difference that could be measured.

I don't dispute the fact that lowering a cars center of gravity is a good thing, that making it lighter is a good thing, even if it's only one pound. BUT I'd bet that for 99% of the population (including pro drivers) that the 8lbs savings from the roof would be irrelevant to the performance of the car - i.e. driver error, lack of skill, tire temp, track condition, wind speed, how much gas is in the tank, etc would all make more difference than the 8 pounds not on the roof.

Now I agree that I love the look of the CF roof and I would definitely check the box if I got one, but since a 1M is not in the stars for me, I'll have to live with my 135i. :-)

YES!

I don't care if a machine spinning a 1M along its long axis, through its "old" cg can detect a wobble at 5000 rpm. If we can't measure it on a track or calculate a meaningful difference in dynamic forces which would measurably degrade performance, then the change is irrelevant.

Last edited by Kurt_OH; 10-20-2010 at 11:42 AM.. Reason: clarification
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      10-20-2010, 08:30 PM   #108
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^ I heard from the horses mouth (Larry Koch-N.A. M Brand Manager) in person recently that the reason for the CF roof in the M3 was to indeed lower the center of weight and increase overall performance.
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      10-20-2010, 08:44 PM   #109
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Quote:
Originally Posted by Tuned1 View Post
^ I heard from the horses mouth (Larry Koch-N.A. M Brand Manager) in person recently that the reason for the CF roof in the M3 was to indeed lower the center of weight and increase overall performance.
That's a good source.
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      10-24-2010, 07:21 PM   #110
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Quote:
Originally Posted by SCOTT26 View Post
Not at all. When you look back at the M3 either in E30,E36 and indeed E46.
There was no specific equipment you look to see in M cars today,
Although it was the E46 CSL that begun the whole looking at removing weight from the M cars.
Scott, you overlooked the '95 E36 M3 LTW (Lightweight), it was such a car. I had one, fantastic car.
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