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      02-13-2008, 10:52 AM   #89
bruce.augenstein@comcast.
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Quote:
Originally Posted by swamp2 View Post
A DOHC design carries some extra weight up top and that is a small draw back of its deisgn. However, the redline of the M3 is quite stupendous. Your post above is a bit dismissive of the value of a high rpm engine. The Vette engine is not absolutely better in all regards, hands down.
OK. maybe I can learn something here, as I am genuinely at a loss.

What is the value of a high rpm engine?

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Originally Posted by swamp2 View Post
Also as far as engine weights go: If we can barely agree on what cars weigh and they are regulated by laws, standards and conventions how can we expect folks to meausure and report engine weights in a fair and consistent fashion. For example I seriously doubt that the 6.3 l AMG motor weighs close to the same as the M3s engine. It is so much larger and unless made of unobtainium larger generally = heavier. And they are the same basic layout/design as well making it an "apples to apples".
First of all, in this forum, we can barely agree that the sun rises in the east, so of what value is that particular comment?

Secondly, engine weights are regulated under SAE Standard J2038, and although I don't know what the DIN/EC standard is that regulates these things, you can absolutely bet that there is one.

Are they different? Almost certainly yes, but by how much? I don't know, but I have been told that the standards are different only in detail. That is to say, published weights, DIN/EC to SAE will only vary by relatively small amounts. Of course, this isn't proof.

If anybody actually has specific info on this, I'd appreciate hearing about it.

Meanwhile, Swamp, you can believe that the Mercedes vs BMW engine weights are published under the same standard - although I'm quite sure you won't.

Bruce
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      02-13-2008, 10:56 AM   #90
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Originally Posted by sayemthree View Post
the corvette is not as cheap as you think. you must invest in an array of gold chains and several toupes to drive one.
, good stuff. In regards to a comparison between the two, I guess the reason why they are being compared is because both are world class sports cars/coupes. I am a huge BMW fan. My dad has a 7 series that made me fall in love. For such a huge sedan, it did all the right things. It handled well(esp. for its size), it was quick, it looked good, it had great brakes, and the amount of refinement and quality was unsurpassed. My brother just picked up a 335 Coupe about 6 months ago and equals all points of the 7series, but hauls ass while looking even better. Its very nice cruising down the road being so isolated from the elements, it really gives you a different view on the driving experience. I know back when I was on my huge BMW kick from the 7 series, all of this technology mattered to me to. Vanos, variable intake/exhaust cam timing, variable lift tech., and all of the different programming parameters that BMW now offers on all of their cars it seems. But in the end, if all of the technology that costs SOOOO much to develope could be done more simply and just as effectively, then why have it other than to just say "I have it." That is the approach the corvette team took. If a vette had Vanos tech in the engine, a completely programmable traction control/stability control system, and some fancy electronic user adjustable diff but was only .1sec faster around a track, then what good is it REALLY doing other than just making things more complicated and probably creating more problems than solutions. The vette team seems to operate by the simple philosophy known as KISS - Keep It Simple Stupid. Many times, the best way to solve a problem is the most simple design. Its cheaper, it works 95% as well as the other much more expensive solution, and its more reliable. Leaf springs are a derivative of this philosophy. The pushrod LS3 V8 is another. Pull the motor from the Escalade, touch up the heads, lighten the valvetrain, employ some new machining specifications on the block for added strength and oil control, work the pistons for small, but numerous revisions and walla....you have 436hp and your getting 30mpg on the highway. I was able to get a best of a 12.49@115.54mph in my 08 C6 in completely stock trim. In the end, they are both great cars. BMW offers a great all around vehicle. One that can be tailored to the needs of each individual driver. They offer the flexability the vette does not and for those that bask in new technology, there is no substitute. I work with German engineers, their approach to many design ideas is often ingenious and very unique. There are certainly more simple ways to accomplish the task(see honda and toyota), but in the end the Germans are responsible for the technology push as they are more often on the frontier in their never ending quest for very advanced systems in regards to all aspects of the driving experience. Buy what pleases you, but at the same time, don't trash somebody elses pride and joy. It may not be your cup of tea, but the world isn't made of people like "you".
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      02-13-2008, 11:41 AM   #91
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Originally Posted by 1.8t View Post
, good stuff. In regards to a comparison between the two, I guess the reason why they are being compared is because both are world class sports cars/coupes. I am a huge BMW fan. My dad has a 7 series that made me fall in love. For such a huge sedan, it did all the right things. It handled well(esp. for its size), it was quick, it looked good, it had great brakes, and the amount of refinement and quality was unsurpassed. My brother just picked up a 335 Coupe about 6 months ago and equals all points of the 7series, but hauls ass while looking even better. Its very nice cruising down the road being so isolated from the elements, it really gives you a different view on the driving experience. I know back when I was on my huge BMW kick from the 7 series, all of this technology mattered to me to. Vanos, variable intake/exhaust cam timing, variable lift tech., and all of the different programming parameters that BMW now offers on all of their cars it seems. But in the end, if all of the technology that costs SOOOO much to develope could be done more simply and just as effectively, then why have it other than to just say "I have it." That is the approach the corvette team took. If a vette had Vanos tech in the engine, a completely programmable traction control/stability control system, and some fancy electronic user adjustable diff but was only .1sec faster around a track, then what good is it REALLY doing other than just making things more complicated and probably creating more problems than solutions. The vette team seems to operate by the simple philosophy known as KISS - Keep It Simple Stupid. Many times, the best way to solve a problem is the most simple design. Its cheaper, it works 95% as well as the other much more expensive solution, and its more reliable. Leaf springs are a derivative of this philosophy. The pushrod LS3 V8 is another. Pull the motor from the Escalade, touch up the heads, lighten the valvetrain, employ some new machining specifications on the block for added strength and oil control, work the pistons for small, but numerous revisions and walla....you have 436hp and your getting 30mpg on the highway. I was able to get a best of a 12.49@115.54mph in my 08 C6 in completely stock trim. In the end, they are both great cars. BMW offers a great all around vehicle. One that can be tailored to the needs of each individual driver. They offer the flexability the vette does not and for those that bask in new technology, there is no substitute. I work with German engineers, their approach to many design ideas is often ingenious and very unique. There are certainly more simple ways to accomplish the task(see honda and toyota), but in the end the Germans are responsible for the technology push as they are more often on the frontier in their never ending quest for very advanced systems in regards to all aspects of the driving experience. Buy what pleases you, but at the same time, don't trash somebody elses pride and joy. It may not be your cup of tea, but the world isn't made of people like "you".


good post, I too use to purchase BMW's, my father only buys a Benz, but what people don't realize it's good to drive other vehicles and open up your mind.

I like all high performance vehicles, each has great attributes and each has it's strengths and weakness.

hope to see you at one of the drag events @ Moroso, a lot of corvette forum members go there, and run sub 12 sec times with just bolt ons

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      02-13-2008, 01:31 PM   #92
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Quote:
Originally Posted by gmund1948 View Post
anything that is not modern is not good?

Take my 1994 Porsche 911 RSAmerica that has basically the same suspension as the 1964 911 in front and a 1952 Porsche 356 in the rear and will handle as well as any E36 or earlier M-3 and stay with many E-46 Ms on a track.

I drove a e92 M3 hard for nearly an hour on Sunday, followed by the 08 Corvette Z-51 and followed by the E93 335I.

I am glad I ordered the M-3, it is fantastic,a true super coupe or sedan. The Corvette however has much cleaner lines and is fun to toss around it is more of a super car feel. The Z-06 is almost too much.

I am a true M-3 believer, and was as ignorant and as stubborn as you are in acknowledging the Corvette as a world class sports car, I talked trash about
Vettes until I took one out on a track. \\

If you refuse to try you refuse to learn,

That said, since you likely had to look-up the direction the leaf-springs
on a vette were facing but not why they are part of the design then
then you allow yourself to be uneducated. Old Technology is not so bad
My house in Germany was built using a brick design that dates back 500
years, holds heat in the winter, and is cool in the summer. The Beer I drink is a 600 year old recipe.

There is much danger in keeping a closed mind
another
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      02-14-2008, 03:15 AM   #93
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Quote:
Originally Posted by gmund1948 View Post
anything that is not modern is not good?

Take my 1994 Porsche 911 RSAmerica that has basically the same suspension as the 1964 911 in front and a 1952 Porsche 356 in the rear and will handle as well as any E36 or earlier M-3 and stay with many E-46 Ms on a track.

I drove a e92 M3 hard for nearly an hour on Sunday, followed by the 08 Corvette Z-51 and followed by the E93 335I.

I am glad I ordered the M-3, it is fantastic,a true super coupe or sedan. The Corvette however has much cleaner lines and is fun to toss around it is more of a super car feel. The Z-06 is almost too much.

I am a true M-3 believer, and was as ignorant and as stubborn as you are in acknowledging the Corvette as a world class sports car, I talked trash about
Vettes until I took one out on a track. \\

If you refuse to try you refuse to learn,

That said, since you likely had to look-up the direction the leaf-springs
on a vette were facing but not why they are part of the design then
then you allow yourself to be uneducated. Old Technology is not so bad
My house in Germany was built using a brick design that dates back 500
years, holds heat in the winter, and is cool in the summer. The Beer I drink is a 600 year old recipe.

There is much danger in keeping a closed mind
No, I didn't had to look up direction of leaf springs on the vette. I don't know everything about the vette, but basics I do know. Even without knowing, it is pretty intuitive to figure they wouldn't place leaf springs as they do on a full size Silverado. Anyway...believe what you want.

If the word handling was such subjective term as you perceive it to be, we might as well place F-350 dually as the ultimate handling machine or maybe Ford fusion or any deviation thereof. My M3 rides on 550lb springs and poly bushings. I classify its handling as mediocre at best, certainly not because it will be faster on track than average car, but because handling entails so much more than how fast you go around the track. Level of damping, rebound, braking balance, weight shift and overall optimization is all part of the equation. (E90 325i handles better than E36 M3. It is newer and better optimized design). Taking all this into account M3 is few million light years ahead of vette. It was since E21 generation.

Sure, vette is fast and has tons of grip, but it is infinitely more unstable in the corner if it gets upset, and you better be a master of opposite lock if back end drifts away. Inherent design of leaf springs will always lag behind handling prowess of multi-link rear.

My opinion is that corvette makes up for its lack of better suspension design with more rubber. C6 Z06 carries 275s front and 325/30 series back. Now compare that to NEW M3, 245f/265b. So now you have a lighter car with more rubber. Even if you had truck suspension (which you do heh) you would grip so much more to the point where even mediocre suspension would stop being a bottleneck. Put the same tires on the heavier M3 and see how it would compare on the track. It would be a comical comparison at that point.

I am not discrediting vette for what it is, but for what it is not. I appreciate the car for its intended purpose and for its low budget great performance. Is it a supercar in terms of speed performance? Yes. Is it best bang for the buck in universe? Yes.

There is nothing wrong with old technology. I wouldn't doubt if vette has more durable and sturdier suspension, especially for street. M3s need suspension replacement every 50k to handle like they do. M3 probably has dozen more bushings than a vette, none of which help with durability.
LSX engines aren't even remotely as maintenance needy as I-6 or the new V8. I could go on...but to draw parallels that old technology suspension is equivalent to handling of newer designs is absurd. It works, it is durable, it handles decently, but lets leave it at that.

Swamp2,

Seriously you have not just wrote this:

Quote:
As I like to say, a spring is a spring is a spring. The function of a spring is simple; to support the weight of the car
read up on some of the simple stuff such as progressive springs, which are getting outdated.



...still after everything, i want a big bad american V8 to abuse

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      02-14-2008, 02:25 PM   #94
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Interesting comments but I don’t agree with you on the following:



Quote:
Originally Posted by malter2.0 View Post
If the word handling was such subjective term as you perceive it to be, we might as well place F-350 dually as the ultimate handling machine or maybe Ford fusion or any deviation thereof. My M3 rides on 550lb springs and poly bushings. I classify its handling as mediocre at best, certainly not because it will be faster on track than average car, but because handling entails so much more than how fast you go around the track. Level of damping, rebound, braking balance, weight shift and overall optimization is all part of the equation.
But damping, rebound, braking balance, and weight shift and optimization does dictate how fast you go around the track, if a car is not well balanced it will not put the power down well around corners, it will not post a good time, now some cars take more finesse and skill to drive fast, while others are easier to post good numbers, unfortunately the vette is a tricky car to drive fast, because the power can put you sideways real fast, ask me how I know.

Quote:
Originally Posted by malter2.0 View Post
Sure, vette is fast and has tons of grip, but it is infinitely more unstable in the corner if it gets upset, and you better be a master of opposite lock if back end drifts away. Inherent design of leaf springs will always lag behind handling prowess of multi-link rear.
Yes leaf springs is old technology, but in the 24 hrs of Lemans in the GT1 class:

2007
vette 2nd place

2006
vette 1st and 7th

2005
vette 1st and 2nd

2004
1st and 2nd

the competitors that race in the GT1 class all use multi-link rear suspension,
Aston Martin
Saleen
Ferrari, who?, yes Ferrari
Lamborghini
Yet wow look how well the vette finishes each year, mind you it's a different suspension, but if the ZO6 did not have a good suspension, it would not do such a good time on the ring, 7:42, which is only 4 seconds slower than the mighty GTR.

Quote:
Originally Posted by malter2.0 View Post
My opinion is that corvette makes up for its lack of better suspension design with more rubber. C6 Z06 carries 275s front and 325/30 series back. Now compare that to NEW M3, 245f/265b. So now you have a lighter car with more rubber. Even if you had truck suspension (which you do heh) you would grip so much more to the point where even mediocre suspension would stop being a bottleneck. Put the same tires on the heavier M3 and see how it would compare on the track. It would be a comical comparison at that point.
nope, the regular vette, uses 245 in front and 285 in the rear, and handles better than the M3, also if you change those run flats to regular tires like in the M3 you get much better grip and road feel and breaking. The biggest problem I have with the vette is the tires, but I’m not going to better tires, due to the fact I have no spare.

Quote:
Originally Posted by malter2.0 View Post
There is nothing wrong with old technology. I wouldn't doubt if vette has more durable and sturdier suspension, especially for street. M3s need suspension replacement every 50k to handle like they do. M3 probably has dozen more bushings than a vette, none of which help with durability.
I think the vette’s suspension is just as fragile as any other, but one thing about the leaf springs is the ride sucks, but hey I knew what I was buying and I can live with it.

but you are 100% right if I was to scrap my leaf springs and go with coil overs I would handle and ride much better than now, damn, now I have to break my piggy bank, just when I thought I was done modding my car.


and to my knowledge the M3 will have per side on the rear suspension
2 upper control arms
1 lower
1 tailing arm
1 track bar
that is only 11 bushings inlcluding the one on the knuckle

just for your information

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      02-14-2008, 03:47 PM   #95
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[quote=malter2.0;2143754](E90 325i handles better than E36 M3. It is newer and better optimized design). Taking all this into account M3 is few million light years ahead of vette. It was since E21 generation.

Sure, vette is fast and has tons of grip, but it is infinitely more unstable in the corner if it gets upset, and you better be a master of opposite lock if back end drifts away. Inherent design of leaf springs will always lag behind handling prowess of multi-link rear.

My opinion is that corvette makes up for its lack of better suspension design with more rubber. C6 Z06 carries 275s front and 325/30 series back. Now compare that to NEW M3, 245f/265b. So now you have a lighter car with more rubber. Even if you had truck suspension (which you do heh) you would grip so much more to the point where even mediocre suspension would stop being a bottleneck. Put the same tires on the heavier M3 and see how it would compare on the track. It would be a comical comparison at that point.

There is nothing wrong with old technology. I wouldn't doubt if vette has more durable and sturdier suspension, especially for street. M3s need suspension replacement every 50k to handle like they do. M3 probably has dozen more bushings than a Vette, none of which help with durability.
LSX engines aren't even remotely as maintenance needy as I-6 or the new V8I could go on...but to draw parallels that old technology suspension is equivalent to handling of newer designs is absurd. It works, it is durable, it handles decently, but lets leave it at that.

I would wager you have not driven the 08 Corvette, Or the M3 have you ?
You ignored the parts about Porsche using the same technology in suspensions as they have for 50 years !

BMW has a winner in the New M3, Chevy has brought the Vette to levels
that amaze, My question is how you can rate handling without driving a car ?

This is not fantasy football, people make decisions from some facts they can glean from this forum, and misinformation, or information pulled out of some magazine articles doesn't mean you can't have an opinion its your right

Basing a conclusion on information where you have some experience but have not actually tested something else is well ah misleading

I can respect a lot of cars, learned from being a Porsche snob that there is a lot more than one marque. I had never owned a Corvette, I had not owned a BMW since a 2002 Tii and now own a 335 vert and will add the M3

The best thing you can do is drive some other cars without concern to who makes them, If you are a track guy, do It there

Maybe you will see there are a lot of choices
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      02-14-2008, 06:21 PM   #96
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Originally Posted by spearfisher View Post
But damping, rebound, braking balance, and weight shift and optimization does dictate how fast you go around the track, if a car is not well balanced it will not put the power down well around corners, it will not post a good time, now some cars take more finesse and skill to drive fast, while others are easier to post good numbers, unfortunately the vette is a tricky car to drive fast, because the power can put you sideways real fast, ask me how I know.
I disagree. How fast you go around the track is also largerly associated with power, as much as it is with handling. In that analogy, we could say lotus exige should be the fastest around the track, but it is not. N-ring with quite a few long streches tends to favor big powered cars, which is the reason Z06 tracks under 8 minutes. M3 without a doubt is more optimized than corvette in just about any handling characteristics, but it doesn't compare in power. Reason again goes back to inherent design of leaf springs. Power wise Z06 will demolish it, which is why it is pointless to take one track (as n-ring was the case in this argument) and set a basis for what a particular car is capable of.

Agree that vette is trickier to drive at the limit. From your experience why is that?

Quote:
Yes leaf springs is old technology, but in the 24 hrs of Lemans in the GT1 class:

2007
vette 2nd place

2006
vette 1st and 7th

2005
vette 1st and 2nd

2004
1st and 2nd

the competitors that race in the GT1 class all use multi-link rear suspension,
Aston Martin
Saleen
Ferrari, who?, yes Ferrari
Lamborghini
Yet wow look how well the vette finishes each year, mind you it's a different suspension, but if the ZO6 did not have a good suspension, it would not do such a good time on the ring, 7:42, which is only 4 seconds slower than the mighty GTR.
I don't follow LeMans closely, but if they are using different suspension then you don't really have an argument? It's a race prepped car. Does lemans vette uses leaf springs? I don't know?
M3 GTR in race version put out 444hp, which is some 60hp less than Z06 along with 3.0L of deficit in displacement. With similar power to Z06 it would have been more than 20 sec or maybe even more.


Quote:
nope, the regular vette, uses 245 in front and 285 in the rear, and handles better than the M3, also if you change those run flats to regular tires like in the M3 you get much better grip and road feel and breaking. The biggest problem I have with the vette is the tires, but I’m not going to better tires, due to the fact I have no spare.
I specified Z06 in my post, not regular vette. Z06 has the tires I stated.
Handles better than which M3? E92?
Quote:
I think the vette’s suspension is just as fragile as any other, but one thing about the leaf springs is the ride sucks, but hey I knew what I was buying and I can live with it.
It might be fragile, but I don't see vette owners bitching about LCAB, RTAB, FCAB and other XXXX all the damn time like you see on all BMW forums.



Quote:
and to my knowledge the M3 will have per side on the rear suspension
2 upper control arms
1 lower
1 tailing arm
1 track bar
that is only 11 bushings inlcluding the one on the knuckle

just for your information
track bar=sway bar? add differential bushings? how about subframe bushings? those are big time wear items. with great build quality on E36 you'll be riding on the straight asphalt if you dont change subframe bushings.
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      02-14-2008, 06:54 PM   #97
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Quote:
Originally Posted by gmund1948 View Post
I would wager you have not driven the 08 Corvette, Or the M3 have you ?
Drove a '93 Z28. I heard it's a same setup as '08 Z0666.

Quote:
You ignored the parts about Porsche using the same technology in suspensions as they have for 50 years !
Actually I addressed it between the lines in my previous post, but I can do it more directly. Porsche handled well back in 13th century, let alone now. In comparison to corvette (or BMW for that matter), it used a superior design since its inception. With generations they optimized, reduced immense, both understeer and oversteer on kill-yourself 930 and just built upon their racing heritage, which is the reason all P-cars nowadays are considered Rolex of track cars.

On the other hand, take American icon like Stingray - it never was a model of great handling car, just powerful straight line muscle car. Much like Porsche continued its path of great handling cars, chevy did also with power, which is why you don't see too many people drag racing their 911 turbos as you do people in supercharged C5 Z06s and C6 and bla bla bla...

Quote:
BMW has a winner in the New M3, Chevy has brought the Vette to levels
that amaze, My question is how you can rate handling without driving a car?
Reading is fundamental, so they say. Oh, wait, is that a wrong answer?


Quote:
This is not fantasy football, people make decisions from some facts they can glean from this forum, and misinformation, or information pulled out of some magazine articles doesn't mean you can't have an opinion its your right

Basing a conclusion on information where you have some experience but have not actually tested something else is well ah misleading

Agreed. You are entitled to your opinion 100%, especially since you drove both cars, but on the other hand I would not so easily discredit opinions of those who have read and researched a lot. Collectively, a certain product or "thing" is deemed as good or bad, as the average of all the opinions.
Most of the magazine car reviewers have extensive car design experience or have worked for a long time in automotive industry, not to mention substantial track time. These people are professionals in their field and do this for living. On average their review of the car will be far more accurate than a weekend racer's opinion. I purposely say on average, as reviewers are not all created equal.

Quote:
I can respect a lot of cars, learned from being a Porsche snob that there is a lot more than one marque. I had never owned a Corvette, I had not owned a BMW since a 2002 Tii and now own a 335 vert and will add the M3

The best thing you can do is drive some other cars without concern to who makes them, If you are a track guy, do It there

Maybe you will see there are a lot of choices
I respect a corvette for what it is, just as I respect a crown vic for being a great taxi car. Nothing more, nothing less.
I like BMWs, but I am not a fanboy, as you might classify me.
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      02-14-2008, 09:17 PM   #98
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Quote:
Originally Posted by malter2.0 View Post
read up on some of the simple stuff such as progressive springs, which are getting outdated.
What exactly is the value of a progressive spring for a vehicle that will need to support a fairly constant mass? If the total m of the system is pretty much a constant, a spring with non-linear k should not provide any noticable benefit. One should be able to control the velocity dependent response characteristics of the suspension system with the damping ratio, which is F=-cv. Also, I believe the Corvette has a variable damping suspension system, which should allow for even futher control of the response characteristics of the suspension.

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      02-14-2008, 10:41 PM   #99
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Quote:
Originally Posted by malter2.0 View Post
Swamp2,

Seriously you have not just wrote this:

Quote:
Originally Posted by swamp2 View Post
As I like to say, a spring is a spring is a spring
read up on some of the simple stuff such as progressive springs, which are getting outdated.
Yup, I sure did write that and it is true. In this context either a coil or a leaf, ALL THEY DO IS PROVIDE A SPRING CONSTANT, k and provide the basic functions I mentioned above. Sure I know about non-linear springs (i.e. "progressive") but they are not used that often at all. All we would have to change is to say a spring is a spring is a spring and provides a k = k(x)! You said yourself that they are getting outdated as well. They simply feel strange. It is better to extract any desired non-linearity out of the suspension linkage design. By the way I cut my teeth doing suspension design in the mountain bike industry (disc brake design as well). A very different field and massively different ratios of sprung and unpsprung weights compared to a car, but the fundamentals are all the same.

So I stick by my statement. Much more entertaining is yours,

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Originally Posted by malter2.0 View Post
Inherent design of leaf springs will always lag behind handling prowess of multi-link rear.
You do realize the the two terms have nothing to do with each other? Apparently not. The number of links, layout of the linkage system and the device used to provide a spring force are all separate and can be mixed and matched at a designers will.
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      02-14-2008, 10:52 PM   #100
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Originally Posted by bruce.augenstein@comcast. View Post
OK. maybe I can learn something here, as I am genuinely at a loss.

What is the value of a high rpm engine?
Bruce you don't really need me to tell you this do you? Again all of these things may or may not have been achieved or may have been achieved in varying degrees in the M3. Furthermore, there are certainly some counter examples to these points meaning they are not absolutely/universally true.
  • Power to the ground per weight is key. High rpm engines generally develop more power than lower revers (all other things equal)
  • High rpm engines can hold gears longer than low rpm designs, which when all other things are equal will produce a faster car
  • Throttle control and precision is enhanced with high rpm designs
  • High rpm designs can be made to withstand less torque and can therefore be lighter.
  • High rpm engines can provide more hp/l which can offer improved efficiency and emmissions for a given power
  • High hp/l engines can avoid costly taxes in some countries based on displacement
  • High rpm engines are darn fun and sound heavenly, let's not forget the importance of these somewhat subjective points
  • Lastly what about F1 cars? Yeah I know, the GT-ish M3 is not an F1 car but there would be no way to get these to perform the way they do without very high rpms and gears to match.

I too would like more information on European engine weight standards. I would expect all manufacturers to follow the regs if they exists. Does it makew fundamental sense to you that a 4l and 6.2l engine of more or less the same design can weigh very close to the same?
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      02-15-2008, 12:42 AM   #101
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What exactly is the value of a progressive spring for a vehicle that will need to support a fairly constant mass? If the total m of the system is pretty much a constant, a spring with non-linear k should not provide any noticable benefit. One should be able to control the velocity dependent response characteristics of the suspension system with the damping ratio, which is F=-cv. Also, I believe the Corvette has a variable damping suspension system, which should allow for even futher control of the response characteristics of the suspension.
Springs do not support constant mass. Technically, they do support constant mass, but not constant weight. Weight=force. People often use weight and mass interchangeably, which is ok, but in physics there is a clear delineation because weight takes into account gravity. Nit picking...anway. If you assume frictionless, even road, then yes. Real world ...definitely not. If you are in a curve do you think your springs are experiencing the same force as on the straight?

Damping and springs are two separate things. I believe vette on one of the packages (and caddy as well) have MR fluid suspension which can vary damping and rebound.

Last edited by malter2.0; 02-15-2008 at 01:53 AM.
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      02-15-2008, 01:17 AM   #102
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Swamp2,

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Yup, I sure did write that and it is true. In this context either a coil or a leaf, ALL THEY DO IS PROVIDE A SPRING CONSTANT, k and provide the basic functions I mentioned above. Sure I know about non-linear springs (i.e. "progressive") but they are not used that often at all. All we would have to change is to say a spring is a spring is a spring and provides a k = k(x)! You said yourself that they are getting outdated as well. They simply feel strange. It is better to extract any desired non-linearity out of the suspension linkage design. By the way I cut my teeth doing suspension design in the mountain bike industry (disc brake design as well). A very different field and massively different ratios of sprung and unpsprung weights compared to a car, but the fundamentals are all the same.
Oh my god you are thick. Have you ever installed a set of springs on your car? Any car? If all springs provide basic function (can you tell me what function is that?), why don't you install a set of springs from buick park avenue and let us know how the car responds in twisties. Progressive springs not used often? Wow...funny because just about every aftermarket suspension for your car, which happens to be my car too, comes with progressive springs. I have them on my car right now in form of TEIN coilovers. Bilstein PSS9, H&R, TEIN SS coilovers...and few others all come with progressive springs. They feel funny? How is the word funny even used in describing a suspension feel?

Maybe you could write a nice email to technical support and headquarters of industry giants such as Bilstein, H&R, TEIN and tell them It is better to extract any desired non-linearity out of the suspension linkage design.

Leaf springs have their purpose ...in trucking industry. Chevy can make them out of carbon nanotubes for all I care.
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      02-15-2008, 02:35 AM   #103
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the Vette leaf springs are low tech, even if they are turned the wrong way.

the M3 still uses an ancient strut front suspension and not an independant supnsion.

its all irrelevent IMO - the fact is the 4 seat "sedan" M3 can keep up and surpass the dedicated two seat plastic sports car made by chevy. the fact that a sedan can keep up with a two seats sports cars is impressive enough for me.
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      02-15-2008, 04:01 AM   #104
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Originally Posted by malter2.0 View Post
Springs do not support constant mass. Technically, they do support constant mass, but not constant weight. Weight=force. People often use weight and mass interchangeably, which is ok, but in physics there is a clear delineation because weight takes into account gravity. Nit picking...anway. If you assume frictionless, even road, then yes. Real world ...definitely not. If you are in a curve do you think your springs are experiencing the same force as on the straight?
Huh? So the mass of the overall spring mass damper system for the car changes over time? The only way that's going to happen is if the number of passengers or the cargo mass changes. Well, fuel is being burned, so mass does decrease at a very negligible rate. Apart from that the mass is constant. You are mixing up spring force (and damper force for that matter) with the mass of the system. Again, the vehicle can be modeled as a spring mass damper system for many intents and purposes. You can write the system equation for it and solve for displacement, velocity, acceleration of different point of the chassis of the car for given inputs. Force is simply a variable in that consideration. Force can also be one of the inputs to that model depending on how complex your model is, such as air resistance related down force.

Quote:
Originally Posted by malter2.0 View Post
Damping and springs are two separate things. I believe vette on one of the packages (and caddy as well) have MR fluid suspension which can vary damping and rebound.
Of course they are different variables. The solution for the displacement of the two ends of a spring/damper (suspension) assembly over time is a function of k, c, and m. One can control for that displacement by varying k, c, or both.

Anyway, a highly non-linear spring might be useful in a truck where the vehicle mass can change drastically, but that is clearly not what you are talking about. I am not sure how non-linear progressive springs are for a car exactly, but they can't be that non-linear. In the case of the Corvette, assuming the leaf spring is fairly linear, what exactly is the problem? Knowing your vehicle mass will not change, you can still control for a significant part of the transient response with the dampers.

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      02-15-2008, 07:45 AM   #105
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I disagree. How fast you go around the track is also largerly associated with power, as much as it is with handling.
I am not here to start an argument, but if there is ONE equalizer to having more power than someone, its called being on a track. Sure, Nurinbergring(sp?) has a lot of straights, but the rest of the 102345363456 tracks in the world the Z06 was tested on does not.....and its still going to absolutely burn an M3 around one. Stop being irrational man, your going on a tangent and the Z is in another performance league in regards to handling, braking, and power. I would tell you this if even if my DD were a Kia.

Unlike most of you who are on here and have all of these theoretical opinions about how each car would perform under a certain track temp, rel. humidity, pressure, wet bulb, dry bulb, blah blah blah.....I am out there doing it. Drag strip, roadcourse, autox....I do them all and I have probably done more than 99% of this forum. In regards to suspension tuning, springs are about 10%. The other 90% is in tuning the shock. Have your opinion all you want about leaf springs, I just find it funny that you are trying to dismiss ANY car because of what it is sprung by. Go work with some IT cars and do some HPDE events and I promise you won't argue about "progressive" springs anymore(as if progressive springs are any sort of cutting edge tech. btw). Hell, for that matter, talk to some of the best autox'ers and ask them about their $200 springs or their $4k+ Motons/Penskes/Ohlins.
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      02-15-2008, 09:24 AM   #106
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Huh? So the mass of the overall spring mass damper system for the car changes over time? The only way that's going to happen is if the number of passengers or the cargo mass changes. Well, fuel is being burned, so mass does decrease at a very negligible rate. Apart from that the mass is constant. You are mixing up spring force (and damper force for that matter) with the mass of the system. Again, the vehicle can be modeled as a spring mass damper system for many intents and purposes. You can write the system equation for it and solve for displacement, velocity, acceleration of different point of the chassis of the car for given inputs. Force is simply a variable in that consideration. Force can also be one of the inputs to that model depending on how complex your model is, such as air resistance related down force.
.
Read my previous post in its entirety, that is, past what you put in bold.

Quote:
Anyway, a highly non-linear spring might be useful in a truck where the vehicle mass can change drastically, but that is clearly not what you are talking about.
Exactly. I'm definitely not talking about that. Why would you want a progressive spring in the truck? Leaf springs=more reliable, and able to hold more weight.

Last edited by malter2.0; 02-15-2008 at 09:46 AM.
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      02-15-2008, 11:17 AM   #107
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Originally Posted by swamp2 View Post
Bruce you don't really need me to tell you this do you? Again all of these things may or may not have been achieved or may have been achieved in varying degrees in the M3. Furthermore, there are certainly some counter examples to these points meaning they are not absolutely/universally true.
  • Power to the ground per weight is key. High rpm engines generally develop more power than lower revers (all other things equal)
  • High rpm engines can hold gears longer than low rpm designs, which when all other things are equal will produce a faster car
  • Throttle control and precision is enhanced with high rpm designs
  • High rpm designs can be made to withstand less torque and can therefore be lighter.
  • High rpm engines can provide more hp/l which can offer improved efficiency and emmissions for a given power
  • High hp/l engines can avoid costly taxes in some countries based on displacement
  • High rpm engines are darn fun and sound heavenly, let's not forget the importance of these somewhat subjective points
  • Lastly what about F1 cars? Yeah I know, the GT-ish M3 is not an F1 car but there would be no way to get these to perform the way they do without very high rpms and gears to match.

I too would like more information on European engine weight standards. I would expect all manufacturers to follow the regs if they exists. Does it makew fundamental sense to you that a 4l and 6.2l engine of more or less the same design can weigh very close to the same?
OK, look. I tend to agree in concept on all points you list (except the third and fifth), but that's all food for thought in some other fairly esoteric string. The thing is, you wrote:

Quote:
Originally Posted by swamp2 View Post
A DOHC design carries some extra weight up top and that is a small draw back of its deisgn. However, the redline of the M3 is quite stupendous. Your post above is a bit dismissive of the value of a high rpm engine. The Vette engine is not absolutely better in all regards, hands down.
In response to that I asked what the value of a high rpm engine was, and since I wasn't specific, you gave me the general answers.

So-o, in that context, with the LS3 and M3 engines having similar weights and overall sizes, and the LS3 having power and torque advantages (plus possible bsfc advantages), specifically what is the value of the M3's 8400 rpm red line vs the 6500 rpm red line of the LS3?

The more I think about it, the more I'm beginning to believe that the LS3 really is "absolutely better in all regards, hands down". I'm perfectly willing to be disabused of that notion, however, so fire away, and maybe I can learn something.

Thanks in advance,

Bruce

PS - I really am perfectly willing to believe that the Mercedes and BMW engines have similar weights, on general grounds that there are DIN/EC standards for such things, but also on technical grounds that the Merc and bimmer motors are built to differing engineering standards, very possibly of different grades of aluminum. The Merc engine, offered in larger volumes than the BMW unit across several different car lines (therefore amortization costs are lower per unit), still goes for $56K over the counter - so it really may be made of unobtanium.
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      02-15-2008, 01:29 PM   #108
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Quote:
Originally Posted by malter2.0 View Post
I disagree. How fast you go around the track is also largerly associated with power, as much as it is with handling. In that analogy, we could say lotus exige should be the fastest around the track, but it is not. N-ring with quite a few long streches tends to favor big powered cars, which is the reason Z06 tracks under 8 minutes. M3 without a doubt is more optimized than corvette in just about any handling characteristics, but it doesn't compare in power. Reason again goes back to inherent design of leaf springs. Power wise Z06 will demolish it, which is why it is pointless to take one track (as n-ring was the case in this argument) and set a basis for what a particular car is capable of.
Agree that vette is trickier to drive at the limit. From your experience why is that?
Wrong again, the 05 C6 does a faster time around the ring than the M3 and that had less HP, and has leaf springs, explain that.
The 04 C5 Z06 had a faster time around the ring also and has less HP also, and by the way has leaf springs, also it brakes worse that the M3 also, explain that.I really want you to explain this.

Having auto-x a E46 M3 and a 08 C6, if you go full throttle a little early out of the corner with a E46 M3 you won’t go sideways or spin, do that in a C6 and you’ll face the other way or be putting in some quick counter steer.
The complete opposite is I drove the ISF on Moroso and the Audi S4 on Homestead, the Audi is next near to impossible to go sideways on no matter throttle position, ISF easier to go sideways but very controllable (not much throttle feathering required, remember the throttle is not an on off switch)
Quote:
Originally Posted by malter2.0 View Post
I don't follow LeMans closely, but if they are using different suspension then you don't really have an argument? It's a race prepped car. Does lemans vette uses leaf springs? I don't know?
M3 GTR in race version put out 444hp, which is some 60hp less than Z06 along with 3.0L of deficit in displacement. With similar power to Z06 it would have been more than 20 sec or maybe even more.
M3 GTR in a different class anyway, just like the classes above the C6R have more HP.

wrong again, the C6R suspension can be ordered for a regular C6, but of course race parts, called the T1 suspension which can be purchased, but I doubt the ride is nice or the 1.5 inch ground clearance., T1 suspension parts available on the GM performance catalog.
sit down let me explain.
I’m pointing out that the CR6 is not a multi-link suspension and does quite well beating out other multi link suspension designs, you stated a multi-link suspension will always be superior performance wise, I don’t think so.


By the way the definition of a multi-link suspension is one that does not use just
1 upper control arm
1 lower control arm
1 knuckle

instead is uses multiple link points hence the name,
example.
All Acura’s use a rear multi-link suspension, and only on the rear, multi-link is not used on the front.
Other types of suspension are:
1. SLA
2. MacPherson Strut
3. Solid Axle
4. Double wishbone

Leaf springs is a type of spring used in one of these type of suspension but not a suspension type, because you can change the leaf spring on a vette and go with coil overs, does not change the suspension type, it’s still a SLA/double wishbone.

Multi-link is a great design, but it’s how well the suspension is tweaked that determines how well it handles, as long as you have a good design base, hence no solid axle.

Quote:
Originally Posted by malter2.0 View Post
I specified Z06 in my post, not regular vette. Z06 has the tires I stated.
Handles better than which M3? E92?
.
yeah but you stated that tire sizes make that much of a difference, apples to apples, the regular C6 has the same front sizes as the M3 E92 and only slightly larger on the rear, even though the rears are slightly larger the tires grip worse. The GY are not that great of performing tire compared to other non-run flat performance tires or even other high performance run flats for that matter. You can’t attribute the better handling on the vette to the tires, wrong.


Quote:
Originally Posted by malter2.0 View Post
It might be fragile, but I don't see vette owners bitching about LCAB, RTAB, FCAB and other XXXX all the damn time like you see on all BMW forums.



track bar=sway bar? add differential bushings? how about subframe bushings? those are big time wear items. with great build quality on E36 you'll be riding on the straight asphalt if you dont change subframe bushings.
for your info, all cars have sway bars, 2 bushings
sub-frame bushings all except for a few use 4 bushings

but anyway the M3 does not have a dozen more bushings as you stated.

Also reference to bushings wearing out, I know I’m not the only one that had front lower control arm bushings wearing out prematurely on the E46 M3 and E46 330, by the way that was not wear and tear, they usually failed prematurely, part defect, they wore out 14k on my M3 and 24k on my 330. I don’t think that will happen on the E92.

But in this case your right, bushings on the vette don’t wear out pre-maturely but then we have other problems.

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      02-15-2008, 03:07 PM   #109
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Wrong again, the 05 C6 does a faster time around the ring than the M3 and that had less HP, and has leaf springs, explain that.
The 04 C5 Z06 had a faster time around the ring also and has less HP also, and by the way has leaf springs, also it brakes worse that the M3 also, explain that.I really want you to explain this.
Post a source that C5 Z06 has faster time.

Quote:
Having auto-x a E46 M3 and a 08 C6, if you go full throttle a little early out of the corner with a E46 M3 you won’t go sideways or spin, do that in a C6 and you’ll face the other way or be putting in some quick counter steer.
The complete opposite is I drove the ISF on Moroso and the Audi S4 on Homestead, the Audi is next near to impossible to go sideways on no matter throttle position, ISF easier to go sideways but very controllable (not much throttle feathering required, remember the throttle is not an on off switch)
ok, most of it makes sense, but how is this relating to this discussion?

Quote:
M3 GTR in a different class anyway, just like the classes above the C6R have more HP.
yep, which is what i stated. i never brought up M3 GTR, merely answering what other poster initiated. however, race version still has 60hp less than stock z06.

Quote:
wrong again, the C6R suspension can be ordered for a regular C6, but of course race parts, called the T1 suspension which can be purchased, but I doubt the ride is nice or the 1.5 inch ground clearance., T1 suspension parts available on the GM performance catalog.
aha, and where was i wrong? point out exact statement in my previous post.
i ASKED whether lemans vette has leaf springs or not. i claimed nothing.

Quote:
sit down let me explain.
I’m pointing out that the CR6 is not a multi-link suspension and does quite well beating out other multi link suspension designs, you stated a multi-link suspension will always be superior performance wise, I don’t think so.
wow more strawman argument. i never stated multi link suspension is superior performance wise. i said it is more modern and it handles better. performance is only one aspect of handling. we learnt that earlier. balance, driver's confidence at car limit, stability through a turn with uneven surface, comfort, etc..


Quote:
Multi-link is a great design, but it’s how well the suspension is tweaked that determines how well it handles, as long as you have a good design base, hence no solid axle.
which is why im saying that multilink has inherently superior design over suspension that INCORPORATES leaf springs. time around the track will vary on million other variables, power, driver, tires etc

Quote:
yeah but you stated that tire sizes make that much of a difference, apples to apples, the regular C6 has the same front sizes as the M3 E92 and only slightly larger on the rear, even though the rears are slightly larger the tires grip worse.
which is the reason c6 is slower than m3 around n-ring, unless you can show me a source that it tracks faster than current 8:05

Quote:
The GY are not that great of performing tire compared to other non-run flat performance tires or even other high performance run flats for that matter. You can’t attribute the better handling on the vette to the tires, wrong.
pfffffff 325 on z06 will have far more grip and advantage than 265 rear thats on m3, EVEN though michelin cup 265 thats on e92 m3 is indeed a better quality performance tire. maybe i should also add M3 is missing 3L of displacement, 100hp and is what 400lb heavier?


Quote:
for your info, all cars have sway bars, 2 bushings
sub-frame bushings all except for a few use 4 bushings
really? wouldn't have known that if you didn't inform me.

Quote:
but anyway the M3 does not have a dozen more bushings as you stated.
it may not have exactly 12 more, but it has more bushings, because multi link by design dictates more bushings.
lets count for measly e36 m3 for rear: 2 sway, 2 trail, 4 upper wishbone (2 on each corner), 4 lower arm (2 on each corner), 4 sub frame, 2 diff. add in 2 upper and lower rubber spring pads per corner which do disintegrate over time, which leaf springs dont have.

crude drawing...courtesy of bimmerworld

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      02-15-2008, 03:42 PM   #110
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you guys have too much time on your hands!
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