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Old 11-29-2003, 08:25 PM   #76
OoNismoO
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heh yea i know...its polar moment of inertia... i realized that after my last post, but i got tired of editing, so i just left it the way it was. i figured that when someone else replies, and brings the thread back up, i could just say something about it.
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Old 11-29-2003, 10:03 PM   #77
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Re: Re: Re: Re: Re: Re: Re: z06 vs modena

Quote:
Originally Posted by Deakins
And there you go..
A mid engined car with a static weight balance at ~40:60 will achieve dynamic balance under breaking, superior to a car with static 50:50 weight balance.

And OoNismoO, the term you are looking for is 'polar moment of inertia'. A mid/rear engined car, like the 360 should have a lower polar moment of inertia compared to a mid/front engined car like the Z06. This should give it better steering respons, in theory.
Sorry, but I hardly see how your 40:60 is anything special, mostly because it isn't. The amount of weight shifted forward is dependant upon the amount of braking done, deceleration in G force, the same goes for acceleration. But, if the numbers are anything like these 2 cars are capable of, that car would have less weight on the front tires during hard braking (whether that's good or bad I can't say, but with enough tire that would be inferior). Where it would fault is front tire traction during a turn exit, with enough throttle you could easily pull enough weight from them to understeer, and neither of these cars has the downforce to make up for that.

At least you said in theory, we don't all have millions in aerodynamic R&D giving us 7000 #'s of downforce at speed giving all the traction we could possibly need.
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Old 12-01-2003, 04:47 PM   #78
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Re: z06 vs modena

There are a lot of very valid points being made, but it still just isn't that simple or cut and dried. Rear/mid-engine rwd and front-engine rwd (or front/mid-engine which is exceedingly rare although some designs blur the line) both have enough respective benefits and liabilities that neither is simply "all around superior" as a street vehicle.

I have yet to even hear the term "roll center" come up and that is extremely critical to handling. Especially in a mid engined production car which often have issues with how "high" within the car itself the weight sits no matter how "low" the car looks.

Ferrari's own Testarossa, and the awesome cars later based on that chassis, suffered very weird handling quirks due to a top heavy rear end. Not too much weight in the rear, but too much weight too high in the rear. This was largely due to the boxer-style engines necessarily high placement in the chassis, partially explaining why the mid engine Modena and other mid engine cars following the Testarossa chassis packed V-8's instead of a Boxer.

In the 348/355/360 Ferrari did a great job of addressing this issue and not making the cars a mile long in the process.(An often found side effect of one of this problems solutions in rear/mid engined cars.) That is not the first, or last issue mid engine car designs face, and front engine designs have theirs as well.

The fact that companies like Ferrari, and Aston Martin still choose to build front engine sports cars only demonstrates that there are advantages to both. Enzo Ferrari and Carroll Shelby both thought that front engined cars were preferable as street vehicles........both know (And in Enzo's case knew..may he reast in peace) more than all of us put together. Lotus today, and it's founder Mr. Chapman back in the day, would disagree with Enzo and Shelby proving great minds apparently do not always think alike.

By the way I would prefer the Modena to the Z06 given the available bucks. The Vette is impressive, but I just cannot take the plastic interior's rendition of Darth Vader's bathroom, or the bland, and big back end styling. Not to mention the "I am a Japanese designer's version of a Vette" overall styling theme. Styling may seem a shallow deciding factor for the difference in bucks, but I cannot imagine spending even Z06 like money on a car I couldn't stand to look at or sit in.
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Old 12-01-2003, 06:54 PM   #79
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i do agree that for street cars, front engine rear drive is better than mid rear, but for a pure racecar, i think id rather go with mid rear like f1. since i probably wont be racing like that anyways, id prefer front engined or front mid mounted rear drive cars. in f/r set up you usually get more room, especially trunk space to carry your luggage or whatever, and sometimes you can have back seats. i havent driven the z06 or the modena, but for now, id rather get the z06 if i could afford both.
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Old 12-05-2003, 03:57 PM   #80
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I have been a long time reader of this forum, mainly for $hits and giggles but registered to chime in on this thread. I was surprised no one remembered the one head to head comparo of the Z06 and 360 I can remember. I have the bad habit of reading ~20 industry and gen pop car rags a month and seem to commit all of them to memory (I just usually can't remember which mag or year/month it was!), it took me a while to dig the article up but I did and was lucky that it is online as well.

R/T did their "Great Grip" article in 2002, the premise was to find the best road/track handling car, which included the 360 and the Z06, the 360 finished first and the Z06...fifth (ouch). As far as bang for the buck goes the Z06 also loses, the Lotus Elise took second, and the Elise will be available stateside in less than a year, with a more potent federal power to weight ratio, which well could have put it ahead of the 360 all for sub 40k. You wanted numbers, you have numbers, side by side, same day, same driver, the Z06 bested by a Ferrari, Lotus, 996TT and an Evo VII not even an VIII or FQ300 or Evo "8.5".

http://www.roadandtrack.com/article....&page_number=1

Vandy

PS I will take care of the "reasons" for you:

1. The 360 was an Enzo prototype, and Michael Shumacher pushed Herta outta the seat
2. Bryan Herta is a Viper guy so he sand bagged the Z06
3. The Z06 had a plug wire pulled, maybe two
4. The Z06 was running snow tires
5. Herta is allergic to fiberglass
6. insert your choice of bowtie drivel here ___________
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Old 12-05-2003, 08:37 PM   #81
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thats a pretty cool comparo. didnt think that the evo 7 would beat the z06.
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Old 12-05-2003, 09:11 PM   #82
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Re: z06 vs modena

Nice. I'm lovin it... I have mucho respect for the elise. That's a great car. I really can't wait for the elise to hit state side.
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Old 12-05-2003, 10:05 PM   #83
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Re: z06 vs modena

Quote:
Originally Posted by IR/IR04M3
I have been a long time reader of this forum, mainly for $hits and giggles but registered to chime in on this thread. I was surprised no one remembered the one head to head comparo of the Z06 and 360 I can remember. I have the bad habit of reading ~20 industry and gen pop car rags a month and seem to commit all of them to memory (I just usually can't remember which mag or year/month it was!), it took me a while to dig the article up but I did and was lucky that it is online as well.

R/T did their "Great Grip" article in 2002, the premise was to find the best road/track handling car, which included the 360 and the Z06, the 360 finished first and the Z06...fifth (ouch). As far as bang for the buck goes the Z06 also loses, the Lotus Elise took second, and the Elise will be available stateside in less than a year, with a more potent federal power to weight ratio, which well could have put it ahead of the 360 all for sub 40k. You wanted numbers, you have numbers, side by side, same day, same driver, the Z06 bested by a Ferrari, Lotus, 996TT and an Evo VII not even an VIII or FQ300 or Evo "8.5".

http://www.roadandtrack.com/article....&page_number=1

Vandy

PS I will take care of the "reasons" for you:

1. The 360 was an Enzo prototype, and Michael Shumacher pushed Herta outta the seat
2. Bryan Herta is a Viper guy so he sand bagged the Z06
3. The Z06 had a plug wire pulled, maybe two
4. The Z06 was running snow tires
5. Herta is allergic to fiberglass
6. insert your choice of bowtie drivel here ___________


You should've stayed a lurker.
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Old 12-06-2003, 07:30 AM   #84
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Re: Re: z06 vs modena

Quote:
Originally Posted by FYRHWK1


You should've stayed a lurker.
You can thank yourself for my interjection of objective relevent information.

"You get better steering response? if the wheels turn, and the car does not break traction, your car will turn as fast as you crank the wheel over, thats all there is to it."

When you made statements like the above that fail to grasp some of the basic physics and dynamics of car handling it seemed important to help shed some light onto a relatively simple subject.

Lets take your above statement for example. A car among other things has what is called a moment of inertia. I=mr

Without delving into Newton's second law of rotation or parallel and perpendicular axis theorum too heavily it comes down to the farther away the average mass distribution from the center of rotation the more force it will take to accomplish this rotation. If you watch a figure skater as she spins in one place. she spins slowly when her arms are extended from her body, when she pulls them in (but adds no more energy to her spinning action) she speeds UP spinning much faster around her rotational center. This is the same with a vehicle, that is why you do not simply "turn as fast as you crank the wheel" each car will rotate at a different rate depending in large part to how far from the rotational center the avarage mass distribution is. The closer the average mass distribution is to the center the less resistance to the turning force will be present and the sooner and quicker the car will begin to rotatate on the axis. This is part of reason, for example, that a Lotus Elise needs less force to change direction than a Z06 and will turn quicker when it overcomes this moment of inertia. Of course another big issue is the much lower mass of the Elise along with suspension issues (I have not compared spring rates to mass etc for the Z06 and Elise, so this is an issue that may hurt or help the Elise or Z06, I just don't know). This is one of the reasons mid engine/rear drive cars have a design advantage as a track car. MR cars have the potential design advantage of locating the majority of the mass of the car near the axis of rotation, making it potentially more responsive and quicker around the track. F/R cars have to overcome this physics to compete.

The bottom line is the 360 starts with a chassis more condusive to good handling. The Z06 engineers due to its F/R layout had far more to overcome, they did an admiral job but just can't match a well sorted M/R chassis. There is no shame in what Chevrolet has done with the Z06, it is an excellent track car which is one of the value leaders in road going track cars in the WORLD. Eclipsed only in track "value" by cars such as the Elise and Vauxhall VX 220 turbo.

The LS6 is a marvel of pushrod technology, strong and tunable but Chevy is not an engine builder at the pinacle of engine building, case in point their defeated call to Cosworth to build a competative engine for IRL last season. For engine tech at the outer edge one must look to three companies, BMW, Ferrari (Fiat) and Mercedes. One needs look no farther than the gems these companies put in their F1 cars to see this.

The Z06 is a world class road going track car BUT fans should see and admit that it isn't the best, even at the price. As for the 360/Z06 comparison these cars are close at the track, really a drivers race, but the 360 has an advantage on most tracks, nothing for the Z06 to be ashamed of at 1/3 the price.

This all said if I were to buy a new track car for lapping but not racing in a strict class today, it would most likely be a Z06, this opinion will likely change when the federal Elise arrives on US shores.

Vandy

Last edited by IR/IR04M3; 12-06-2003 at 09:01 AM.
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Old 12-06-2003, 07:49 AM   #85
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IR/IR04M3 let me be the first to say welcome to the forums....i was really impresed by your posts...very well written...well informed and easy to read...btw the skater analogy was perfcet

its also nice that you bring verifiable info and you are not biased(very rare araound here)

and i love the article you posted....the best comparisons are only side by side and with a profesional driver...

hope you stay around the forums
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Old 12-06-2003, 11:57 PM   #86
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Re: Re: Re: z06 vs modena

Quote:
Originally Posted by IR/IR04M3
You can thank yourself for my interjection of objective relevent information.

"You get better steering response? if the wheels turn, and the car does not break traction, your car will turn as fast as you crank the wheel over, thats all there is to it."

When you made statements like the above that fail to grasp some of the basic physics and dynamics of car handling it seemed important to help shed some light onto a relatively simple subject.

Lets take your above statement for example. A car among other things has what is called a moment of inertia. I=mr

Without delving into Newton's second law of rotation or parallel and perpendicular axis theorum too heavily it comes down to the farther away the average mass distribution from the center of rotation the more force it will take to accomplish this rotation. If you watch a figure skater as she spins in one place. she spins slowly when her arms are extended from her body, when she pulls them in (but adds no more energy to her spinning action) she speeds UP spinning much faster around her rotational center. This is the same with a vehicle, that is why you do not simply "turn as fast as you crank the wheel" each car will rotate at a different rate depending in large part to how far from the rotational center the avarage mass distribution is. The closer the average mass distribution is to the center the less resistance to the turning force will be present and the sooner and quicker the car will begin to rotatate on the axis. This is part of reason, for example, that a Lotus Elise needs less force to change direction than a Z06 and will turn quicker when it overcomes this moment of inertia. Of course another big issue is the much lower mass of the Elise along with suspension issues (I have not compared spring rates to mass etc for the Z06 and Elise, so this is an issue that may hurt or help the Elise or Z06, I just don't know). This is one of the reasons mid engine/rear drive cars have a design advantage as a track car. MR cars have the potential design advantage of locating the majority of the mass of the car near the axis of rotation, making it potentially more responsive and quicker around the track. F/R cars have to overcome this physics to compete.

The bottom line is the 360 starts with a chassis more condusive to good handling. The Z06 engineers due to its F/R layout had far more to overcome, they did an admiral job but just can't match a well sorted M/R chassis. There is no shame in what Chevrolet has done with the Z06, it is an excellent track car which is one of the value leaders in road going track cars in the WORLD. Eclipsed only in track "value" by cars such as the Elise and Vauxhall VX 220 turbo.

The LS6 is a marvel of pushrod technology, strong and tunable but Chevy is not an engine builder at the pinacle of engine building, case in point their defeated call to Cosworth to build a competative engine for IRL last season. For engine tech at the outer edge one must look to three companies, BMW, Ferrari (Fiat) and Mercedes. One needs look no farther than the gems these companies put in their F1 cars to see this.

The Z06 is a world class road going track car BUT fans should see and admit that it isn't the best, even at the price. As for the 360/Z06 comparison these cars are close at the track, really a drivers race, but the 360 has an advantage on most tracks, nothing for the Z06 to be ashamed of at 1/3 the price.

This all said if I were to buy a new track car for lapping but not racing in a strict class today, it would most likely be a Z06, this opinion will likely change when the federal Elise arrives on US shores.

Vandy
Lets take a look at what I said, while everything you have posted makes sense, it still proves nothing. If you turn the wheels, and the car does not break traction, you WILL turn at the rate that you turn the wheel. There isn't any other option, because if the forward inertia is too much for the tires, then you'll simply understeer instead of turn. If it doesnt overload the front tires, then you'll turn at the rate dictated by their angle, there isnt another option.

Polar movement dictates how easily the car rotates, not whether it does and the rate of it. The physics article was nice, but it didn't prove anything.

Another thing that is never taken into account is the amount of traction each wheel has. No fan of MR seems to understand that there are sacrifices as well, and the only time MR really shows its inertial qualities is when you've got it in a racecar that has the aerodynamics to make up for the lack of front wheel weight. FR is far superior for a street car, unless you've got the aerodynamics of an enzo, you won't be seeing the great gains of MR because you'll be too busy correcting the understeer that comes with it.

GM went to cosworth because they can build small volume, specified engines, and last time I checked, GM began losing BADLY after htey went to cosworth, good job on their part. Before they went to them, the 4L (loosely) based northstar was beating everyone.
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Old 12-07-2003, 01:43 AM   #87
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Both of you have great points, but I want to throw somethings in here.. first I=mr? I believe in my physics class it was I=mv.. Inertia=mass x the velocity of the mass... r.. is that maybe rate of motion?

The location of the center of gravity is the largest part of a cars rotational characteristics obviously. But right now we are considering the horizontal rotation only. Let me throw a wrench into the works. A mid engine sports car has the great advantage of having the rotational axis very close to the center of the car, and that's why in general the mr cars are the best handling. But between the z06 and the F360 the closest to the center weight distribution goes to the z06. (f/r) 43/57 (F360) 53/47 (Z06) Also we need to take a glance at the lateral (side to side) rotation. Ferrari has gotten so much better at this than in the past but there are still major problems with most of the MR cars in this aspect. MR cars the weight is higher up. I don't care that the F360 sits physically lower, because the weight is still higher up than the z06's. I think actually that one of the best cars in the lateral handling (IMO of course) is probably the viper. For a 8.3L v10 the weight is surprisingly low. But anyways back on topic. A car that has weight high up means that there is more movement because the axis of rotation is higher up. look at the difference between a jeep and a lotus.. the lotus won't flip nearly as easy as the jeep because the jeep has a higher center of gravity. There is more lateral movement when the jeep turns than when the lotus turns. So because the MR car has a higher center of gravity (weight placement/ rotational axis whatever the hell you want to call it) it will rotate more. So with more rotation there will me more of the weight pushed towards the outer wheel and so the friction won't be as evenly distributed. So because the center of gravity in the z06 is lower and closer to the center it should have better turning than the f360 modena. yes you just called my bluff.. it should have better handling, but the suspension and steering systems set up by gm pm the z06 (maybe even the tires?) are not nearly as well set up as the F360's set up. So the F360 should maintain the better handling. And yes the F360 doesn't have as much weight on the turning tires so it has more understeer than the z06, but then again it also has great downforce as said by FYRE, so that can make up for it. There's my 2 cents and I'm sticking to it. Cheers!
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Old 12-07-2003, 08:12 AM   #88
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Re: Re: Re: Re: z06 vs modena

Quote:
Originally Posted by FYRHWK1
If you turn the wheels, and the car does not break traction, you WILL turn at the rate that you turn the wheel. There isn't any other option, because if the forward inertia is too much for the tires, then you'll simply understeer instead of turn. If it doesnt overload the front tires, then you'll turn at the rate dictated by their angle, there isnt another option.
You obviously don't understand the concept of slip angles.

Quote:
Originally Posted by VenomInMyVeins
But between the z06 and the F360 the closest to the center weight distribution goes to the z06.
This still doesn't mean anything.

Quote:
MR cars the weight is higher up. I don't care that the F360 sits physically lower, because the weight is still higher up than the z06's.
And you know this because?
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Old 12-07-2003, 11:11 AM   #89
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I would think that both setups will have their different advantages. The easiest way to achieve a 50/50 weight balance would be using a FR setup, right. Wouldn't you usually get better even handling when your car is closer to 50/50? Now a car that is heavier in the front will have a larger slip angle compared to a car with a rear heavy design having more slip angle in the back. A car with a 50/50 balance will have less slip angle to the front and back due to its more even weight distribution right? So in this sense wouldn't a 50/50 design achieve better handling since it wouldn't be as prone to a front/rear biased setup to oversteer/understeer?

But a mid-engined car will have a better steering response and dynamic balance due to its lower polar moment of inertia and rear biased weight setup. Wouldn't that be mroe than enough to make up for its lack of even weight distribution?

I found a good site that relates to a lot of what its being discussed here

http://autozine.kyul.net/technical_s...handling_4.htm

check it out
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Old 12-07-2003, 11:29 AM   #90
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Re: z06 vs modena

Quote:
Originally Posted by Kurtdg19
Wouldn't you usually get better even handling when your car is closer to 50/50? Now a car that is heavier in the front will have a larger slip angle compared to a car with a rear heavy design having more slip angle in the back. A car with a 50/50 balance will have less slip angle to the front and back due to its more even weight distribution right? So in this sense wouldn't a 50/50 design achieve better handling since it wouldn't be as prone to a front/rear biased setup to oversteer/understeer?
It's not that simple. A car with 50:50 weight distribution is only balanced at constant speeds.
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