[Z06] functional real spoiler?
Thread Starter
Melting Slicks
Joined: Oct 2000
Posts: 3,368
Likes: 30
From: dfw Texas
im not looking for something to glue me upside down to a tube @200 mph
just something to hadd a little down force.. the fe z06s i have driven in seem a little " light in the ***" over 140ish.
just something to hadd a little down force.. the fe z06s i have driven in seem a little " light in the ***" over 140ish.
Team Owner
Joined: Sep 2003
Posts: 43,084
Likes: 33
From: Raleigh / Rolesville NC
Corner balance, proper rake and alignment will take care of the light feeling.
The proper rake is most important for high speed stability.
Last edited by AU N EGL; Jan 7, 2008 at 02:49 PM.
Race Director
Joined: Mar 2005
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Uh, the only thing that can change an RPM:MPH relationship is gearing. Are you running a track wheel/tire setup that is a different diameter than before? That would change your gearing.....
You can't be going a slower MPH at the same RPM..... Drag will cause your car to not be able to power to a higher RPM at top speed.
What gives, dude?
You can't be going a slower MPH at the same RPM..... Drag will cause your car to not be able to power to a higher RPM at top speed.
What gives, dude?
Race Director
Joined: Jul 2007
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From: Texas Hill Country
you tell me how wind affects your mph to rpm ratio when your engine speed, gearing, and tire sizing is fixed. please type it out. thanks for helping out the forum!
a tailwind can certainly increase your rpms but your mph will also be higher! vice versa w/headwind.
I bet your cruising rpms dropped 500 rpms when you installed an intake, right?
Last edited by Higgs Boson; Jan 8, 2008 at 10:05 AM.
Race Director
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No need to be combative and confrontational about it. It takes more horsepower to move against wind than to move with it. You will notice a variance of rpm vs vehicle speed to compensate for this difference. The engine will have to work harder to move the vehicle the same speed in both directions.
Now YOU think about it. If it were a purely mechanical relationship, you could calculate your speed vs. rpm and disregard wind drag. You could easily calculate top speeds in excess of what is practically possible.
P.S. I 'thought' about it for four years in a classical mechanical engineering curriculum at the University of Alabama in Huntsville. That's why my screen name says BSME in it.
Now YOU think about it. If it were a purely mechanical relationship, you could calculate your speed vs. rpm and disregard wind drag. You could easily calculate top speeds in excess of what is practically possible.
P.S. I 'thought' about it for four years in a classical mechanical engineering curriculum at the University of Alabama in Huntsville. That's why my screen name says BSME in it.
lol. wrong. think about it. seriously. think.
you tell me how wind affects your mph to rpm ratio when your engine speed, gearing, and tire sizing is fixed. please type it out. thanks for helping out the forum!
a tailwind can certainly increase your rpms but your mph will also be higher! vice versa w/headwind.
I bet your cruising rpms dropped 500 rpms when you installed an intake, right?
you tell me how wind affects your mph to rpm ratio when your engine speed, gearing, and tire sizing is fixed. please type it out. thanks for helping out the forum!
a tailwind can certainly increase your rpms but your mph will also be higher! vice versa w/headwind.
I bet your cruising rpms dropped 500 rpms when you installed an intake, right?
Burning Brakes
Joined: Apr 2007
Posts: 1,030
Likes: 1
From: Douglasville Ga
No need to be combative and confrontational about it. It takes more horsepower to move against wind than to move with it. You will notice a variance of rpm vs vehicle speed to compensate for this difference. The engine will have to work harder to move the vehicle the same speed in both directions.
Now YOU think about it. If it were a purely mechanical relationship, you could calculate your speed vs. rpm and disregard wind drag. You could easily calculate top speeds in excess of what is practically possible.
P.S. I 'thought' about it for four years in a classical mechanical engineering curriculum at the University of Alabama in Huntsville. That's why my screen name says BSME in it.
Now YOU think about it. If it were a purely mechanical relationship, you could calculate your speed vs. rpm and disregard wind drag. You could easily calculate top speeds in excess of what is practically possible.
P.S. I 'thought' about it for four years in a classical mechanical engineering curriculum at the University of Alabama in Huntsville. That's why my screen name says BSME in it.
Its like saying you could take the Z06 engine, drive train, and whatever else essential parts and slap a ford F450, or whatever, on it and still be able to reach 170+ mph, although it might take you a lot longer.
Race Director
Joined: Mar 2005
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As a side note, it is humorous to me that you think being condescending in your response somehow validates your thinking process, regardless of how uneducated it may be.
Engine load is the dynamic that you are ignorant of. It will take a slightly different rpm to maintain 60 mph in any gear while cruising, versus, say, pulling a boat behind you.
btw- what is your educational background, that you seem to know so much?
how's that for condescending?
Engine load is the dynamic that you are ignorant of. It will take a slightly different rpm to maintain 60 mph in any gear while cruising, versus, say, pulling a boat behind you.
btw- what is your educational background, that you seem to know so much?
how's that for condescending?
Last edited by 2000BSME; Jan 8, 2008 at 02:09 PM.
Burning Brakes
Joined: Oct 2001
Posts: 983
Likes: 23
From: Northeast Ohio
Well let me add that like downforce, a trailer will add weight to the back of the car, which will alter the tire radius some, which will change the rpm/speed ratio.
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Race Director
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No it won't if you're using a manual transmission and the clutch isn't slipping, the rpm and gear ratios are fixed. It will take more throttle opening to maintain the same rpm/speed towing a trailer than not towing a trailer.
Well let me add that like downforce, a trailer will add weight to the back of the car, which will alter the tire radius some, which will change the rpm/speed ratio.
Well let me add that like downforce, a trailer will add weight to the back of the car, which will alter the tire radius some, which will change the rpm/speed ratio.
Also, trailer WON'T affect tire CIRCUMFERENCE, which is waht will determine rpm/speed ratio.
Sorry.
Here is a pretty good example of using only gear ratios/rpms, and tire sizes to calculate speeds.
As you can see, my stock vette would be capable of 215 mph if wind drag and road friction were not taken into consideration. This is what I am talking about when I say 'engine load'.
Feel free to see how spectacular your car would perform under the ignored circumstances of 'engine load' here;
http://www.catherineandken.co.uk/sti/tyres.html
--your 6 speed vettes are capable of almost 250mph in top gear!
Last edited by 2000BSME; Jan 8, 2008 at 03:31 PM.
Burning Brakes
Joined: Oct 2001
Posts: 983
Likes: 23
From: Northeast Ohio
Ignoring tire circumference for a second, with fixed gear ratios explain how it's physically possible get different rpm's at a fixed speed?
It isn't. If you're not sure about this, better go reread your me books on gearing.
Circumference is Pi2R, In the case of a tire that will compress, measured circumference will not be identical to rolling circumference because R between the axle and the ground isn't the same as the R to any other part of the tire. The more the tire will compressed the bigger the difference is.
Race Director
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Ignoring tire circumference for a second, with fixed gear ratios explain how it's physically possible get different rpm's at a fixed speed?
It isn't. If you're not sure about this, better go reread your me books on gearing.
Circumference is Pi2R, In the case of a tire that will compress, measured circumference will not be identical to rolling circumference because R between the axle and the ground isn't the same as the R to any other part of the tire. The more the tire will compressed the bigger the difference is.
It isn't. If you're not sure about this, better go reread your me books on gearing.
Circumference is Pi2R, In the case of a tire that will compress, measured circumference will not be identical to rolling circumference because R between the axle and the ground isn't the same as the R to any other part of the tire. The more the tire will compressed the bigger the difference is.
We aren't talking about a closed system 'gearbox input and output' theoretical equation, where real world effects can be disregarded. See #29.
You are confusing yourself. Measured circumference and rolling circumference will be the same, regardless of the 'compressed' distance, as you call it, between the bottom of the tire, and the axle.
Radius will be affected, but circumference will not. Mark a spot on the tire, and roll it on the concrete, and measure. This will be your measured circumference, as well as your calculated (negleting minor tire wear).
This situation is exaggerated with larger tires, like on my truck, a 2500HD with 285/75/16 tires. There is a very noticeable decrease in total tire height from the 'compression' effect, as you call it, but the rolling circumference is the same as the calculated, and it corresponds to the indicated speed on the speedometer. I have checked this, time and time again, with my various programmers, Diablosport, Bulldog and HPTuners, and verified it with my GPS, which is insanely accurate on MPH readout.
Race Director
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How about this, if you still can't understand, even though I've outlined it clearly, and given you everything you need to understand the dynamics involved, try this:
Drive down the interstate at a fixed speed, and apply a braking force (your brakes). Do what you have to do to maintain speed. Note your rpms's. The rpm will change with brakes on vs. off, for the same speeds. I'm not saying it will be a difference of 500 or 1000, but the difference will be evident. It will be the additional engine load required to provide the horsepower to overcome the brakes.
Drive down the interstate at a fixed speed, and apply a braking force (your brakes). Do what you have to do to maintain speed. Note your rpms's. The rpm will change with brakes on vs. off, for the same speeds. I'm not saying it will be a difference of 500 or 1000, but the difference will be evident. It will be the additional engine load required to provide the horsepower to overcome the brakes.
Burning Brakes
Joined: Oct 2001
Posts: 983
Likes: 23
From: Northeast Ohio
The amount of throttle required to make the proper amount of power to maintain exactly that rpm will change, you adjust the load with the throttle not the rpm.
As for the tires again, if you take a tape measure and measure the circumference by wrapping the tape around the tire, then put the tire on your truck, and mark how far 1 exact rotation moves, you'll see the truck moved less that the circumference you measured, you can see the same effect by measuring the distance of 1 rotation with the tire at say 40 psi vs 20 psi.
If you don't believe that, you wasted your Dad's money on your BSME.
Race Director
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At 60 mph, in a manual transmission car, the rpm if you maintain exactly 60 mph, will not change, going up hill, down hill, into the wind towing a trailer or not, it will be exactly the same if the mph is exactly the same.
The amount of throttle required to make the proper amount of power to maintain exactly that rpm will change, you adjust the load with the throttle not the rpm.
As for the tires again, if you take a tape measure and measure the circumference by wrapping the tape around the tire, then put the tire on your truck, and mark how far 1 exact rotation moves, you'll see the truck moved less that the circumference you measured, you can see the same effect by measuring the distance of 1 rotation with the tire at say 40 psi vs 20 psi.
If you don't believe that, you wasted your Dad's money on your BSME.
The amount of throttle required to make the proper amount of power to maintain exactly that rpm will change, you adjust the load with the throttle not the rpm.
As for the tires again, if you take a tape measure and measure the circumference by wrapping the tape around the tire, then put the tire on your truck, and mark how far 1 exact rotation moves, you'll see the truck moved less that the circumference you measured, you can see the same effect by measuring the distance of 1 rotation with the tire at say 40 psi vs 20 psi.
If you don't believe that, you wasted your Dad's money on your BSME.
I paid my way through college with my own money, while living in my own house, and bought my vette with my own income as well. In fact, I more than doubled my dad's income in less than 5 years with my degree.
You are only showing your ignorance with repeatedly posting what you 'think' the rpm's vs. speed will be.
Check your speed calculator, like I schooled you to. You might learn something.
And, no, you won't notice the truck moves less than the measured circumference based on 'tire compression' or whatever it is you think.
Maybe you should stick with software consulting, and let the mechanical aptitude stuff to more qualified people.
And for your sake, I hope you are better at your software job than you are at your 'internet engineering and mechanical aptitude' knowledge.
Last edited by 2000BSME; Jan 8, 2008 at 03:59 PM.
Burning Brakes
Joined: Oct 2001
Posts: 983
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From: Northeast Ohio
THanks.
I paid my way through college with my own money, while living in my own house, and bought my vette with my own income as well. In fact, I more than doubled my dad's income in less than 5 years with my degree.
You are only showing your ignorance with repeatedly posting what you 'think' the rpm's vs. speed will be.
Check your speed calculator, like I schooled you to. You might learn something.
And, no, you won't notice the truck moves less than the measured circumference based on 'tire compression' or whatever it is you think.
Maybe you should stick with software consulting, and let the mechanical aptitude stuff to more qualified people.
I paid my way through college with my own money, while living in my own house, and bought my vette with my own income as well. In fact, I more than doubled my dad's income in less than 5 years with my degree.
You are only showing your ignorance with repeatedly posting what you 'think' the rpm's vs. speed will be.
Check your speed calculator, like I schooled you to. You might learn something.
And, no, you won't notice the truck moves less than the measured circumference based on 'tire compression' or whatever it is you think.
Maybe you should stick with software consulting, and let the mechanical aptitude stuff to more qualified people.
Exactly what school did you go to?
Race Director
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I'm pretty sure I outlined the school above. You probably missed it because you've been so intent on stating your 'opinion'. RIF.
Race Director
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Did you even get an education?
Burning Brakes
Joined: Oct 2001
Posts: 983
Likes: 23
From: Northeast Ohio
It doesn't matter if it changes or not, it's incorrect, period. It doesn't take into account loads, friction, aerodynamics, etc. It was an examply to you and anyone else who doesn't understand the concepts of engine load.
I'm pretty sure I outlined the school above. You probably missed it because you've been so intent on stating your 'opinion'. RIF.
I'm pretty sure I outlined the school above. You probably missed it because you've been so intent on stating your 'opinion'. RIF.
If you adjust the throttle to maintain the exact same rpm regardless of load, the mph will stay the same.
But here's a link to a Engineering Site talking about tire growth and it's effect on mph at a fixed rpm.
Just to save you from getting confused, I quoted the more important part:
In the Really fast sportsman classes and pro's, tire growth becomes a large factor in varying the final (effective) gear ratio to load the engine past the 330' mark. This can have a huge effect on the amount of fuel a car can burn and in effect make large changes in ET (large meaning .05 to .10 sec in extream cases). An example of this is, we went from a 33" to a 34.5' tall tire, the full growth circumferance was about 13% larger compared to the 4.5% dia differance at rest. This made a large change to the whole system and loading on the engine.
Last edited by QKSLVRZ; Jan 8, 2008 at 04:17 PM.
Race Director
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Are you really this dense? Or did you get that degree out of a CrackerJacks Box?
If you adjust the throttle to maintain the exact same rpm regardless of load, the mph will stay the same.
But here's a link to a Engineering Site talking about tire growth and it's effect on mph at a fixed rpm.
If you adjust the throttle to maintain the exact same rpm regardless of load, the mph will stay the same.
But here's a link to a Engineering Site talking about tire growth and it's effect on mph at a fixed rpm.
Now you're trying to mix a drag tire with a fixed wall radial for tire growth comparison? Tires don't 'grow' on street cars. The circumference remains constant.
Like I asked before, do you even have an education?
Didn't think so.