My 88S4 after the 2.54 rogerbox install..
12-31-2011, 03:55 PM
#17
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others wont want that kind of voodoo lesson 
according to Newton, who i do trust and can validate, gearing doesnt make HP.
remember:
acceleration=power / (mass x velocity)
HUGE difference = SLOWER speed
yes, same car, but slower in each gear.
having pushed the 84 gear box to the limits on the track, and having driven the exact same car with a 2.75, and then back again to a 2.2 as scot has done with his 300rwhp his times didnt improve, but he was less busy at laguna. BUT, a little more optimal for thunderhill.
However, gearing changes like this , on the street, can make it feel different, certainly, because the numerical (1st -5th) gears you are using are all at lower speeds. acceleration over all is not effected over all, because that is specifically determined by the speed ranges you are operating in.
in other words , do you want to "feel better" in 2nd, or do you want to accleraterate faster from 50 to 80mph.
so, if it feels better driving around a lower geared car, great, enjoy it.
dont think that you bought any performance though , over all, because i can EASILY PROVE for every gain you think you get, you have a loss somewhere else.
the only way you can take better advantae of the available HP , which is not arguable as the only way to accelerate better, is to get closer gear ratios, which a higher ratio rear end doesnt give you.
sorry, i had to chime in and set the record straight.
according to Newton, who i do trust and can validate, gearing doesnt make HP.
remember:
acceleration=power / (mass x velocity)
HUGE difference = SLOWER speed
having pushed the 84 gear box to the limits on the track, and having driven the exact same car with a 2.75, and then back again to a 2.2 as scot has done with his 300rwhp his times didnt improve, but he was less busy at laguna. BUT, a little more optimal for thunderhill.
However, gearing changes like this , on the street, can make it feel different, certainly, because the numerical (1st -5th) gears you are using are all at lower speeds. acceleration over all is not effected over all, because that is specifically determined by the speed ranges you are operating in.
in other words , do you want to "feel better" in 2nd, or do you want to accleraterate faster from 50 to 80mph.
so, if it feels better driving around a lower geared car, great, enjoy it.
dont think that you bought any performance though , over all, because i can EASILY PROVE for every gain you think you get, you have a loss somewhere else.
the only way you can take better advantae of the available HP , which is not arguable as the only way to accelerate better, is to get closer gear ratios, which a higher ratio rear end doesnt give you.
sorry, i had to chime in and set the record straight.
12-31-2011, 03:55 PM
#18
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My near stock 87 accelerates better and has a higher top speed with the 2:73 than it did with a 2:20. (pure best guess on the top speed, never going to try that one)
But you are going to be in for a very long thread if you try to convince Mark of that, I sure am not going to try to.
But you are going to be in for a very long thread if you try to convince Mark of that, I sure am not going to try to.
12-31-2011, 04:57 PM
#19
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I don't know jack**** about hp and don't care. Torque neither. Hung up the engineering degree long ago when I figured out my colleagues were theoretical optimization blowhards. Pert and Gant charting each other into mediocrity, missing the product objectives as they fought over the details of the process. There's more to life.
Like an 89 928 autobox (thanks kccampro) which has Speedtoys gearing, paired with an 84 16V car. Love it.
So does my daughter who's put 25,000 miles on it on the street and is signed up for her first DE this spring.
The gearing, combined with the 89's shiftpoint change over the 84 valve body (VB) transforms the 84 car. I have 86 4spd, 85 4spd and 84 Euro 5 speed, and drove all of them today. Hers, all-in at sub $5000, is the best.
So I understand what Speedtoys sees.
Like an 89 928 autobox (thanks kccampro) which has Speedtoys gearing, paired with an 84 16V car. Love it.
So does my daughter who's put 25,000 miles on it on the street and is signed up for her first DE this spring.
The gearing, combined with the 89's shiftpoint change over the 84 valve body (VB) transforms the 84 car. I have 86 4spd, 85 4spd and 84 Euro 5 speed, and drove all of them today. Hers, all-in at sub $5000, is the best.
So I understand what Speedtoys sees.
12-31-2011, 05:31 PM
#20
Rennlist Member
I drove my buddies 90 S4 as well as a GT, several times.....for everyday street driving both versions are better then the stock 2:20 rear ratio and 87/88 gear ratios, by far.
Changes to both gearbox and diff gearing are difficult so a compromise is reached and the 2:20 was to decrease revs at higher speeds in attempt to conserve fuel in the mid eighties.
Now that we have ample we can consider 9 speed boxes with 2:80 rear ends........folks who live in locations with less than ample, we've lots for sale
Changes to both gearbox and diff gearing are difficult so a compromise is reached and the 2:20 was to decrease revs at higher speeds in attempt to conserve fuel in the mid eighties.
Now that we have ample we can consider 9 speed boxes with 2:80 rear ends........folks who live in locations with less than ample, we've lots for sale
12-31-2011, 06:00 PM
#21
Rennlist Member
others wont want that kind of voodoo lesson
according to Newton, who i do trust and can validate, gearing doesnt make HP.
remember:
acceleration=power / (mass x velocity)
i am hoping you are not saying by quoting newton that gearing will not improve acceleration. If this is what you are saying, then you only understand part of that equation. While the equation of acceleration=power is correct, you fallaciously neglect the mechanical advantage of gearing. gearing provides a mechanical advantage multiplying force. this occurs the same way that a longer lever increases torque. the horsepower is the force applied to the lever, the legnth of the lever is the gearing....
HUGE difference = SLOWER speed
yes, same car, but slower in each gear.
having pushed the 84 gear box to the limits on the track, and having driven the exact same car with a 2.75, and then back again to a 2.2 as scot has done with his 300rwhp his times didnt improve, but he was less busy at laguna. BUT, a little more optimal for thunderhill.
However, gearing changes like this , on the street, can make it feel different, certainly, because the numerical (1st -5th) gears you are using are all at lower speeds. acceleration over all is not effected over all, because that is specifically determined by the speed ranges you are operating in.
in other words , do you want to "feel better" in 2nd, or do you want to accleraterate faster from 50 to 80mph.
so, if it feels better driving around a lower geared car, great, enjoy it.
dont think that you bought any performance though , over all, because i can EASILY PROVE for every gain you think you get, you have a loss somewhere else.
the only way you can take better advantae of the available HP , which is not arguable as the only way to accelerate better, is to get closer gear ratios, which a higher ratio rear end doesnt give you.
sorry, i had to chime in and set the record straight.
according to Newton, who i do trust and can validate, gearing doesnt make HP.
remember:
acceleration=power / (mass x velocity)
i am hoping you are not saying by quoting newton that gearing will not improve acceleration. If this is what you are saying, then you only understand part of that equation. While the equation of acceleration=power is correct, you fallaciously neglect the mechanical advantage of gearing. gearing provides a mechanical advantage multiplying force. this occurs the same way that a longer lever increases torque. the horsepower is the force applied to the lever, the legnth of the lever is the gearing....
HUGE difference = SLOWER speed
yes, same car, but slower in each gear.
having pushed the 84 gear box to the limits on the track, and having driven the exact same car with a 2.75, and then back again to a 2.2 as scot has done with his 300rwhp his times didnt improve, but he was less busy at laguna. BUT, a little more optimal for thunderhill.
However, gearing changes like this , on the street, can make it feel different, certainly, because the numerical (1st -5th) gears you are using are all at lower speeds. acceleration over all is not effected over all, because that is specifically determined by the speed ranges you are operating in.
in other words , do you want to "feel better" in 2nd, or do you want to accleraterate faster from 50 to 80mph.
so, if it feels better driving around a lower geared car, great, enjoy it.
dont think that you bought any performance though , over all, because i can EASILY PROVE for every gain you think you get, you have a loss somewhere else.
the only way you can take better advantae of the available HP , which is not arguable as the only way to accelerate better, is to get closer gear ratios, which a higher ratio rear end doesnt give you.
sorry, i had to chime in and set the record straight.
Assuming the tires can maintain traction and deliver the force to the road surface, gearing changes will dramatically affect the acceleration times... but as with all physics there is a trade off... top speed will be affected. Fuel economy will also be affected as you will be running a higher rpm at highway speeds. the energy that the motor produces can be delivered in different ways
remember that energy is neither created or lost, it merely changes forms, like converting to heat, etc...
your assumptions also are based on HP, which is a measure of work versus time. one horsepower is the energy required to lift 500 pounds one foot in one second. so there is a time, so there is a power componet, but also a time componet.
measuring torque or Nm, is a much more accurate way of measuring power delivery.
if gearing made no difference, then why do race teams change gearing for various tracks?
why do drag racers change their gearing for 1/8 and 1/4 mile tracks?
12-31-2011, 06:18 PM
#22
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The bottom line is that any 928 will accelerate better in every gear with a higher numerical rear end gear, IE 2:20 vs 2:73.
sorry to disagree mark, but you are very much mistaken on this fact... i minored in physics, so throw all the math you wish...i will be more than happy to show you where you are obviously misunderstanding the equations..
Assuming the tires can maintain traction and deliver the force to the road surface, gearing changes will dramatically affect the acceleration times... but as with all physics there is a trade off... top speed will be affected. Fuel economy will also be affected as you will be running a higher rpm at highway speeds. the energy that the motor produces can be delivered in different ways
remember that energy is neither created or lost, it merely changes forms, like converting to heat, etc...
your assumptions also are based on HP, which is a measure of work versus time. one horsepower is the energy required to lift 500 pounds one foot in one second. so there is a time, so there is a power componet, but also a time componet.
measuring torque or Nm, is a much more accurate way of measuring power delivery.
if gearing made no difference, then why do race teams change gearing for various tracks?
why do drag racers change their gearing for 1/8 and 1/4 mile tracks?
Assuming the tires can maintain traction and deliver the force to the road surface, gearing changes will dramatically affect the acceleration times... but as with all physics there is a trade off... top speed will be affected. Fuel economy will also be affected as you will be running a higher rpm at highway speeds. the energy that the motor produces can be delivered in different ways
remember that energy is neither created or lost, it merely changes forms, like converting to heat, etc...
your assumptions also are based on HP, which is a measure of work versus time. one horsepower is the energy required to lift 500 pounds one foot in one second. so there is a time, so there is a power componet, but also a time componet.
measuring torque or Nm, is a much more accurate way of measuring power delivery.
if gearing made no difference, then why do race teams change gearing for various tracks?
why do drag racers change their gearing for 1/8 and 1/4 mile tracks?
12-31-2011, 10:18 PM
#25
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Thread Starter
My near stock 87 accelerates better and has a higher top speed with the 2:73 than it did with a 2:20. (pure best guess on the top speed, never going to try that one)
But you are going to be in for a very long thread if you try to convince Mark of that, I sure am not going to try to.
But you are going to be in for a very long thread if you try to convince Mark of that, I sure am not going to try to.
12-31-2011, 11:59 PM
#27
Can't close off 2011 with out a good hp/tq/gear/turbo/sc/oil thread huh?
12-31-2011, 11:59 PM
#28
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Thread Starter
I dunno, im leaving it alone. SOMEONE is gonna prep a "race car" and hurt themselves in the Church Of Kibort, and with luck, they'll live to point out the thread they got the invaluable advice from.
As far as THIS thread is concerned..im OK with the laydude mixing the terms "faster" and "quicker" to describe a gearing change to their car.
All I know now..is that to pass someone on a road, I dont need to hang back and let the car wind up to the pass. It _happens_ in a much more compressed time envelope..it will force some re-learning of applying power in the friction circle for sure...no questions about this.
As far as THIS thread is concerned..im OK with the laydude mixing the terms "faster" and "quicker" to describe a gearing change to their car.
All I know now..is that to pass someone on a road, I dont need to hang back and let the car wind up to the pass. It _happens_ in a much more compressed time envelope..it will force some re-learning of applying power in the friction circle for sure...no questions about this.
01-01-2012, 12:10 AM
#29
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SHHHH, listen to Sean..................
I dunno, im leaving it alone. SOMEONE is gonna prep a "race car" and hurt themselves in the Church Of Kibort, and with luck, they'll live to point out the thread they got the invaluable advice from.
As far as THIS thread is concerned..im OK with the laydude mixing the terms "faster" and "quicker" to describe a gearing change to their car.
All I know now..is that to pass someone on a road, I dont need to hang back and let the car wind up to the pass. It _happens_ in a much more compressed time envelope..it will force some re-learning of applying power in the friction circle for sure...no questions about this.
As far as THIS thread is concerned..im OK with the laydude mixing the terms "faster" and "quicker" to describe a gearing change to their car.
All I know now..is that to pass someone on a road, I dont need to hang back and let the car wind up to the pass. It _happens_ in a much more compressed time envelope..it will force some re-learning of applying power in the friction circle for sure...no questions about this.
01-01-2012, 12:19 AM
#30
Rennlist Member
Thread Starter
That's weak.
It must also include surface -vs- core DC electrical transmission efficiency, and of course...porsche cam gear tooth design.
I propose, that this "Debate Ending Tool" will solve the problem.
Heck Yes.
It must also include surface -vs- core DC electrical transmission efficiency, and of course...porsche cam gear tooth design.
I propose, that this "Debate Ending Tool" will solve the problem.
Heck Yes.