Gear ratio discussion. Yet another 3.09 vs S4 2.2 comparison.
07-12-2009, 10:30 PM
#1
Rennlist Member
Thread Starter
Gear ratio discussion. Yet another 3.09 vs S4 2.2 comparison.
Guys, Glen was highjacking the other clutch thread, so I thought I would start one on its own. Glen has a great spreadsheet that calculates acceleration over time and distance in the same fashion that the website simulator did. But, its in excel and easy to work with . So, when you want to know what the effects of a change of a rear end, gear set , or tire diameter has on speed ranges and associated acceleration rates, this is your spreadsheet.
Now Glen was poking a jab at the gear ratio theme, but put out some actual values. I plugged in those values showing that I was not "cherry picking" my speed ranges, but just using the common ones I use at the track. the results were interesting. as I have always said, there are trade offs, for any speed range with gear ratios. (except, I will concede that the launch is debateable, and could work to the higher numerical ratio value. But, that depends on driver and grip , so lets just stay away from that. Lets start at 25 to 40mph and higher as that is where we spend most of our time on the street and racing around the track)
This is what I posted to Glen:
Here again I am posting the results of you own spread sheet, which I do like by the way. As expected, there is an even greater diff from 0-25 or 0-40mph that can be take off for road racing. (.25 to .6 seconds) Your condecention has reached new levels. Im trying to explain the effects of gearing and acceleration and you, ironically, find isolated instances where you are right. Overall, this is misleading and wrong. You find an infinite set of speed ranges and Ill show no gains at all for any rear end gear set up, becuase gears dont make HP! The simulator is a great way to prove this. Im just wondering why are numbers are not matching up.
By the way, where did you get 2 seconds??? plus why didnt the values I have with your spreadsheet match what I got. I changed nothing but the 3.09 where the 2.75 was and then did it for the S4 2.2.
3 seconds for the 2.2 vs the 2.75, and 3.09's 2.39/2.7second advantage. (roughly .3 to .6 second diff) . Now, take that off for road racing comparisons below.
speeds for the 2.2:1 S4 gear box, vs *( 3.09 / 2.75 on glens car)
0-100mph 11.46sec for the 2.2 ( 11.13 / 11.53 for the 3.09/2.75)
0-118mph 16.49sec for the 2.2 ( 16.19/15.86)
0-130mph 20.49sec for the 2.2 ( 20.33/20.86)
0-140mph 25.00sec for the 2.2 (24.76/25.69)
so, remove the launch tmes to 25 or 40mph ( .25 to .6 seconds depending on the other gear box or 25mph or 40mph starting speeds) and look what you got! (the 3.09 is .45 seconds faster 0-25, and .61 seconds faster 0-40mph) The 2.2 is better than all of the gear at all the above speeds, except the 2.75 at 118mph. (probably due to a gear shift... yes, just confirmed, you have the 2.2 shifting at 106mph with your car and tire size)
It is clear to see above that if you take off the start launch time diffs of .3 to .6 seconds (2.75/3.09 respectively) you can see that the 2.2 is more optimum for these speed ranges. Kind of a departuure from what you are claiming to be an advange in racing by just going up in gear box final drive ratio. It proves my point of speed ranges and ratio mixes being optimized for one another and one is not nessesarily better for all speed ranges. Again, I didnt cherry pick the speeds, I used ones that I frequent at the track. As a racer, this is the stuff you NEED to look at to optimize you set up.
There you have it glen. depending on the speed range you frequent, all sorts of gear boxes will allow for best acceleration. Again, it depends!
Quote:
Originally Posted by GlenL
The simple fact is that my understanding is beyond yours but you're determined to not be taught. And your little jabs irritate me.
But I'll try one anyways...
I modeled my Euro using both a 2.2 and a 3.09 rear end. (This would be with the BenchRace.xls I wrote that you jerkily implied was "not professional" without the barest understanding of how it works or that I am a professional.) Running from 5 to 140 mph the 3.09 car takes 25.26 seconds while the 2.2 car takes 27.33 seconds. Just over 2 seconds faster for the shorter gears.
Now I could, being a professional, create an analysis for all 10000+ increments between 1 and 140 mph. (2 to 140, 7 to 25, all of them) and show which rear end provided the best acceleration at each increment, which had the most "won" increments, what the total advantage was, etc. But you'd just deny the value of the data and instead continue to cherry pick and ignore.
I really just threw this topic in as a follow-on to other people's frustration on your intransigence in technical discussions. Here's some friendly advice: learn to write from the perspective of your intended audience and also proofread. The lecture in your head is from and to someone who already believes your position and consequently won't convince or educate a non-believer.
Now Glen was poking a jab at the gear ratio theme, but put out some actual values. I plugged in those values showing that I was not "cherry picking" my speed ranges, but just using the common ones I use at the track. the results were interesting. as I have always said, there are trade offs, for any speed range with gear ratios. (except, I will concede that the launch is debateable, and could work to the higher numerical ratio value. But, that depends on driver and grip , so lets just stay away from that. Lets start at 25 to 40mph and higher as that is where we spend most of our time on the street and racing around the track)
This is what I posted to Glen:
Here again I am posting the results of you own spread sheet, which I do like by the way. As expected, there is an even greater diff from 0-25 or 0-40mph that can be take off for road racing. (.25 to .6 seconds) Your condecention has reached new levels. Im trying to explain the effects of gearing and acceleration and you, ironically, find isolated instances where you are right. Overall, this is misleading and wrong. You find an infinite set of speed ranges and Ill show no gains at all for any rear end gear set up, becuase gears dont make HP! The simulator is a great way to prove this. Im just wondering why are numbers are not matching up.
By the way, where did you get 2 seconds??? plus why didnt the values I have with your spreadsheet match what I got. I changed nothing but the 3.09 where the 2.75 was and then did it for the S4 2.2.
3 seconds for the 2.2 vs the 2.75, and 3.09's 2.39/2.7second advantage. (roughly .3 to .6 second diff) . Now, take that off for road racing comparisons below.
speeds for the 2.2:1 S4 gear box, vs *( 3.09 / 2.75 on glens car)
0-100mph 11.46sec for the 2.2 ( 11.13 / 11.53 for the 3.09/2.75)
0-118mph 16.49sec for the 2.2 ( 16.19/15.86)
0-130mph 20.49sec for the 2.2 ( 20.33/20.86)
0-140mph 25.00sec for the 2.2 (24.76/25.69)
so, remove the launch tmes to 25 or 40mph ( .25 to .6 seconds depending on the other gear box or 25mph or 40mph starting speeds) and look what you got! (the 3.09 is .45 seconds faster 0-25, and .61 seconds faster 0-40mph) The 2.2 is better than all of the gear at all the above speeds, except the 2.75 at 118mph. (probably due to a gear shift... yes, just confirmed, you have the 2.2 shifting at 106mph with your car and tire size)
It is clear to see above that if you take off the start launch time diffs of .3 to .6 seconds (2.75/3.09 respectively) you can see that the 2.2 is more optimum for these speed ranges. Kind of a departuure from what you are claiming to be an advange in racing by just going up in gear box final drive ratio. It proves my point of speed ranges and ratio mixes being optimized for one another and one is not nessesarily better for all speed ranges. Again, I didnt cherry pick the speeds, I used ones that I frequent at the track. As a racer, this is the stuff you NEED to look at to optimize you set up.
There you have it glen. depending on the speed range you frequent, all sorts of gear boxes will allow for best acceleration. Again, it depends!
Quote:
Originally Posted by GlenL
The simple fact is that my understanding is beyond yours but you're determined to not be taught. And your little jabs irritate me.
But I'll try one anyways...
I modeled my Euro using both a 2.2 and a 3.09 rear end. (This would be with the BenchRace.xls I wrote that you jerkily implied was "not professional" without the barest understanding of how it works or that I am a professional.) Running from 5 to 140 mph the 3.09 car takes 25.26 seconds while the 2.2 car takes 27.33 seconds. Just over 2 seconds faster for the shorter gears.
Now I could, being a professional, create an analysis for all 10000+ increments between 1 and 140 mph. (2 to 140, 7 to 25, all of them) and show which rear end provided the best acceleration at each increment, which had the most "won" increments, what the total advantage was, etc. But you'd just deny the value of the data and instead continue to cherry pick and ignore.
I really just threw this topic in as a follow-on to other people's frustration on your intransigence in technical discussions. Here's some friendly advice: learn to write from the perspective of your intended audience and also proofread. The lecture in your head is from and to someone who already believes your position and consequently won't convince or educate a non-believer.
07-12-2009, 10:43 PM
#2
Not the sharpest tool in the shed
Rennlist Member
Rennlist Member
Glen has a great spreadsheet that calculates acceleration over time and distance....
07-13-2009, 01:56 AM
#5
Rennlist Member
Thread Starter
generally, most all euros of the OBs, were 2.75s, in the US, most after 82 were 2.22 and then 2.2 with the S4. there are 2.64, 2.54, 2.72s with the GTS. there are all sorts of options for the different years and models. However, Its not just the rear end ratio that is different, its the entire gear box indiv. gears
I think someone had a chart on a thread.
mk
I think someone had a chart on a thread.
mk
07-13-2009, 02:26 AM
#6
Race Director
Everyone knows that the ultra rare 2.64 is by far the best rear end ratio out there.....its the strongest, accelerates the best and has the highest top speed too :>)
