Wheel weight and Performance??
09-18-2010, 02:51 PM
#16
Rennlist Member
Hey, sorry Ive hurt your feelings, but you run the risk of that when you post outragious claims, that expecially are unsubstantiated. You are making it very easy to correct you or raise questions of your experience and results. There is NO ONE In the racing world that would agree with you that a 5lb wheels change results in a 3 second lap time difference, nor is there ANY physics that would support it. if you have a clue, aside from just name calling, show it here besides giving further clue that you dont.
Sheez. Im not going to sit by and listen to this advice that someone might take serously, so that they spend $1000 on new rims expecting a similar result.
(by the way, i have done a very controlled test of adding and subtracting 200lbs of balast, and it was right around 1 second a lap on a very turney course)
you have no video, no data, nothing. and you are autox'ing where you get 1 min of track time, maybe 3-4 times in a day! A while back, here was someone that posted their telemetry for a similar performance difference claim, which I studied for him. He thought that his 17s vs his 18s caused a 1 second a lap difference, and 10mph stronger straight line speed. in the end, it was due to slightly different driving style, proved by faster exit speeds, earlier throtttle application and later braking points . It had NOTHING to do with diameter changes, or lighter weels, as proved by the acceleration times at matched speed range.
Now, putting the dukes down, you said you did a back to back comparison of pulling 100lbs out of the car and it wasnt as effective as you wheel change? what was weight saving on the wheel change, 5 lbs? thats 20lbs x 1.5 = 30lbs as its effect as if it was in the car as far as acceleration. because of the gyroscopic effects and damping reqired for the difference, on an AutoX, it would have been such of a factor, compared to running on a track with a lot of high speed transitions. (i.e. Sears point, or "S"s at a road course near you.)
why do you think it caused a 3 second a lap time change??
just ask'n
Mark
BTW: Edit: Here is an idea. Start video taping, or using telemetry of some kind and then you will be able to have a better ability to review and assess differences in lap times, rather than thinking that sprinkling magic dust is the cause of the changes. Its hard to read and doesnt help anyone here.
Sheez. Im not going to sit by and listen to this advice that someone might take serously, so that they spend $1000 on new rims expecting a similar result.
(by the way, i have done a very controlled test of adding and subtracting 200lbs of balast, and it was right around 1 second a lap on a very turney course)
you have no video, no data, nothing. and you are autox'ing where you get 1 min of track time, maybe 3-4 times in a day! A while back, here was someone that posted their telemetry for a similar performance difference claim, which I studied for him. He thought that his 17s vs his 18s caused a 1 second a lap difference, and 10mph stronger straight line speed. in the end, it was due to slightly different driving style, proved by faster exit speeds, earlier throtttle application and later braking points . It had NOTHING to do with diameter changes, or lighter weels, as proved by the acceleration times at matched speed range.
Now, putting the dukes down, you said you did a back to back comparison of pulling 100lbs out of the car and it wasnt as effective as you wheel change? what was weight saving on the wheel change, 5 lbs? thats 20lbs x 1.5 = 30lbs as its effect as if it was in the car as far as acceleration. because of the gyroscopic effects and damping reqired for the difference, on an AutoX, it would have been such of a factor, compared to running on a track with a lot of high speed transitions. (i.e. Sears point, or "S"s at a road course near you.)
why do you think it caused a 3 second a lap time change??
just ask'n
Mark
BTW: Edit: Here is an idea. Start video taping, or using telemetry of some kind and then you will be able to have a better ability to review and assess differences in lap times, rather than thinking that sprinkling magic dust is the cause of the changes. Its hard to read and doesnt help anyone here.
Nope, sorry Mark, won't stop posting my real world experiences no matter how silly or "amateur" you think those experiences may be. And I think you are an ******* for calling my experiences silly and not "real" and am personally offended. I did state there is a difference in our race courses and the typical track, say maybe a lot more lower gear acceleration. So, Bite Me *** Hole.
And by the way, removing 100 lbs, by taking out interior bits, did not measurably decrease lap times in that same Boxster S before the wheel change.
And by the way, removing 100 lbs, by taking out interior bits, did not measurably decrease lap times in that same Boxster S before the wheel change.
Last edited by mark kibort; 09-18-2010 at 03:43 PM.
09-18-2010, 03:46 PM
#17
Intermediate
Join Date: Aug 2010
Location: Elmira Ont. Canada
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Last year at a DE day at Mosport my friend with a Saleen Mustang swaped his stock 20" wheels with street rubber for a set of standard 18" Mustange GT rims with BF Gooodridge R1 dot slicks. His times went from mid 140's to high 130's. Obviously a lot of the gain came from the dot slicks but I also think a good chunk of the gain came from the smaller and lighter 18" wheels. Never the less my friend chopped over 5 seconds off his lap times that day with the wheel change and that is huge. So for sure big gains can be found in the wheel and tire area. On a side note, I have a 2008 FX2 F-150 Sport truck that came stock with 20" wheels and I can say without a doubt that 20" wheels on a pickup truck, suck big time.
09-18-2010, 03:49 PM
#18
Rennlist Member
I have no recorded data and am not a "real" racer because I autocross instead of track so, I am sure you will discount anything I have to say. But just to prove you are narrow minded...
My experience is on an autocross track with mostly 1st and 2nd gear acceleration and turns, at least 1 60mph slalom and chicanes to keep speeds below 100 on straights. FTD lap times are around 70 seconds...and I've done this with 5 different cars for over 10 years and I typically set FTD if not overall then for street tires and have been setting FTD since my 3rd year and learning what was important to car setup.
Adding and removing sprung weight up to 250 lbs made no difference in overall lap times of around 70 seconds. I noticed that with more weight the top speeds were lower but corner apex 4 wheel drift speeds were higher. With less weight top speeds were higher but corner speeds were lower. I found this by removing seats, carpets, etc. to remove weight and adding passengers to increase weight. I initially discovered this because someone left the timers on and noticed I was matching my FTDs during the fun runs after the event while carrying passengers. That got me to adding and removing weight to see if there was a difference in my lap times. I am NOT saying significant weight reduction or increase will not make a big difference, but on our course 200# either way did not make any difference in overall lap time. After that I quit removing my spare tire and toolkit for an event.
After putting on the heavier wheels with same street tires I had been running I noticed my lap times were significantly slower. Where I was competing for overall FTD including those running on Racing Compound tires I was then only able to get FTD for those running street tires. The added weight of the heavier rims decreased the acceleration but did not add enough weight to increase corner 4 wheel drift speeds enough to compensate, hence the higher lap times with heavier wheels.
Race Compound tires versus Street tires in and autocross environment is typically 3 to 5 seconds difference.
And again, first and second gear acceleration and turns, not 3rd.
Disclaimer:
I am not a "real" racer (according to Mark) and have never stayed in a Holiday Inn Express.
My experience is on an autocross track with mostly 1st and 2nd gear acceleration and turns, at least 1 60mph slalom and chicanes to keep speeds below 100 on straights. FTD lap times are around 70 seconds...and I've done this with 5 different cars for over 10 years and I typically set FTD if not overall then for street tires and have been setting FTD since my 3rd year and learning what was important to car setup.
Adding and removing sprung weight up to 250 lbs made no difference in overall lap times of around 70 seconds. I noticed that with more weight the top speeds were lower but corner apex 4 wheel drift speeds were higher. With less weight top speeds were higher but corner speeds were lower. I found this by removing seats, carpets, etc. to remove weight and adding passengers to increase weight. I initially discovered this because someone left the timers on and noticed I was matching my FTDs during the fun runs after the event while carrying passengers. That got me to adding and removing weight to see if there was a difference in my lap times. I am NOT saying significant weight reduction or increase will not make a big difference, but on our course 200# either way did not make any difference in overall lap time. After that I quit removing my spare tire and toolkit for an event.
After putting on the heavier wheels with same street tires I had been running I noticed my lap times were significantly slower. Where I was competing for overall FTD including those running on Racing Compound tires I was then only able to get FTD for those running street tires. The added weight of the heavier rims decreased the acceleration but did not add enough weight to increase corner 4 wheel drift speeds enough to compensate, hence the higher lap times with heavier wheels.
Race Compound tires versus Street tires in and autocross environment is typically 3 to 5 seconds difference.
And again, first and second gear acceleration and turns, not 3rd.
Disclaimer:
I am not a "real" racer (according to Mark) and have never stayed in a Holiday Inn Express.
Last edited by RKD in OKC; 09-18-2010 at 04:06 PM.
09-18-2010, 04:29 PM
#19
Rennlist Member
Are you not paying attention? a 1:30 time is a good time for a car like mine on street tires. This "guy", went from 20s, with no side wall, street rubber, hard as rock, to a 18" DOT race rubber? Yeah, you had me at " A lot was gained from the DOT rubber". Why dig yourself in a hole of BS?? no, the lighter weight wheels had NOTHING to do with it. in fact here is usually a trade off of sorts with changing diameter with the metal vs the rubber parts. my 17s and 18s with the same diameter and width tire, weigh near the same and for good reason. I chopped 10 seconds off my lap time at Road america over the day and I went to, what turned out to be slower wheels and tires. The guy was in a DE. DE times are always suspect, and never really credible. not the times, as those can be captured from all sorts of methods, but by technique, experience -learning curve, and conditions. by the way, 4-5 seconds is a standard for going from decent street rubber to decent brand of DOTs.
On a Professional level, thats what we all saw, without exception.
as far as the truck, what do you mean? i did the same for my tahoe! 16s to 20s!! 75 llbs to near 100lbs per tire and wheel. I noticed nothing. But then again ,what would you look for? better acceleration??
what i did notice was much less sidewall flex and better handling at the expense of a stiffer, more bumpy ride.
On a Professional level, thats what we all saw, without exception.
as far as the truck, what do you mean? i did the same for my tahoe! 16s to 20s!! 75 llbs to near 100lbs per tire and wheel. I noticed nothing. But then again ,what would you look for? better acceleration??
what i did notice was much less sidewall flex and better handling at the expense of a stiffer, more bumpy ride.Last year at a DE day at Mosport my friend with a Saleen Mustang swaped his stock 20" wheels with street rubber for a set of standard 18" Mustange GT rims with BF Gooodridge R1 dot slicks. His times went from mid 140's to high 130's. Obviously a lot of the gain came from the dot slicks but I also think a good chunk of the gain came from the smaller and lighter 18" wheels. Never the less my friend chopped over 5 seconds off his lap times that day with the wheel change and that is huge. So for sure big gains can be found in the wheel and tire area. On a side note, I have a 2008 FX2 F-150 Sport truck that came stock with 20" wheels and I can say without a doubt that 20" wheels on a pickup truck, suck big time.
09-18-2010, 04:44 PM
#20
Rennlist Member
If you have no recorded data, and the quantity of the date is minimal at best, its really hard to make an intellegent assesment to what your results mean.
this is based on the difference of what you do on an autocross, vs what happens on a "real" race track. a lot of good autocrossers can make good "real" race track drivers, but it ususally takes some time. many have gone this route before, but its not required. Im sure its fun, teaches low speed car control, and certainly is a form of racing. however, you are severly limited on track time and, consistancy of the course year over year.
now, during your 3 runs that day, you had the ability to notice and mark straight line speeds and corner speeds, without video and data? Now that is a remarkable feat. Im sorry, there is a few short fractions of a second where I can look down and notice things like that. usually, top speed and after exit speeds I do note. But this is on a very fast circuit like Laguna.
Now, some physics . addiing weight doesnt give you better cornering speed.
FACT I dont care what you saw.
Now, you think you notice the acceleration differences of 5lb per wheel?? Com'mon! there is nothing behind that to make any sence at all. 5lb per wheel as far as acceleration is a KNOWN, 30lbs as if it was in the car, and that is about 3hp. 3 hp is a normal variance on a dyno run. your car will vary that much each lap, and at any other time in a day. you are really reaching if you think the rims are doing any of this. IF you are serious, just mount a camera, so we ALL can see shift points. (or get a cheap data aqcuisition system) I do. its easy to see and matches up perfectly with data aquasition. By the way, when I added ONLY 60hp to my car and that was the ONLY change, I gained about 1 second. it was on acceleration. you could clearly see how much further I got in each gear down the race track for the same redline shift. about 200ft further on my 3rd gear shift . Those are the type of things you can look at to prove any acceleration difference. Im sorry, AutoX is a poor place to really quantify any changes based on feel and memory.
Mark
this is based on the difference of what you do on an autocross, vs what happens on a "real" race track. a lot of good autocrossers can make good "real" race track drivers, but it ususally takes some time. many have gone this route before, but its not required. Im sure its fun, teaches low speed car control, and certainly is a form of racing. however, you are severly limited on track time and, consistancy of the course year over year.
now, during your 3 runs that day, you had the ability to notice and mark straight line speeds and corner speeds, without video and data? Now that is a remarkable feat. Im sorry, there is a few short fractions of a second where I can look down and notice things like that. usually, top speed and after exit speeds I do note. But this is on a very fast circuit like Laguna.
Now, some physics . addiing weight doesnt give you better cornering speed.
FACT I dont care what you saw.
Now, you think you notice the acceleration differences of 5lb per wheel?? Com'mon! there is nothing behind that to make any sence at all. 5lb per wheel as far as acceleration is a KNOWN, 30lbs as if it was in the car, and that is about 3hp. 3 hp is a normal variance on a dyno run. your car will vary that much each lap, and at any other time in a day. you are really reaching if you think the rims are doing any of this. IF you are serious, just mount a camera, so we ALL can see shift points. (or get a cheap data aqcuisition system) I do. its easy to see and matches up perfectly with data aquasition. By the way, when I added ONLY 60hp to my car and that was the ONLY change, I gained about 1 second. it was on acceleration. you could clearly see how much further I got in each gear down the race track for the same redline shift. about 200ft further on my 3rd gear shift . Those are the type of things you can look at to prove any acceleration difference. Im sorry, AutoX is a poor place to really quantify any changes based on feel and memory.
Mark
I have no recorded data and am not a "real" racer because I autocross instead of track so, I am sure you will discount anything I have to say. But just to prove you are narrow minded...
My experience is on an autocross track with mostly 1st and 2nd gear acceleration and turns, at least 1 60mph slalom and chicanes to keep speeds below 100 on straights. FTD lap times are around 70 seconds...and I've done this with 5 different cars for over 10 years and I typically set FTD if not overall then for street tires and have been setting FTD since my 3rd year and learning what was important to car setup.
Adding and removing sprung weight up to 250 lbs made no difference in overall lap times of around 70 seconds. I noticed that with more weight the top speeds were lower but corner apex 4 wheel drift speeds were higher. With less weight top speeds were higher but corner speeds were lower. I found this by removing seats, carpets, etc. to remove weight and adding passengers to increase weight. I initially discovered this because someone left the timers on and noticed I was matching my FTDs during the fun runs after the event while carrying passengers. That got me to adding and removing weight to see if there was a difference in my lap times. I am NOT saying significant weight reduction or increase will not make a big difference, but on our course 200# either way did not make any difference in overall lap time. After that I quit removing my spare tire and toolkit for an event.
After putting on the heavier wheels with same street tires I had been running I noticed my lap times were significantly slower. Where I was competing for overall FTD including those running on Racing Compound tires I was then only able to get FTD for those running street tires. The added weight of the heavier rims decreased the acceleration but did not add enough weight to increase corner 4 wheel drift speeds enough to compensate, hence the higher lap times with heavier wheels.
Race Compound tires versus Street tires in and autocross environment is typically 3 to 5 seconds difference.
And again, first and second gear acceleration and turns, not 3rd.
Disclaimer:
I am not a "real" racer (according to Mark) and have never stayed in a Holiday Inn Express.
My experience is on an autocross track with mostly 1st and 2nd gear acceleration and turns, at least 1 60mph slalom and chicanes to keep speeds below 100 on straights. FTD lap times are around 70 seconds...and I've done this with 5 different cars for over 10 years and I typically set FTD if not overall then for street tires and have been setting FTD since my 3rd year and learning what was important to car setup.
Adding and removing sprung weight up to 250 lbs made no difference in overall lap times of around 70 seconds. I noticed that with more weight the top speeds were lower but corner apex 4 wheel drift speeds were higher. With less weight top speeds were higher but corner speeds were lower. I found this by removing seats, carpets, etc. to remove weight and adding passengers to increase weight. I initially discovered this because someone left the timers on and noticed I was matching my FTDs during the fun runs after the event while carrying passengers. That got me to adding and removing weight to see if there was a difference in my lap times. I am NOT saying significant weight reduction or increase will not make a big difference, but on our course 200# either way did not make any difference in overall lap time. After that I quit removing my spare tire and toolkit for an event.
After putting on the heavier wheels with same street tires I had been running I noticed my lap times were significantly slower. Where I was competing for overall FTD including those running on Racing Compound tires I was then only able to get FTD for those running street tires. The added weight of the heavier rims decreased the acceleration but did not add enough weight to increase corner 4 wheel drift speeds enough to compensate, hence the higher lap times with heavier wheels.
Race Compound tires versus Street tires in and autocross environment is typically 3 to 5 seconds difference.
And again, first and second gear acceleration and turns, not 3rd.
Disclaimer:
I am not a "real" racer (according to Mark) and have never stayed in a Holiday Inn Express.
09-18-2010, 06:17 PM
#21
Rennlist Member
From my previous post...
"I am sure you will discount anything I have to say. But just to prove you are narrow minded..."
Proof made and confirmed.
Your narrow mined opinion of autocross drivers is that they aren't "real" drivers and can't be either fast or consistent because they don't spend hours and hours droning around the same track with all kinds of data logging, analyzing every shift point, brake zone, turn-in, corner G, and corner exit. So, therefore their observations are not valid or useful. Obviously, you should keep those blinders on and ignore my posts.
For the benefit of everyone but Mark...I am a VERY consistent driver with a keen feel for my car and setup. It is my observations and the resulting setup changes that has taken every car I've competed with from middle of the pack or worse to FTD. At our events we do 2 sessions of 4 laps each and the difference between my slowest lap and FTD lap is only 2 seconds. That is very consistent.
And I do know something about the difference between autocross and track. I've done a few track days on R compounds with my autocross car and matched laps with the fastest more experience driver/cars there despite my lack of lap after lap after lap of track experience and data analysis. To be honest I found track driving rather boring. Sure, the speeds are faster making the handling dynamics a little different, but driver input is slower, more leisurely, and things like line and driver input timing have less effect on lap times compared to autocross.
Just because I don't enjoy pounding around the track all day doesn't mean I am going dis those that do enjoy it or their experiences, to each their own. I could say that because trackies aren't able to be consistent and/or tell differences in setup without data acquisition and hours of seat time, then they are obviously slow learners, aren't driving their car at the limits, and don't know what they are talking about. But I won't because I'm not a narrow minded *******.
Do what everyone else does and you will merely be competitive. Do what makes you faster and you will win.
If everyone else hangs a bag of manure on their bumper and says it makes them faster, would you?
Strive to be consistent not fast. By being consistent you will know the effect of any changes you make so you can keep only the changes that make you faster.
"I am sure you will discount anything I have to say. But just to prove you are narrow minded..."
Proof made and confirmed.
Your narrow mined opinion of autocross drivers is that they aren't "real" drivers and can't be either fast or consistent because they don't spend hours and hours droning around the same track with all kinds of data logging, analyzing every shift point, brake zone, turn-in, corner G, and corner exit. So, therefore their observations are not valid or useful. Obviously, you should keep those blinders on and ignore my posts.
For the benefit of everyone but Mark...I am a VERY consistent driver with a keen feel for my car and setup. It is my observations and the resulting setup changes that has taken every car I've competed with from middle of the pack or worse to FTD. At our events we do 2 sessions of 4 laps each and the difference between my slowest lap and FTD lap is only 2 seconds. That is very consistent.
And I do know something about the difference between autocross and track. I've done a few track days on R compounds with my autocross car and matched laps with the fastest more experience driver/cars there despite my lack of lap after lap after lap of track experience and data analysis. To be honest I found track driving rather boring. Sure, the speeds are faster making the handling dynamics a little different, but driver input is slower, more leisurely, and things like line and driver input timing have less effect on lap times compared to autocross.
Just because I don't enjoy pounding around the track all day doesn't mean I am going dis those that do enjoy it or their experiences, to each their own. I could say that because trackies aren't able to be consistent and/or tell differences in setup without data acquisition and hours of seat time, then they are obviously slow learners, aren't driving their car at the limits, and don't know what they are talking about. But I won't because I'm not a narrow minded *******.
Do what everyone else does and you will merely be competitive. Do what makes you faster and you will win.
If everyone else hangs a bag of manure on their bumper and says it makes them faster, would you?
Strive to be consistent not fast. By being consistent you will know the effect of any changes you make so you can keep only the changes that make you faster.
Last edited by RKD in OKC; 09-19-2010 at 02:30 AM.
09-18-2010, 09:45 PM
#22
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Nope, sorry Mark, won't stop posting my real world experiences no matter how silly or "amateur" you think those experiences may be. And I think you are an ******* for calling my experiences silly and not "real" and am personally offended. I did state there is a difference in our race courses and the typical track, say maybe a lot more lower gear acceleration. So, Bite Me *** Hole.
And by the way, removing 100 lbs, by taking out interior bits, did not measurably decrease lap times in that same Boxster S before the wheel change.
And by the way, removing 100 lbs, by taking out interior bits, did not measurably decrease lap times in that same Boxster S before the wheel change.
09-18-2010, 10:14 PM
#23
Rennlist Member
