Sebring: Boxster S New Personal Best
02-04-2011, 11:55 PM
#16
Race Director
Raptor...I hear the steam I really do! LOL
02-05-2011, 12:37 AM
#17
I'm in....
Rennlist Member
Rennlist Member
Nice Chad! I miss running with you. Obviously not all 996 engined Boxsters are created equal but yours has evolved nicely while mine hasn't for a while. I'd like to think that I've been converging with the cars potential but I'm not ever sure of that. 
Should have gotten in on the Moton group buy, my pss9s are about worn out.
Should have gotten in on the Moton group buy, my pss9s are about worn out.
02-05-2011, 02:31 AM
#18
Rennlist Member
I'm wrong? Please elaborate. Im curious where. I posted a 997 dyno graph for you review. Your right though, I have little 996 993 seat time but have driven cars with high strung engines before. they all follow the same laws all the other engines and cars follow. why do you think an early shift is a good idea? just because it isnt pulling hard anymore? what are you basing this on , butt dyno? 9 times out of 10, that will be wrong. Is acceleration going down with speed? sure it is, it has too, ( even with a flat Hp curve it goes down inversely proportional to speed) but the fall off off acceleration post shift to a lower hp is MUCH greater. So, unless you can give me a real clear answer of why, I would say you are giving anyone a diservice by suggesting an early shift to optimize lap times. Brinkley's video is good, but it sounds like he is short shifting a bit and certainly would be leaving time on the table, unless he is grip limited.
So, what you are saying, is that a short shift makes little or no difference, so by sayng that, you better show me a pretty flat HP curve, which I dont know of any 996 or 997s that have that. Otherwise, a short shift kills acceleration overall. was the 997 curve representitive of Brinkely's motor or other non GT3 motors?
So, what you are saying, is that a short shift makes little or no difference, so by sayng that, you better show me a pretty flat HP curve, which I dont know of any 996 or 997s that have that. Otherwise, a short shift kills acceleration overall. was the 997 curve representitive of Brinkely's motor or other non GT3 motors?
02-05-2011, 11:05 AM
#19
Rennlist Member
Mark,
What data system do you use in your car ? Maybe we can provide some overlays.
I know VR is a regular data user when coaching as I am also,while some of our experiences are butt data when a student doesn't have a data system, most of our experience is supported by a real data system.
What data system do you use in your car ? Maybe we can provide some overlays.
I know VR is a regular data user when coaching as I am also,while some of our experiences are butt data when a student doesn't have a data system, most of our experience is supported by a real data system.
I'm wrong? Please elaborate. Im curious where. I posted a 997 dyno graph for you review. Your right though, I have little 996 993 seat time but have driven cars with high strung engines before. they all follow the same laws all the other engines and cars follow. why do you think an early shift is a good idea? just because it isnt pulling hard anymore? what are you basing this on , butt dyno? 9 times out of 10, that will be wrong. Is acceleration going down with speed? sure it is, it has too, ( even with a flat Hp curve it goes down inversely proportional to speed) but the fall off off acceleration post shift to a lower hp is MUCH greater. So, unless you can give me a real clear answer of why, I would say you are giving anyone a diservice by suggesting an early shift to optimize lap times. Brinkley's video is good, but it sounds like he is short shifting a bit and certainly would be leaving time on the table, unless he is grip limited.
So, what you are saying, is that a short shift makes little or no difference, so by sayng that, you better show me a pretty flat HP curve, which I dont know of any 996 or 997s that have that. Otherwise, a short shift kills acceleration overall. was the 997 curve representitive of Brinkely's motor or other non GT3 motors?
So, what you are saying, is that a short shift makes little or no difference, so by sayng that, you better show me a pretty flat HP curve, which I dont know of any 996 or 997s that have that. Otherwise, a short shift kills acceleration overall. was the 997 curve representitive of Brinkely's motor or other non GT3 motors?
02-05-2011, 11:30 AM
#20
Rennlist Member
Mark, street 996 non-GT3 motors are not "high strung" like their GT3 cousins are. In addition, upshifting 200-300 RPM short of redline is not what I would call "short shifting". Remember, since these engines are not "high strung", they don't make their power at redline. 
Again, please get some seat time in a car with a non-GT3 street-based 996 motor. I think then you'd concur.
Professional Racing and Driving Coach
Again, please get some seat time in a car with a non-GT3 street-based 996 motor. I think then you'd concur.
Professional Racing and Driving Coach
02-05-2011, 12:41 PM
#21
Rennlist Member
Mark, street 996 non-GT3 motors are not "high strung" like their GT3 cousins are. In addition, upshifting 200-300 RPM short of redline is not what I would call "short shifting". Remember, since these engines are not "high strung", they don't make their power at redline.
Again, please get some seat time in a car with a non-GT3 street-based 996 motor. I think then you'd concur.
That's why I posted a 997 street dyno run for your review. Do you see the probem for shifting 2-300rpm shorter than redline as far as maximizing acceleration at whatever speed it happens to be at? have you looked at comparing this mild short shift, (yes, I agree, a real short shift is when I shift 500 to 1000rpm below redline, usually for reasons or grip or other control reasons), to not shortshifting with the data?
When I say high strung, this doesnt only mean that the rpm is relatively higher than most, but it generally points to an engine that has a climbing HP curve. (which is usually a flat or slightly falling torque curve) The ONLY engines that are not effected by ANY kind of short shift would be one like my engine that has a realtively flat HP curve. (this means, a post shift HP level is near the same whether shifted at redline or 2-500rpm below redline)
Data logging will detect this difference, if you know what you are looking for. Certainly, here are other variables that will effect lap time, even if your straightline speed is optimized on every shift.
If what Im saying is true, then by short shifting 2-300rpm, and it takes .25 or .5 seconds to accelerate over this range, its like dragging the brakes, or lifting the accelerator, because you are suddently down 50-60hp for that period of time. Not a huge difference, but certainly isnt helpign someone trying to optimize lap time. In a race, thats a huge difference. we all know, how just a slow shift can kill your speed in a nose to nose battle with a competitor.
So, again, did you see the non GT3 HP curve? this is from a 997. is it not like the HP curves you have seen on a 996 or 997 based engine?
Professional Racing and Driving Coach
Again, please get some seat time in a car with a non-GT3 street-based 996 motor. I think then you'd concur.
That's why I posted a 997 street dyno run for your review. Do you see the probem for shifting 2-300rpm shorter than redline as far as maximizing acceleration at whatever speed it happens to be at? have you looked at comparing this mild short shift, (yes, I agree, a real short shift is when I shift 500 to 1000rpm below redline, usually for reasons or grip or other control reasons), to not shortshifting with the data?
When I say high strung, this doesnt only mean that the rpm is relatively higher than most, but it generally points to an engine that has a climbing HP curve. (which is usually a flat or slightly falling torque curve) The ONLY engines that are not effected by ANY kind of short shift would be one like my engine that has a realtively flat HP curve. (this means, a post shift HP level is near the same whether shifted at redline or 2-500rpm below redline)
Data logging will detect this difference, if you know what you are looking for. Certainly, here are other variables that will effect lap time, even if your straightline speed is optimized on every shift.
If what Im saying is true, then by short shifting 2-300rpm, and it takes .25 or .5 seconds to accelerate over this range, its like dragging the brakes, or lifting the accelerator, because you are suddently down 50-60hp for that period of time. Not a huge difference, but certainly isnt helpign someone trying to optimize lap time. In a race, thats a huge difference. we all know, how just a slow shift can kill your speed in a nose to nose battle with a competitor.
So, again, did you see the non GT3 HP curve? this is from a 997. is it not like the HP curves you have seen on a 996 or 997 based engine?
Professional Racing and Driving Coach
Mark,
What data system do you use in your car ? Maybe we can provide some overlays.
I know VR is a regular data user when coaching as I am also,while some of our experiences are butt data when a student doesn't have a data system, most of our experience is supported by a real data system.
What data system do you use in your car ? Maybe we can provide some overlays.
I know VR is a regular data user when coaching as I am also,while some of our experiences are butt data when a student doesn't have a data system, most of our experience is supported by a real data system.
bottomline, if your post shift RPM has less hp, you are accelerating proportionally slower.
02-05-2011, 12:52 PM
#22
Rennlist Member
is this not the shape of most of the 3.6 liter 996 engines hp curves?
https://rennlist.com/forums/996-foru...96-dyno-s.html
Boxter gear spacing from 3-4th gear is: 7000rpm to 5600rpm. look at the hp drops in that range.
from 7300rpm to 5900rpm would be the drop at 300rpm higher.
the moral of the story is that , by shifting early , at any rpm below redline, you are losing about 40hp.
Transmission
Gear Type 6 Speed Manual
Final Drive 3.44:1
1st Gear Ratio 3.82:1
2nd Gear Ratio 2.2:1
3rd Gear Ratio 1.52:1
4th Gear Ratio 1.22:1
5th Gear Ratio 1.02:1
6th Gear Ratio 0.84:1
https://rennlist.com/forums/996-foru...96-dyno-s.html
Boxter gear spacing from 3-4th gear is: 7000rpm to 5600rpm. look at the hp drops in that range.
from 7300rpm to 5900rpm would be the drop at 300rpm higher.
the moral of the story is that , by shifting early , at any rpm below redline, you are losing about 40hp.
Transmission
Gear Type 6 Speed Manual
Final Drive 3.44:1
1st Gear Ratio 3.82:1
2nd Gear Ratio 2.2:1
3rd Gear Ratio 1.52:1
4th Gear Ratio 1.22:1
5th Gear Ratio 1.02:1
6th Gear Ratio 0.84:1
02-05-2011, 01:00 PM
#23
Rennlist Member
Chad-great lap and time.
I have the same debate in T10. I'm trying to carry 3rd thru there and momentum but many times I overbrake, kill the momentum and generally **** that turn up. If in 2nd I have to shift quickly just past apex. Definitely need to work it.
Never tried anything other than downshifting into T15- it seems very right.
Btw- I'm almost exactly a second off your time in the 996 3.4L/all-tin-mobile (R5) but with plenty of time to be gained.
I have the same debate in T10. I'm trying to carry 3rd thru there and momentum but many times I overbrake, kill the momentum and generally **** that turn up. If in 2nd I have to shift quickly just past apex. Definitely need to work it.
Never tried anything other than downshifting into T15- it seems very right.
Btw- I'm almost exactly a second off your time in the 996 3.4L/all-tin-mobile (R5) but with plenty of time to be gained.
02-05-2011, 01:09 PM
#24
Rennlist Member
[QUOTE=mark kibort;8275023]is this not the shape of most of the 3.6 liter 996 engines hp curves?
https://rennlist.com/forums/996-foru...96-dyno-s.html
Mine (3.4L 996) is not that steep. Peak hp is @ 6700 and is down 50 hp @ 5k.
TQ is pretty flat from 4400 to 6000.
https://rennlist.com/forums/996-foru...96-dyno-s.html
Mine (3.4L 996) is not that steep. Peak hp is @ 6700 and is down 50 hp @ 5k.
TQ is pretty flat from 4400 to 6000.
02-05-2011, 01:09 PM
#25
Rennlist Member
My point was really that you seem to bash the seat of the pants opinion which I believe is all you use in your own car. So you rely on other peoples data found on the www in which you really don't know all the parameters to argue with others that are using data and spend countless hours on dynos.
So......... please answer my original question, what data system do you have in your car?
Oh, and here is one more, how many dyno pulls or hours on a dyno do you have on your car in say the last year ?
So......... please answer my original question, what data system do you have in your car?
Oh, and here is one more, how many dyno pulls or hours on a dyno do you have on your car in say the last year ?
what are you saying is supported? that short shifting an engine, with a cuve like i had posted, will yield no difference in acceleration. what comparative test did you do? the reason I ask, is just because you dont see a lap time change, doesnt mean you were not sacraficing straightline acceleration. there are lots of factors as you know. My point is, i have not seen any 993/6/7 based engines where a short shift of even 200rpm wouldnt hurt acceleration.
bottomline, if your post shift RPM has less hp, you are accelerating proportionally slower.
bottomline, if your post shift RPM has less hp, you are accelerating proportionally slower.
02-05-2011, 01:13 PM
#27
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David,
Are you at Sebring this weekend? If so, good luck and let us know how much time you were able to gain through out the weekend.
After all the discussion on if to downshift through T10, Tower, T15a I would need to run some clean laps with this same set up to actually show you guys the difference. The limitation to downshifting to 2nd (which I'd love to do) is that I'm already at or near 2nd gears redline (about 62mph). So as David stated in T10, for example, if I downshift to 2nd, get back on the gas I would need to up-shift just past apex and well before I reach the left hand curbing that starts the double apex left hander. I used to go to 2nd in Tower but had to shift back to 3rd before the end of the left hand blue and white curbing.
While I don't think it will help in T10 or Tower I think I need to try it at 15a again. I've worked both ways on data and staying in 4th and carrying 6-9mph more through the apex of 15a was better for the overall lap.
Are you at Sebring this weekend? If so, good luck and let us know how much time you were able to gain through out the weekend.
After all the discussion on if to downshift through T10, Tower, T15a I would need to run some clean laps with this same set up to actually show you guys the difference. The limitation to downshifting to 2nd (which I'd love to do) is that I'm already at or near 2nd gears redline (about 62mph). So as David stated in T10, for example, if I downshift to 2nd, get back on the gas I would need to up-shift just past apex and well before I reach the left hand curbing that starts the double apex left hander. I used to go to 2nd in Tower but had to shift back to 3rd before the end of the left hand blue and white curbing.
While I don't think it will help in T10 or Tower I think I need to try it at 15a again. I've worked both ways on data and staying in 4th and carrying 6-9mph more through the apex of 15a was better for the overall lap.
02-05-2011, 06:18 PM
#30
Rennlist Member
David,
Are you at Sebring this weekend? If so, good luck and let us know how much time you were able to gain through out the weekend.
After all the discussion on if to downshift through T10, Tower, T15a I would need to run some clean laps with this same set up to actually show you guys the difference. The limitation to downshifting to 2nd (which I'd love to do) is that I'm already at or near 2nd gears redline (about 62mph). So as David stated in T10, for example, if I downshift to 2nd, get back on the gas I would need to up-shift just past apex and well before I reach the left hand curbing that starts the double apex left hander. I used to go to 2nd in Tower but had to shift back to 3rd before the end of the left hand blue and white curbing.
While I don't think it will help in T10 or Tower I think I need to try it at 15a again. I've worked both ways on data and staying in 4th and carrying 6-9mph more through the apex of 15a was better for the overall lap.
Are you at Sebring this weekend? If so, good luck and let us know how much time you were able to gain through out the weekend.
After all the discussion on if to downshift through T10, Tower, T15a I would need to run some clean laps with this same set up to actually show you guys the difference. The limitation to downshifting to 2nd (which I'd love to do) is that I'm already at or near 2nd gears redline (about 62mph). So as David stated in T10, for example, if I downshift to 2nd, get back on the gas I would need to up-shift just past apex and well before I reach the left hand curbing that starts the double apex left hander. I used to go to 2nd in Tower but had to shift back to 3rd before the end of the left hand blue and white curbing.
While I don't think it will help in T10 or Tower I think I need to try it at 15a again. I've worked both ways on data and staying in 4th and carrying 6-9mph more through the apex of 15a was better for the overall lap.
I'm not saying 2nd in T10 is necessarily correct- I'm saying I'm, uh, having difficulties in 3rd.