View Poll Results: Where do you shift your 996 3.6L street engine'd racer
shift at redline to maximize HP and acceleration on any straight
13
36.11%
shift at 300rpm below redline to save then engine and its "noise" anyway.
11
30.56%
I dont know, but want to learn how to maximize acceleration on any straight on the track.
1
2.78%
I dont know and dont care. Ill just do whatever VR says I should do.
11
30.56%
Multiple Choice Poll. Voters: 36. You may not vote on this poll
996 3.6L street engine race car owners. Where do you shift?
02-09-2011, 07:19 PM
#46
Three Wheelin'
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The real world is irrelavent in this situation because those involved real cars, the spreadsheet posted earlier were hypothetical numbers of a different car and my post is based purely off those numbers. Based on the info from the spread sheet, shifting at 7250rpm for all gears would be the quickest, for that car. Your post #42, which was in regard to that spread sheet, is wrong. For a 996(or whatever we're comparing at this point) I don't know the answer, but if someone sends me the info I'm asking for I'd be willing to find out.
02-09-2011, 07:20 PM
#47
Rennlist Member
Thread Starter
Sorry, here you go! >>>>
really, my question too!
Let me know, ill send you one
Ummmm, are we looking at the same chart Dave??
all you mention, and this post and you still dont get it?? I give up......
maybe not.
exactly. I dont think Dave reads charts too well. certainly hasnt for years, why start now.
yes, in gear 4-5 transition. what chart or values are you looking at???
as a note, look at the drama that happens in the 2-3rd shift too. 100ft-lbs and thats before the final drive!!! you still stand by your "Data" and "experience".
I wouldnt lump the other guys into your corral, just yet.
yes, exactly right.
Let me know, ill send you one
So wait....this chart seems to show that--GASP!--you don't really need to upshift at redline with this motor. But...but...but...how could that be? 42,000 defensive words of protest in 2 separate threads seem to indicate it is impossible! Zut alors!!! 
Professional Racing and Driving Coach
Professional Racing and Driving Coach
all you mention, and this post and you still dont get it?? I give up......
maybe not.
as a note, look at the drama that happens in the 2-3rd shift too. 100ft-lbs and thats before the final drive!!! you still stand by your "Data" and "experience".
I wouldnt lump the other guys into your corral, just yet.
No it's not, you make more transmission output torque at 7250 RPM in 4th gear than you do at 6060rpm in 5th gear. You also make more transmission output torque at 7250rpm in 5th gear than you do at 5970rpm in 6th gear.
Using my old car as an example, with a 7000rpm redline. From 1st to 2nd and 2nd to 3rd my optimal shift was 7000rpm, for 3rd to 4th it was 6800rpm, for 4th to 5th it was 6500rpm. So yes it's true for some cars, but it depends on the torque/power curve and gearing.
Using my old car as an example, with a 7000rpm redline. From 1st to 2nd and 2nd to 3rd my optimal shift was 7000rpm, for 3rd to 4th it was 6800rpm, for 4th to 5th it was 6500rpm. So yes it's true for some cars, but it depends on the torque/power curve and gearing.
02-09-2011, 07:20 PM
#48
Rennlist Member
02-09-2011, 07:24 PM
#49
Three Wheelin'
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02-09-2011, 07:24 PM
#50
Rennlist Member
Thread Starter
in any car with a peaky hp curve, or even a flat top, its going to be true. your "real world" data is cluttered up a bit with other factors. If you have the data, show us a run to run comparison down a straight, with the g's listed at 7000rpm vs 7200rpm vs the post shift rpm. Because you failed to even see the difference on a very clear spreadsheet, something tells me you would have a hard time reading more complex information on the data aqu. output. Just a guess. in fact, you can try and find a dyno run that simulates your theory, but unfortunately, it would have probably had to be a 928. 
anyway, as Greg posted, from 4th to 5th, the difference is from 204 vs the post shift torque of 180. 24ftlbs BEFORE even a rear end multiplier. so, more like near 100ftlbs difference! But, your data shows to the contrary. Hmmm, I wonder why. seriously. Or, i would like to really know the true comparison you did or what you are looking at, in order for others to not make this same mistake!
anyway, as Greg posted, from 4th to 5th, the difference is from 204 vs the post shift torque of 180. 24ftlbs BEFORE even a rear end multiplier. so, more like near 100ftlbs difference! But, your data shows to the contrary. Hmmm, I wonder why. seriously. Or, i would like to really know the true comparison you did or what you are looking at, in order for others to not make this same mistake!
02-09-2011, 07:26 PM
#51
VR,
Have you looked at this article?:
http://www.allpar.com/eek/hp-vs-torque.html
It covers much of this. Here is another paragraph:
Not all cars should be shifted at the redline for maximum performance. But it's true for many cars. You can determine optimal shift points by graphing horsepower vs. velocity or transmission torque vs. RPM. Engine torque alone will not determine shift points.
That is what Greg is talking about and he is willing to do the math to show what the optimal shift points actually are.
Scott
Have you looked at this article?:
http://www.allpar.com/eek/hp-vs-torque.html
It covers much of this. Here is another paragraph:
Not all cars should be shifted at the redline for maximum performance. But it's true for many cars. You can determine optimal shift points by graphing horsepower vs. velocity or transmission torque vs. RPM. Engine torque alone will not determine shift points.
That is what Greg is talking about and he is willing to do the math to show what the optimal shift points actually are.
Scott
02-09-2011, 07:30 PM
#52
Rennlist Member
Thread Starter
02-09-2011, 07:39 PM
#53
Drifting
The real world is irrelavent in this situation because those involved real cars, the spreadsheet posted earlier were hypothetical numbers of a different car and my post is based purely off those numbers. Based on the info from the spread sheet, shifting at 7250rpm for all gears would be the quickest, for that car. Your post #42, which was in regard to that spread sheet, is wrong. For a 996(or whatever we're comparing at this point) I don't know the answer, but if someone sends me the info I'm asking for I'd be willing to find out.
https://rennlist.com/forums/996-foru...light=996+dyno
This is the chart I used Greg. It was easier to get the dyno numbers off it than the one in this thread. Feel free to check my work.
Here are the gear ratios: http://www.californiamotorsports.net...oxster%20S.htm
02-09-2011, 07:39 PM
#54
Rennlist Member
He's ONLY doing a 2:05 here. As many of us said in the other thread, sometimes it makes sense & is faster to shift short of redline, and this is often true with a street based 996 motor. Which neither you nor Mark have seat time in.
Ay ay ay....
Professional Racing and Driving Coach
02-09-2011, 07:51 PM
#55
Rennlist Member
VR,
Have you looked at this article?:
http://www.allpar.com/eek/hp-vs-torque.html
It covers much of this. Here is another paragraph:
Not all cars should be shifted at the redline for maximum performance. But it's true for many cars. You can determine optimal shift points by graphing horsepower vs. velocity or transmission torque vs. RPM. Engine torque alone will not determine shift points.
That is what Greg is talking about and he is willing to do the math to show what the optimal shift points actually are.
Scott
Have you looked at this article?:
http://www.allpar.com/eek/hp-vs-torque.html
It covers much of this. Here is another paragraph:
Not all cars should be shifted at the redline for maximum performance. But it's true for many cars. You can determine optimal shift points by graphing horsepower vs. velocity or transmission torque vs. RPM. Engine torque alone will not determine shift points.
That is what Greg is talking about and he is willing to do the math to show what the optimal shift points actually are.
Scott
Professional Racing and Driving Coach
02-09-2011, 08:39 PM
#57
Rennlist Member
02-09-2011, 08:39 PM
#58
Sure. I raced motorcycles (even more peaky motors) which are more sensitive than cars to traction changes in corners. With the higher horsepower bikes there were places on most tracks where I would up shift before red line so I would not upset the bike in the corner.
Would Mr. Law be shifting before red line if he were on the Mulsanne Straight? I don't think he would.
Unlike one other, I am not arguing absolutes here. I know there are good reasons to not shift at red line. But, if we narrow the scenario to accelerating down a straight, I think we can say that in that case, shifting early would not allow one to get down that straight faster.
Scott
02-09-2011, 08:42 PM
#59
Rennlist Member