Login
09262013, 05:08 PM  #89 
Apex Everything!
847
Rep 4,376
Posts
Drives: 2007 Honda S2000, 2017 GT350
Join Date: Sep 2008
Location: Cedar Park, TX

The drag strip isn't a race track.
__________________
2011 E92 M3(Sold). 2007 Honda S2000 (Track Car). 2016 Cayman GT4 (Sold). 2017 Shelby GT350 (AKA Crowd Killer).
My pet project: https://stickershift.com 
Appreciate
0

09262013, 05:09 PM  #90 
Major General
4450
Rep 5,335
Posts 
how about both? u don't think BMW would make a slower car, do you?
__________________
2020 HS M2C DCT (Perfect)
2 x N54 (Unreliable) 1 x N55 (Slow) 
Appreciate
0

09262013, 05:13 PM  #91 
Apex Everything!
847
Rep 4,376
Posts
Drives: 2007 Honda S2000, 2017 GT350
Join Date: Sep 2008
Location: Cedar Park, TX

No but the power difference will be negligible on the track. A good driver in an S2000 will still pass the average joe in the new M4.
__________________
2011 E92 M3(Sold). 2007 Honda S2000 (Track Car). 2016 Cayman GT4 (Sold). 2017 Shelby GT350 (AKA Crowd Killer).
My pet project: https://stickershift.com 
Appreciate
0

09262013, 05:17 PM  #92 
Major General
4450
Rep 5,335
Posts 
... thanks, I thought the moon was flat
__________________
2020 HS M2C DCT (Perfect)
2 x N54 (Unreliable) 1 x N55 (Slow) 
Appreciate
0

09262013, 05:19 PM  #93 
Apex Everything!
847
Rep 4,376
Posts
Drives: 2007 Honda S2000, 2017 GT350
Join Date: Sep 2008
Location: Cedar Park, TX

Based on the original comment I replied to, maybe you do?
__________________
2011 E92 M3(Sold). 2007 Honda S2000 (Track Car). 2016 Cayman GT4 (Sold). 2017 Shelby GT350 (AKA Crowd Killer).
My pet project: https://stickershift.com 
Appreciate
0

09262013, 05:30 PM  #94 
Lieutenant General
529
Rep 10,408
Posts 
Torque, power, redline shift points, etc. A reply to many who asked various questions.
I think the easiest way to think about shift points and whether they are at redline or not is the shape of the torque curve. If it is more flat and flatter closer to redline the car will be a redline shifter. Another way to say this is that engine has a linear power curve (and the E92 M3 is epically linear in this particular regard). For power and torque curves typical of a turbo BMW or say many Corvettes with a flat or knee shaped and declining power at high rpm, these cars will need to be shifted before redline for maximum performance. The simplest way to determine exact shift points is as follows. Plot on a single graph force at the drive wheels vs. vehicle speed (torque would do as well, but we clearly are not/can not use crank torque nor a plot vs. rpm) for all of the gears. If any two of these curves intersect that means one has better acceleration (simply more force can be applied) by shifting to the next gear rather than holding higher or to redline. In particular note the green to blue change, i.e. 2nd to 3rd shift in the first plot for the M4. When you look at these curves and play with the gear ratios making sure you not done something absurd like a 30 mph top speed in 1st gear at redline, that you have closely spaced gears and that top speed issues are sorted out, the falling torque curve simply haunts you not allowing all of the curves to fit together without the intersections. When the cars has a linear power curves it becomes trivial to have nonintersecting curves. Make sense? Make some of your own spreadsheets will really help if you care about the details... See the attached plots for more, the first with my assumed gears for the F82 M4 (but actual torque and power curves) and the second for the E92 M3 MDCT. Sure my gears for the M4 are bound to be off a bit, heck even the final drive I predicted may be off, but that does not change the essence of the cars power delivery  the entire shape of its torque curve. The 1M and the new M5 both should be shifted prior to redline in many of its gears to obtain maximum possible acceleration, period. Similarly I can guarantee the new M4 will be the same given a 7500+ rpm redline. Sorry for the very bold traces in the plots, I suspect a java bug has made many graphs from my CarTest software nearly invisible without the very bold traces. You'll still clearly get the idea. It is worth noting that these curves also tell one a lot about the feel and experience of the car. They show how the M4 will really hit a quick and dramatic wall in the upper rpms whereas the M4 tapers off much less dramatically. This gives the very "linear" feel to the M3 along the lines of its linear power curve. Not so much for the M4. Lastly when a cars torque falls dramatically at high rpm it is essentially turning into a poor air pump and hence a poor "breather". This is the nature of the beast with most production turbo systems compared to a high performance NA engine which is designed to be as free flowing as possible from intake to exhaust at very high flow rates (rpm).
__________________
E92 M3  Space Gray on Fox Red  MDCT  CF Roof  RAC RG63 Wheels  Brembo 380mm BBK   Vorsteiner Ti Exhaust  Matte Black Grilles/Side Gills/Rear Emblem/Mirrors   Alekshop Back up Camera  GP Thunders  BMW Aluminum Pedals  Elite Angels   XPEL Full Front Wrap  Hardwired V1  Interior Xenon Light Kit  
Appreciate
0

09262013, 05:30 PM  #95  
Banned
175
Rep 7,299
Posts 
Quote:
GT3 owners get 500hp out of a 6cyl 4.0NA engine. The new GT3 is 6cyl 3.8NA 475hp or so. They will never come to a turbo m3 regardless. Why cant we get naturally aspirated engines with those numbers? Cmon bmw. There is a reason why us owners move into porsche. 

Appreciate
0

09262013, 05:31 PM  #96 
Banned
175
Rep 7,299
Posts 

Appreciate
0

09262013, 06:17 PM  #97 
European Editor
9878
Rep 23,010
Posts 
Nice to see the new M4 will also have the M1/M2 M Sport switches(ala M5/M6) on the steering wheel.
__________________

Appreciate
0

09262013, 06:38 PM  #98  
Lieutenant
24
Rep 512
Posts 
Quote:
You should be concerning yourself with the shape of the power curve, only. Your own analysis demonstrates this because you've plotted tractive effort versus wheel speed. With some units manipulation (change the abscissa units from km/h to m/s and the ordinate values to newtons without the multiplier), that becomes power, not torque. The intersection of those curves you plotted occurs at the point where the power (not torque) available with engine speed increases is less than that available with an upshift. Since induction performance is not gear dependent, this point occurs at the same engine speed, no matter how fast or slow you are going. And it isnt necessarily at the point when power begins to drop off, either. It all depends on how wide or narrow the next gear is. To use hyperbole to demonstrate; If second gear drops engine speeds to 1500 RPM after a sprint to 65mph and 6800rpms, it's always better to keep going to ~7750rpms than upshift. But, of course, you know that since thats what the intersections demonstrates. Now, if I am to be specific and talk about the S55, I'll have to wait and see when that horsepower curve inflects, and what the actual ratios look like. However, I'm confident that BMW is far more aware of the math behind picking shift points than you and I. As such, the car will favor higher shift points than is currently believed. After all, short shifting is not in keeping with the ///M aesthetic. That's reserved for the N series drivers. Last edited by Jonjt; 09262013 at 06:56 PM.. 

Appreciate
0

09262013, 06:47 PM  #100  
M3chaser
0
Rep 58
Posts 
Quote:


Appreciate
0

09262013, 06:50 PM  #101 
Lieutenant
24
Rep 512
Posts 

Appreciate
0

09262013, 06:57 PM  #102 
Goldmember
20
Rep 315
Posts 
I don't think short shifting would make it faster, as horsepower is almost flat on the top of the rev range, if anything short shifting would make it slower since in the next gear the horsepower would. It be optimal.

Appreciate
0

09262013, 07:12 PM  #103  
Captain
22
Rep 634
Posts 
Quote:


Appreciate
0

09262013, 07:17 PM  #104  
Major
196
Rep 1,248
Posts 
Quote:
ACE_M3 great tidbit re the "last user" mode on M cars. Thanks for that. 

Appreciate
0

09262013, 07:41 PM  #106 
Moderator
7269
Rep 19,394
Posts 

Appreciate
0

09262013, 07:45 PM  #107 
Second Lieutenant
13
Rep 298
Posts 
Having owned an E46 M3 with a 8000RPM redline and now owning a 1M with a 7000RPM redline, I can honestly tell you I don't miss the extra 1000RPM. There's nothing like revving to 3000RPM in the 1M and mashing the throttle and having that extra torque plant you in the seat. The extra torque is especially appreciated on the highway in 6th gear when you want to pass someone without downshifting. My 1M accelerates so hard in 6th gear that some passengers that I have had in the car asked me if I was in 4th gear..
__________________
2018 BMW M3 ZCP
1999 BMW Z3 M Coupe Turbo 2017 Ram Rebel 2015 Porsche Cayman S 
Appreciate
0

09262013, 08:00 PM  #108  
is nonexistent with N/A
19
Rep 1,127
Posts 
Quote:
EDIT: it's exactly 7500. Who wins? 

Appreciate
0

09262013, 08:16 PM  #110  
Lieutenant Colonel
130
Rep 1,885
Posts 
Quote:
"bring this engine to redline, everytime"
__________________
'11 E92 M3 ZCP SG 6MT Tech Sound USB Heat Cloth Aluminium Sunshade
http://www.m3post.com/forums/showthread.php?t=422151 

Appreciate
0

Post Reply 
Bookmarks 
Thread Tools  Search this Thread 

