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      09-26-2013, 06:08 PM   #89
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Quote:
Originally Posted by ASAP View Post
I highly doubt that there will be any S65 owners disappointed by the S55... if there are, then they will be really disappointed when an S55 flies by them at the track lol.
The drag strip isn't a race track.
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      09-26-2013, 06:09 PM   #90
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Quote:
Originally Posted by radiantm3 View Post
The drag strip isn't a race track.
how about both? u don't think BMW would make a slower car, do you?
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      09-26-2013, 06:13 PM   #91
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Quote:
Originally Posted by ASAP View Post
how about both? u don't think BMW would make a slower car, do you?
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.
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      09-26-2013, 06:17 PM   #92
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Quote:
Originally Posted by radiantm3 View Post
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.
... thanks, I thought the moon was flat
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      09-26-2013, 06:19 PM   #93
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Quote:
Originally Posted by ASAP View Post
... thanks, I thought the moon was flat
Based on the original comment I replied to, maybe you do?
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      09-26-2013, 06:30 PM   #94
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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 non-intersecting 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 M-DCT. 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).
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      09-26-2013, 06:30 PM   #95
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Quote:
Originally Posted by Endless619
Ugh, do folks actually really care about this stuff? I might say cool if we were looking at a 9000 redline. 7500? Ok....

I also see a lot of NON-M owners voicing their opinions and getting on ACTUAL M owners. Come on guys. Leave it be.
I wanted to say this 2,3,4,5 months ago

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.
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      09-26-2013, 06:31 PM   #96
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Quote:
Originally Posted by radiantm3
Quote:
Originally Posted by ASAP View Post
I highly doubt that there will be any S65 owners disappointed by the S55... if there are, then they will be really disappointed when an S55 flies by them at the track lol.
The drag strip isn't a race track.
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      09-26-2013, 07:17 PM   #97
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Nice to see the new M4 will also have the M1/M2 M Sport switches(ala M5/M6) on the steering wheel.
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      09-26-2013, 07:38 PM   #98
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Quote:
Originally Posted by swamp2 View Post
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 non-intersecting 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 M-DCT. 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).
A decent analysis, aside from one big issue. Torque does not perform work, it doesn't propel the car forward. This torque roll off you are speaking of might be inconsequential only because the fall off seems slower than the corresponding increase in engine speed. The slope of the torque curve is greater than -1, up to a point. The result is that the power either continues to climb or remains flat, until the curve inflects and it no longer does.

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; 09-26-2013 at 07:56 PM..
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      09-26-2013, 07:47 PM   #99
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Technical jargon blah blah go to the track and "feel" where you need to shift lol. You guys lose me after a couple sentences!
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      09-26-2013, 07:47 PM   #100
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Quote:
Originally Posted by solstice View Post
Thanks!

With that picture combined with the Dyno chart I think it's safe to say that this engine will act like a typical FI engine in terms of power delivery across the rev band.

With a 7500 rpm redline it looks from the dyno chart that plots the S65 on it as well that the power plateau should be around 5500 rpm. I.e when power stops building and maintain hp until redline. The quick run to peak hp and the square tq curve will make for a very fat midrange but the car will not be very exciting to rev past 5500 - 6000 rpm. The ferocious pull to redline from the S65 will not be there.

I.e much more S63TU than S65 as expected. No surprise here.
Remains to see if throttle response ( I inlcude all type of lag from throttle to engine response in "throttle lag" ) will set this engine apart from a typical FI engine.
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      09-26-2013, 07:50 PM   #101
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Quote:
Originally Posted by pkim1079 View Post
Technical jargon blah blah go to the track and "feel" where you need to shift lol. You guys lose me after a couple sentences!
Meh, it's always academic. No one except for drag racers actually shift at the exact speed when it's most mathematically advantageous.
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      09-26-2013, 07:57 PM   #102
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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.
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      09-26-2013, 08:12 PM   #103
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Quote:
Originally Posted by ACE_M3
Quote:
Originally Posted by ROM3 View Post
Do you guys see that there's an auto start/stop function! I hope that's disabled from start.

Because that'll be bad if it shuts off on traffic lights and stop signs

BMW M models come with Last User Mode enabled, which will start the car with stop/start in the same mode as when the car was shut down
Pheww that's good news!
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      09-26-2013, 08:17 PM   #104
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Quote:
Originally Posted by Boss330 View Post
I said 7600rpm because BMW said slightly ABOVE 7500rpm and the red marking seems to begin at 7500. On my N53 engined F10 the red markings begin at 7000rpm, but redline is 7200rpm.

And BMW has said that torque is well above 500Nm/396lb.ft, so that's why it's safe to assume a higher torque than that... And as HP and torque is related some have also extrapolated what sort of HP goes with that torque

That's why different numbers are being thrown around here
Trust me, your original post made sense to people with brains. You don't want to feed that troll.

ACE_M3-- great tidbit re the "last user" mode on M cars. Thanks for that.
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      09-26-2013, 08:37 PM   #105
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Love those graphs!!
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      09-26-2013, 08:41 PM   #106
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Quote:
Originally Posted by ASAP View Post
To be 100% fair, so far your 8k assumption is far off...
8k assumption? Need I link to your post insisting it would not be over 7200? And, you do remember this was just a friendly wager with proceeds going to a charity, right?
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      09-26-2013, 08:45 PM   #107
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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..
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      09-26-2013, 09:00 PM   #108
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Quote:
Originally Posted by mkoesel View Post
8k assumption? Need I link to your post insisting it would not be over 7200? And, you do remember this was just a friendly wager with proceeds going to a charity, right?
Gonna find that pic

EDIT: it's exactly 7500. Who wins?
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      09-26-2013, 09:07 PM   #109
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Quote:
Originally Posted by turbolag View Post
Gonna find that pic

EDIT: it's exactly 7500. Who wins?
If it turns out to be exactly 7500 RPM, I clearly lose.
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      09-26-2013, 09:16 PM   #110
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Quote:
Originally Posted by Jonjt
Quote:
Originally Posted by BlackJetE90 View Post
Bascially the entire first part of his post that you didn't quote told what he thinks.

Swap always makes very valid points and backs them up with some very detailed data most of the time.
Yeah, I saw that part and responded to it in another post. I don't believe his conclusion follows from the data. Power is conserved through a cars drivetrain, it is not multiplied by leverage. There is no reason that shift points would differ by gear, if the power curve is flat through the powerband. Downshifting early would just drop the engine speed to a point where the engine can breath better (surely) but does not make a much power. You'll end up with the same wheel speed but less tractive effort. That's just a different way of saying that you will have less power available to accelerate the car.

Bring this engine to redline, everytime.
sounds Very Catchy!

"bring this engine to redline, everytime"
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