BMW M3 Forum (E90 E92)

BMW Garage BMW Meets Register Search Today's Posts Mark Forums Read


Go Back   M3Post - BMW M3 Forum > M3 (E90 / E92 / E93) > General M3 Forum (E90 + E92 + E93)
 
EclipsisNA
Post Reply
 
Thread Tools Search this Thread
      04-04-2012, 05:12 AM   #45
MerchantSailor03
Im on a Boat!
 
MerchantSailor03's Avatar
 
Drives: 08 M3
Join Date: Apr 2012
Location: Trumbull, CT

Posts: 49
iTrader: (0)

Garage List
2008 BMW M3  [0.00]
Just cruising 2.5k-3.5k, when my foot gets heavy is a different story
__________________
Eisenmann Race w/conn pipes, AFE filter & scoops, TMS pedals, M performance steering wheel, black gloss kidney grills w/ M striping, carbon fiber side gills, painted reflectors....
MerchantSailor03 is offline   United_States
0
Reply With Quote
      04-04-2012, 07:20 AM   #46
Epacy2
Major
 
Drives: M3/X5
Join Date: Jan 2009
Location: KC

Posts: 1,255
iTrader: (0)

Garage List
2008 M3  [0.00]
2008 M3  [0.00]
Redline or GTFO. Better yet, just GTFO.
__________________
Epacy2 is offline  
0
Reply With Quote
      06-02-2012, 09:47 PM   #47
Drifty//
First Lieutenant
 
Drives: A4 quattro 3.2 MT6; E92 6MT
Join Date: Mar 2012
Location: Boston

Posts: 310
iTrader: (0)

Wow. So many replies an not one link to the optimal shift points? Way to go M3post.

There are two answers to this question. The first answer is how to shift when cruising. This is a matter of personal style, wife in the car, interest in fuel economy, longevity, etc.

The second answer is how to shift when you need to go fast in a hurry. I can absolutely guarantee you that the best quarter mile times are not set by shifting all gears at 8.4k RPMs. To find the optimal shift points, you need to find at what RPMs you can get more wheel torque by upshifting, and it's progressively lower as you get to higher and higher gears.
__________________
Drifty// is offline   United_States
0
Reply With Quote
      06-03-2012, 07:35 AM   #48
mkoesel
Moderator
 
Drives: IB/PS M-DCT E93 M3
Join Date: Jun 2006
Location: Canton, MI

Posts: 13,490
iTrader: (1)

Quote:
Originally Posted by Drifty// View Post
Wow. So many replies an not one link to the optimal shift points? Way to go M3post.
Why so snarky? And why not look up the information yourself and add it to the discussion if you think it would be useful?

Quote:
I can absolutely guarantee you that the best quarter mile times are not set by shifting all gears at 8.4k RPMs. To find the optimal shift points, you need to find at what RPMs you can get more wheel torque by upshifting, and it's progressively lower as you get to higher and higher gears.
http://www.m3post.com/forums/showpos...2&postcount=20

If traction is not an issue, then shifting @ redline is indeed the answer for optimal acceleration.
__________________
2008 Interlagos Blue E93 M3 - FOR SALE - Engine failure at 95k miles.
Best offer takes it: http://www.m3post.com/forums/showthr...1#post16279561
mkoesel is offline   United_States
0
Reply With Quote
      06-03-2012, 10:04 AM   #49
767IJP
Second Lieutenant
 
Drives: 2012 M3
Join Date: Dec 2011
Location: Lower Rubber Boot, Canada

Posts: 248
iTrader: (0)

I shift at the the lowest rpm possible to keep obnoxious engine noise to a minimum.
__________________
Don't tell my Mother I'm a pilot.... She thinks I play piano at the whorehouse...
767IJP is offline  
0
Reply With Quote
      06-03-2012, 10:48 AM   #50
bruce.augenstein@comcast.
Lieutenant Colonel
 
Drives: Subaru Legacy GT
Join Date: Jul 2007
Location: Manheim, PA

Posts: 1,852
iTrader: (0)

Quote:
Originally Posted by Drifty// View Post
...There are two answers to this question. The first answer is how to shift when cruising. This is a matter of personal style, wife in the car, interest in fuel economy, longevity, etc.
Pretty much agreed, but if fuel mileage is at issue, BMW says to shift at minumum rpm and max throttle, and they've been saying this for at least thirty years that I know of.

In this car, that means a low 2000s shift point (or even a bit lower as the gears progress), using a bunch of throttle. One could shift even lower than this, but you're likely to get into some engine lugging after the shift, which will absolutely not harm the engine, but is hard on the driver's teeth.

Quote:
Originally Posted by Drifty// View Post
The second answer is how to shift when you need to go fast in a hurry. I can absolutely guarantee you that the best quarter mile times are not set by shifting all gears at 8.4k RPMs. To find the optimal shift points, you need to find at what RPMs you can get more wheel torque by upshifting, and it's progressively lower as you get to higher and higher gears.
Drive wheel torque is obviously important, but you don't need to bother with calculating it, because horsepower is the great shorthand in this context. More power means more drive wheel torque and quicker acceleration at any given car speed, and torque and gearing simply don't matter - at all - in that context.

The only - ONLY - modifier to this is that rotational inertia is reduced every time you upshift, which has the effect of lowering optimal shift points to some degree, more on the one-two shift, and less and less as the gears progress.

A general rule of thumb is to shift at around 10% above the power peak (if you can) for best acceleration. In point of fact, using one of the many currently available software packages available that model vehicle acceleration, you'll find that a completely stock current M3 would be quicker than it currently is if you shift it at somewhere in the vicinity of 9000 rpm - providing it didn't blow up, of course.

Now, about that guarantee. How about you provide some data to prove your point.

Bruce
bruce.augenstein@comcast. is offline  
0
Reply With Quote
      06-03-2012, 11:25 AM   #51
Drifty//
First Lieutenant
 
Drives: A4 quattro 3.2 MT6; E92 6MT
Join Date: Mar 2012
Location: Boston

Posts: 310
iTrader: (0)

Quote:
Originally Posted by mkoesel View Post
Why so snarky? And why not look up the information yourself and add it to the discussion if you think it would be useful?
I had a much easier time finding this info on 135i, 335i, and several other cars. It started to give me the feeling like this board is full of posers. I know it's not, but then why is it so hard to find serious discussion of a topic that most serious car guys should care about?

Thanks. That looks like some actual data. I just wish the axis and measurement methodology were specified, however. For all I know, someone just took the crank tq and just multiplied it by the different gear ratios, which fails to correctly account for certain frictional losses and such.
__________________
Drifty// is offline   United_States
0
Reply With Quote
      06-03-2012, 11:37 AM   #52
Drifty//
First Lieutenant
 
Drives: A4 quattro 3.2 MT6; E92 6MT
Join Date: Mar 2012
Location: Boston

Posts: 310
iTrader: (0)

Quote:
Originally Posted by bruce.augenstein@comcast. View Post
Now, about that guarantee. How about you provide some data to prove your point.
I'm still looking. I'm still in disbelief at the paucity of quality data on this subject, for the E92 M3.

For most other cars, I stand by my claim. It's a function of gearing and the torque delivery, but I think it's much more common that optimal wheel tq is achieved by shifting most gears before peak hp.

My experience in the M3 has been that the lower gears feel sluggish at high revs, which is why I just assumed that you should also shift it before peak hp.
__________________
Drifty// is offline   United_States
0
Reply With Quote
      06-03-2012, 11:45 AM   #53
gblansten
Beandoc
 
gblansten's Avatar
 
Drives: 2014 BMW M5 SG/SS
Join Date: Sep 2007
Location: Thick ascending limb

Posts: 2,078
iTrader: (0)

Quote:
Originally Posted by Drifty// View Post
I'm still looking. I'm still in disbelief at the paucity of quality data on this subject, for the E92 M3.

For most other cars, I stand by my claim. It's a function of gearing and the torque delivery, but I think it's much more common that optimal wheel tq is achieved by shifting most gears before peak hp.

My experience in the M3 has been that the lower gears feel sluggish at high revs, which is why I just assumed that you should also shift it before peak hp.
If you want optimal shift points just be the passenger and watch the tach while the driver uses the launch control mode.
gblansten is offline   United_States
0
Reply With Quote
      06-03-2012, 12:22 PM   #54
Drifty//
First Lieutenant
 
Drives: A4 quattro 3.2 MT6; E92 6MT
Join Date: Mar 2012
Location: Boston

Posts: 310
iTrader: (0)

Quote:
Originally Posted by gblansten View Post
If you want optimal shift points just be the passenger and watch the tach while the driver uses the launch control mode.
I assume you're referring to DCT? Wouldn't help, since it has more gears with different ratios than 6MT.

Nice idea, however.
__________________
Drifty// is offline   United_States
0
Reply With Quote
      06-03-2012, 12:29 PM   #55
FJS
Private First Class
 
FJS's Avatar
 
Drives: M
Join Date: Jun 2011
Location: Somewhere

Posts: 135
iTrader: (0)

FJS is offline  
0
Reply With Quote
      06-03-2012, 02:10 PM   #56
Drifty//
First Lieutenant
 
Drives: A4 quattro 3.2 MT6; E92 6MT
Join Date: Mar 2012
Location: Boston

Posts: 310
iTrader: (0)

Quote:
Originally Posted by FJS View Post
Well, at least this thread is doing some good.
__________________
Drifty// is offline   United_States
0
Reply With Quote
      06-03-2012, 03:46 PM   #57
CanAutM3
Brigadier General
 
CanAutM3's Avatar
 
Drives: 2008 E92 M3 (2015 M4 on order)
Join Date: Jan 2012
Location: Montreal

Posts: 3,425
iTrader: (0)

Garage List
2008 BMW M3  [0.00]
2006 Audi S4  [0.00]
Quote:
Originally Posted by Drifty// View Post
I'm still looking. I'm still in disbelief at the paucity of quality data on this subject, for the E92 M3.

For most other cars, I stand by my claim. It's a function of gearing and the torque delivery, but I think it's much more common that optimal wheel tq is achieved by shifting most gears before peak hp.

My experience in the M3 has been that the lower gears feel sluggish at high revs, which is why I just assumed that you should also shift it before peak hp.
Maybe because M3 drivers understand that shifting BEFORE power peak is definitely NOT the way to go to maximize acceleration . With a power peak only 100 RPM below redline, shifting at redline in every gear is the way to go .

The graph from Radiation Joe indicates the same thing.

For the turbocharged N54 and N55 engines that have peak torque low in the rev range and peak power 1000-1500 RPM below redline, optimal shift points may not be at redline. This might be why there are so many threads on optimal shift points for these engines...

Last edited by CanAutM3; 06-03-2012 at 07:38 PM.
CanAutM3 is offline   Canada
0
Reply With Quote
      06-03-2012, 04:44 PM   #58
bruce.augenstein@comcast.
Lieutenant Colonel
 
Drives: Subaru Legacy GT
Join Date: Jul 2007
Location: Manheim, PA

Posts: 1,852
iTrader: (0)

Quote:
Originally Posted by Drifty// View Post
I'm still looking. I'm still in disbelief at the paucity of quality data on this subject, for the E92 M3.

For most other cars, I stand by my claim. It's a function of gearing and the torque delivery, but I think it's much more common that optimal wheel tq is achieved by shifting most gears before peak hp.

My experience in the M3 has been that the lower gears feel sluggish at high revs, which is why I just assumed that you should also shift it before peak hp.
You're confused because, in any given gear, a car will accelerate according to its torque curve, so it will accelerate hardest at the torque peak, and taper off as it closes in on the power peak and beyond.

However, at any given road speed, any car will accelerate hardest when it is at the power peak.

Shifting early drops you way down on the power curve, and if you insist on doing that torque-at-the-drive-wheels thing, you'll find that you are way off what the car is making at the power peak, and even beyond that by a certain amount, as I've mentioned.

The ideal shift point is when the car is making the same power after the shift as it did when you made the shift. That isn't possible in the M3 because the power peak and red line are so close together, but you'll need every one of those 8400 rpm in each gear for max acceleration.

This isn't opiniom. This is physics.

Bruce

PS - Go here for an explanation of power vs torque that may be of help.
bruce.augenstein@comcast. is offline  
0
Reply With Quote
      06-03-2012, 06:29 PM   #59
mkoesel
Moderator
 
Drives: IB/PS M-DCT E93 M3
Join Date: Jun 2006
Location: Canton, MI

Posts: 13,490
iTrader: (1)

Quote:
Originally Posted by Drifty// View Post
I had a much easier time finding this info on 135i, 335i, and several other cars. It started to give me the feeling like this board is full of posers. I know it's not, but then why is it so hard to find serious discussion of a topic that most serious car guys should care about?
Most of the discussions you are looking for took place years ago. I recommend google as a search engine to find some of the older posts simply because it is a bit easier to manipulate search parameters and find what you wish. In point of fact, the post that I took from RJ was actually a repeat post from an earlier, much more in depth thread that covered shifting points for M3 vs a number of other cars, including the 335i which I also owned at that time. Other discussions of M3 shifting strategies and acceleration characteristics have taken place as well.

This forum is full of excellent and accurate information, along with some very, very knowledgeable and experienced individuals. I hope you can appreciate the quality of the information available here. I would point out to you, in the friendliest manner possible, that a good attitude goes a long way toward getting good results.

Cheers
__________________
2008 Interlagos Blue E93 M3 - FOR SALE - Engine failure at 95k miles.
Best offer takes it: http://www.m3post.com/forums/showthr...1#post16279561
mkoesel is offline   United_States
0
Reply With Quote
      06-04-2012, 01:23 AM   #60
Drifty//
First Lieutenant
 
Drives: A4 quattro 3.2 MT6; E92 6MT
Join Date: Mar 2012
Location: Boston

Posts: 310
iTrader: (0)

Quote:
Originally Posted by mkoesel View Post
Most of the discussions you are looking for took place years ago. I recommend google as a search engine to find some of the older posts simply because it is a bit easier to manipulate search parameters and find what you wish.
I also did a bit of googling, but I will continue down that path.

Quote:
This forum is full of excellent and accurate information, along with some very, very knowledgeable and experienced individuals.
Yes, that's why I was surprised at the trouble I was having finding the kind of shift point data I expected, or even plain old raw wheel tq dyno plots.

Thanks for your advice.
__________________
Drifty// is offline   United_States
0
Reply With Quote
      06-04-2012, 01:27 AM   #61
White person
Private First Class
 
Drives: Jet black M3
Join Date: Apr 2012
Location: 61727

Posts: 128
iTrader: (0)

Quote:
Originally Posted by mot
Whenever the shift light tells me to shift
+1
White person is offline   United_States
0
Reply With Quote
      06-04-2012, 02:23 AM   #62
kchu221
JDM whore
 
kchu221's Avatar
 
Drives: 2009 Porsche 911 Turbo
Join Date: Jan 2012
Location: los angeles

Posts: 2,984
iTrader: (8)

what RPM's do yo guys shift at when first starting the car in the morning and driving slow till the oil temp is up and the engine is fully warmed up?
kchu221 is offline   South Korea
0
Reply With Quote
      06-04-2012, 03:18 AM   #63
duk
///M
 
Drives: 2011 AW/FR 6MT E92
Join Date: Jun 2007
Location: San Jose, CA

Posts: 2,915
iTrader: (0)

Quote:
Originally Posted by kchu221 View Post
what RPM's do yo guys shift at when first starting the car in the morning and driving slow till the oil temp is up and the engine is fully warmed up?
just revving it slower up to 4.5k rpms til full warm up is good
__________________
2011 AW/FR 6MT E92 | Powered by Premier | Alekshop | ESS |
Rok n Peace Clothing: www.roknpeace.com

duk is offline   United_States
0
Reply With Quote
      06-04-2012, 10:51 AM   #64
kchu221
JDM whore
 
kchu221's Avatar
 
Drives: 2009 Porsche 911 Turbo
Join Date: Jan 2012
Location: los angeles

Posts: 2,984
iTrader: (8)

Quote:
Originally Posted by duk View Post
just revving it slower up to 4.5k rpms til full warm up is good
thanks man!
kchu221 is offline   South Korea
0
Reply With Quote
      06-04-2012, 11:22 PM   #65
Drifty//
First Lieutenant
 
Drives: A4 quattro 3.2 MT6; E92 6MT
Join Date: Mar 2012
Location: Boston

Posts: 310
iTrader: (0)

Quote:
Originally Posted by kchu221 View Post
what RPM's do yo guys shift at when first starting the car in the morning and driving slow till the oil temp is up and the engine is fully warmed up?
I don't move the car until revs @ idle drop below 1k. Then, I keep it below 2k until oil temps are at about the 1/4 mark (sorry, forget what temp that is). Then I rev up to 3k until the oil temp gauge is in the middle. Of course, I will go above those points as and when situation demands it.

Aside from tracking your car, the biggest risk to your engine is probably romping on it while it's cold.
__________________
Drifty// is offline   United_States
0
Reply With Quote
      06-05-2012, 07:53 AM   #66
hieu1004
Second Lieutenant
 
hieu1004's Avatar
 
Drives: Space Gray e92 M3
Join Date: Feb 2012
Location: Bothell, WA

Posts: 223
iTrader: (0)

Quote:
Originally Posted by kchu221 View Post
what RPM's do yo guys shift at when first starting the car in the morning and driving slow till the oil temp is up and the engine is fully warmed up?
I keep it below 3k until up to operating temp.
hieu1004 is offline  
0
Reply With Quote
Post Reply

Bookmarks

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -5. The time now is 07:20 AM.




m3post
Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
1Addicts.com, BIMMERPOST.com, E90Post.com, F30Post.com, M3Post.com, ZPost.com, 5Post.com, 6Post.com, 7Post.com, XBimmers.com logo and trademark are properties of BIMMERPOST