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04042012, 05:12 AM  #45 
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Just cruising 2.5k3.5k, when my foot gets heavy is a different story
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06022012, 09:47 PM  #47 
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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.
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06032012, 07:35 AM  #48  
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If traction is not an issue, then shifting @ redline is indeed the answer for optimal acceleration.
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06032012, 10:04 AM  #49 
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I shift at the the lowest rpm possible to keep obnoxious engine noise to a minimum.
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06032012, 10:48 AM  #50  
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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:
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 onetwo 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 

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06032012, 11:25 AM  #51  
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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.
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06032012, 11:37 AM  #52  
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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.
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06032012, 11:45 AM  #53  
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06032012, 12:22 PM  #54  
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Nice idea, however.
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06032012, 03:46 PM  #57  
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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 10001500 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; 06032012 at 07:38 PM. 

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06032012, 04:44 PM  #58  
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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 torqueatthedrivewheels 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. 

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06032012, 06:29 PM  #59  
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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
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06042012, 01:23 AM  #60  
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Thanks for your advice.
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06042012, 02:23 AM  #62 
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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?

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06042012, 03:18 AM  #63 
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just revving it slower up to 4.5k rpms til full warm up is good
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06042012, 11:22 PM  #65  
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Aside from tracking your car, the biggest risk to your engine is probably romping on it while it's cold.
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06052012, 07:53 AM  #66 
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