335 - where in the RPM band is the engine the strongest

bones · 06-13-2013, 09:24 PM

I've got an AT w/ paddles. Yes, I know the computer shifts better than I do but sometimes using the paddles is fun.

Where are the optimal starting and ending points on the tach? ie, if I'm rolling and want to accelerate as fast as possible what RPM do start in and where do I upshift?

KevRyd · 06-13-2013, 09:37 PM

Turbos kick in around around 2500 and the pull is strong from that point on, I usually upshift before 6000. I think the Comp ups at around 5500

Kevin

Quote:

Originally Posted by bones

I've got an AT w/ paddles. Yes, I know the computer shifts better than I do but sometimes using the paddles is fun.

Where are the optimal starting and ending points on the tach? ie, if I'm rolling and want to accelerate as fast as possible what RPM do start in and where do I upshift?

BmwF30alpine · 06-13-2013, 10:26 PM

Quote:

Originally Posted by KevRyd

Turbos kick in around around 2500 and the pull is strong from that point on, I usually upshift before 6000. I think the Comp ups at around 5500

Kevin

+1

Roki_014 · 06-13-2013, 10:36 PM

Quote:

Originally Posted by KevRyd

Turbos kick in around around 2500 and the pull is strong from that point on, I usually upshift before 6000. I think the Comp ups at around 5500

Kevin

If ur in sport mode and u floor it, it shifts right before redline

drob23 · 06-14-2013, 07:41 AM

Most of these high performance FI engines are designed from the factory to protect themselves in the high-end of the RPM band - wastegate bleeds off boost as seen here

source here: http://www.f30post.com/forums/showthread.php?t=652127

If you want to calculate the optimal shift point, you'll map a function of geared torque/power (since different gears will give you different mechanical advantage) vs ground speed. An example will be here:

If it turns out that you should always just shift at redline, then you'd see a figure like this:

My guess is that in low gears the best solution is to shift at redline while later on it might change since the engine dyno tapers off and the differences in relative mechanical advantage are not that great amongst the higher gears.

Elk · 06-14-2013, 04:59 PM

For greatest acceleration, you want to maximize the area under the torque curve. Typically, this means running the RPMs just passed peak torque and then shifting.

You need to know both the shape of the torque curve and the amount of RPM drop for each shift. Each shift may thus be different.

Shifting at redline is often not the fastest.

06-13-2013, 09:24 PM	#1
bones Private First Class 123 Rep 180 Posts Drives: 2020 M340 RWD Join Date: Sep 2008 Location: Boston iTrader: (0)	335 - where in the RPM band is the engine the strongest I've got an AT w/ paddles. Yes, I know the computer shifts better than I do but sometimes using the paddles is fun. Where are the optimal starting and ending points on the tach? ie, if I'm rolling and want to accelerate as fast as possible what RPM do start in and where do I upshift?
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06-14-2013, 07:41 AM	#5
drob23 Lieutenant Colonel 50 Rep 1,730 Posts Drives: S4 Join Date: Oct 2012 Location: Michigan iTrader: (1)	Most of these high performance FI engines are designed from the factory to protect themselves in the high-end of the RPM band - wastegate bleeds off boost as seen here source here: http://www.f30post.com/forums/showthread.php?t=652127 If you want to calculate the optimal shift point, you'll map a function of geared torque/power (since different gears will give you different mechanical advantage) vs ground speed. An example will be here: If it turns out that you should always just shift at redline, then you'd see a figure like this: My guess is that in low gears the best solution is to shift at redline while later on it might change since the engine dyno tapers off and the differences in relative mechanical advantage are not that great amongst the higher gears. __________________ UNDRSTR
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06-14-2013, 04:59 PM	#6
Elk Major 32 Rep 1,285 Posts Drives: 2012 335i Join Date: Apr 2012 Location: * iTrader: (0)	For greatest acceleration, you want to maximize the area under the torque curve. Typically, this means running the RPMs just passed peak torque and then shifting. You need to know both the shape of the torque curve and the amount of RPM drop for each shift. Each shift may thus be different. Shifting at redline is often not the fastest.
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