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      09-10-2019, 08:00 AM   #9
Second Lieutenant

Drives: M240i xdrive Convertible
Join Date: Apr 2017
Location: NJ

iTrader: (0)

Originally Posted by zinner View Post
The aftermarket calibration gives you more boost/tq down low, just take a look at a dyno graph, it's a huge uptick in boost/power down low. Given the initial post it looks like the engine is spinning around 2600 rpm if you do the math. If you take the PTF provided dynos that around 90-100+ tq over stock. It is ~25% more tq than stock at a low RPM it's just lugging the motor with not a lot of gearing advantage (1:1 in 5th gear). The stock tune won't let you do that because well it's not good for the powertrain. Just take a look at a stock vs tuned dyno, the tq increase with a tune is 25% more over stock about 1/2 the rpm window stock takes to develop less tq. Is it good to have that huge hit of TQ down low? Sure. Is it good in 5th gear @ 60mph to exercise that extra power no.

BMW has that kick down switch automatic transmissions thing they do, I dunno why probably something lame like MPG or emissions. Just click down a gear or two or just pedal to the metal and let the transmission shift.
What you are describing is the torque after tune being higher than the transmission limits (which a transmission tune would raise). Has nothing to do with lugging .... unless you drive stick or overwrite the auto to fully manual control (which the OP didn’t do) you can not lug an engine (as the auto would downshift if the rpm is getting too low)
And torque at low rpm being a problem? Look at a Diesel engine and how it develops torque and you see that the same transmission in the same car with a Diesel engine has to “suffer” higher torque stock.
The problem is again mostly with stick or fully manual auto as in case of WOT the trans wouldn’t downshift but stay in the rpm range which has the highest torque .....

Last edited by marcthedark; 09-10-2019 at 08:05 AM..