Think I surprised an M4 driver.......

Jasey said:
jimmybell said:
Always thought April Fools finished at midday...

to be honest the only person who could be construed (incorrectly) as arguing, would be me, by daring to question how this situation outlined by OP is possible ... Id probably categorise 'how fast it is' as an aspect of ownership worthy of discussion.

Personally i'd quite welcome some graphs to explain how it's feasible that under full load an M4 would lose to a 35is - not so fussed about the diesel though :D

:fuelfire:
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Here's a diagram showing the only way the 35is will beat an M4.

bmw-m4-crash-ditch-750x500.jpg
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Haha! True, there is a tuned 1M (around 400) on youtube which is left standing by the new M3.

Or maybe you just need a few tweaks to the n54 to get this...;)

753whp, beast!

10365582_10154207514130294_4037559872130786187_o.jpg
 
:rofl:

My friend has an M4 and my 35is kept it honest almost everywhere, albeit mapped..


The M4 can be a monster when all the stars align, traction being a big problem..
 
Z4M-2006 said:
:rofl:

My friend has an M4 and my 35is kept it honest almost everywhere, albeit mapped..


The M4 can be a monster when all the stars align, traction being a big problem..
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So we've done a complete round circle, and I've put a deposit on a 435d xi :rofl:
 
So what happens when you floor the throttle at 30mph 35iS & 335dX in comfort with the ‘box in D when side by side? Well in the first 15~20 meters the 335dX steels a bit of a march on the 35iS, it edges the bonnet about 1 meter ahead… but now the 35iS’ DCT box is in 2nd and in the words of Chris Harris - It’s an annihilation. At the 250m mark there’s about 15m clear space between the cars, by 500m this is over 40m & it manages over 100 meters at the 1km mark.

PS. Anyone else find their car in 6th when doing 30mph in D? About 1100 rpm seems low to me & certainly makes the DCT box very sluggish to kick down. Changing down into 5th before letting rip gives a much faster kick down change.
 
I never both with kickdown.It usually revs the car above its powerband and is pretty brutal on the gearbox. In fact I have it disabled on my car.

You want to be changing gear at 6.2k rpm in these cars.

Is kickdown some sort of bullshit safety feature enforced on manufacturers of automatic cars?
 
It puts no more load on the gearbox than a manual change down or indeed considerably less than somebody who dumps the clutch !

You should always catch the last bit of the power curve on a petrol engined car on a kick down change.
 
ronk said:
It puts no more load on the gearbox than a manual change down or indeed considerably less than somebody who dumps the clutch !

You should always catch the last bit of the power curve on a petrol engined car on a kick down change.
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Anyone with a highly tuned DCT car will tell you othewise. Start using kickdown and you get serious clutch slip and temp warnings.

Even on a stock car you can feel the slip on engagement. There's a reason they sell kickdown blockers by the thousands on this platform, not just for the DCT but on the slushbox in the rest of the N54 cars purely because you hit kickdown and it revs up to 6k and changes at the line.
 
R.E92 said:
ronk said:
It puts no more load on the gearbox than a manual change down or indeed considerably less than somebody who dumps the clutch !

You should always catch the last bit of the power curve on a petrol engined car on a kick down change.
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Anyone with a highly tuned DCT car will tell you othewise. Start using kickdown and you get serious clutch slip and temp warnings.

Even on a stock car you can feel the slip on engagement. There's a reason they sell kickdown blockers by the thousands on this platform, not just for the DCT but on the slushbox in the rest of the N54 cars purely because you hit kickdown and it revs up to 6k and changes at the line.
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Kick down is not good because it forces maximum torque in the least mechanically sympathetic way possible. I cringe when I use it by accident - but I wonder if I can code the overboost to work without it. I guess it doesn't matter when I get MHD stage 1 anyway ...

Much better to be in complete control of the gears and floor it when you're ready.

Ronk, think about the situation you're in a manual, in 3rd, and you floor it - gears are already engaged, clutch isn't "active"
DCT, you floor it, then it starts changing gear, and sometimes not just 1 gear, it could be 4-5 gears! Hence the massive gearbox temp increases when using kickdown. Can you imagine the mess you'd make in a manual car doing that - not good. :thumbsdown:
 
Oddly enough I had one time when I the box overhearing and that was when I ended up doing 3 near WOT or at WOT rapped fire 4/5 gear down shifting in a row overtaking cars. Using kick down in similar situations has NOT overheated the gearbox. Now I don't use the 'box in auto and just manual mode at all.

As for changing at 6.2k. Not according to the thrust graphs in 1t, 2nd & 3rd
 
Depends how you're shifting. If manually, then doing 4 or 5 low-load changes then flooring it doesn't put nearly as much load on the gearbox. However, when auto shifting you need to have the engine under high-load for it to do rapid fire changes, in such cases a single change is less stressful than multiple changes.
 
techathy said:
Oddly enough I had one time when I the box overhearing and that was when I ended up doing 3 near WOT or at WOT rapped fire 4/5 gear down shifting in a row overtaking cars. Using kick down in similar situations has NOT overheated the gearbox. Now I don't use the 'box in auto and just manual mode at all.

As for changing at 6.2k. Not according to the thrust graphs in 1t, 2nd & 3rd
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I personally haven't done the testing to confirm but it's just one of those bits of information I've picked up.

The engine tapers off the boost really heavily beyond 6k revs. It's been done to death already across most forums, a quick google for N54 optimum shift points shows how much the horse has been beaten!

Here's the engine load targets on the 1M, should be similar on the 35is.


One of the benefits of a tune is that you can alter the power curve to your own liking. An optimum tune would always be stronger in the midrange as the stock tubos cant move enough air up top but you can sacrifice a little midrange power to get that nice linear feel.
 
I agree with the boost tapering off at 6k, or even 4.5k on overboost.

I'll not repost the graphs but if you look at the non-overboost thrust graph on 6k torque drops off but in the first 3 gears there’s no thrust overlap. On over-boost graph the first 2 gears have no meaningful overlap, from 3rd gear on the choice of gear gets rather complicated with the power being developed over a wide rev band of being effectively the same unless you’re going for every last 100th of a second. Of course this is all based on one car which was noted held on to power better than other cars with the N54TO engine.
 
techathy said:
I agree with the boost tapering off at 6k, or even 4.5k on overboost.

I'll not repost the graphs but if you look at the non-overboost thrust graph on 6k torque drops off but in the first 3 gears there’s no thrust overlap. On over-boost graph the first 2 gears have no meaningful overlap, from 3rd gear on the choice of gear gets rather complicated with the power being developed over a wide rev band of being effectively the same unless you’re going for every last 100th of a second. Of course this is all based on one car which was noted held on to power better than other cars with the N54TO engine.
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I think you're right that the first 2 gears you can hold 'til the line without worrying. For the rest I think you want to shift early. The yanks are drag strip mad and have done a few timeslip comparisons between shift points on E90post.

Found a good post about it by Mr.5 here: http://www.e90post.com/forums/showthread.php?t=433394

There's a little research going on behind the scenes for MHD flasher, investigating the possibility of modifying to TCU code purely to allow people to customise the shift points of the engine.
Also to change the RPM for launch control. Our current 5k RPM launch control is junk!
 
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