DSC off = +5% to 10% power gain!!!!!

[Arxangel]

First and foremost, I would like to say that I am NOT starting this thread with the intent of posting misleading information. I would like to discuss the plausibility of this statement and if someone can even provide evidence for or against this claim, I would be most grateful.

So to begin, over the past 6 years I have driven pretty much only diesel BMWs, except when test driving a car, and during the summer I drive with the DSC switched off all the time, even in rain. Driving with the DSC off for such a long time, here in Bulgaria the period is close to 7 months, I get used to the car accelerating a certain way. In mid Autumn I stop switching the DSC off. At this point I notice that the car's acceleration is, at least to me, slower and although not by much I can still tell that there is a difference. I am not sure how it is with the petrol engines. I currently drive my 3.0si with the DSC on seeing as it is winter.

I have talked to my dealership's Service Center Manager and the Sales Manager, they both have worked there for over 20 years BUT one drives very calmly the other likes to raise his adrenalin. So the calm driver says that he has rarely turned the DSC off and even when he did, he was not able to find a difference in acceleration. I am inclined to think that when you drive in a calm manner, i.e. normal driving, it is much more difficult to detect such a change in performance, especially when you are not looking for it. The adrenalin seeker confirmed that the car should go faster when the DSC is off. He also said that he does not turn if off very frequently, but when he does he can feel the difference. He also said that BMW programmed their DSC system to actually reduce the engines power between 5% to 10% when it is on in order to help it manage the car's performance better and prevent under/oversteer easier.

I would like to ask, since the Z4 comes only with petrol engines, whether anyone else has looked into this and maybe even tried it to see if there really is a difference.

[O-cha]

False, not worth providing any evidence to prove it's falseness.

[Arxangel]

Originally Posted by O-cha

False, not worth providing any evidence to prove it's falseness.

You mean false for petrol engines only, or you think also false for the diesels?

[r4gs]

have not heard of this before, even though some of the reasoning makes sense. going with o-cha here, do not think dsc intentionally reduces engine power output be it a diesel or petrol motor.

if i remember correctly, there was an extremely informative thread around here tt detailed everything to know about dsc....

[dazed^]

Perhaps the misunderstanding is coming from the way in which the DSC 'emulates' an LSD in the non-M cars? It does so by briefly reducing power (I read this here somewhere but can't find the thread atm). But that's not happening continuously, of course.

[pokeybritches]

That's why we were telling you to spend your money on a LSD. On your car as it is now, once the wheel with the least traction starts to slip the engine cuts torque. So yes, you do see less power, but only when a wheel is slipping. If no wheel is slipping you see the same power as if DSC is off. Do a google search for some info on the DSC. Once a wheel starts to slip the system applies its individual brake. If your rear wheels are slipping it's usually because you are on the throttle (during daily driving). Typically when I'm on the throttle it's because I want to go faster, not put on the brakes.

With a LSD, the system will intervene less often if you have some static lock. But that's more of a perk than the reason to get a LSD. With DSC off you'll notice a huge difference in the ability to put power down, especially when coming out of a corner.


On the M the system will mildly intervene without flashing the traction control light, and the only indication it's active is the loss of torque.

Summary - With DSC on, you will see a loss of power if a wheel starts to slip. Your wheels will slip less often with a LSD in the back.

[Arxangel]

Originally Posted by pokeybritches

That's why we were telling you to spend your money on a LSD. On your car as it is now, once the wheel with the least traction starts to slip the engine cuts torque. So yes, you do see less power, but only when a wheel is slipping. If no wheel is slipping you see the same power as if DSC is off. Do a google search for some info on the DSC. Once a wheel starts to slip the system applies its individual brake. If your rear wheels are slipping it's usually because you are on the throttle (during daily driving). Typically when I'm on the throttle it's because I want to go faster, not put on the brakes.

With a LSD, the system will intervene less often if you have some static lock. But that's more of a perk than the reason to get a LSD. With DSC off you'll notice a huge difference in the ability to put power down, especially when coming out of a corner.


On the M the system will mildly intervene without flashing the traction control light, and the only indication it's active is the loss of torque.

Summary - With DSC on, you will see a loss of power if a wheel starts to slip. Your wheels will slip less often with a LSD in the back.

Nice info, but I do know how DSC works and that's fine. I am referring to the differences in the amount of pull the car seems to have when DSC is on or off WITHOUT one or both wheels slipping. We are talking about the right amount of throttle in both states, that will let you accelerate as fast as possible without slipping.

It is interesting that other people driving BMWs, as I have described in the first thread (there are other examples too), have also felt differences with DSC on and off.

Actually, the power gain for NA petrol engines might not even be as high as 5%, due to the lack of a turbine, but even 2% might be noticeable in certain situations.

[pokeybritches]

There is no difference in your engine's power with DSC on or off.

[Arxangel]

Originally Posted by pokeybritches

There is no difference in your engine's power with DSC on or off.

OK

[esqu1re]

Pure placebo effect of having DSC off. Funny how our brains work.

[johanness]

Placebo, yet still the DSC goes off and the SPORT button goes on - each an every time I get in the car. (unless it's raining heavy etc)

Don't most people go thru the same procedure? I dislike nannies and like the edginess it provides.

[mfanatic325]

I don't know about DSC on vs. off, since I had no choice when doing my dyno (DSC on = impossible to put down maximum power, since system will try to brake wheel(s) individually as it thinks it's losing grip while on the dyno).
However, I do remember that when I tried Sport mode vs. non-Sport mode, the #'s were actually higher without Sport mode on. Very peculiar

edit: HOWEVER! I always did non-Sport mode runs first, followed by Sport mode run after, so that may have affected the overall #'s due to heat?

[Arxangel]

Originally Posted by esqu1re

Pure placebo effect of having DSC off. Funny how our brains work.

I am not sure how many of the people on this forum, seeing how Z4s are only petrol and that diesel is not all that popular in the US yet, have driven a diesel BMW, but honestly I can swear that there is notable difference in pull when the DSC is off on DIESEL BMWs.

[FerRrari]

Sport mode and DSC have nothing to do with the engine.

[FerRrari]

Originally Posted by johanness

Placebo, yet still the DSC goes off and the SPORT button goes on - each an every time I get in the car. (unless it's raining heavy etc)

Don't most people go thru the same procedure? I dislike nannies and like the edginess it provides.

if DSC is engaging while regular driving maybe you should slow down a bit...

[johanness]

It's not engaging at all. I just have always switched it off to allow me to control the car fully. If conditions warrant it, it goes back on. It think ur missing my point Ferrari

[mfanatic325]

Originally Posted by FerRrari

Sport mode and DSC have nothing to do with the engine.

But they definitely have a lot to do with how power is put down to the ground.
In any case, I'm still unsure about DSC vs. non-DSC
Likewise with Sport mode vs. non-Sport

^ all in-terms-of/with-respect-to overall power output to the wheels.

[pokeybritches]

I leave DSC on in the M because it's more lenient. I've almost gotten into trouble with it active in the 3.0i. I pulled out into traffic, stomped it, and torque was cut almost completely for what seemed like an eternity. Now I press the button once so that DTC illuminates in the cluster.

[Arxangel]

Originally Posted by pokeybritches

Now I press the button once so that DTC illuminates in the cluster.

I do that when I want to make short easily controlled slides when turning in the city. The asphalt here in Sofia is so worn out that it is not at all difficult to power slide through a turn, the DTC just keeps the car from getting overly excited.

[mfanatic325]

I track with DSC off; always. But I personally prefer the full rev range, so I don't use Sport mode often at all.

[ZStig]

Originally Posted by FerRrari

if DSC is engaging while regular driving maybe you should slow down a bit...

ok grandpa!

[Arxangel]

Originally Posted by Roffle Waffle

ok grandpa!