This time, one more example of how you can manipulate the data. And not only. But – about everything in a row.
Here, a ”reputable” chip tuner posted a photo of an “upgraded” car with the caption: “Here, watch and learn!” 200Nm of torque (from 450Nm to 650Nm) is gained!
Although the vertical-axis division is not visible, simple math shows that it is 30Nm.
Looking at this image, I have several objections.
First, the initial torque looks like an engine with 500Nm of torque (for example, G series M540i of the first years).
Second, as we see, BMW offers a small “bonus”: the torque plateau is around 530Nm (+30Nm above the promised level), which the stand shows as “additional power”.
Do you see how the gained 200Nm has reduced? Already, only around 120Nm are left. But let’s see more!
If we pay attention to the middle part of the graph, we see that the gain of the torques is only 60Nm! More than three times worse than promised in the advertising.
Why do I look at the middle of the graph, not the “pump” at the lowest RPM range of the torque curve? I have an explanation:
a. on the go (if the vehicle is equipped with an automatic gearbox), this range will NEVER be used! As soon as the owner of the car requires larger torque, the gearbox will switch to a lower gear/larger RPM!
b. When starting the drive, everything depends on the start sequence, but my humble experience says – if there were no Launch control, the time turbolag will not allow the turbo spin so fast to reach 600+Nm before the RPMs have not reached over that “pump”.
c. if the car is equipped with the manual gearbox, when starting the movement in the 1st gear, RPMs grow so fast/the turbo comes in with such a delay that its flowrate does not even reach 500Nm, not even talking of 600Nm or more! Instead, (manually) switching to the 2nd and next gears, the RPM of the engine has long outreached this torque “pump”.
d. If with a car, which has a manual transmission, you decide to use the range of the low RPMs, again, the RPMs in 2nd – 3rd gear are growing faster than the turbo can “squeeze” the necessary boost pressure to reach those 600+Nm. Instead, if we use 4th to 6th gears, you can accelerate much faster by shifting to a lower gear (not waiting for the “eternity” when the torque “pump” appears).
Yes, the tuner opposed – the torque of the car is always measured on the stand! True. But the car is used on the street, in completely different conditions. On the stand, the slow RPM “spinning” happens, for example, in the 3rd gear, on the street, much faster “spinning”. On the stand, the car is “spun” in around 6 .. 10 seconds, but in actual conditions, such a car “passes” the 1st gear during 1. X seconds, 2nd gear in 2. X seconds! The first two gears are “spun” in around 4 seconds, including the switching of gears! This is a RADICALLY different situation!
My assessment of such “chippers” showing the highest torque in the low RPM range is that it’s not pretty. It is not correct. Yes, formally the number looks nice, but – it’s on the verge of cheating. In addition, this time, an additional 80Nm is “cheated” to the already pushed number!
In their documents, BMW indicates that, for example, for the F series, the torque in the 1st gear is reduced to 440Nm to not overreach the allowed load to the running gear. If we assume that such 650Nm torque is real, is it safe for the running gear? + around 40% torque? No, it’s not the “reserve” of 10% anymore!
Another obstacle, which allows additional reserves in the upper range of the RPM, is the target Lambda reduction from 1.00 to 0.95 .. 0.90. Yes, the combustion temperature is lowered, and all air is used more efficiently. Why doesn’t BMW do this? There are two counterarguments:
a. emission standards. Yes, this is where the chip tuners seem to have a chance to express themselves.
b. load of the CO catalytic converters. If we allow such a lowered Lambda, it means the catalytic converter is saturated with the fuel. If, after such a kickdown, the overrun follows (logical option – after the spurt, the braking with the engine is done), the air is blown into the catalytic converter. Air + fuel = combustion process starts. Here, one of the reasons for the short life of the catalytic converters!
And I have objections regarding this RPM range – my cars (yes, equipped with manual gearbox) logs on the go (it means, REAL conditions) indicate that in the 1st and 2nd gears in 5000 .. 7000 RPM range the WG is closed. It means – there is no reserve even in perfect conditions. Yes, starting with 3rd gear, a slight reserve appears (it means, in speeds of 130 km/h and more). Unfortunately, in the 3rd gear, this slight reserve “melts” in the mountain area, in the summer, in hot, dry weather. And this is all due to the mechanical inertia of the turbo! We can hope on the 4th and next gears, which means, in speeds around 170 km/h and more. Yes, if the race is happening with 100 .. 200 km/h, it means something, but until reaching 100 km/h, it is useless. Although when slowly “spinning” the car on the stand, everything looks excellent!
Yes, for the cars with an automatic gearbox, the situation is better, without a doubt. This time, I emphasised the topic – when I talked about his topic (the significantly different situation in a car with a manual vs. automatic transmission) with a tuning specialist, he did not understand these nuances.
Sentence of this entry: unfortunately, you can not believe nice numbers. The situation in real conditions is fundamentally different from beautiful stand printouts. Unfortunately, a significant increase in the torque reduces the longevity of the transmission and running gear, but the rich fuel mixture in the kick-down mode is deadly to the CO catalytic converter. This time, the saying about free cheese in a mousetrap is really appropriate!
