Gears While Racing.

[PuShAkOv]

Hello.. I am starting to only drive in (fake) manual on my 330CiC and I have this question:

While Racing (from start) . . .

1. Is it better to switch gears at 3.5~4.5 or 5.0~6.0 ?

I just think that REVing too high on lower gears will set you back compared to switching earlier and getting to higher gears.

2. Should I just leave it in a SPORTS MODE when starting a race and let my car switch the gears?

Thanx!!

 

[brahtw8]

You should be aware of my reply in this thread, as you were a part of the thread:

http://www.bmwboard.com/forum/showthread.php?s=&threadid=2231&highlight=shift+at+redline

That thread contains all of the information you seek.

To fully answer your question you need a graph of your engine's powerband, the gear ratios for each gear, and the final drive ratio.

I would expect that your 1-2 shift should occur between 6000-6300 rpm for max use of the powerband, and each successive shift would go down 1-200 rpm as you went higher.

One thing to remember is that the lower gear puts more power to the wheels at a given RPM. In other words, the car accelerates more at 5000 rpm in 2nd than at 5000 rpm in 3rd. This is because 3rd spreads the power over a greater mph range than 2nd does.

Here is a simpler explanation: Figure out where your engine makes peak torque, and try to upshift at an rpm that puts you at peak torque in the next gear. I would guess peak torque on a 330 is around 3800-4000 rpm.

 

[codex57]

People who race in Steptronic say that driving in Sport mode with the DSC off results in fastest times. Shifting manually in fake manual mode is slower than letting the computer do it itself.

 

[PuShAkOv]

Thanx.. I lost track of the thread.

 

[Wadula]

i made a funny observation. our 540 has the steptronic, too and the sports mode etc. now, when i floor the car the engine revs to red line and then the gearbox changes the gear. according to brahtw's explanation which is just right of course, the electronic should be intelligent enough to switch the gear at the right point. now is it perfect engineering that the best shifting point is red line or is the electronis dumb?

 

[brahtw8]

i made a funny observation. our 540 has the steptronic, too and the sports mode etc. now, when i floor the car the engine revs to red line and then the gearbox changes the gear. according to brahtw's explanation which is just right of course, the electronic should be intelligent enough to switch the gear at the right point. now is it perfect engineering that the best shifting point is red line or is the electronis dumb?

I think steptronic was designed to hold the gear until redline on purpose, as many people complain when the automatic does not hold the gear all the way. I would expect that you could let off the gas when you reach the 'sweet' spot in a particular gear and the car would downshift at that time. However, that approach may not result in a faster time than letting the steptronic shift at redline, as letting off the gas to get it to shift may slow you down.

Automatics complicate the issue for a variety of reasons. You should experiment with a variety of approaches and find the one that is right for you.

One thing to remember is that if the gears are spaced far apart, you will want to shift at redline, because the shift at redline will take you below the powerband in the next gear. That may be the case with your 540. The gears have to be close enough that redline in 2nd corresponds to above the power band in 3rd (for example) before you need to worry about shifting a little before redline.

 

[Wadula]

gears at that car are of course far spaced. it is designed for comfort. a big point in comfort is little shifting. as the engine has loads of torque you can afford to stay in one gear along a wide range of tempi. due to that i would make it a wide spaced gear box too.

for the shifting spot, the S mode should not bother customers opinions. however i understand that for regular kickdown the driver expects super high revs, but when somebody drives in S mode on purpose this purpose is being fast and then he should trust the car.