SilberGrauE60

Where can I find the performance in each gear for the 2004 545i 6-speed manual. The following table is from Car & Driver for the 2004 530i 6-speed manual, but I do not believe they are the same based on a test drive I made. I would like to have my observations confirmed...

DRIVETRAIN
Transmission: 6-speed manual
Final-drive ratio: 3.15:1, limited slip
Gear ... Ratio ... Mph/1000 rpm ... Max. test speed
I ... 4.35 ... 5.4 ... 35 mph (6500 rpm)
II ... 2.50 ... 9.4 ... 61 mph (6500 rpm)
III ... 1.66 ... 14.2 ... 92 mph (6500 rpm)
IV ... 1.23 ... 19.1 ... 124 mph (6500 rpm)
V ... 1.00 ... 23.5 ... 149 mph (6350 rpm)
VI ... 0.85 ... 27.7 ... 149 mph (5400 rpm)

dlevi67

In theory - based on standard 225/45 17 tyres, speed in gears should be as per Car & Driver table (actually, 5th and 6th should top out at 150 using those values), given those rpm figures.

"Performance may vary" only because:

1. Rev limiter may cut you off before 6500 (I can't redline my auto 535d, no matter how hard I try, in any gear between 1 and 4, and there is never enough space to try it in 5 or 6) and or vMax is hit.
2. Tyre size changes
3. Worn out clutch (slipping)

Otherwise, there is not much left. In which ways were your observations during the test ride different from the table?

dlevi67

Actually - I misread your post; what you have are 530i gear ratios (and probably there are subtle differences between US and Europe and/or years among those, as they don't match my brochure!). For a 2006 550i (don't have a 545, sorry!) the table would look like this:

1 4.06 6300 39
2 2.40 6300 67
3 1.58 6300 101
4 1.19 6300 134
5 1.00 6100 155
6 0.87 5350 156

assuming nominal Vmax of 155, final drive ratio of 2.93 and standard tyres.

Ray Hull

I would add, considering your address, that your results may vary due to altitude. Dunno anything about it other than magazine test location altitude used to be listed, way back when. But maybe that's for carburated engines only. But if anyone's going to notice it, it'll be you.

Cheers,
Ray Hull

heezy545i

The maximum mph in each gear depends on the gearing and should be the same regardless of the altitude.

UUronL

Search out a thread about a Dinan differential - I posted the formula I used to factor the speeds in each gear for a 545i - Dinan vs. stock rear diff.

cobradav

Here is your chart

EBMCS03

Cool thanks for the chart. So I can only reach a max of 179 mph huh given that the engine doesnt go KA-BOOM? BLAH.

SilberGrauE60

Thanks for your posts.

My observations were closer to the ones predicted in cobradev's chart than dlevi67's. I observed 140+ mph in 4th gear at 6500 rpm. Cobradev's chart predicts 141.808 mph at 6500 rpm while dlevi67's chart predicts 138.254.

The "max speed" in the computer was set to 120 mph by the previous owner, so that didn't do any good. Since then, I have reset the max speed to 140 mph and will await my next test run for verification. I will also have my Garmin StreetPilot record the max speed the next time out.

My car has 22,000 total miles, but the Dunlop run flats are new due to recent Certified Pre-Owned purchase. This car is a blast, esp. in the Colorado mountains!

dlevi67

You are welcome.

Two points:

1) I am puzzled as to why there is a difference at all, unless it's just a rounding error; I took rounded values to the nearest mile. Both tables should use the same formula - I just have given you one speed corresponding to max power rpm and for the 545 manual only

2) remember that there is a ~2-3% difference between "true" speed (which both tables give, plus or minus errors of non-circularity in the wheels) and speedo indicated speed. So the indicated 141 is probably an actual 138...

BTW - for those who are interested: the formula is:

V = rpm / (60 * g * f) * pi * (2 * Ts/1000 * Ta + 0.0254 * R) * 3600/(1000 * 1.609)

where:

V = theoretical speed in mph
rpm = engine speed
g = gear ratio
f = final ratio
pi = 3.14
Ts = tyre size in mm (i.e. the 225 in 225/45 R 17)
Ta = tyre aspect in % (i.e. the 45 in 225/45 R 17)
R = rim diameter in inches (i.e. the 17 in 225/45 R 17)

The numbers are just converting units in other units:

60: seconds in a minute
1000: millimetres in a metre
0.0254 = metres in an inch
3600 = seconds in an hour
1000 = metres in a kilometre
1.609 = kilometres in a mile

If you want a slightly shorter formula, then

V = rpm / (g * f) * pi * (2 * Ts/1000 * Ta + 0.0254 * R) * 0.03729

simply substitutes many of the unit conversion factors for a single one.