Hi all,
My 520i Auto performance, I know it is very modest compared to your cars, but anyways :

The time was recorderd as an average of the same strip of road on two ways (go and return) to eleminate the effect of wind and/or inclination of the road. Power braking applied with DSC off. The temperature was 21 deg C (69.8 F), the altitude from sea level is around 60m.

0-62 mph: 9.86 s
0-100 mph: 24.22 s
0-1000 m: 31.46 s

All of these numbers are faster than what BMW claims . Maybe due to the low temperature (21 C), or is it possible that my car is faster than average?

 

Hi Shebs:

How did you record your passes? And, what does BMW claim for your car? I hope that all of your car problems have been sorted out. Also, your altitude and temperature don't appear to be too far from "standard." So, hopefully, your car is faster than average.

 

Hi Znod,
I recorded my passes using a stop watch and the speedometer and the odometer. I know that it is not the most accurate method, but that is what was available to me then.

My car is claimed to have a 0-62 mph of 9.9s, 0-100 mph of 25.4 (I got that from Autocar), 0-1000 of 32.5, and max speed of 226 km/h (I got over 240 km/h, but I had the wind, the slope, and god by my side ). Anyways I am satisfied with the performance of my car.

Regarding my problems I am still suffering from all of them:

1) I added 7 litres of oil since I bought the car. That is 7 litres in 24,000 km, BMW is saying that this is pretty normal .

2) I replaced three sets of frot brake discs under warranty in 23,000 km. Today, after 1000 km from last replacement, the vibration while braking is back .

3) The rear brake pads were replaced at 23,000 km, and according to Mr. I-Drive, the front ones won't last beyond the 30,000 km mark .

As you can see I am a very happy man with my E60 , especially that now no one in Egypt will agree to buy my car since it consumes that unbelievable amount of oil .

Thanks for asking, and sorry if I had to share my problems, but now I really feel better.

 

I am glad your car is fast, but I am sorry for your problems. Good luck when you decide to dispose of your car.

 

Hi All:

I attached a 545i HP/TQ chart, interpreted using US measurement standards, to post #34 of this thread. I used this chart in several iterations of my thinking about optimal shift points for a Step 545i--assuming that one has a choice--as with a shift program. I am getting ready to see if I have changed my mind about anything I said previously. I am attaching the HP/TQ charts that I will be using, along with the raw data, in thinking more about the issue at hand. Another thing I will be doing is trying to reconcile the HP/TQ values shown in the charts with BMW's claims about the HP and TQ of the 545i. If you have any thoughts about any of these matters, then please let them fly. For now, note how different my new charts appear in comparison to the one attached to post #34. My new chart for first gear seems the closest to the one I posted before, but note that it covers the whole RMP range while my other new charts just cover the ranges after the 1st to 2nd and 2nd to 3rd shifts. Happy thinking if you so choose.

 

The above graphs show maximum all-loss RWHP of about 250. My Pro RR indicated average maximum all-loss RWHP over 48 passes is 239. This value implies an overall average percentage loss of .26462 = 1 - .73538 (239/325). Four types of loss are possible, drive train (including rolling resistance), aerodynamic drag, altitude, and weather. Assuming drive-train losses of 15% or 20%, the percentage losses from the remaining factors would have to be .11462 and .06462, respectively. I am inclinded to accept the 15% value because contemporary drive-train losses from automatics are not as severe as their historical counterparts.

My average density altitude is 1,532.26. Given this value, the calculated values below imply a percentage loss of approximately .01384 = {[1.016(239) - 239] / .85 / 325} from altitude and weather (assuming loss of .15 from drive train). This value implies a loss of .10078 from aerodynamic drag (.26462 - .15 - .01384). The only problem with these calculations is that the value of .01384 seems to be low given that an average density altititude of 1532.26 implies a reduction in 1/4 ET of about .165 sec on average for my car. At this point, I would think that this large a reduction in ET would require more like a .05 HP reduction. In this regard, I think I can, as indicated here in post #442, document about a ten HP decrease in maximum flywheel HP from weather alone, while .01384 X 325 is only 5.5 flywheel HP. The percentage decrease related to the documented 10 HP decrease is .03385.

Another factor that could be a problem in my calculations is vehicle weight. I have made several attempts to estimate this value. My best estimate is 4150 lbs--which is one of the settings my Pro RR relies on in calculatng all-loss RWHP. Nevertheless, I am pressing on to try to figure out the loss that might be attributable to aerodynamic drag.

Engine Tuner's Calculator
Inputs:
Air Temperature: 55 degrees F
Altimeter Setting: 30.185 inches Hg
Dew Point: 40 degrees F
Altitude: 1600 feet

Calculated Values:
Relative Horsepower: 98.4 %
Air Density: 1.1716 kg/m3
Relative Air Density: 95.6 %
Density Altitude: 1532 feet
Virtual Temperature: 56.7 deg F
Absolute Air Pressure: 28.49 inches Hg
Vapor Pressure: 0.248 inches Hg
Relative Humidity: 56.8 %
Dyno Correction Factor: 1.016

 

The May 2006 issue of Road and Track, page 90 tests the 750i and states that the new engine "lops 0.4 second off both its 0-60 sprint and quarter-mile time (now 5.7 and 14.1 sec...)." But maybe the results will differ with the 550.

 

I have found a calculator that yields aerodynamic HP--the HP loss from aerodynamic factors at a given MPH. My maximum HP tends to be produced at about 6k RPM--which corresponds to 89.46 MPH. Given these values, plus a CD of .29 and a frontal area of about 22 sq. ft., etc., my aerodynamic HP is 32 HP. This value is .09846 or stated HP (32 / 325)--which is surprisingly close to the .10078 value caclulated above.

So, assuming that a 15% drive-train loss is reasonably accurate, here is how is a summary:

.15000 = Drive-train HP-loss percentage
.09646 = Aerodynamic-HP percentage
.01384 = HP-loss percentage from weather and altitude
.26030 = Calculated average percentage max HP loss

.26462 = Average percentage max HP loss as indicated by Pro RR--which is surprisingly close the above value)

From an overall perspective, my calculations provide independent confirmation of the RWHP values produced by my Pro RR assuming that 15% is a good drive-line loss value for our cars. They also suggest that my car-weight value of 4150 is reasonably accurate under this assumption. On the other hand, they do not support my demonstrable reduction in HP from weather. I will continue to this about this failure to explain. Perhaps, a dirve-train loss of 20% actually is closer to the truth and that the dyno-related weather/altitude adjustment factor of 1.016 is off.

For now, note, as indicated above, that .01384 seems to be low given that an average density altititude of 1532.26 implies a reduction in 1/4 ET of about .165 sec on average for my car. At this point, I would think that this large a reduction in ET would require more like a .05 HP reduction--i.e., .05 X 325 = 16.25. Coincidentally, the .165 and 16.25 values are precisely consistent with the rough rule of thumb that 10 FWHP equates to 0.1 second in the 1/4 mile.

Here is what the calculator for aerodynamic HP looks like.

Coefficient of drag: .29
Frontal Area (Square Feet): 22
Test Temperature in Degrees F: 55
Test Barometric Pressure in Inches Hg: 30.185
Vehicle Miles Per Hour (MPH): 89.46
Vehicle Weight in Lbs: 4150
Tire Inflation Pressure in psi:
Vehicle Coefficient of Frontal Lift: .075

Input Parameters Are the Following:
? Coefficient of drag = 0.3
? Frontal Area = 22.00 sq feet
? Test Temperature = 55.00 degrees F
? Test Barometer = 30.18 inches Hg
? Vehiche MPH = 89
Computation Results:
Air Density Computed is 0.00241
Aerodynamic "Drag Factor" is 0.01656
Rolling "Drag Factor" is 21.33690
? Computed Aerodynamic Horsepower Required is 32
? Computed Rolling Horsepower Required is 21
? Computed Frontal Lift Force is 34 Lbs.

 

Hi Zman.You are really putting up some interesting data.I can't disagree with any of your info,but I can think of only a couple of minor points.
The rule of thumb of 10 HP =.1 sec in a 1/4 was always based on gross HP readings.Using rear wheel HP would probably equate to about 7.5 HP/.1sec.
The driveline losses for our vehicle are probably between 15 & 20%.I would venture the losses are more than a standard trans,but not as much as a typical autuomatic.I think great strides have been made in the newer automatics in reducing internal losses.Maybe 17.5% would be a better figure to use for our cars.
This still doesn't account for the .165 sec diff vs the .01384 weather correction.It would probably take about 12.5 RWHP to make a .165 sec diff in the 1/4.

 

Hi g-man. Thanks for reading, commenting, and contributing. Note that the .01384 value is derived from the RWHP-related tuner/dyno-chart value of 1.016 - 1 = .016. So, the .01384 value is related to FWHP. And, yes, 17.5% may be the best value for the drive-train losses on our cars. I am continuing to try to reconcile all. Do you have any thoughts about why the tuner-related value of 1.016 would be so low given a density altitude of over 1500'? I am going to nose around on what sorts of adjustments are typical given dyno testing.