Interview w/ M chief engineer Biermann hints at M3/M4 0-60 in 4.3 seconds and 26 MPG

[basscadet]

Originally Posted by Sapper_M3

Agreed, but if it's even POSSIBLE to spec a 3306 lb M3/M4, it will be a huge victory.

I am pretty sure we have already debunked the 3300lb myth. Based on weight-loss %'s straight from BMW, I believe the popular current story is that the weight of the car, with no driver but with all fluids, is between 3450 and 3550 lbs.

(correct me if I am wrong, guys)

[Sapper_M3]

Originally Posted by basscadet

I am pretty sure we have already debunked the 3300lb myth. Based on weight-loss %'s straight from BMW, I believe the popular current story is that the weight of the car, with no driver but with all fluids, is between 3450 and 3550 lbs.

(correct me if I am wrong, guys)

I'll start: When was this debunked...?

EDIT: And I'll add that a figure of 3450-3550 lbs makes absolutely NO SENSE in line with BMW's quoted weight savings. You understand that the 3704 lb figure for the E92 M3 was EU weight correct? Do the math: BMW's listed weight for the E92 M3 was 3704 lbs. EU weight is calculated as the following: Weight of Car with 90% fuel, 68 kg driver, 7 kg cargo. Subtracting the 75 kilograms for driver and cargo, you're already down to 3539 lbs. When you add back the remaining 10% of fuel from the 63 liter tank, you're only up to 3550 lbs -- and that's CURB WEIGHT (all fluids, including 100% gas, no driver or cargo). You're claiming we should anticipate that the new M4 might (you gave a range, but that range extends all the way back to 3550 lbs) have the same exact curb weight as the E92 M3...?

[Sapper_M3]

Originally Posted by basscadet

I am pretty sure we have already debunked the 3300lb myth. Based on weight-loss %'s straight from BMW, I believe the popular current story is that the weight of the car, with no driver but with all fluids, is between 3450 and 3550 lbs.

(correct me if I am wrong, guys)

And to add to it, I'll maintain--as always--that I've never been optimistic about these weight savings, but BMW (and M specifically) is fanning the flames with this specific weight figure.

You're talking about weight loss percentages "straight from BMW," but Albert Bierman himself is the source of the 3306 lb speculation. I won't do the math for you, but read on for the "1500 kg" figure offered.

http://f80.bimmerpost.com/forums/sho...d.php?t=915648

Now, in Biermann's defense, he never unequivocally states that they ACHIEVED the sub-1500 kg goal, but he's the one putting that number out there, and he even uses it as the rationale for cost-cutting in other areas ("we saved money to spend on cutting weight more aggressively" followed immediately by his unsolicited offering of a 1500 kg weight figure). If the car is 150 lbs heavier than this claim, there will be a lot of unhappy folks, and BMW/M will only have themselves to blame. Car mags aren't coming up with these numbers on their own.

[CanAutM3]

Originally Posted by Sapper_M3

And to add to it, I'll maintain--as always--that I've never been optimistic about these weight savings, but BMW (and M specifically) is fanning the flames with this specific weight figure.

You're talking about weight loss percentages "straight from BMW," but Albert Bierman himself is the source of the 3306 lb speculation. I won't do the math for you, but read on for the "1500 kg" figure offered.

http://f80.bimmerpost.com/forums/sho...d.php?t=915648

Now, in Biermann's defense, he never unequivocally states that they ACHIEVED the sub-1500 kg goal, but he's the one putting that number out there, and he even uses it as the rationale for cost-cutting in other areas ("we saved money to spend on cutting weight more aggressively" followed immediately by his unsolicited offering of a 1500 kg weight figure). If the car is 150 lbs heavier than this claim, there will be a lot of unhappy folks, and BMW/M will only have themselves to blame. Car mags aren't coming up with these numbers on their own.

I think the most reliable number we can use is the "80kg less than a similarly equiped E92" quoted by BMW.

[Sapper_M3]

Originally Posted by CanAutM3

I think the most reliable number we can use is the "80kg less than a similarly equiped E92" quoted by BMW.

...and E92 curb weight of 3550 lbs - 80 kg (176 pounds) still puts us at 3374 curb weight, or listed as EU weight at approximately 3528 lbs (slightly less, as I factored in the 75 kg driver and cargo, but did not account for the 10 percent fuel).

3374 lbs in the lightest trim possible wouldn't be a bad figure, but--again--Albert Biermann, the HEAD of development for BMW M, is the guy throwing out the "less than 1500 kg" figure. If they don't intend on delivering a product that at least approaches this, they should expect people to be miffed.

[CanAutM3]

Originally Posted by Sapper_M3

As a side note, thinking about the area under torque vs RPM curve is still eating away at me. If we integrate force vs time, do we get work?? Do we need to integrate twice with respect to time in order to find power???

Work = Force x distance (not time)
Power = Work / time
Power = Force x Distance / Time = Force x speed

In the polar referential:
Force=Torque
Distance=Rotation
Time=Time

Work = Torque x Rotation
Power = Torque x Rotation / Time = Troque x RPM (agular velocity)

Hope this helps

[Sapper_M3]

Originally Posted by CanAutM3

Work = Force x distance (not time)
Power = Work / time
Power = Force x Distance / Time = Force x speed

In the polar referential:
Force=Torque
Distance=Rotation
Time=Time

Work = Torque x Rotation
Power = Torque x Rotation / Time = Troque x RPM (agular velocity)

Hope this helps

Well, it's a little helpful. I'm actually even more wrong than you suggested here. I talked about integrating force with respect to time, but in reality the Torque vs RPM graph doesn't even give me those values, since RPM is neither time nor distance, but a rate relating distance and time.

I guess my issue begins with my optimistic (assumption) that some amount of integration of the Torque vs RPM graph would ever give me power, when in reality (I believe now; someone correct me if I'm wrong) it never will. Torque and Power themselves are certainly directly related (in fact, by distance and time--the same variables that make up the rate/angular velocity that is RPM), but the Torque vs RPM curve does not enclose an area equivalent to power.

Now a Torque*Angular Distance vs Time graph (essentially a Work vs Time graph), that would be both generally useless for most purposes and PERFECT for giving me power by summing the area underneath the curve.

[ersin]

Originally Posted by Sapper_M3

Well, it's a little helpful. I'm actually even more wrong than you suggested here. I talked about integrating force with respect to time, but in reality the Torque vs RPM graph doesn't even give me those values, since RPM is neither time nor distance, but a rate relating distance and time.

I guess my issue begins with my optimistic (assumption) that some amount of integration of the Torque vs RPM graph would ever give me power, when in reality (I believe now; someone correct me if I'm wrong) it never will. Torque and Power themselves are certainly directly related (in fact, by distance and time--the same variables that make up the rate/angular velocity that is RPM), but the Torque vs RPM curve does not enclose an area equivalent to power.

Now a Torque*Angular Distance vs Time graph (essentially a Work vs Time graph), that would be both generally useless for most purposes and PERFECT for giving me power by summing the area underneath the curve.

Look at the last line in his derivation: P = T x R, where P= power, T=torque and R=angular speed (RPM). Convert to calculus: P \int T dR. So, yes, power is the area under the torque vs. rpm curve.


Cheers.

[Sapper_M3]

Originally Posted by ersin

Look at the last line in his derivation: P = T x R, where P= power, T=torque and R=angular speed (RPM). Convert to calculus: P \int T dR. So, yes, power is the area under the torque vs. rpm curve.


Cheers.

I think this is where the disconnect is happening, and why it's been easy for myself (and you) to be confused:

Torque * RPM is indeed power, which is why CanAutM3's math earlier (arriving at reasonable numbers) worked.

But the area under the torque vs RPM curve is NOT the power, which is why CanAutM3's math showed summing the area under the torque curve does NOT arrive at a reasonable number.

Further Explanation: Torque vs RPM is indeed power, but your formula in this post is incorrect. "P \int T dR" is wrong. Instead, it should be rendered "P \int T*D dS" where D is the angular distance, and S is time (to avoid confusion with the T we used for Torque).

[ersin]

Originally Posted by Sapper_M3

Further Explanation: Torque vs RPM is indeed power, but your formula in this post is incorrect. "P \int T dR" is wrong. Instead, it should be rendered "P \int T*D dS" where D is the angular distance, and S is time (to avoid confusion with the T we used for Torque).

Technically you are correct. However, D should be real distance, I'm not sure what angular distance is. But D is directly proportional to RPM and time. That is, "D dS" equals "dR", with a constant thrown in for units.


Cheers.

[Sapper_M3]

Originally Posted by ersin

Technically you are correct. However, D should be real distance, I'm not sure what angular distance is. But D is directly proportional to RPM and time. That is, "D dS" equals "dR", with a constant thrown in for units.


Cheers.

More than technically. It is angular distance because we are talking about the distance covered by the crankshaft (hence, horsepower "at the crank") as it rotates. The crankshaft is not actually moving any straight line distance as we normally refer to distance being covered.

And despite the relationship between angular velocity (RPM), which is distance/time, you can't perform the integration you're suggesting. To get power you need to integrate Torque * Distance with respect to Time. Integrating Torque with respect to Distance/Time is NOT the same thing.

For proof, look up to one of CanAutM3's earlier posts. Doing integration of the curve manually by summing up the area results in nonsensically lower power figures. Try it yourself to see.

[CanAutM3]

Originally Posted by ersin

Technically you are correct. However, D should be real distance, I'm not sure what angular distance is. But D is directly proportional to RPM and time. That is, "D dS" equals "dR", with a constant thrown in for units.


Cheers.

Sapper got it. The area under the torque curve has nothing to do with power. Torque and power only correlate for each individual RPM points on the graph.

Distance in the polar referential is rotations (rads, a non-dimensional unit; 1 rotation = 2 pi rads). So rotations in the polar referential is a "real distance".

[Boss330]

Originally Posted by basscadet

I am pretty sure we have already debunked the 3300lb myth. Based on weight-loss %'s straight from BMW, I believe the popular current story is that the weight of the car, with no driver but with all fluids, is between 3450 and 3550 lbs.

(correct me if I am wrong, guys)

Originally Posted by Sapper_M3

I'll start: When was this debunked...?

EDIT: And I'll add that a figure of 3450-3550 lbs makes absolutely NO SENSE in line with BMW's quoted weight savings. You understand that the 3704 lb figure for the E92 M3 was EU weight correct? Do the math: BMW's listed weight for the E92 M3 was 3704 lbs. EU weight is calculated as the following: Weight of Car with 90% fuel, 68 kg driver, 7 kg cargo. Subtracting the 75 kilograms for driver and cargo, you're already down to 3539 lbs. When you add back the remaining 10% of fuel from the 63 liter tank, you're only up to 3550 lbs -- and that's CURB WEIGHT (all fluids, including 100% gas, no driver or cargo). You're claiming we should anticipate that the new M4 might (you gave a range, but that range extends all the way back to 3550 lbs) have the same exact curb weight as the E92 M3...?

Originally Posted by Sapper_M3

And to add to it, I'll maintain--as always--that I've never been optimistic about these weight savings, but BMW (and M specifically) is fanning the flames with this specific weight figure.

You're talking about weight loss percentages "straight from BMW," but Albert Bierman himself is the source of the 3306 lb speculation. I won't do the math for you, but read on for the "1500 kg" figure offered.

http://f80.bimmerpost.com/forums/sho...d.php?t=915648

Now, in Biermann's defense, he never unequivocally states that they ACHIEVED the sub-1500 kg goal, but he's the one putting that number out there, and he even uses it as the rationale for cost-cutting in other areas ("we saved money to spend on cutting weight more aggressively" followed immediately by his unsolicited offering of a 1500 kg weight figure). If the car is 150 lbs heavier than this claim, there will be a lot of unhappy folks, and BMW/M will only have themselves to blame. Car mags aren't coming up with these numbers on their own.

Originally Posted by CanAutM3

I think the most reliable number we can use is the "80kg less than a similarly equiped E92" quoted by BMW.

Originally Posted by Sapper_M3

...and E92 curb weight of 3550 lbs - 80 kg (176 pounds) still puts us at 3374 curb weight, or listed as EU weight at approximately 3528 lbs (slightly less, as I factored in the 75 kg driver and cargo, but did not account for the 10 percent fuel).

3374 lbs in the lightest trim possible wouldn't be a bad figure, but--again--Albert Biermann, the HEAD of development for BMW M, is the guy throwing out the "less than 1500 kg" figure. If they don't intend on delivering a product that at least approaches this, they should expect people to be miffed.

In the European E9x M3 brochure the unladen weight is stated as 1655kg (1675kg with DCT), or 3645lbs and 3689lbs respectively in the old School way of measuring things That weight includes 90% fuel and 68+7kg (75kg) driver and cargo plus all fluids.

As has been stated above, BMW has said that a similarily equipped F8x M will weigh 80kg less than a comparable E9x M3. The E9x M3 has also been quoted as having a curb weight of 1580kg (3480lbs), which doesn't include the driver (1655-75=1580kg).

From this we can deduct that the lightest F8x will weigh 1500kg (or a bit less) WITHOUT driver, but WITH 90% fuel and all fluids.

So, yes the standard F8x ready to drive, but without driver, will most likely weigh around 1500kg or 3303lbs.

Add the driver and we are at 1575kg or 3469lbs.

[solstice]

Originally Posted by Boss330

In the European E9x M3 brochure the unladen weight is stated as 1655kg (1675kg with DCT), or 3645lbs and 3689lbs respectively in the old School way of measuring things That weight includes 90% fuel and 68+7kg (75kg) driver and cargo plus all fluids.

As has been stated above, BMW has said that a similarily equipped F8x M will weigh 80kg less than a comparable E9x M3. The E9x M3 has also been quoted as having a curb weight of 1580kg (3480lbs), which doesn't include the driver (1655-75=1580kg).

From this we can deduct that the lightest F8x will weigh 1500kg (or a bit less) WITHOUT driver, but WITH 90% fuel and all fluids.

So, yes the standard F8x ready to drive, but without driver, will most likely weigh around 1500kg or 3303lbs.

Add the driver and we are at 1575kg or 3469lbs.

For the US the E92 Curb weight including driver is 3704 lbs. Deduct 80kg and we have 3528 lbs.

[Boss330]

Originally Posted by solstice

For the US the E92 Curb weight including driver is 3704 lbs. Deduct 80kg and we have 3528 lbs.

Sure, but since BMW talks about a weight in kilogrammes and they are a German company, I suspect they are talking about the EU weights.

And as I understand the US weight of 3704lbs, that is the curb weight with the DCT wheras the EU weight is with manual (20kg difference). Add the extra 10% of fuel (US has a full tank) and the 1675kg (EU weight for DCT with 90% fuel and driver) and 1681kg (US weight of 3704lbs with 100% fuel, driver and DCT) makes sense. The extra 10% of fuel probably accounts for the 6kg difference between a EU DCT at 1675 and a US DCT at 1681kg.

Deduct the 20kg for the DCT and you end up at 3484lbs (1581kg) US weight WITH driver, or 3318lbs (1506kg) US weight WITHOUT driver!

So, a US manual M4 without driver and with 90% fuel should also weigh in at 1500kg

[Kadema]

I think you've got it perfectly right, boss!

[solstice]

Originally Posted by Boss330

Sure, but since BMW talks about a weight in kilogrammes and they are a German company, I suspect they are talking about the EU weights.

And as I understand the US weight of 3704lbs, that is the curb weight with the DCT wheras the EU weight is with manual (20kg difference). Add the extra 10% of fuel (US has a full tank) and the 1675kg (EU weight for DCT with 90% fuel and driver) and 1681kg (US weight of 3704lbs with 100% fuel, driver and DCT) makes sense. The extra 10% of fuel probably accounts for the 6kg difference between a EU DCT at 1675 and a US DCT at 1681kg.

Deduct the 20kg for the DCT and you end up at 3484lbs (1581kg) US weight WITH driver, or 3318lbs (1506kg) US weight WITHOUT driver!

So, a US manual M4 without driver and with 90% fuel should also weigh in at 1500kg

Do you have a reliable source that the 3704 figure is with DCT? I hope you are right on that one. Here are some other interresting option weights for the E92 M3 that I found:

Sunroof: 44lbs
Power seats: ~15lbs
NAV: ~12lbs
Fold Down Seats: ~38-40lbs
Ehanced Audio: ~20lbs
EDC: ~10lbs
DCT: ~58lbs
TOTAL 197lbs


Most of these are options on the F8X as well if I understand it correctly.

[Boss330]

Originally Posted by solstice

Do you have a reliable source that the 3704 figure is with DCT? I hope you are right on that one. Here are some other interresting option weights for the E92 M3 that I found:

Sunroof: 44lbs
Power seats: ~15lbs
NAV: ~12lbs
Fold Down Seats: ~38-40lbs
Ehanced Audio: ~20lbs
EDC: ~10lbs
DCT: ~58lbs
TOTAL 197lbs


Most of these are options on the F8X as well if I understand it correctly.

Not really reliable source, but it was mentioned in one of the other threads that US curb weight included the "Automatic" transmission option. And when I looked into the weights they add up...

US weight: 1681kg
EU weight: 1675kg (confirmed with DCT)

Difference between US and EU is 90% and 100% fuel. The M3 has a 63l fuel tank. 10% of 63l is 6,3l. Density of petrol is 737.22 kg/m3 and those 6,3l extra will weigh in at 4,64kg extra weight, getting us to 1679,64kg...

Also according to EPA regulations, options that are expected to be installed in more than 33% of the sold cars must be included in the curb weight. I'm pretty sure BMW expected the DCT to be sold in more than 33% of the M3's



http://www.gpo.gov/fdsys/pkg/CFR-200...86-1803-01.pdf

Curb weight means the actual or the
manufacturer’s estimated weight of the
vehicle in operational status with all
standard equipment, and weight of fuel
at nominal tank capacity, and the
weight of optional equipment computed
in accordance with § 86.1832–01

§ 86.1832–01

http://www.law.cornell.edu/cfr/text/40/86.1832-01

a) (1) Where it is expected that more than 33 percent of a car line, within a test group, will be equipped with an item (whether that item is standard equipment or an option), the full estimated weight of that item must be included in the curb weight computation for each vehicle available with that item in that car line, within that test group.

[CanAutM3]

Originally Posted by solstice

Do you have a reliable source that the 3704 figure is with DCT? I hope you are right on that one. Here are some other interresting option weights for the E92 M3 that I found:

Sunroof: 44lbs
Power seats: ~15lbs
NAV: ~12lbs
Fold Down Seats: ~38-40lbs
Ehanced Audio: ~20lbs
EDC: ~10lbs
DCT: ~45lbs
TOTAL 197lbs


Most of these are options on the F8X as well if I understand it correctly.

My E92 has most of the common options (DCT, iDrive, power seats, heated seats, fold down back seat, adjustable lumbar and side bolsters, premium sound, EDC, leather, carbon roof) and weighed 3688lbs with a full tank.

Getting pretty close to that 3704lbs...

PS: fixed the DCT line, IIRC 45lbs is what has mostly been quoted in the past.

I still doubt we will see many F8X on the street at 3300lbs...

[Boss330]

Originally Posted by CanAutM3

My E92 has most of the common options (DCT, iDrive, power seats, heated seats, fold down back seat, adjustable lumbar and side bolsters, premium sound, EDC, leather, carbon roof) and weighed 3688lbs with a full tank.

Getting pretty close to that 3704lbs...

PS: fixed the DCT line, IIRC 45lbs is what has mostly been quoted in the past.

I still doubt we will see many F8X on the street at 3300lbs...

DCT is a 20kg (44lbs) option according to the EU brochure, so 45lbs sounds right.

And yes, most F8x will have DCT and a few options, so around 3400-3450lbs for the majority perhaps?

But then again, how many will have the CCB option that SAVES weight

[swamp2]

Originally Posted by CanAutM3

I think the most reliable number we can use is the "80kg less than a similarly equiped E92" quoted by BMW.

Strongly agree.

No cars perform acceleration runs without a driver. That leads me to say that weights should always be reported with driver, with fluids, 90% or 100% fuel (what ever you like). I'm not too fussed about 7 kg of cargo.

There is not a chance in hell that we'll see a single new M4 with driver weigh in at less than 1500 kg...

1500 kg with no driver, no DCT, no cargo is within about 10 lbs of "80 kg lighter than" 3704 lb assuming it includes DCT. Specifically

1500 + 68(driver) + 7(cargo) + 20(DCT) + 80(difference) = 1675 kg = 3692 lb. I sure hope the 1500 kg figure does not include CSiC brakes... Thus APPLES TO APPLES for a US DCT car is the following:

E92 M3: 3704 lb
F82 M4: 3528 lb (again simply 80 kg less)

Edit: And this 3528 lb should be very close to what the US website/brochure will list.

My earliest estimate/calculation of the car's weight was about 3590 back in December of 2010...

[swamp2]

Originally Posted by CanAutM3

Sapper got it. The area under the torque curve has nothing to do with power. Torque and power only correlate for each individual RPM points on the graph.

Distance in the polar referential is rotations (rads, a non-dimensional unit; 1 rotation = 2 pi rads). So rotations in the polar referential is a "real distance".

+1

Lot's of internet car experts like to talk about good old "areas under the curves"...torque or power. They are largely meaningless physically but the point folks are trying to talk about is somewhat relevant. They are basically meaningless because in any accelerating vehicle rpms don't grow linearly with time and they way they do grow with time depends on gear and drag... Comparing two torque curves where one is always making more torque does indeed have more area under its curve of course said engine is also consistently making more power and that is what matters...

I think the confusion generally goes like this:

How quickly velocities can grow depends on the work done (ΔE = W, work-energy theorem). When forces vary work must be integrated. You can integrate F*v dt (power vs. time) or F dx (force vs. position). Both expressions contain force the instantaneous force applied to the ground depends on the engines torque. Q.E.D. let's just integrate torque (in some loose definition vs rpm) vs. the only thing we typically see torque plotted against - rpm.

To discuss anything in regards to integrating one must carefully distinguish between engine parameters (rpm, rotations, etc.) vs. "real world" parameters (time, distance, etc., these are what the car does, not the engine).