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      02-21-2013, 02:10 AM   #221
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Quote:
Originally Posted by swamp2 View Post
All of you torque folks really grate on me (and on other clued up enthusiasts as well).

More torque is fine, nothing wrong with it, however, it does next to nothing for actually making a car faster. Isn't that what most of us actually care about (or profess to care about). Torque is great for mashing the throttle in 7th gear (maybe 8th in the new M3/M4) at 50 mph, but in REAL contests, when choosing the best gear possible to maximize acceleration, hp is the single figure that matters, pretty well totally independent of torque (well again technically power to weight ratio... but POWER not torque).

I don't give a single rats ass about how much more or how much total torque the car will make, neither should any true M enthusiast.
Agree 100%!!! Torque really is not what determines how fast a car will accelerate!!

Even in my world of 60-120 Litre turbo diesel engines, torque ratings are never quoted it is always HORSEPOWER or KW. The reason for this is because the horsepower rating is what determines how much work can be done by that engine, not the torque rating!
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      02-25-2013, 05:06 PM   #222
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Originally Posted by swamp2 View Post
More torque is fine, nothing wrong with it, however, it does next to nothing for actually making a car faster.

...

I don't give a single rats ass about how much more - torque the car will make, neither should any true M enthusiast.
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Torque really is not what determines how fast a car will accelerate!!
I disagree with Swamp and others here that torque doesn't matter. If M3/M4 owners care about acceleration, they should be very happy the new car is getting 100+ lbs lbs more torque.

At the risk of exacerbating the whole 1M vs M3 debate, I'm going to use real-world numbers to illustrate, 1M vs M3 convertible, both 6MT at 95 MPH in 4th, the best starting gear for either MT car at that speed. I'm going to walk through this so you guys can calculate this yourselves to better understand it.

You want to estimate the car's thrust first, which is essentially how much torque it puts to the ground including gearing, etc. The equation:

Wheel torque (ft lbs) x final drive ratio x 4th gear ratio / tire radius (in feet, ie 25.5 / 12 / 2)

Let's say the M3 makes 255 ft lbs at the wheels on a dynojet. We'd do 255 x 3.85 x 1.19 / 1.06 = 1102 lbs of thrust. Pretend this is moving a 4200 lb car (with driver, and yes convertibles are heavy), so 1102/ 4200 = .26, or basically .26 Gs ignoring aero, wheel-spin and rotational inertia.
Take the 1M in the same gear: 350 x 3.15 x 1.18 / 1.06 = 1227 lbs of thrust, 3700 lb car = .33 Gs. So 27% better acceleration for our example 1M.

The next step, however, is to calculate acceleration at a specific speed. Speed in MPH is: RPM x tire radius x pi x 2 x 60 / final drive ratio / 4th gear ratio / 5280 feet
So 5800 rpm in the M3 is 5800 x 1.06 x 3.1415 x 2 x 60 / 3.85 / 1.19 / 5280, or 96 mph. Take thrust using torque from the dyno curve at that specific RPM, and you get thrust to weight at that speed- I already used the ~255 ft lbs the M3 makes at 5800.

Same thing for the 1M: 4700 x 1.06 x 3.1415 x 2 x 60 / 3.15/ 1.18 / 5280 = 96 mph. And again, the 1M makes about 350 at the wheels at that rpm depending on the dyno.

So you now know how to calculate thrust to weight ratio for a particular speed. All you need are the gear ratios, weights, plus the dynos, such as:

And

And you can calculate which car will accelerate harder in any gear at any speed (again, ignoring aero, rotational inertia, etc).

Now to one of the reasons I chose these particular cars and dynos for comparison. Using the dynos shown above plus the weights, the 1M and M3 have near identical power to weight ratios. So 4200 lbs / 375 whp = 11.2:1, plays 3700 lbs/ 330 whp, also 11.2:1.

Now if torque really doesn't matter the numbers say the cars should accelerate be very close to identically. As we calculated above, however, this is not the case at most speeds. In fact, using these weights and dynos (and identical power to weights), the 1M in this example would pull an average of about ~10% harder if both cars were shifted perfectly. That looks like the graph below- the 1M is pulling harder from any starting speed until 125 mph, at which point they are equal:



Now this is not supposed to be a 1M vs M3 argument. This is to illustrate that power to weight is not the only thing that matters. Area under the power curve is what matters, and all else being equal, more torque gives you that. You're welcome to do the actual math with any numbers you like, but any time you put power to weight equal and raise the torque the results are likely to be similar.

Bottom line for me: The extra 100 ft/lbs from the M4 will probably give it the equivalent of ~10% more hp in the from of more area under the horsepower curve, which will have a bigger effect on real-world acceleration than the roughly 8% less weight it will be carrying around. So from that point of view, even at a rated 415 hp, the M4 is shaping up rather well.

Now I'm as big a fan of normally aspirated motors as the next guy, but I clearly understand there will be gains other than fuel economy from forced induction. And I certainly understand that torque can be fun too.
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      02-26-2013, 04:09 AM   #223
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Quote:
Originally Posted by Pete_vB View Post
I disagree with Swamp and others here that torque doesn't matter.
Wow where to begin... here we go again...

Let me start with this correction by rearranging your words a bit...

If a lazy driver who won't properly put the car in the gear which maximizes acceleration and at the same time "requests" maximum acceleration cares (continue reading on with the quote...)
Quote:
Originally Posted by Pete_vB View Post
about acceleration, they should be very happy the new car is getting 100+ lbs lbs more torque."
Anyway no, no, no on the torque. Weight reduction, if present in the new car, will be more important than a power increase (since it improves handling) but what is far more sensible than a torque increase is a power increase. And although we are very likely to get one, again partly in the form of under-rating, BMW now has some believing the exact opposite of what they've been saying (and doing) for decades. Nothing is particularly wrong with torque nor with a broad torque curve, but FOR THE SIMPLICITY of a single number peak power (to weight) rules, period.

Now that we have that straight let's continue.
  • If you know the entire torque curve that's fine, you then also know the entire power curve. The torque results are still meaningless without knowing gearing. Look at your own forumula! Thus torque isn't meaningless, just massively less important than just knowing peak power (certainly over peak torque or any other such under the curve BS - do you think most enthusiasts can do an bloddy integral...). And again assuming on a per weight basis, of course.

  • Do you note the importance of the final drive in your formulae? 3.85 vs. 3.15. If you look more closely you will realize this ratio is basically a short cut to using power instead of torque. Not conincidentally, (3.85/3.15) x 350 = 423. More on the 350 number below. Do you still not see it?

  • Numbers can be chosen at any given single speed to show a result not in line with general results. What matters in the real world is results across a broad speed range and typically across multiple gears. You need a very fancy spreadsheet (I've actually built one) or something like the CarTest physics based simulation software to show this.

  • The 1M is pretty clearly under-rated and that's why it does a better job of keeping up with an M3 that its factory QUOTED peak power would indicate. 350 hp at the crank provides performance numbers much more in line with typical results from journalists.

  • Let me give you a formula anyone can walk through.

    a = P/mV

    Thus at any given speed the vehicle that can make the higher power to weight ratio WILL out accelerate the other. Period, no if and's or but's. Basic physics, no torque, no gear ratios, no nothing.

  • You've got your 1M weight way off. Using the correct US unladen weights of each vehicle, 4145 lb and 3362 lb and a realistic power figure, which by all accounts is again about 350 hp for the 1M, you will find that the 1M has a better power to weight ratio and in a full physics based simulation slightly outperforms the M3 particularly in time to distance (which means who is ahead in a drag race). Of course at higher speeds, say a 60-130 or similar, power to drag dominates the performance and the M3 would best the 1M. See attached simulation results, across gears, not at once speed nor in one gear... These particular cars are close enough it is pretty well a drivers race, but technically the M3 even has a slight advantage in the 1/4.
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      02-26-2013, 05:28 AM   #224
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^,^^ The advantage of higher torque at low rpm (=higher power at low rpm) only matters when you are at low revs, which only happens once from idle, afterwards you are shifting at higher rpm so it becomes irrelevant.
This advantage of turbo is negated by the time penalty of turbo lag, when you get only the power of 6 instead of 8 cylinders at zero boost.

Area under Power curve, hp/weight, and drag at high speed, you guys have mentioned are completely accurate as I can see it.
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      02-26-2013, 11:12 AM   #225
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Quote:
Originally Posted by swamp2 View Post
Thus at any given speed the vehicle that can make the higher power to weight ratio WILL out accelerate the other. Period, no if and's or but's. Basic physics, no torque, no gear ratios, no nothing.
Correct. At any given speed the vehicle that can deploy more hp to the ground for its weight will accelerate harder (ignoring aero and rotational inertia). Again, I'm using the dynos above and I have adjusted weights so that the peak power to weight ratio is equal. This is just an example- it could be any two cars.

So, we now have the formula. Gearing we have. So let's look at how much HP the examples are putting down, both peak and at different speeds in 4th, and compare it to your statement above:

At 105 mph, per the formula above, the M3 is turning 6350 RPM. We go to the blue line on the M3 dyno above and see it's making about 255 tq, or 308 hp as you'd prefer. 4150 lbs / 308 hp = 13.5 lbs per hp.
The 1M turns 5150, makes 335 tq/ 328 hp per the graph, and again I'm using a heavy 3700 lbs to make peak power to weight equal. So 3700 / 328= 11.3:1.

Per your statement above, the best power to weight at that speed will accelerate harder, so the 1M is ahead at that speed.

Now look at 110 mph and so on.

105 MPH: M3 13.5, 1M 11.3
110 MPH: M3 12.9, 1M 11.2
115 MPH: M3 12.3, 1M 11.2
120 MPH: M3 11.9, 1M 11.4 (11.3 in 5th)
125 MPH: M3 11.6, 1M 11.5 (11.2 in 5th)
130 MPH: M3 11.4, 1M 11.6 (11.2 in 5th)
135 MPH: M3 11.2, 1M 11.7 (11.2 in 5th)

Now even without shifting, the 1M is averaging 11.4 lbs per hp over this speed range with these example numbers. The M3 matches its peak of 11.2, but it averages 12.1. So it's averaging 6% lower power to weight. 8% less power to weight if the 1M shifts. The M3 can't shift to a better gear, 3rd ends before 105.

So per your statement, two cars with equal peak power to weight ratios, but the one with more torque is accelerating harder almost everywhere. Again, shifted perfectly, no lazy driver. 8%- that's the equivalent of going from 415 to 448 hp.

This is the advantage the M4 is going to have in acceleration due to area under the power curve, and why you should care how much torque the car has. Even if you know how to shift. Or drive a car that shifts for you.
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      02-27-2013, 01:00 AM   #226
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Quote:
Originally Posted by Pete_vB View Post
Now even without shifting, the 1M is averaging 11.4 lbs per hp over this speed range with these example numbers. The M3 matches its peak of 11.2, but it averages 12.1. So it's averaging 6% lower power to weight. 8% less power to weight if the 1M shifts. The M3 can't shift to a better gear, 3rd ends before 105.
Thanks for your patience, I think I better understand your point and specifically the more hypothetical nature of the example you have chosen. I've never said that torque or the shape of it is meaningless, just much less meaningful than the best simple figure of merit of peak power (to weight, of course). As well calculating, making sense of units and practically utilizing some integrated form of "area under a torque vs. rpm curve" is quite problematic...

Since, we've already pretty well determined that it is impossible for the next M3/4 to have a 7k+ rpm redline, 400 ft lb of torque and only 415 hp, we should examine a known case. What gives a car like an M3 a better overall performance gain: a 10% increase in peak power to weight ratio (which will realistically probably mean a 5% increase in power at an rpm of redline/2) or a 10% increase in torque, likely at an rpm much lower than redline? Some initial simulations showed these cars would perform very closely in most drag racing related competitions. My simulations were actually surprisingly closer than I suspected they would be.

Of course then I immediately recalled the use of the M3 in the way it really "should" be used. On more of a road coarse / track type setting (of course corner to corner in a canyon, as well, not necessarily on a track per se). Taking into account the mostly correct statement just below:

Quote:
Originally Posted by grimlock View Post
The advantage of higher torque at low rpm (=higher power at low rpm) only matters when you are at low revs, which only happens once from idle, afterwards you are shifting at higher rpm so it becomes irrelevant.
I also ran a bunch of simulations from 20-100, 30-120, 60-130, etc. These cases showed distinct advantage in all cases for the PROPERLY shifted car with 10% more power rather than 10% more torque.

Again nothing particularly wrong with BMW giving us more torque. It is particularly great for drivers who simultaneously demand peak acceleration but will not choose the best gear for obtaining it . I'd simply prefer, for a somewhat more real world speed x to speed y performance (i.e. non-drag race performance gains) more peak hp. With more peak power you do get the near equity in drag racing type of results but get a clear advantage in more canyon/track type of results.

I certainly can not guarantee the universality of such a result but I strongly suspect that for most cars the same general trend will hold on this point.
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      03-01-2013, 07:06 PM   #227
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I just cannot believe that they expect people to give up on the 414hp V8 over 1 horse power, that's just ridiculous. I don't think the improvements over E9X is anywhere NEAR as those back in the day were for the E46. 300 lb in weight reduction (and that's optimistic)? Come on. Who gives a crap about weight reduction of a few hundred pounds, I, among many people, will chose super charging the E9X for 10-20k (for an amazing ESS supercharger) over buying into the turbo campaign. At the end of the day, it's the engine that makes an M3 an M3. I just don't have that special feeling towards the F80 M3.

And please don't compare the new M5 vs the old one, the new M5 has had a massive torque improvement over the old one, and the difference between the old V10 and the new V8 in terms of the sound, feel, etc is much less than that of the new proposed I6 and the old V8 in the old M3. I think once you hit the V8 category, anything above is a marginal gain in terms of that special sports car feeling. This I6 feels nothing but a japanese turbo charged engine. Who cares about efficiency, I can pay 80 grand for a car do you think I'll even think about $20/week more for the gas? What are these guys thinking about?
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      03-01-2013, 07:08 PM   #228
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I also dare everyone who is showing favoritism toward the new car to get in a E9X M3 and go for a 3rd gear roll from 40 mph to 120 all the way to 8400 rpm and tell me how that feels. Probably one of the best feelings I have ever had in my life.
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      03-01-2013, 08:10 PM   #229
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^^^

Accelerating from 40 mph, I would grab 2nd gear for sure. But yes, it's quite a rush running through the gears while shifting at 8000+ RPM.
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      03-01-2013, 09:17 PM   #230
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300 lb in weight reduction (and that's optimistic)? Come on. Who gives a crap about weight reduction of a few hundred pounds[?]
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      03-01-2013, 10:08 PM   #231
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Come on now, you know I'm right. Most of us aren't going to go for drag racing or tracking this car at a competitive level. Who cares if it's lighter, 200 lbs here and there "on spec" means nothing. Once you start adding features one after another, the improvement will be negligible (it's like having another passenger in the car, do you really feel the difference?). I'd pick the V8 over any 415hp I6 turbo, I'm sure a big majority of the existing M3 owners will either do the same or look at other options.
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      03-02-2013, 06:36 AM   #232
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^^^ Consider power to weight.

It sure sounds to me like you've already reached the conclusion that the new M3/M4 will not see an incremental improvement in performance over the E9x M3 as its predecessors have over their respective outgoing models, or indeed as the new M5/M6 did vs. the E6x. When you factor in your demonstrably cocky attitude, it seems like a recipe for egg on face to me. Just my opinion.
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      03-02-2013, 07:54 AM   #233
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I just cannot believe that they expect people to give up on the 414hp V8 over 1 horse power, that's just ridiculous. I don't think the improvements over E9X is anywhere NEAR as those back in the day were for the E46. 300 lb in weight reduction (and that's optimistic)? Come on. Who gives a crap about weight reduction of a few hundred pounds, I, among many people, will chose super charging the E9X for 10-20k (for an amazing ESS supercharger) over buying into the turbo campaign. At the end of the day, it's the engine that makes an M3 an M3. I just don't have that special feeling towards the F80 M3.

And please don't compare the new M5 vs the old one, the new M5 has had a massive torque improvement over the old one, and the difference between the old V10 and the new V8 in terms of the sound, feel, etc is much less than that of the new proposed I6 and the old V8 in the old M3. I think once you hit the V8 category, anything above is a marginal gain in terms of that special sports car feeling. This I6 feels nothing but a japanese turbo charged engine. Who cares about efficiency, I can pay 80 grand for a car do you think I'll even think about $20/week more for the gas? What are these guys thinking about?
The massive torque is probably reason alone why the next gen M3 will sell well.

People hardly track their M3's, the new one will fit a daily driver mentality better since you'll gain so much off the line performance.
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      03-02-2013, 08:16 AM   #234
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I just cannot believe that they expect people to give up on the 414hp V8 over 1 horse power, that's just ridiculous.
So just stick with your E90. Nobody expects you to give up anything.

Can we now please stop whining over the loss of cylinders.
It's the world we live in today, and that's how it's going to be. Deal with it, or become an old-timer fanatic.
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      03-03-2013, 05:53 PM   #235
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^^^

Accelerating from 40 mph, I would grab 2nd gear for sure. But yes, it's quite a rush running through the gears while shifting at 8000+ RPM.
Do you really drive around like that all day? More often then not, when I want to pass someone I prefer to do it in a high gear (and at low-rpm) to avoid giving them an earful of exhaust. That's why I absolutely love the overboost on the 335is, of course going to lower gears will always be faster but it's nice to also have the flexibility to accelerate hard in the low and midrange. I can accelerate from 40 in 2nd, but I could also do it in 5th or even 6th quickly enough to pass whoever I want unless they're going full throttle (for some reason haha). I once raced my buddy's E46 330ci in my 135i, him shifting at redline and me upshifting at 3,000rpm in each gear, and we were dead even. These turbo motors have tons of power all over the place which can be entertaining in its own way.
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      03-03-2013, 06:27 PM   #236
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Do you really drive around like that all day?
Not at all. I think you may have inadvertently failed to consider the context of my post as established by the one I replied to. If you have a chance, you may wish to go back and reread.

Neither an M3 nor a 335is will accelerate well from 40mph in 5th or 6th gears. It can be done in either car (or any car, really), but its not the most effective use of the engine and gearbox.
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      03-03-2013, 08:52 PM   #237
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Quote:
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Do you really drive around like that all day? More often then not, when I want to pass someone I prefer to do it in a high gear (and at low-rpm) to avoid giving them an earful of exhaust. That's why I absolutely love the overboost on the 335is, of course going to lower gears will always be faster but it's nice to also have the flexibility to accelerate hard in the low and midrange. I can accelerate from 40 in 2nd, but I could also do it in 5th or even 6th quickly enough to pass whoever I want unless they're going full throttle (for some reason haha). I once raced my buddy's E46 330ci in my 135i, him shifting at redline and me upshifting at 3,000rpm in each gear, and we were dead even. These turbo motors have tons of power all over the place which can be entertaining in its own way.
I'd like to add to the reply above.

Do I drive around at 7 or 8k+ rpm all the time, no. Do I consistently use 6000-7000 rpm, you bet. Similarly, when I do want maximum acceleration I have absolutely no reservations/qualms/misgivings/hesitations, etc. about using the best gear and using the full 8400 rpm.

I think the debate can also be looked at this way. Is there anything wrong with gobs of torque down low in the rpm range? Absolutely not. The key thing is that in nearly all real world motors a strong low end torque curve is accompanied by both a low redline as well as a strongly falling torque curve some significant rpm below redline (another way to say this is you end up with a power curve having a peak with hump, again well below redline. You can really feel this type of power curve. It is the classic "nothing left up top" type of feel.

For me personally, if I had to choose between the two, I prefer the linear power curve and high redline. It's more fun and better on the track or in the twisties. Should you choose to push the motor and transmission, you get a big reward, both acoustically, in the vibration and in the visceral sense of acceleration at high rpms, not to mention the performance itself.
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      03-03-2013, 09:01 PM   #238
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I'd like to add to the reply above.

Do I drive around at 7 or 8k+ rpm all the time, no. Do I consistently use 6000-7000 rpm, you bet. Similarly, when I do want maximum acceleration I have absolutely no reservations/qualms/misgivings/hesitations, etc. about using the best gear and using the full 8400 rpm.

I think the debate can also be looked at this way. Is there anything wrong with gobs of torque down low in the rpm range? Absolutely not. The key thing is that in nearly all real world motors a strong low end torque curve is accompanied by both a low redline as well as a strongly falling torque curve some significant rpm below redline (another way to say this is you end up with a power curve having a peak with hump, again well below redline. You can really feel this type of power curve. It is the classic "nothing left up top" type of feel.

For me personally, if I had to choose between the two, I prefer the linear power curve and high redline. It's more fun and better on the track or in the twisties. Should you choose to push the motor and transmission, you get a big reward, both acoustically, in the vibration and in the visceral sense of acceleration at high rpms, not to mention the performance itself.
Look at the new M5 dyno plot. Looks like the S65 curve! Very atypical curve for a turbo car. Flat torque curve and completely linear power curve. Only difference is the curve is shifted 1200 rpms to the left. Makes some promise for the m3.

Keep in mind 415 hp will be clearly underrated given every single other turbo motor is. Probably realistically looking at 440hp and a couple hundred pounds less which is good for an equivelent of 25hp in acceleration/power or so given their power to weight. So realistically 50hp equivelent is realistica if you consider weight factored in
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      03-04-2013, 03:10 AM   #239
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Look at the new M5 dyno plot. Looks like the S65 curve! Very atypical curve for a turbo car. Flat torque curve and completely linear power curve.
Uhhh, no. Not at all.

E9X M3 power curve - nearly perfectly linear
F10 M5 power curve - a big hockey stick (totally flat in power for the entire top 1500 rpm)

Do I really need to paste in images of these stark differences for you to see them?

Now that being said, up to about 5700 rpm the torque and power curves are very similar and will feel so.
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      04-21-2013, 08:02 AM   #240
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I hope it gets at least 450hp. For me, 415hp even with the weight reduction and increase in torque, is not gonna do it.
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      04-21-2013, 08:35 AM   #241
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I hope it gets at least 450hp. For me, 415hp even with the weight reduction and increase in torque, is not gonna do it.
415hp for the base car, 445hp for the competition package

Well, that's completely speculative on my part with not even a hint that I am on the right track from any source. But, given the latest M5 news, I'd give myself pretty decent odds. What do you think?
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      04-21-2013, 10:33 AM   #242
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415hp for the base car, 445hp for the competition package

Well, that's completely speculative on my part with not even a hint that I am on the right track from any source. But, given the latest M5 news, I'd give myself pretty decent odds. What do you think?
Yep, that sounds better! And as you said, given the recent M5 news, I believe you're not far off.
But, why not start at ~440-450hp, and then offer a comp package increasing power up to 460-470? You and I both know that with the numbers I'm suggesting this car will be an absolute BEAST and will sell even better, without hurting the M5/M6 sales. But, I'm only a car enthusiast with no knowledge of what these numbers mean to BMW. We'll see...
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