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02072012, 11:59 AM  #23  
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E92 M3 DCT...Powered by ESS VT2 650/DCT GTS Software/Aquamist HFS3 50/50/Morr /Toyo R888's
ATCO RACEWAY: 10.65 @ 131.79MPH 1.725 60FT (Stock ESS 625) 

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02072012, 12:04 PM  #24 
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02072012, 12:14 PM  #25  
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Second, those 2WD hypercars have fairly long gears (extremely long when compared with the M3), so they're not getting close to max power for a long time (relatively speaking) in this short run. The M3 hits max power in first, and starts getting close in second gear as it hits 60, so average power over that run is closer to max power than what the big guns get. They'll get a fair bit closer to 60 before they hit max power in first, and are barely into second (and way down the power scale in that gear) as they hit 60. Third (and as has already been mentioned), traction limits have a way of equalizing times over such a short span. Fourth, the M3 weighs less than either the Mustang or Camaro, so powertoweight is somewhat closer than what the disparity in actual power suggests. Last, an 060 time is not particularly meaningful out here on the actual planet. Time to speed is essentially unrelated with time to distance, so you have no way of knowing who's actually ahead at 60 based on an 060 time. Bruce 

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02072012, 05:54 PM  #26  
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What makes the M3 unique is that its performance envelope is very accessible. You don't have to be a superhero to make it go fast on a racetrack but at the same time it still rewards good driving habits, so you have room to grow with it. It keeps things interesting and exciting, without scaring the $hit out of you. I'm hitting nearly 150mph on my local track in the basically stock M3  I mean, how much faster do I want to go?
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02102012, 02:58 AM  #28  
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I will say this though..these cars are going to tear from a roll though. Congrats on your good times..
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02102012, 02:59 AM  #29  
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2013 M3 CoupeMR/BLK ZCP, ACM test pipes, BPM Stg2 dev. tune and Megan catback, AFE Stg2. with C/F elbow VMRV810 19x10&19X11 275/295 Mich PSS.
Previous rides: 2011 M3 CoupeMR/Blk 2007 Porsche 997C2S Speed Yellow/Blk sport seats 2004 BMW M3 Imola/Blk 

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02102012, 02:25 PM  #30 
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Mind giving more detail about what you mean by this? I assume you mean something about how the engine spins up quicker perhaps? Just curious about the explanation, and what has been engineered into the car for this.
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02112012, 01:34 PM  #31  
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One reason the transmission can be engineered for lower rotational inertia is that the engine makes relatively low torque per cylinder (much lower than the 335is, for instance), and torque per cylinder is all the transmission needs to be designed to withstand. Overall torque is not an issue, since only one cylinder is firing at a time. All this doesn't matter a bunch when you're running for red line in, say, fifth gear (because you're not picking up a lot of rpm per unit of time), but it matters a bunch in first and second  hence a positive effect on 060 times. If you'd like to do a basic rotational inertia test your self, get an automotive Gmeter (available from several vendors, sold to measure acceleration/deceleration figures such as 060, quartermile, etc.). Then on a nice warm day on a sunwarmed, hightraction surface, measure max acceleration (expressed as max G) in both first and second gear. You'll notice that the peak G number falls well short of what you'd expect in first gear, based on observed secondgear peak G numbers. The best numbers I've ever gotten were on a stock (light flywheel) '85 Vette. That car had a first and second gear relationship of three to two, numerically speaking, so with a baseline max G of .5 (point five) in second gear, one would have an expectation of .75 (point seventyfive) in first, given good traction. Instead, what I got was .66 G max, or 88% of what I had expected. That 12% shortfall was due almost entirely to rotational inertia. The engine, flywheel, clutch plate and disc, engine accessories and transmission input shaft, etc. all had to accelerate 50% more for each mph gained in first gear compared to second gear, and per Mr. Newton, they just don't like to do that. I've tested at least a couple of dozen cars since then, and 12% was the smallest shortfall I've gotten. Most were in the lower 80s, percent/wise. My '95 M3 had a shortfall of 17.5%, as an example. The big guns from Ford and Chevy will have a lot more rotational inertia than the M3, including a big chunk from the transmission, which has to be designed to absorb a bunch more torque per cylinder. Of course, first and second gears in those cars are a lot lower (numerically speaking) than the M3, so they will be able to absorb more torque per cylinder, everything else equal. Still, they have to be more massive than the bimmer box, which costs in terms of rotational inertia, along with massive pistons and rods, a more massive crankshaft, etc. If you're interested in more detail on the topic, get a copy of Gillespie's book, "Fundamentals of Vehicle Dynamics". It's a worthwhile read, authored by an internationally famous engineering teacher, covering virtually all aspects of automotive performance dynamics. Bruce PS  If you do an M3 test, you're still likely to get a significant firstgear shortfall, because there is a large gap (around 40%) in gearing between first and second gears. Quite a bit bigger than the gaps in the Ford and Chevy. However, the test is only measuring the difference in rotational inertia between gears. Not the inertia values themselves. PPS  Understand that I have no specific knowledge of the weight of various parts of the M3 engine and drive train. I just know that the M Group has worked very hard on reducing rotational inertia in this car, since even with its overall very aggressive gearing (thereby increasing rotational inertia) it still spins up like a maniac freezing ice cream. Last edited by bruce.augenstein@comcast.; 02112012 at 01:51 PM. 

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02122012, 03:53 AM  #32 
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02122012, 04:27 AM  #33 
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They can't put the power down duhh. The M3 could crack a 3.9 or faster with drag radials, or on a prepped surface, new tires with a great launch...
2011 GT500 1/4 mile record. 11.16@124
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02122012, 08:01 AM  #34 
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02122012, 12:18 PM  #35  
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It gets a little more complicated, however. On those engines with broad torque curves, the perceived power band will begin well before peak torque, and extend past peak power. The M3, for instance, starts to feel very happy at anything past 3000 rpm, and trust me, if you could rev it to 9000 rpm (in deadstock form), it would rev very happily to that number. Of course, it would blow up fairly quickly. The other bit of complication is with engines that make a lot of torque. The current Corvette Z06 powerplant makes max torque at 4800 rpm and max power at 6300, which seems to be a pretty narrow band. However, smacking the gas at 2000 rpm in this car will shorten your eyeballs up by a diopter or two, because the engine is already making a bunch of torque. It's also screaming for more at 7000 rpm. Perhaps the best definition of the power band is "everywhere the engine makes the driver smile". Yeah, I know it ain't science, but it works. Bruce Last edited by bruce.augenstein@comcast.; 02122012 at 02:09 PM. 

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02122012, 06:34 PM  #37 
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law of diminishing returns...maybe?? I dont know.......am not a techie, but, seems like you would need an exponential power increase (in a geometric progression of sorts) to shorten acceleration times and increase top speed as you keep going up on the power scale........what I mean to say is, i guess, the difference perceived from the increase in power depends on where your baseline is  the power difference noticeable between 100hp to 180hp will be a lot more than what is noticeable between say 400hp to 480hp, although the delta is the same (80hp).........
thats the best way I can make myself understand...... the tech gurus on here will probably be able to explain it better...... 
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02122012, 06:39 PM  #38  
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02132012, 12:04 PM  #39  
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In English, that means you need to add a lot of power to get a relatively small result. As an example, adding 30% more power nets a 9.2% improvement in acceleration. (1.092 X 1.092 X 1.092 = 1.30). In other words, if your car was finishing a quarter mile in 14 seconds flat at 100 mph, adding 30% more power would theoretically net you a 12.82 @ 109.2 mph  reached by dividing the ET by 1.092 and multiplying the trap speed by 1.092. Of course, in real life, adding 30% more power might very well have you going up in smoke, tractionwise, so the 12.82 is suspect. The trap speed prediction will probably be pretty close, though. Bruce 

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02142012, 11:46 PM  #40  
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02152012, 01:11 PM  #41  
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Take the trap speed, divide it by the constant 234, cube the result, and multiply that figure by car weight with driver. The result is a reasonable horsepower estimate. As an example, Car & Driver ran a ZL1 Camaro to a trap speed of 119 mph, so assuming a 4300 pound curb weight with driver (4120 empty), we get: 119/234 = .508547, times .508547, times .508547 = .1315, times 4300 = 565 HP. Close enough to the rated 580. Doing the same thing with the Mustang at 4100 pounds, trapping at 126 mph, one gets a result of 625 HP. Again, close enough. ET? A goal for frontengine, rearwheeldrive street cars on stock rubber is that ET times mph should equal about 1400 or so, or as close as you can get. This is easy with lowpowered cars, but gets tougher as power goes up. Using this as a guideline, the new Mustang could likely be in the very low 11s in the quarter mile. Doubt it, though. Consider the ZL1 at 12.3 @ 119 mph. That product is about 1464, so assuming the Mustang could hook up as well as the Camaro, 126 mph gets you in the mid 11s. With wellwarmed slicks? High 10s, I think. Bruce PS  Its not as if the goal of ET times mph equaling 1400 is unobtainable in higher powered street cars, though. I have watched a stock ZR1 Vette go 10.75 at 130 mph at a carefully sprayed drag strip on a perfect day, so it's possible. Of course, the Vette has better weight distribution, and extremely aggressive street meats on it right from the factory. 

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02172012, 02:22 AM  #42  
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The Getrag designed MDCT is rated for 443 ft lb and 9000 rpm. It was not specifically designed for the M3 but did have it's debut in that. Thus is was not specifically designed for the relatively low 295 ft lb torque in the M3 and certainly has a much greater capacity than the S65 generates. Also I've never seen a transmission speced based on torque per cylinder. It is always dynamic torque or torque which is not measured per firing or per cylinder. It would be the same way an electric motors torque would be measured. Also from way back you said: Quote:
One key reason the M3 is an overachiever is because of its fairly low total drive train parasitic loss. The most accurate measurement of this is done by Rototest Research Institute (rri.se). They found only an 11% loss (less tire losses). This is not comparable to other loss specs that do often include tire losses.
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02172012, 02:41 AM  #43 
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For all those saying the M3 cannot do a 3.9 s 060 please get your facts straight. Yes, this number is the best magazine number achieved and yes it is an outlier of sorts in that regard. However, it has indeed delivered the magic sub 4.0 s run, 3.9 s to be precise.
Evidence here from C&D. Other reasons the car is sort of an overachiever based on it's power and weight. 1. Good traction which requires both good tires and good rear suspension design 2. Broad torque curve so acceleration can be near peak in gear levels at the rpm right after launch. 3. DCT transmission (obviously DCT model only). Some recent simulation work regarding the "power equivalence" of the DCT transmission puts the number close to 50 hp (mostly from a 1/4 mi perspective). In other words a MT M3 would need 50 extra hp to have about the same 1/4 mi performance as a stock DCT car. Prior efforts of mine put that figure at about 20 hp but I was probably using unrealistically short human/manual shift times which does lower this advantage. Also this "power equivalence" argument does depend of which performance contest you are looking at 060 vs. 0100 vs. 60130 vs. 1/4 mi, etc. Since the 060 contest does include 1 shift in a DCT car you will see this advantage equal to roughly the time for 1 human executed shift, perhaps 0.30.6 seconds. Link with the evidence for this as part of another lengthy loosely related debate here. Any way you look at it DCT makes the car substantially faster.
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02172012, 04:21 PM  #44  
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