Quote:
Originally Posted by Pete_vB
Now about your simulations. Garbage in, garbage out. What gearing are you using for the 1M that has you at 215 mph in 6th? Your gearing looks off across the board.
The power curves for the 1M and M3 also don't look accurate... What power and weight are you using for the cars? I listed the power and weights I used in my initial post.
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Easy there champ. Go easier and slow down and take the time to look and think a bit more before opening up the insults. The graphs axes, drag and loss curves are automatically calculated to speeds far beyond the max speed a vehicle will actually reach. You can see the actual sim traces ending but you obviously did not look close enough.
My power and weight figures are accurate, guaranteed. I used quoted figures for the 1M and I already covered the case of possible underrating which very well might be the case. If you really want a list of inputs I can provide that. Although power and weight are keys, there are literally dozens of inputs to these sims including some pretty small and subtle effects. Anyway I did not post "power curves". These are thrust curves and take into account much more than just the torque curves and gearing. Losses are the key thing you are missing. CarTest includes rpm and speed dependent losses for: transmission, axles, diff, tires and aero losses. Tire losses are very significant above about 75 mph. I agree a per weight way of looking at calculations is important. If you want a thrust per weight just look at the acceleration curves, that is essentially what those are and I posted them (the very last set of results).
Quote:
Originally Posted by Pete_vB
Clearly a full simulation is the way to go running these numbers. If it's not set up right, however, it's pretty worthless. You've also given the M3 a lot more area under the power curve than the dynos show. What peak torque was that run at? Way too high.
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Yes, a full simulation is the way to go. Yes it is also true that all such sims are garbage in garbage out. Can you give me some actual real world performance results from your "simulations"? No, you can't because they lack enough physics. I reported the results I got for the 1M and they are right in line with real world reported numbers. My M3 numbers are too as well (since I worked on those years ago before the M3 was even launched). I hate to say "trust me" but I've spent countless hours using this simulator, tweaking and tuning it and comparing to real world results. My M3 engine power and torque values at the crank are exactly the values from the available dyno curves from BMW. Although I have found that using the simulator to curve fit based only on peak torque and rpm of peak along with peak hp vs. using an rpm by rpm input of the torque curve typically produces changes in results that are basically at the noise level. I have not "given" anything to the results, the simulator has calculated them given the correct inputs I have provided.
Quote:
Originally Posted by Pete_vB
You come off as defending the M3's honor. I'm simply trying to run some valid comparisons between the two. As I said, based on the dyno data to date the 35is motors look 15hp under-rated, so I used 350 hp, a fairly accurate torque curve based on the 1M and M3 and the published weights we have. Maybe try plugging that into the sim with the corrected gearing, both cars running manuals, get the torque right and let's see what it looks like. I have no doubt that the M3 is faster up top, but I think you'll be surprised how close it is.
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There is no need and no point of defending anything. I'm much more concerned about your ability to calculate useful metrics and interpret them rather than "defending my car's honor" or some such silly concept. Your "analysis" and commentary was painting a false picture of the cars being pretty close or advantages going to the 1M at certain speeds. This simply is not the case. I was and am thus critical of your clarity, your results and your interpretation of the results. Power to weight is the figure that matters. That is seen in the simulations and in the real world results the cars have achieved.