Quote:
Originally Posted by Propagator
But the problem with that logic is that the variation is way too big. We are not talking about ~5HP difference, but rather 60HP.
If your binning hypothesis was true, then the distribution of the N20's output coming out of the assembly line, which would be roughly bell shaped, would have to have its peak around 210HP, with the sigma of the distribution on the order of 50HP. But that's just crazy. For one thing, then the distribution of the output for 328i would not peak at 240HP, but rather a falling distribution that cuts off abruptly on the lower end. For the 320i, it would cut off on the high end.
Alternatively, the peak could be at 240HP, in which case the sigma of the distribution would have to be around 100HP. That's even crazier.
It's not inconceivable that they do some testing on the block or whatever other parts, and use the lower quality ones for the 320i, since it would not have to withstand as much stress. But that difference in quality is very unlikely to be the direct cause of the difference in output. It could make a difference in the longevity of the engine when chipped, but that's not the same thing.
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The variance need not be that big. As we all know, cars with 28i are regularly dyno'ed with much more than 245ps. It can very simply be that anything less than 245ps on the factory bench will be destined as a 20i, & anything more a 28i.
BMW claims the 20i have 184ps & the 28i have 245ps, those are only factory claims (i.e. minimum baseline) & it's perfectly fine to beat those figures on a regular basis. There are evidence that the 20i have more than 184ps, e.g. Autozeitung tested a 520i & recorded 0-100 time of 7.3s.