Quote:
Originally Posted by Propagator
Clarence, the biggest problem with your binning argument is that it doesn't explain at all why tuners are not able to get the same level of power out of x20i as the x28i ON THE DYNO.
I am sure some level of binning exist in any manufacturing. But, let's think about this hypothetical binning of yours. The ones that pass the test are the ones that can generate ~240HP for a reasonable amount of mileage, say 100K, without blowing up. And the ones that fail are the ones that can't generate the same power at the same boost, so they would detune it and sell it as x20i.
BUT, this does not mean that the failed ones would blow up as soon as you up the boost to 328i level, even if your conjecture was true. It could mean that when the boost gets turned up, the longevity of the engine will fall below the acceptable level. But that alone will most definitely not stop a tuner from bumping up the power and selling the reflash. No aftermarket company is going to do a 100k mile test to see if the tune holds up.
Now, it could be that BMW has put extra guard against high boost in the software to prevent people from pushing these "defective" engines too far. But if that is the case, then the direct reason for the tuners' supposed inability to get the power is NOT the quality of the engine, but the software. It could be that once they crack the software, the owners with the tune may find that their engines break down after 50k miles. But that hasn't happened, apparently because people can't make big power out of it. This very strongly suggests that binning cannot be the only, and even the most relevant, explanation for this problem.
|
There are 2 versions of the U0 engine (U0 is 20i's state of tune whereas O0 is 28i's state of tune) - high compression version & low compression version. The HC version has comp ratio of 11:1 whereas the LC version has comp ratio of 10:1 (i.e. same as O0). As confirmed by BMW China tech staff, the HC version have different piston crowns. They also confirmed that detonation will occur if the HC engine is ran at O0's (i.e. 28i's) level of boost.
Hence tuners cannot get O0's level of output using this version of U0 with just a piggy-back (AFAIK the DME on the N20 has not been cracked). Major upgrades need to be done to reach around 235ps (confirmed by poster several pages back).
The LC version of the U0 can theoretically be made to output at O0's level of output by running at O0's level of boost (or close to it's rated output if binned due to some "defect"), but it seems no tuner have tried to distinguish between these 2 versions of U0. There can be several reasons for this, e.g. this engine is only fitted to E84 & F25 during certain production dates, & for certain production dates it also had a different turbo, so it may be difficult to find a development car. As BMW themselves don't disclose why each of these LC engines are classified as U0 rather than O0, the tuners had to play safe. Again as the DME has not been cracked so all they can offer is a piggy-back.
The testing u mentioned is already done during prototyping stage, wht they do at the plant is a dyno run. A failure can be caused by sth as simple as the engine missing a few Nm's compared with the rated torque at idling speed.