Quote:
Originally Posted by reallyreallyslow
It is impossible that BMW bins the N20 such that if an engine makes <245hp, it is a 20i or if an engine makes >245hp, it is a 28i.
This is because...20i and 28i ARE DIFFERENT ENGINE.
While many MAY think and claim that the 20i and 28i are exactly the same engine, bulk of the 20i around are on 11:1 compression ratio. 28i are 10.1:1. These engines have different part number.
Only those 20i (135kw) engines with the low compression option will have the exact part numbers as the 180kw version of the engine. In this case, it is the dme software that will limit your power. Apparently, a dme swop can bring it back to 180kw. Of course, there is still the intercooler and exhaust diameter...
My opinion: Ideally, a 135kw version can be tuned to perform just like a tuned 28i engine, i.e. near 300hp. The reason why the 20i version does not chip to near 300hp like the 28i does is because of limp mode. Why limp mode? I don't know. What I know is that beyond a certain level of extra boost, a 20i goes into limp mode. Similarly 28i engine goes into limp mode if really pushed. I suspect it is the dme interferring.
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if that is really the case the 20i should make higher power boost for boost. higher compression=higher power. Just that it cannot take too much boost