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      01-22-2013, 08:25 PM   #303
clarence
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Drives: F30 328i M-Sport
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Quote:
Originally Posted by reallyreallyslow View Post
Truth be told, I have actually been through almost many threads on n20 engine and many of them are more like people who don't actually own one speculating what is the difference between the differen power level. Some are people who have not even seen the part number catalogue, telling people the engine are the same or different. Perhaps it will be nice if you could point me to the compression ratio discussion.

Yes, part number is different between different time of manufacturing, but in all instances, the short engine for the n20 is the same whether you order the 20i with 858A option or 28i. The turbo is the same.

However, if yours is ordered without the 858A option, the turbo is the same, but the short engine is not, because the pistons are different. Correct me if I am wrong, but it is really difficult to build an engine, dyno it, and then open up the engine to replace the piston/change the compression ratio, isn't it?

In any case, we are talking about 245hp out of a turbo di engine for their lowest end market, not 800hp. It isn't that difficult to achieve that in the first place.
Search for member E90fleet & u'll see the discussion. As I said before, yes, the part numbers are different, but are they of a different design? Different part numbers could mean many things - different design, materials, supplier or even manufacturing grade. Nobody has done a direct comparison between a high compression 20i piston w/ a low compression one, so we don't know wht is the exact difference. If u look at the specs on all X-series BMWs w/20i engine, they're all fitted with the low compression version, don't u think tuners would've noticed that?
Yes, 245ps is not difficult for a 2 litre turbo, but wht's difficult is that this engine has a very wide & consistent operating range which no other can match save for one or two (on paper Subaru's FA20T & GM's cherry-picked Ecotecs). There are many things apart from peak power & torque that can fail an engine, plus nobody knows the exact defect rates they have.
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