[1.8t]

RPM's kill motors. They are harder on bearings, they are more expensive, they require more up-keep, they consume more oil, and have more oil control issues than an equivalent motor with a lower redline. The do allow more hp given a fixed displacement provided the head/cam selection is up to the task. Most high rev engines are derived from rule requirements and or space requirements. They make it into street cars touting race technology, which helps sell the brand. I also hear that the tq multiplication via gearing is better optimized with a higher redline but I honestly have not looked into that any further that just "hearing" that statement(honestly, based off of some minor brainstorming, I don't see how that comment has any merit).

However, don't fool yourself. If the E92 motor could last 150k miles with a 8400rpm redline, how long do you think it coud last with a 7k rpm redline? Before anyone tries to inform me, yes, I know motors can be built to withstand high rpm use(I had an S2k), but that doesn't take away from the fact that there is less margin for error and assembly process mistakes are more pronounced in the form of blown motors on high rpm engines. Also syncronizers have to be extra snappy since WOT shifts are happening at 8400rpm. There are a whole host of upgrades that have to be accounted for when building a high rpm production car, but it does get the heart churning and the mind racing better than any other form of power production.