Quote:
Originally Posted by chaungo
If you only have access to 91. Meth is your only choice to hit 450whp+
The good thing Pure stage 2 is it's affordable and the lag will save your drivetrain and engine.
If you did not have lag and spooled the same as stock turbo, you will break your driveshaft or an axel.
You want a gradual increase of power, it'll also help with launching too as you won't have full torque and won't spin as much.
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Do not confuse progressive or linear power delivery with turbo lag. Exactly the opposite, power would be perfectly linear without lag at all. Less of it you have, more linear it will be. It's a tuning strategy, which many like, to crack up boost early on as high as hardware allows, which is only possible with fast spooling turbo, making a false public perception of it being not linear. Ideally the boost target being met at idle rpm and being held constantly till redline working like a naturally aspirated engine on another plant with higher atmosphere pressure.
Turbo lag means more exhaust flow energy it needs to reach its rpm threshold to make boost. And when it does, power surges and it increases at a much higher rate and thus put much more pressure on everything than fast spooling turbo. Do not try to whitewash turbo lag just because you have it - turbo lag is a con from almost all the angles you look at it.
If you're familiar with GTR R35 world you'll see clearer my point. In there turbo upgrade is elementary just like a piece of cake everybody easily does. No one can brag about power without having 1000whp. No other platforms in the world breaks more things than R35 in pursuing power. What happens when you have a "too fast spooling turbo" is compressor surge (compressor makes more flow than motor can eat at lower rpm, how is that fking possible with our tiny little n55 turbo?). It can cause turbo mechanical failure or wear out quickly. Next thing it can break is rod/piston (I'm speaking when timing is set properly, no knocks), but bigger turbo does that way sooner and also stresses transmission and drive shift way more.
TBH, the things in the way doing turbo upgrade on N55 platform is not the hardware but tuning. DME was just hacked less then 2 years ago and they are barely ready for hybrid turbo. N55 is being phased out by BMW but aftermarket tuning of it is yet in its infancy. That's why I urge OP to only work with a tuner that's knowledgeable enough and most importantly fully committed.