[KB7]

Being new to turbo'd BMW's I always wondered as to why I haven't seen more BIG builds. The N55 is an inline 6 correct? When comparing it to my brothers Mk IV Supra's engine design, wouldn't the same logic apply? Slap a larger turbo on, add a front mount, and adjust timing/fuel, hell even reinforce with better rods, etc. Is this just not possible with our cars (strength of block, clearance issues, lack of after market support)or has it just not been figured out yet? I'm hoping that tuners or anyone with experience can step in and shed some light on this?

[Jimefam]

Well for one the 2jz has been around alot longer than the N54/N55 so the aftermarket is much more mature. Second the Supra was strictly a sports car and it's owners were far likelier to heavily modify a car the bought only for performance whereas the BMW is a sedan first and sporty car second which dilutes the "hardcore" enthusiasts %. But mainly the issue is the newness of the technology and how complicated BMW makes it to work on/modify these cars. For instance on the N54(and probably N55) the turbo is cast into the manifold making your "slap a bigger turbo on it" all the more difficult. The fact that these motors are DI is the biggest obstacle to progress due to lack of availability of parts and the difficulty in tuning the stock computer.

[KB7]

Jimefan, that's what I figured for the most part. There are some monster M3's running BIG hp turbo motors so I am hoping that those tuning capabilities trickle down to these motors. When you say these motors are "DI", what does that mean?