I thought I'd share my latest information regarding the turbo in the R56 MCS [model year 2007+] The turbo is a Borg Warner K03, which has a maximum flow rate of 22.4 lb/min of air, which is good for up to 200 HP. This matches very well with the stock configuration of the MINI's 1.6L and 172 HP. Coupled with the aggressive 10.5:1 static compression ratio and direct injection fueling, the K03 is able to spool quickly and provide an excellent torque shelf across most of the engine's RPM band.
At the upper RPM's, the ECU opens the wastegate more and tapers the boost level to maintain about 170 HP from 5000 RPM to 6500 RPM. What that boost goes to and from is still unclear [until it's properly datalogged], however what is more prevalent is the combination of the ultra high compression ratio, DI, and the boost level in which the K03 achieves its max flow rate. To put it simply, the stock engine/turbo configuration on the R56 MCS will not be able to support over 200 HP not only due to the limitation of the turbo itself, but also a large risk of piston damage from detonation. Since I suspect the ECU is at least as good at avoiding knock as the R53's excellent system, the R56 MCS will reach a proverbial glass ceiling of power. My initial calculations show that about 16 pounds of boost will be all the stock engine will handle with the stock turbo. This 16psig ceiling is due to the high compression ratio in conjunction with the direct injection. However, this also means that a larger, more efficient turbo pressurizing the engine at 16 pounds of boost will make more power.
To get over 200 HP, there is really only one option:
*A turbo swap to something that flows more air more efficiently at the same or lower boost levels [similar to what I discovered on my MM2 Turbo Project going from supercharger to mis-matched turbo, mis-matched turbo to well-matched turbo [very low efficiency to good efficiency to very good efficiency]. A comparable Garrett model to the Borg Warner K03 is the Garrett GT2052, a very tiny turbo, about 3 families down the scale from the unit I installed in MM2. The K03 is the same type of turbo used in VW's old and famous 1.8T engine, used in Mk4 GTI's. It's a respectable piece, with excellent spool characteristics, it's just that it can't make a ton of power. My initial instinct is to call for either the Garrett GT2554R or GT2560R. Both of these turbo's will get the R56 MCS engine into the 230 and 260 HP range respectively while keeping under 16 pounds of boost.
To get over 260 HP, there is yet again only one option:
*new pistons with lower compression! Lowering the compression allows much greater boost to be run [thus making much more power] while maintaining that we use "only" 93 octane pump gas, which is the only acceptable solution for most of us. Obviously, having new low-compression pistons implemented will be timely and expensive, as the engine block should come out and the whole rotating assembly balanced. A reasonable expectation for "low-compression" R56 MCS pistons could be somewhere around 9.0:1. This would allow us to run up to 22 pounds of boost [Big power = 350 HP+!] while only sacrificing a bit of the R56's newfound fantastic fuel economy. Of course, all this is assuming the R56's fuel system are up to the job, and we can hack into the ECU system and control or at least manipulate it to our needs.
Fun times ahead!
Cheers,
Ryan
and then I'll let you know if it works good or not.