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      03-29-2012, 10:57 PM   #1
Maxx2
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Drives: 18 X5M
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BMW N63 Tuning...

The purpose of this thread is to share and collect as much information as possible regarding the BMW N63 50i engine and the tuning potential. Anyone with any information can post in this thread allowing us to collect as much useful data as possible in one central location for quick reference and ongoing discussions.

Thought it would be a good idea to get this started and to post what I have collected so far...
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Ever since I received my new X5 50i a month ago I have been researching the N63 platform and the potential for improving on this already excellent engine.

The obvious first comparison is with the S63 offered in the "M" X-series vehicles. With an identical 4.4L V8TT configuration these two engines have many similarities, however, it appears they have many differences with the biggest being the 155hp deficit for the N63. That is a significant difference for two engines which on paper look to be the same. The comparison chart below obtained from another forum is useful for understanding some of the basic differences between these two engines:

(S63 on the left and N63 on the right)


When deciding what the first step should be for increasing the performance of the N63 I initially looked for a tune which is the most common upgrade done to quickly increase the hp and torque.

The tunes currently available in the U.S. today range from very mild +40hp up to +96hp and even +120hp for one tuner in europe. The claimed gains are subject of great debate and each tuner has reasons why their tune is the best. Some believe that the larger claims are impossible to achieve on this engine with just a tune on factory turbos. Although this may prove to be true, for the time being we should explore the possibility that the gains are real and there may be more to these higher hp tunes that needs to be understood. Unfortunately when trying to validate these high hp numbers on a dyno and they are not achieved, the blame is often placed on improper dyno testing which is very hard to dispute and opens a whole new discussion on proper dyno testing procedures.

One of the topics of recent discussions with a few tuners on this board has been the limited gains achieved with their products relative to some of the other tuners and the reasons for that. Some of the arguments made have been that the turbos installed on the N63 are the bottleneck when compared to the S63 and are significantly limiting the tuning potential. Again, this may be true, but we need more information before reaching that conclusion. With that information I decided to research the specifics of the turbos used on both engines and then determine if that is indeed the reason for the limited gains. The following information is what I have discovered so far:

1) The N63 uses the same P/N turbo for both the right bank and left bank
2) The S63 has two different P/N's labeled "right" and "left" respectively for each bank
3) The N63 Garrett model number for each turbo is MGT2256GS
4) The S63 Garrett model number for each turbo is MGT2260SDL
5) The Garrett GT Series turbos use the first 4 digits in the model number to identify turbine & compressor wheel diameters in millimeters
5A) The N63 turbo uses a 22mm turbine wheel and a 56mm compressor wheel
5B) The S63 turbo uses a 22mm turbine wheel and a 60mm compressor wheel
6) The letters at the end of each model number are used to designate features of the turbo
6A) The N63 turbo features a "Compressor recirculation valve" and "Single passage bypass turbine"
6B) The S63 turbo features a "Single passage bypass turbine", "Dual passage bypass turbine" and "Water
cooled center housing"

Below is the Garrett GT series model designation chart for understanding turbo model numbers:



Using the information above it appears the turbos have the same size turbine wheel diameter, but have a 4mm larger compressor wheel on the S63. This information is not enough to fully understand the differences which may exist between these two turbos, but it is a starting point for discussion. I am still searching for more information including the compressor flow maps which are another important piece of the puzzle.

Another aspect of the N63 which has been discussed recently as a contributor to the power deficiency vs the S63 is the intake system. Thanks to TahoeM3 for posting this recent picture showing the N63 with the plastic shroud removed:



It is pretty clear from this picture that there is a considerable restriction in the intake path when compared to the S63. This is a very important aspect of tuning this engine and possibly an area of significant gains. To fully understand the differences between these two engines in this area it will require more research on the S63. The feasability of using components from that system on the N63 should also be explored as this may be a viable option.

Last edited by Maxx2; 03-29-2012 at 11:11 PM..
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