The zenith of naturally aspirated M engines were still restricted.
"These build journal entries are part of a Special Series on the V3 product update the InfinityDesign Long Tube & Equal Length S85 V10 headers.
This journal entry covers backstory to the development of InfinityDesign's V10 headers along with in-depth look at key features in collaboration with Sal at InfinityDesign."
The S85 and the S65 were the pinnacles of naturally aspirated engine development by BMW M.
BMW M engineers managed to create equal length headers for the S85 and S65. Yet, like many street engines, it needed to meet emissions targets.
The V10 has primary cats right after the merge collectors and are built into the headers. The design immediately impacts exhaust flow and pressure - inhibiting potential performance from the S85B50.
The primary cats shortened the overall design of the OEM headers and forced BMW M designers to crimp and reduce the diameter of the primaries in sections of the design.
None of this is good for performance - yet BMW M engineers still achieved an equal length design to obtain the signature exhaust note we crave
Uncorking the V10.
The V8 benefitted from the experiences learned with the V10 by placing the primary cats on the front pipes and created a full unobstructed equal length header design.
It's been common knowledge in the M5 V10 communities that performance gains are mostly found by replacing the primary cats and improving upon the stock header design with a a lengthier runner design.
There has been multiple solutions brought to the market over the years.
Tuners initially released primary cat delete pipes that were welded onto the OEM merge collectors. This retained the signature S85 sound, and enhanced performance, yet it wasn't optimal.
Many exhaust manufacturers released long tube headers in various runner and merge collector design.
These were the better performing solution, extracting the most power from the V10.
Unfortunately it sacrificed the tone of the V10 as it sounded quite harsh.
Power without sacrificing the S85 legendary exhaust note.
InfinityAutoDesign hit the drawing board and designed the optimal solution for BMW M5 V10 owners.
This equal length design retained the signature S85 exhaust note, while being the best performing header solution on the market.
The design philosophy of InfinityDesign was to retain an even diameter across the runners, while achieving the required length through unique curvatures for max performance.
The design went through multiple design improvements as the primary hurdle was packaging.
The most recent design update was implemented to improve the jig's accuracy and precision in order to make installation easier while retaining the signature sound and highest performing header system on the market.
02 Bungs placement.
The initial design had slight issues with 02 bungs and and made it time intensive to install.
InfinityDesign tested various runner diameters to ultimately settle on 42mm for optimal performance on 5.0 displacement and strokers.
The V3 also eliminated springs on the merge collectors in favour of a slip-on fit. They are sealed at the collector using high temp silicone to allow heat expansion.
As of June 2022, all V3 headers order are now shipped with bolts and nuts with holes on the primaries and merge collector to secure and seal them together. Using high temp silicone is still required.
They are TIG welded and made from 304 Stainless Steel. Each runner is individually tagged and aligned to slip into the merge collector.
Up next: I discuss the installation process and first impressions.