Stage 2, S55 High Performance Engine: F80 M3, F82 F83 M4, GTS, F87 M2C

If you are planning a large power increase with bigger turbos CarBahn Autoworks has designed a high-performance engine to handle very high outputs by pinning the cam sprocket to the crankshaft. To ensure durability we also machine the block to accommodate a full circle thrust main. In addition, we utilize higher quality racing Carrillo connecting rods and forged CP pistons. The stage 2 engine also includes Cylinder head porting for increased flow at high RPM.

This Engine Includes: Forged Carrillo Rods, Forged CP Pistons, CarBahn Pined crankshaft, Full circle main bearing, high performance valve springs, labor and machine work to install them into the block.

Stage 2, S55 High performance engine: F80 M3, F82 F83 M4, F87 M2C

The S55 engine is not designed to take a large increase in boost beyond the OEM spec. Due to the design of the crankshaft, it is known to have the timing chain sprocket spin on the end of the crankshaft, causing the cams to go out of time. In extreme cases, the valves can hit the pistons, causing catastrophic damage. Furthermore, the S55 only has half of a normal crankshaft thrust bearing.

To ensure durability we pin the timing chain sprocket to the crankshaft, machine the block to accommodate a full circle thrust main. In addition, we utilize higher quality racing Carrillo connecting rods and forged CP pistons and CarBahn high-performance valve springs. We also port the cylinder head to ensure maximum flow at high RPM with larger turbochargers.

The stock engine compression ratio is relatively high due to the Corporate Average Fuel Economy (CAFE) standards which push for consistently higher fuel economy in cars and trucks. However, this increased compression limits engine performance with higher boost settings by decreasing the size of the fuel-air charge in the combustion chamber, forcing the ignition timing to retard far below MBT (mean best timing, the theoretical optimal ignition timing). Therefore, the Carbahn S55 engine has 0.5 less compression to optimize the engine for the increased boost. In an emissions-legal street car, the lowered compression has the added benefit of reducing catalyst inlet temperatures and improved drive-ability on pump gas.

CarBahn History

Steve Dinan has been building high performance and racing engines for BMW s since 1977, winning 12 racing championships including 3 prototype championships and two 24 Hours of Daytona. The same engine shop that builds the racing engines also builds the street car engines; these talented engineers, machinists, and builders have built hundreds of engines from OEM street rebuilds to full-blown racing engines.

Engine core acceptance parameters

Must be complete core (factory engine, from oil pan to valve cover)

• Block must have no:
  • Holes or cracks in casting
  • Holes or crack in covers
  • Bore damage that cannot be honed out
  • Thrust surface damage
  • Journal surfaces damage
  • Bolt hole damage that can’t be repaired
• Heads must have no:
  • Holes or cracks in casting
  • Holes or crack in covers
  • Thrust surface damage
  • Journal surfaces damage
  • Bolt hole damage that can’t be repaired
• Additional repair charges could apply for damaged items that are not normally changed during an overhaul and cannot be repaired or serviced
  • Valves
  • Crankshafts
  • Camshafts
  • Guides
  • ValveTronic mechanism
  • Vanos mechanism