4N-N55r26 2.6L race engine

  • Sale
  • Regular price $19,500.00

Contact to Order

The N55r26 is designed for the high rpm track enthusiast. With a 9,000rpm rated rev limit it works perfectly as a track based engine or daily driver who wants more of an exciting driving experience!


 •Pricing includes our custom one piece de-stroked billet crankshaft, custom rods, custom pistons, upgraded valves, springs, retainers, head porting, engine assembly, billet oil pump, machine work, and upgrades to the oiling system.


 Build time is estimated at 12-14 weeks due to the timeframe required for machining our 4340 billet crankshafts. 


• If the engine is to be used specifically for road racing use we recommend utilizing the S55 oil pan and oil vacuum pump system. This will eliminate the possibility of oil starvation through high speed left hand corners. Please let us know via email for the additional pricing on the S55 oil pan and vacuum oil pump. 


 • All engine stages feature the same design, head porting, lightweight valvetrain, HD springs, billet crankshaft, coated bearings, custom pistons, H beam rods, custom billet oil pump, and oil pump block modifications. The differences between each of them is listed below.


•Stock open deck block is limited to around 700whp. Going above that may cause the sleeves to crack due to the slits between the sleeves bmw added across the deck. 


•stage 1 650-700whp rated -$19,500

Standard open deck block, ARP 2000, head port cleanup


•stage 2 850-900whp rated -$22,500

closed deck block conversion by CSS, ARP 2000 head studs, head port clean up


•stage 3 1000whp+ rated -$23,999

closed deck CSS + ARP 625 head studs, shrick exhaust camshaft upgrade, 5 axis cnc ported head. 




•Standard N55B30

•bore/stroke  84mm/89mm

The traditional N55B30 engines feature an under square design. Under square engines are designed for low rpm efficiency. The stock N5X design has a rod ratio of around 1.5. This helps the engine produce lots of torque early on from 2,500-4,500 rpms due to the relatively short rod, and high rod angle effects on piston acceleration down from TDC. 


 •4N- N55r26

•bore/stroke 84/79

The N55r26 is designed differently. We started off by figuring out where we wanted HP and torque to come in. With the new bore/ stroke of 84/79 we effectively created an over-square N55 engine. Over-square engines favor higher rpm power with less torque low in the rev range. They make more HP freely up top and produce less stress and heat on vital components. The benefits to reducing stroke and increasing rod ratio is a rotating assembly that will last a very long time at 9K rpm. Often the immediate response to less displacement is the engine will make less horsepower. However, since the N55r26 2.6L has an increased 9Krpm rev limit with less internal friction it will not lose power vs the standard 3.0L due to this equation Horsepower (HP) = (Torque × RPM) / 5252.


•Benefits to the de-stroked N55r26

increased piston dwell time, reduction in high rpm frictional losses, less rotating mass, reduced mean piston speed, reduction in crankshaft harmonics, more main bearing and rod journal overlap, faster throttle response, less connecting rod angle, ability to gear down the differential to 3.91 or 4.10. All of these changes combined produce an engine that has a faster throttle response, weighs less overall, and is very capable of handling harsh conditions like road course endurance racing. 




•Engine core acceptance parameters

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

• engine core must be shipped to us in good used condition to rebuild. 

• block and head must have no cracks, holes, or signs of oil starvation.