Lang Racing BMW S54 Turbo Prep Bottom End Kit
The Lang Racing crankshaft modification kit addresses the issue of the undersized rod bearing on the S54. We chose a rod bearing that was a significantly wider than the S54 stock bearing but also slightly smaller in diameter. This allows us to take damaged crank journals and have them re-ground to accept our wider bearing. Once the crankshaft is modified we then heat treat, plasma nitride, and dynamically balance it.
This modification has many benefits, both in engine reliability and in economics. Most obviously the wider rod bearing will increase rod bearing/rod journal surface area. This change between the bearing and journal provides increased protection against crankshaft journal to rod bearing contact and prolong the overall life of the rod bearing. This also allows the bearing to handle more potential torque from the piston, a good idea if you are considering forced induction, high compression, or racing. This original kit was the basis of what we turned into our S54 Turbo bottom end prep kit for engines producing up to 1000WHP. We redesigned our Carrillo rod to make it stronger and handle higher horsepower. We use larger bolts to keep things strong due to the increased weight of the heavier piston and rod we use. We added the option to increase wrist pin diameter is increased from 21mm to 22mm for higher loads. This requires a custom piston to be made which increases cost slightly.
Since these engines are unique we do not stock any turbo S54 pistons and every single one is specifically designed for customer requirements using either CP or Mahle Motorsport. With this kit we added the option of upgrading to a completely custom billet crankshaft which will reduce crankshaft weight approximately 3 pounds while also significantly increasing bottom end strength. The billet crankshaft is significantly stronger than the OEM forged crank and is designed to handle the power without flexing. This crankshaft will reduce wear on the main bearings from crankshaft flex and its superior balance allows the engine to spin to higher rpm than stock.
Before any of our crankshaft kits go out we check rod bearing clearances in house and match the rod bearings, rods, and journals to the exact tolerances we require. This gives the builder a little more confidence that one of the most critical clearances in a motor rebuild has been checked before the parts even arrive. We've designed our kit to utilize the OEM rod length compensating for the change in rod bearing. We recommend and can supply CP, and Mahle Motorsport pistons as an additional part of this kit. This kit does require that you provide a core S54 crankshaft (unless you upgrade to the Billet crankshaft), one with spun rod bearings is typically acceptable, there is an extra 150 dollar charge if the mains need to be ground.
We suggest a few additional items that we consider essential for a forced induction S54: ARP Main Stud Kit and ARP L19 Head Stud Kit which are not a part of this kit.
For an additional charge we also do complete bottom end or complete long block assembly in house and international shipping is available. Our assemblies come complete with build sheets including all clearances and weights of the components used.
In an effort to allow our customers the most versatile options we've added new piston and rod options. Each option will increase or decrease the base price based on the relative cost.