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BMW S50B30US race engine preparation

This is a BMW S50B30 US-spec engine we are preparing for a local customer. Engine will be installed in a E30 BMW chassis and used for road course racing and HPDE events.



Engine was delivered to us still assembled with a cylinder head. Short block was a M50B25 stock motor. Cylinder head was a stock single VANOS M50 unit. Cylinder head was recently service by another shop. Since this will be a high RPM race engine we chose to install Supertech valvetrain pakage and cat Camshafts.



-PRE custom forged pistons: 0.5mm oversize, 11,5:1 compression, tool steel piston pins that are only 2.000in long to reduce weight, lateral gas ports for top ring to increase seal, skirt and crown coatings. Pistons were made as light as possible to reduce high RPM reciprocating loads and connecting rod bearing loads. Pistons and pins weight matched as a set to within 0.5 grams.

-Eagle connecting rods: standard Eagle connecting rods with ARP bolts. We weight matched rods at both ends and now weight spread is within 05 grams for the whole set of six rods

-ACL Race main bearings: this is a standard issue item from ACL

-PRE custom connecting rod bearing by ACL: ACL Race series rod bearings for the S/M20/50/52/54 engine are discontinued by ACL leaving very few performance bearing options. We made fixtures and modify bearings to suit this application. We sell this bearing kit. Please inquire by email for availability and pricing.

-ARP head and main stud kit: standard items from ARP

-OEM forged crankshaft micropolished and performance balanced

-OEM S50B30 US-spec engine block was stripped, baked, shot blasted, bored, honed, deck milled, align honed, primed, and painted. New brass expansion plugs fitted as well.



-Supertech valve spring kit: dual valve springs, PRE titanium retainers for 7mm valve stems, viton valve stem seals, hardened spring seats

-Supertech shimless solid camshaft followers(buckets/lifters): this was done to reduce valvetrain weight and risk of hydraulic lifter failure

-Cat Camshaft set: specific for solid lifters

-Since cylinder head was recently service a valve job or guide work was not necessary. Valve faces were reground and lapped by hand for a perfect seal.



-VAC Motorsports oil pickup baffle was fitted to the factory oil pan

-We are in the process of developing an upgraded oil pump drive for these engines. These engines are known for loose oil pump sprocket nuts and even sheared sprocket drives. Our oil pump shaft is made of 4130 pre-hard chrome molybdenum steel, precise machined to match factory shaft dimensions. The shaft incorporated a large flange with four retaining screws that will be fitted with safety wire as well as three hardened dowel pins.



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3 thoughts on “BMW S50B30US race engine preparation

  1. Were any changes made to the cam chains .. What horse power was expected?

  2. OEM chain retained. Engine currently at the ECU tuner’s shop being fitted with a Link ECU so curretly power figures unavailable. Should be right around 300hp though.

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