Virtually every top professional BMW engine builder relies on ARP Pro Series head studs, particularly on the S54 3.2 litre engine. ARP uses a premium grade 8740 alloy that is rated far superior to "aircraft" quality. Each stud is heat-treated to 200,000 psi, ensuring complete heat penetration. ARP studs are threaded after heat-treat, which gives them 1000% (that's ten times!) better fatigue strength than studs threaded prior to heat-treat. Threading the studs after heat-treating is more difficult and costly (as it's harder on tooling) but the results are well worth the effort. These simply are the best S54 head studs we've found for the E46 M3 6 cylinder engines, and we highly recommend them in both the racing and forced induction arena. (Due to the additional clamping force between the head and block, these are IDEAL for turbo charging and supercharging!)
Converting from the factory BMW head bolts to head studs makes it much easier to assemble an engine, especially a racing powerplant which must be serviced frequently (and quickly!), and also ensures proper alignment of the head and gasket. Head studs also provide more accurate and consistent torque loading. Here's why: When you use bolts to secure the head, the fastener is actually being "twisted" while it's being torqued to the proper reading. Accordingly, the bolt is reacting to two different forces simultaneously. A head stud should be installed in a "relaxed" mode -- never crank it in tightly using a jammed nut. If everything is right, the stud should be installed finger tight. Then, when applying torque to the nut, the stud will stretch only on the vertical axis. An information sheet is provided with each set. Kit includes everything pictured -- 14 head bolts, washers, bolts and assembly lubricant.
These head studs fit the following BMWs/engines
2001-2006 E46 M3 coupe & convertible
2001-2002 MZ3 M Roadster & M Coupe (with S54 engine)
2006-2008 MZ4 Z4 M Roadster & M Coupe