Reinforced ARP main studs BMW / MINI / PSA N12 N13 N14 N16 N18 EP6

This kit of reinforced main bearing studs for the BMW, MINI and PSA THP engines is made up of ARP studs, ARP washers and ARP nuts.

The fitting instructions are in the "Download" tab above.

Gary Holzapfel came from the aerospace industry and founded ARP (Automotive Racing Products) in the early 1970s to answer a major problem in motorsport: engine failures caused by bolts and studs that were simply not strong enough. At the time no manufacturer was able to meet that need. Today ARP offers thousands of part numbers across several ranges and product types, such as head bolts, main bearing bolts and con rod bolts. Depending on the application, ARP offers several material ranges:

• 8740: a chrome-molybdenum steel whose standard strength properties are perfectly adequate for a built engine. This steel offers a tensile strength of between 1240 and 1447 N/mm2.
• ARP2000: stronger than 8740, the ARP2000 alloy withstands clamping and tensile loads of up to 1516 N/mm2. This range is widely used on track and drag cars and can be run with hydrogen.
• L19: a treated premium-grade steel offering tensile and fatigue strength well above the 8740 and ARP2000 ranges. Its tensile strength reaches 1792 N/mm2. This material is more prone to corrosion and must therefore be kept oiled and away from moisture. Hydrogen is not recommended with this range.
• CA625+ (Custom Age 625 Plus): this super alloy offers substantially higher technical properties while resisting corrosion and oxidation. Its tensile strength reaches 1930 N/mm2.

All ARP fasteners are designed and manufactured in the United States. Production starts with cold or hot forging, then a heat treatment that differs from one range to another is applied, and shot peening removes any irregularity. Precision grinding follows, to obtain perfect concentricity, then the thread is rolled. Last comes the finish, where a coating such as black chrome-molybdenum oxide is applied, or the stainless steel is polished, depending on the product range.

Every kit is supplied with assembly lubricant and an instruction sheet stating:

• The fitting steps
• The thread of the bolts, studs and nuts
• The tightening torque
• The tightening procedure