ARP Reinforced Cylinder Head Studs BMW 325i E30 525i E34 M20B25

This kit of reinforced cylinder head studs for the BMW 325i E30 and 525i E34 is made up of 14 ARP studs, 14 ARP washers and 14 ARP nuts.

You will find the fitting instructions in the "Download" tab above.

Below (click on the image) you will find the reinforced head gaskets for the BMW M20B25 engine:

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

• 8740: a chrome-molybdenum steel whose standard strength properties are perfectly suited to prepared engines. 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 used with hydrogen.
• L19: a treated premium grade steel offering tensile and fatigue strength properties clearly above the 8740 and ARP2000 ranges. Its tensile strength reaches up to 1792 N/mm2. This material is more sensitive to corrosion, so it must be kept oiled and never exposed to moisture. Hydrogen is not recommended with this range.
• CA625+ (Custom Age 625 Plus): this super alloy has significantly higher technical properties while resisting corrosion and oxidation. Its tensile strength can reach 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 is applied (it differs from one range to another) and shot peening follows to remove any irregularity. Precision grinding then gives perfect concentricity and the thread is cut. Finishing comes last, with a coating such as black chrome-molybdenum oxide, or polishing of the stainless steel depending on the product range.

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

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