ARP Head Stud Kit, BMW N55/S55

This kit is engineered to replace BMW part #11127853937 and is compatible with BMW N55B30 engines found in a range of models, including the F07 535i GT, F10/F11 535i, F06/F12/F13 640i, F25 X3 xDrive35i, F26 X4 xDrive35i, and E84 X1 xDrive35i. Additionally, this kit is also compatible with the S55B30 engine found in F80 M3/F82 M4 and F82 M2 Competition models.

This kit comes with 14x 11mm Studs, 14x Washers, and 14x Nuts offering increased clamping force and enhanced head gasket sealing, which can prevent head gasket failure. This is particularly crucial for high-performance or turbocharged engines, as the increased cylinder pressure puts additional stress on the head gasket and bolts.

Our Custom Age 625+ kit is made from a material with a tensile strength of 260 ksi, substantially higher than the 190 ksi of the ARP 2000 head stud. It’s an ideal choice for individuals who want to push the limits of their N55/S55 builds.

Please note that this Head Stud Kit is not a retrofit from a Chrysler or Volvo stud kit. Unlike those kits, our kit was specifically designed for the BMW N55/S55 engines.

Installation Instructions: 

N55 engines, it is a MUST to drill and tap the four outer 9mm holes in the engine block to increase their size to 11mm holes. This will ensure that all the engine block holes are uniform in size and can accommodate all 14x 11mm Studs. Additionally, it will help distribute even force across the cylinder head-gasket surface.

S55 engines, it’s a Bolt-On kit with no modification necessary.

1. To ensure proper thread engagement and accurate torque readings, clean ALL threads in the block. Chase if necessary with ARP Thread Chaser.

2. Clean and inspect all hardware prior to installation. Look for obvious defects or shipping damages, plus proper fit, length and dimension.

3. If the cylinder head studs protrude into a water jacket, lubricate the block threads of the studs with ARP THREAD SEALER.

4. Screw studs into the block “HAND TIGHT ONLY”.

5. Install the cylinder head(s) and check for binding or misalignment.

6. Lubricate the stud threads, nuts and washers with ARP ULTRA-TORQUE FASTENER ASSEMBLY LUBRICANT.

Then install the washers and the nuts onto the studs and tighten them hand tight.

ARP recommends using the ARP ULTRA-TORQUE FASTENER ASSEMBLY LUBRICANT that is provided with each kit as opposed to motor oil. This is due to higher friction on the studs as well as inconsistencies in the clamping force of the fasteners when motor oil or other low quality lubricants are used.

PRELOAD (TORQUE) RECOMMENDATIONS

7. Following the manufacturers recommended torque sequence tighten the nuts steps 1-3

with ARP Ultra-Torque fastener assembly lubricant

12	10	4	2	6	8	14
13	7	5	1	3	9	11