ARP M8 Rod Bolt Kit for Honda D-Series & B18A/B B20

ARP M8 Rod Bolt Kit for Honda D-Series and B18A/B18B B20 - Part #208-6001

Rod bolts are what let go when you spin a stock bottom end past its comfort zone, and on the D-series and non-VTEC B-series they are a skinny 8mm. If you're building an LS-VTEC, a B20-VTEC, or a D16 that will see sustained trips past 6,400 rpm, the ARP M8 rod bolt kit is one of the first parts that should go in the block.

What It Is and Why It Works

These are ARP High Performance series bolts machined from seamless 8740 chromoly and heat treated to a nominal 200,000 psi tensile strength, with threads rolled after heat treat for fatigue life. That matters because rod bolts fail from cyclic stretch, not one big hit, and the rolled threads plus the large underhead radius are what resist that fatigue. The 208-6001 is the 8mm OE size kit, which covers the D15, D16 (D16A1, D16A6, D16Y5, D16Y7, D16Y8, D16Z6), and the non-VTEC B18A1, B18B1, B20B, and B20Z. It's the classic first step on an LS-VTEC or B20-VTEC build, where the LS bottom end suddenly gets a VTEC head's rev ceiling and the factory bolts become the limiting factor. The kit is 8 bolts and 8 nuts, installed with the rods out of the engine and resized afterward.

Specs

Fitment

These fit engines with 8mm rod bolts: the D-series and the non-VTEC B-series (B18A, B18B, B20). The 99-00 Civic Si's B16A2 and other VTEC B-series engines use 9mm bolts, which is ARP kit 208-6401.

What to Know Before You Buy

Two things trip people up. First, these fit factory rods only, so if you're running Eagle, Manley, or any other aftermarket rod, your bolts came with the rods and you don't need this kit. Second, check your bolt size before ordering: VTEC B-series engines (B16A, B17A1, B18C1, B18C5) take the 9mm 208-6401 kit, not this one. Plan on having the rods resized with the new bolts installed, since clamping the caps with fresh ARP hardware changes the big end bore enough to matter on a careful build. If the engine is apart anyway, new rod bearings alongside these bolts is cheap insurance.