Super Nuts and Bolts: A Look Inside ARP Bolts and What Makes Them Better
When you're making big power, you need an engine that's reliable. ARP fasteners are crucial to make your diesel engine better than stock: the engine keeps running as it puts down monster power on the track.

When you’re making big power, you need an engine that’s reliable. ARP fasteners are crucial to make your diesel engine better than stock: the engine keeps running as it puts down monster power on the track.

The first step to creating a successful business is to identify a public need.
Then, you’ve got to fill it.

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That’s exactly what racing enthusiast Gary Holzapfel did back in 1968 when he noticed friends and fellow racers succumbing to bolt-induced engine failure: He put his background in fastener manufacturing to use and developed a solution. Soon, Holzapfel began making race-quality fasteners with aerospace technology, and ARP was born.

MANUFACTURING

All of ARP fastener manufacturing is done in-house at a Southern California facility. The process starts with wire coils and ends with fasteners, nuts and bolts that are superior to what is widely considered aircraft quality. ARP’s fasteners are built to withstand serious racing and have higher tensile strengths and can survive higher stresses than most aircraft fasteners will ever see.

The process is simple, but more precise than those used for the bolts you’d find at the hardware or aircraft surplus store: First ARP works with their steel suppliers to get the best grade of steel. While steel essentially comes in four grades, ARP uses only the top two (aircraft grade steel is generally only a tier-two material—not up to ARP’s standards). The original line, still produced, is the ARP2000 line, and it exhibits a whopping 220,000-psi tensile strength. But that isn’t even the peak strength of ARP products: The new-to-the-lineup ARP’s Custom Aged 625+ hardware boasts an even-higher tensile strength of 260,000 psi—when you’re boost numbers are climbing, these head studs are a must!

“All or ARP fastener manufacturing is done in-house at a Southern California facility. The process starts with wire coils and ends with fasteners, nuts and bolts that are superior to what is widely considered aircraft quality.”

Here you can see a coil feeding into a cold header machine. No additional heat is used in this process.

Here you can see a coil feeding into a cold header machine. No additional heat is used in this process.

The cold heading process takes coil wire (L) and forms it into a basic bolt head (R). Four stations are needed to get the coil wire into the necessary form for the bolt making process.

The cold heading process takes coil wire (L) and forms it into a basic bolt head (R). Four stations are needed to get the coil wire into the necessary form for the bolt making process.

Each batch of ARP bolts is put through rigorous testing before being packaged for shipping. This Instron unit pulls the bolts apart and then registers the force needed to make them yield and break. Bolt stretch and other factors are checked here to ensure your bolts are perfect for your high-power needs.

Each batch of ARP bolts is put through rigorous testing before being packaged for shipping. This Instron unit pulls the bolts apart and then registers the force needed to make them yield and break. Bolt stretch and other factors are checked here to ensure your bolts are perfect for your high-power needs.

ARP bolts, nuts and studs begin life as coils of top-grade steel.

ARP bolts, nuts and studs begin life as coils of top-grade steel.

When the steel arrives, it’s a coil of raw steel wire and looks like a round bar. This steel wire then undergoes one of two processes: cold or hot heading. Contrary to the name’s implication, cold heading is done at room temperature; meanwhile, hot heading is a tad more literal. (It’s not some angry guy yelling at the parts as they wiz down the line!) Instead, the steel is heated to a glowing state to facilitate the forming of complex shapes and/or tougher than average (for ARP) alloys. This is just one of the many steps it take to produce the bolts that will keep your race engine alive—even under the most extreme conditions.

Here you see an ARP head stud kit being installed on a Ford 7.3L diesel.

Here you see an ARP head stud kit being installed on a Ford 7.3L diesel.

Hot heading involves heating the steel blanks to a precise, red-hot temperature and then putting tons of pressure to form the heads. This process is used for more complicated bolt head designs.

Hot heading involves heating the steel blanks to a precise, red-hot temperature and then putting tons of pressure to form the heads. This process is used for more complicated bolt head designs.

Bolts are sent to the heat-treated ovens to get the correct hardness-- not too soft and not too brittle. This BeaverMatic is a hottie and turns soft steel into hard nuts and bolts.

Bolts are sent to the heat-treated ovens to get the correct hardness– not too soft and not too brittle. This BeaverMatic is a hottie and turns soft steel into hard nuts and bolts.

After forming the basic bolt, stud or nut, with threads, heads and body diameters to suit the application, the stock is sent to ARP’s in-house heat-treat facility and then to shot peening. Heat-treating gives the bolts strength without brittleness, while shot peening further improves the strength and durability.

All ARP products are then random batch tested for quality. Once they’ve passed the grade, they’re packaged up and shipped out to motorsports enthusiasts around the world.

Yep, the race goes on, often because ARP helped keep the heads on and the rod spinning. DW

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ARP recently introduced their 625+ line of fasteners. Here you see a comparison of their ARP2000 and 625+ head stud kits for the Ford 6.0L. The 625+ studs are the shiny ones. However, the difference goes deeper than just the look: The ARP2000 parts are made from chrome moldy steel and have an impressive tensile strength of 220,000 psi. The Custom Age 625+ parts take it to the next level. They are made from a heat-treatable stainless steel and are rated at a minimum tensile strength of 260,00 psi, with higher numbers often seen in testing. If you’re going for Max Race power, the added clamping load the 625+ can provide is perfect. For more mild builds, the ARP2000 line is better than stock and more cost effective.

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ARP is constantly developing new products. We found this Cat 16 engine in their R&D shop being used to engineer another line of diesel engine upgrade assembly hardware.

ARP is constantly developing new products. We found this Cat 16 engine in their R&D shop being used to engineer another line of diesel engine upgrade assembly hardware.

This carded package contains rod-end main-cap bolts for the GM 6.6L Duramax: two bolts per rod and eight rods worth of super-strong rod bolts.

This carded package contains rod-end main-cap bolts for the GM 6.6L Duramax: two bolts per rod and eight rods worth of super-strong rod bolts.

Sources:

ARP (Automotive Racing Products)

800-826-3045

Arp-bolts.com