Part number: AR202-4309

ARP 2000 Series 11mm Head Stud Kit to suit Nissan RB20DET, RB25DET, RB30ET With Twin Cam Head & CA18DET.

Alternate part numbers:

• AR2024309
• 202-4309
• 2024309
  
  

  Q. Which ARP head studs should I use? 625 or 2000's?

  A. In our opinion and using logic, the performance of a bolt is strictly limited to its stretch. The stretch is what gives the benefit of tension of a cylinder head.
  
  Now the only thing that separates a ARP 2000 and a 625 is it ability to stretch before yield, the rate of stretch remains constant so in essence you can pull a 625 further before it yields out
  
  Now because the limiting factor on an RB is the cylinder head tension as it crushes the head with any more than about 110 foot pounds. Most blocks are limited to 105 foot pounds unless it’s an RB 30 RD 28 or an in one version of an RB 26 in which case 110 foot pound also applies.
  
  You’re not reaping the benefits of a better quality bolt as you can only pull it to the tension that the block and combination will allow.
  
  So for arguments sake at 105 foot pound. There is simply no benefit to either type of bolt over the other. You’re not pulling either of them anywhere near their yield.
  
  ARP Recommend pulling a bolt to 75% of a yield in which case an ARP 2000 is around 110 foot pound in an M12 bolt which is fine but the 625 pulls 140 foot pound at 75% of yield and because you’re not tensioning the bolt to 140 foot pound both bolts perform exactly the same
  
  In this application spending the extra thousand dollars on the 625 bolts is a complete and utter waste of money and there is zero benefit, not even a little bit, not even at all.