FORGED PISTON KIT + H-BEAM CONROD SET Explanation of the product Application chart

Code No. 21004-AN017




This high performance STEP2 package includes pistons and connecting rods designed for R35 GT-R with higher engine output.
This Forged Piston Kit + Connecting Rod STEP2 Set is a must to upgrade the engine performance using with the GT800 Racing Specs and/or STEP2 Camshaft.




POINT-1 Parts for Higher Engine Output
  • Factory replacement type piston & connecting rods kit with the standard bore size.
  • To avoid piston land breakage, HKS pistons are made with forged material instead of casting like the factory pistons. The shape of STEP2 is the same as STEP1.
  • It's recommended to use with other items of the GT800 Package.
  • In-house test at 900PS confirmed the durability and safety.
  • The setting range is widened by reducing the compression rate from 9.0 factory ratio to 8.7. This is effective to increase the engine output using the aluminum block specs and/or bigger cylinder bore.
  • STEP2 piston's recess is 1mm deeper than a stock to best use with the STEP2 camshaft.


POINT-2 Factory Replacement Type
  • The weight of the connecting rod is the same as the factory since the affect of the V6 engine's peculiar vibration should be considered.
  • The piston is light-weighted to approximately 25g.
  • The weight is optimized to install to the factory crankshaft so it is not necessary to use a dummy weight to balance.


POINT-3 Higher Reliability by In-house Design & Production
  • The best 3D profile for this piston was selected after various profile tests. The forged material exclusively for HKS was used.
  • With the results of in-house analysis on the factory connecting rod, the durability is improved by approx 46% maintaining the balance.
  • All parts are MADE IN JAPAN.


Left: STEP2 Connecting rods
Right: STEP1 Connecting rods

Piston&Connecting rod set




Small-end dia. (mm) φ23 φ23 φ23
Large-end dia. (mm) φ59 φ59 φ59
Center distance (mm) 165.1 165.1 165.1
Reference weight (g) 734.6 722 724.6
Bolt M9 X 1.0 M9 X 1.0 M9 X 1.0
Capable Torque (kgf-m) 130 114.8 78.6




Recess of STEP2 Piston is deeper than the STEP1.  However, the recess of the STEP1 piston has been changed to the same depth of the STEP2 as of the production on March 11, 2011.  All stock of the STEP1 on April 15 includes pistons with deeper recess.

  Before After
Mark on piston's back [1] & [2] [3] or later
Label on package before 090311 after 090311 (D.M.Y.)




Product Engine Displacement
Type Boring/honing
Full flow
Code # Price
(w/o tax)
Forged piston kit VR38DETT 3799 φ95.5-φ23 Not required Not required 21003-AN009  
H-beam Connecting
rods STEP2
VR38DETT φ23 23004-AN005   for standard stroke


Product Engine Capacity (ml) Type Boring, Honing Full Flow Modification Code No. Price Remarks
Forged Piston + H-beam Con'rod Set STEP2 VR38DETT 3799 φ95.5 - φ23 Not required Not required 21004-AN017