text: The fitment of a twin cam head from any of these engines onto a standard compression RB30E bottom end gives a forced induction friendly compression ratio (around 8.2:1), for a mild to moderately modified street turbo engine, making the conversion popular amongst those who would otherwise convert their RB30E to a high compression RB30ET using original ET bolt on externals.
  Although it has a larger displacement than the RB26DETT, maximum possible horsepower is less, as the RB30 block lacks the RB26 block's internal bracing, and consequently cannot rev as high due to harmonic issues at ~7500 rpm. To compensate, the RB30DET produces more torque at lower revs due to its longer stroke. However they have been known to reach engine speeds up to 11,000 rpm with extensive balancing and blueprinting.
  There is also an 'RB30DETT' kit manufactured by OS Giken of Japan, which bolts an extension on top of the RB26 engine block, and fits liners, to give a bore and stroke of . It is available as an assembled short block, containing billet chrome-molybdenum crank, billet chrome-molybdenum H-beam connecting rods, forged pistons, and costs ¥1,500,000.
  RB-X GT2 and RB28DET (2.8L)
  The RB-X GT2 (designed and built by REINIK) is an engine specially made for the NISMO 400R. The difference between this engine and a RB26DETT is that the engine is bored and stroked  which results in . The engine produces  at 6800 rpm and  at 4400 rpm.