The D within the engine code means twin overhead camshaft (DOHC). This really is completed by fitting an RB25DE or RB26DETT cylinder head and or turbo to an ordinary RB30E/T block. The RB25DET just isn't commonly used.Continue to, The 2 are rather equivalent, as well as the RB25 is basically no slouch. You'll be able to consider the RB25 vs the RB2