RB26 Specs

“RB” indicates the engine code.
“D” indicates a double overhead cam as opposed to a single overhead cam
“E” indicates the engine is electronically fuel-injected
“S” indicates the engine is carburetted
“T” indicates the engine has a factory installed turbocharger
“TT” indicates the engine has factory twin turbochargers

RB25 – 2.5 L (2498 cc, bore: 86.0 mm, stroke: 71.7 mm)
RB26 – 2.6 L (2568 cc, bore: 86.0 mm, stroke: 73.7 mm)

The 2.5 L RB25 engine was produced in three forms:

RB25DE – NON – TURBO twin-cam 190 HP and 200 HP (with VCT) @ 6000 rpm, 255 Nm @ 4000 rpm
RB25DET – twin-cam turbo (T28 Turbo) (245 to 250 HP and 319 Nm
NEO RB25DET – twin-cam turbo 280 HP @ 6400 rpm, 362 Nm @ 3200 rpm

The RB26DETT engine is a 2.6L Inline-6 engine manufactured by Nissan, for use primarily in the 1989-2002 Nissan Skyline GT-R.
The RB26DETT engine block is made from cast iron, and the cylinder head is made from aluminium. The cylinder head contains 24 valves (4 valves per cylinder), and uses a dual overhead camshaft setup. The intake of the RB26DETT varies from other RB-series motors in that it has six individual throttle bodies instead of a single throttle body. The engine also uses a parallel twin turbo system. The turbo system is arranged so that the front turbo is powered by the front 3 cylinders, and the rear turbo is powered by the rear 3 cylinders. The turbo chargers are of equal size, and are set by the wastegates to limit boost pressure to 14.7 psi, although the Skyline GT-R has a built in boost restrictor to keep boost under 10 psi.

The first 2.6 L RB26DETT featured twin-turbochargers and produced around 280 HP @ 6800 rpm and 353 Nm @ 4400 rpm. The last series of the RB26DETT produced 280 HP @ 6800 rpm and 392 Nm @ 4400 rpm. However, several stock (unmodified) engines have been dyno tested and reported to obtain nearer the 320 HP mark. It is widely known for its strength and extreme power potential. With extreme modification, the RB26 motor is capable of power in excess of 1 MegaWatt or over 1340 HP.