Editing Triumph TR4 (section)

===Powertrain===
[[File:Triumph TR4 (1963) - 14253179157.jpg|thumb|TR4 engine with SU carburettors]]
The TR4 uses the same [[Standard wet liner inline-four engine]] that powered the TR2 and TR3 models, but with displacement increased from 1991&nbsp;cc to 2138&nbsp;cc by enlarging the bore from {{cvt|83| to |86|mm|in|3}}. The cast iron block carries the crankshaft in three main bearings, and the cast iron head has two valves per cylinder driven from a camshaft in the block via pushrods and rocker arms. The 1991&nbsp;cc engine was a no-cost option for cars whose owners planned to race in the under-two-litre classes of the day. At different times the factory installed either a pair of SU H6 carburettors, or a pair of Zenith-Stromberg CD175s.

The car's four speed plus reverse [[manual transmission]] has [[synchromesh]] on all forward gears, an upgrade from the transmission in the TR3 which did not synchronize first gear. Additionally, the optional [[Overdrive (mechanics)#In Europe|Laycock de Normanville]] electrically operated overdrive could be selected for second, third, and fourth gears, effectively providing the TR4 with a seven-speed close ratio gearbox.