Paxman Valenta

Paxman Valenta
Paxman Valenta power unit with turbocharger and Brush Traction alternator fitted
Overview
Manufacturer	Paxman
Combustion chamber
Configuration	V12 four-stroke turbo-charged & intercooled diesel
Displacement	79 litres (4,800 cu in)
Combustion
Fuel type	Diesel
Output
Power output	2,250 brake horsepower (1,680 kW) at 1,500 rpm
Chronology
Predecessor	Paxman Ventura
Successor	Paxman VP185

The Paxman Valenta was an engine that was made by Paxman, Colchester for the High Speed Train, and is still in use in various marine applications, such as the Upholder/Victoria-class submarines.

The Paxman Valenta was developed in the early 1970s for British Rail with the aim of using in both freight and passenger locomotives. However the engine ended up only being used in the two pre-production Class 41 and 195 production Class 43 powercars that were delivered to power High Speed Trains between 1975 and 1982.

The engine as originally fitted to the HSTs was designated 12RP200L and was a V12 four-stroke turbo-charged & intercooled diesel unit of 79 litres which developed 2,250 bhp at 1,500 rpm. The design of the Valenta was based on the Ventura which was fitted to the Class 29 diesel locomotives, amongst others. The engine was famous for the "Valenta Scream" on starting from rest, a high pitched whine that was very distinctive caused by the turbocharger. In 1977, the Valenta received the Queen's Awards for Enterprise.

In 1985, four (43167-43170) were fitted with Mirrlees MB190 engines. Beginning in 1995, a small number were fitted with Paxman VP185 engines, however the majority retained Valentas.

In May 2005, First Great Western had Brush Traction fit two with MTU 16V4000 engines. Judged a success, as part of a project to extend the lives off the HSTs, First Great Western decided to repower its entire fleet. GNER, CrossCountry, Network Rail and Grand Central also decided to repower their fleets with MTUs. The only operator not to was East Midlands Trains, which opted to replace its Valentas with Paxman VP185s.