Peugeot 405

" We will be top of the diesel market in Britain, " predict Peugeot managers, on adding two diesels to their 405 fleet-car range. The indirect-injection four-cylinder diesel engines are a nor­mally aspirated 1.9-litre developing 69 h.p. at 4.600 r.p.m. and a turbocharged 1.8-litre (1779 с.с.) engine with intercooling delivering 89 h.p. at 4.300 r.p.m.

The obvious question is: " Why not turbocharge the 1.9-litre? ". The not very convincing answer is that there is not room under the bonnet to get rid of the heat, with the larger engine in turbo form. More likely to do with firing stresses, piston temperatures and water-jacket volume.

Both new diesels are notable for their smoothness and quietness, to such extent that one is little aware, when driving, that a diesel engine is under the bonnet, beyond the usual limitations of power and response. The 1.9-litre performs quite well, and is able to cruise at around 85 m. p. h. in relaxed style; but shortcomings remain in top-end acceleration and hill climbing, which are relieved by the more powerful turbocharged version. For a 1.8-litre diesel this big car performs well, and delay in turbo res­ponse is short enough to be no hin­drance.

The 1.9-litre non-turbo is derived from the existing Peugeot XUD9 unit, and identified as ХUD9A with revised aluminium cylinder head with ram-pipe induction to obtain more oxygen at the higher speeds. Power is up by 5 h.p. and although torque is no higher, it stays high over a wider range, from 2.000 to 3.000 r.p.m.

For the 1.8-litre there is either a KKK K14 or Garrett T2 turbo-charger, generating 1.3 bar pressure at 1.500 r.p.m. rising to a maximum of 1.8 bar. The aluminium heat exchanger that constitutes the induction-air intercooler is mounted on the camshaft cover.

Higher gearing is used for the GTDT, as the turbo version is named, providing 100 m.p.h. in fifth at less than 4.000 r.p.m.; and it is indeed able to cruise surprisingly quietly at this speed. Its ultimate speed is 112 m.p.h. The 1.9-litre is geared for 22.5 m.p.h. per 1.000 r.p.m., and its top speed is 102 m.p.h.

It is interesting that the fuel con­sumption at constant speeds is de­clared as identical for both diesels with figures of 45.6 m.p.g. at 75 m.p.h. and 61.4 m.p.g. at 56 m.p.h. Only in the urban cycle does a small difference (40.4 instead of 37.7 m. p. g) emerge in favour of the normally aspirated engine.

Apart from announcing the diesel 405 models, Peugeot is also introduc­ing an automatic transmission option that is basically Z.F.

Apart from very expensive models such as Mercedes-Benz and the Rover 2.7, it is one of the most impressive automatics – responsive, well-chosen change points and smooth action. In addition, there is torque converter lock-up to give fuel and noise savings when cruising in fourth, and partial lock-up (60 per cent mechanical drive) in third.

Automatic becomes available for the 1.9-litre carburetted engine in a few weeks time, and with fuel-injection petrol engines from mid-August.

An interesting refinement of the transmission, which helps to avoid the sluggishness of many automatics is that it changes down from fourth to third on deceleration at about 30 m.p.h., and goes to lower gears as required ready for snappy acceleration. The top speed is 114 m.p.h. for the carburetted model, and 120 m.p.h. with injection. The fuel consumption on the Transport Engineer formula is 34.9 m.p.g. for the carburetted engine, and 32.5 m.p.g. for the fuel-injected one.