As for initial letters in abbreviations, let's sort them below in more detail.
So, the
diesel engine with an inscription of HDI is own development of PSA Peugeot
Citroen carmaker on the basis of the Common Rail technology. Feature of
operation of such engine that the producer regulates a considerable procedural
service maintenance period. The owner of the car of these French brands
equipped with the diesel engine can drive on HUNDRED for preliminary treatment
once over 30 000 km of run. In addition, there is one more advantage.
Replacement of a Serpentine belt and belt of hinged units isn't provided during
all term of operation of the engine. By the way, the HDI motor not more loudly
petrol even works at single turns. These new qualities allowed to borrow to
cars with such diesel engine to 50% of the market of France.
Schild with
TDI abbreviation for the first time I appeared on engines of the German concern
Volkswagen. It designates the diesel motors developed with use of the
principles of system of direct injection and a turbo-supercharging. The
turbo-supercharging allows to receive the big power, bigger efficiency. Thus
indicators of profitability remain at height as well as purity of an exhaust.
TDI engines are rather reliable and unpretentious in operation. However, there
is one shortcoming: rather small resource of the turbine (about 150 thousand
km) because of high temperatures of a stream of the heated exhaust gases (to
1000 °C) getting on its krylchatka and high rotary speed (200 thousand
revolutions per minute). But, thus, the resource of the engine can make to one
million kilometers.
In
operation atmospheric (naturally aspirated) diesel engines with direct
injection are less expensive. Such engines disappear under identification mark
of SDI. They are the simplest modern diesel motors which are designed on the
Common Rail technology, but at the same time, possess the high level of
reliability. To them big run aren't terrible.
As you
could notice, the basic difference between diesel engines isn't present. All
differences are explained by that each producer doesn't want to resemble
another.
