[Diy_efi] Water Injection (Injector Position) the Cosworth way

[Axel Rietschin]

I went to the Autosport show in Birmingham, UK last week and had a chance to
examine a 2001-spec 2L Zetec Turbo engine, as built by Cosworth Racing for
the Ford Focus World Rally Car.

On this particular engine there is four water injectors, one per cylinder,
on the bottom side of the inlet manifold, below and after the throttle
barrel (litterally 3 cm from the head as the engine has port throttles) - so
we are talking port water injection.

They use Weber IWF2 injectors with a "water rail", identical to a fuel rail,
and the rail has four very tiny sensors - one for each injector. From the
Weber datasheets, those injectors operate at a nominal fluid pressure of
1000 KPa which gives some clue at the water pressure they might use.

On top of the engine there is a small carbon fibre electrical dispatch box
where all the engine connectors are grouped into two larger connectors going
to the ECU (they use Deutsch AS connectors all around). The plugs coming
from the lower rail injectors and sensors are labelled "H2O INJ" and "WP-1"
to "WP-4", respectively, which I tentatively expand to Water Pressure. They
probably use sequential water injection (the ECU they use certainly has this
capability) and I'm willing to bet for open valve injection timing - this
would put the cooling where it belongs, with minimal oxygen displacement.

As a side note, there is a "KNOCK" loom going near the spark coils & plugs
(they probably use the NTK or Kistler pressure washers) and also an "UEGO"
connector on the dispatch box, which hints they may use WB-O2 on the actual
race cars. The engine has redundant crank sensors and throttle position
sensors, the throttle barrel id actuated by a small electric motor.


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