|Practical Performance Car
Workshop Vauxhall XE
& pics by Dave Walker
never could understand the mentality that requires the messenger
with bad news to be shot. I sometimes do power runs for people
with competition cars and when they don't make the power they're
supposed to it's somehow my fault. It's even worse when the engine
is a pro built one and not living up to the quoted power. The
thing to remember is that there's no such thing as two identical
engines. Manufacturers typically quote a 5% tolerance on standard
engines, so on a 100bhp engine you could be 5bhp up or down. On
a 200bhp that becomes 10bhp plus or minus. The problem starts
you are missing multiples of tens!
2-litre Vauxhall XE engine normally makes about 180bhp with a
set of throttle bodies and a decent exhaust. Steve Broughton at
SBD sells a kit with bodies and an exhaust for the stock 2-litre
XE engine called the '208' which made 208bhp on an engine dyno.
The story is that they never make that power figure and I have
to say in the past that has been my experience; until now.
had a very tidy Westfield in with a 208 kit where the original
ECU had failed (quite an old conversion it has to be said). My
task was to map the engine and the owner wasn't looking for anything
special by way of power output form the otherwise standard motor.
Our rolling road cell has correction facility for barometric pressure
and air temperature. I always use this facility and honestly try
to get an accurate figure (as accurate as the rolling road kit
will allow). This is the only way to measure power by correcting
to standard air temp and baro pressure, the figure you then get
is the power that the engine would have made at 20 degree air
temp and 1010 millibar atmospheric pressure (observed bhp can
obviously be up or down on that depending on cell conditions).
finalising the mapping a power run on this Westfield showed a
peak figure of 201bhp. That's damn close to the quoted SBD 208bhp
figure and allowing that my result is from the rolling road (with
its built-in rolling loss correction) it's not inconceivable that
this engine was about right for the quoted engine dyno figure.
So the 208 kit will make the power but if you don't see it then
you probably need to look at your engine, not the kit.
Basic Taper Throttle Kit (formerly called
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