pump fuel, SBD recommend the use of a high-octane fuel (98/99RON) for
all competition engines. If possible, it should always be purchased from
a petrol station with a high turnover.
It is our
opinion that care must be taken when buying fuel from petrol stations
with a slow turnover of fuel as it will often have been stored for some
time, during which time the RON rating reduces through evaporation. Under
these circumstances an Octane booster is highly recommended to ensure
the RON rating of the fuel is sufficient. If it is necessary to use lower
octane fuel (if a high octane is unavailable), it is recommended that
an octane booster is used.
seen good results from Shell V Power 99 & Tesco 99 fuel
It must be
remembered that one of the main reasons for using Race Fuel is down to
the strict control of the RON rating, it is guaranteed standard and can
be relied upon to be consistent throughout the year, something which cannot
be said for pump fuel.
gasket deterioration & pump fuels
noticed towards the end of the 1998 season that our high spec engines
(2.0L 16v XE's running 8 injectors, circa 290bhp), were required to have
the head gaskets changed due to deterioration of the gaskets themselves.
We put this originally down to possibly a batch of head gaskets that had
had the material specification changed. But during the 1999 season, these
same engines needed the head gaskets changed on a more frequent basis.
We still considered the possibility that the gasket material was causing
the problem. At this time we were not seeing any problems occurring with
engines in lower output & specification. By the time we reached the
2000 season, engines were being returned for routine rebuild, it was noted
that the engines of around 270bhp were showing signs of slight deterioration
in gasket material, but this was still producing no problems.
to invest in a higher specification gasket with stainless steel firing
ring. During the 2000 season, we noticed the newer gaskets did give significant
improvement and engines that were inspected mid-season, showed less sign
if any, in gasket deterioration. But by the end of the 2000 season, although
the new gaskets were helping to extend time between maintenance, they
still had not cured the problem. At this point, we decided it was not
the gaskets causing the problem & by replacing the gasket with a higher
specification was trying to cover the problem up, rather than fixing the
cause. By the beginning of the 2001 season we were getting reports from
other engine builders, not only people who build Vauxhall engines, but
other makes as well, who had been suffering similar problems, particularly
on high compression engines. We had also noticed during programming of
engines on the Dyno, that specification engines that require for example,
32 degrees of ignition in 1998, were now requiring ignition advance in
the 20 degree regions.
the problems are being caused by the components used to produce the current
pump fuels. As far as we can gather from various sources, many of the
components such as Tolurine (highly carcinogenic), have been banned from
use. There are other similar components, which have also been banned.
The advantage that was gained with these now banned components was they
took a lot longer to deteriorate in the fuels, than their replacements.
Again from the information we have received, although the octane levels
as far as RON (Research Octane Number) have not changed much since 1998,
obviously the fuel is new. So when the tests are carried out, the fuel
reaches the desired octane level. Unfortunately, due to the fact that
the components being used deteriorate quicker, by the time it has been
stored in the petrol pumps or in your fuel tank, its octane level drops
much faster than it would have done with the now banned components. The
longer it is left in the car, the faster the octane level will deteriorate,
particularly when the weather is hot.
our results cannot be claimed to be conclusive, we recommend that if you
are to use pump fuel, you try and purchase it from a petrol station that
has a regular turn round, therefore making sure the fuel is as fresh as
It is also
suggested that the engine is programmed on the particular fuel you intend
on running the engine on. Due to the fact that pump fuels components are
changed by the fuel manufacturers continually throughout the year, it
makes it extremely difficult to programme the ignition on an engine &
then expect it to run on varying grades of fuel at its optimum. So it
is suggested that you either run a control fuel if possible, if not keep
a good check on the engines condition. Unfortunately it is quite difficult
to determine head gasket deterioration, unless the engine is stripped
on a regular basis. If you wait until the head gasket has failed, the
resulting damage can be quite considerable due to the fact water &
oil are sucked into the combustible fuel, rapidly accelerating detonation.
The resulting appearance to even the most professional eye would make
you think the engine has been programmed with excessive ignition. Since
the cylinder head & pistons will usually be eaten away, giving the
appearance that somebody has chipped away with a small chisel on both
surfaces. The effect accelerates at an exponential rate. We have seen
in some tests the damage described appear in seconds.