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Unleaded fuel in
Rolls-Royce vehicles in South Africa
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From January 2006,
leaded fuel will no longer be available in South Africa. To find out
how this
will affect us, I have called upon the research and experience of
owners in
other countries (particularly Australia, UK and US) who have been very
generous
in sharing their advice and findings relating to unleaded fuel in
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The
advice from all over the world is consistent, so I believe we can
safely assume
that much of it applies here in South Africa as well. In addition to
this, I
have also received valuable input from Jeff Osborne, CEO of the Retail
Motor
Industry (RMI), who is also a member of the Cleaner Fuel Committee.
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The good news
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We
can use unleaded fuel in our cars. Furthermore, should you prefer, Lead
Replacement Fuel will also be available at the pumps. |
What Octane?
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From
January 2006 we will have a choice of the following fuels: |
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91,
93 and 95 unleaded (inland and coast) 93
Lead Replacement Fuel (Inland) 95
Lead Replacement Fuel (Coast) |
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My
research indicates that we should use the highest octane unleaded fuel
we can
get locally. The main advantage of using high-octane fuel is that it
will
mostly avoid any semblance of pinging (pre-detonation). Pinging is
deadly to any
engine, because when it occurs, even briefly, the temperature inside
the
cylinder rises instantly to extreme levels. The extra cost of premium
fuels is
very cheap insurance against damage from momentary localised
overheating. |
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Theoretically,
the low-compression Rolls-Royce V8 engines (7.3:1 or 8:1 colonial
specification) can run on regular octane, but the UK delivered vehicles
(9:1
compression ratio) must use premium high-octane fuel. We seem to have a
mix-match of cars here in South Africa, so rather be safe than sorry,
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Pre-Detonation |
| If you have
the 9:1 compression UK spec V8, your
timing may be set up for 100-octane fuel, in which case you may
experience
pinging with the 95-octane unleaded fuel. What do you do if your car
starts
pinging? The collective wisdom indicates that retarding the timing by 3
degrees
should cure the problem. Try not to retard the timing by more than 3
degrees,
with 5 as the maximum. If you retard the timing too much your engine
may
overheat in our hot climate, and the idle may be rough. |
Additives
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| There will be little
or no need for additives in
our fuel, as we will be able to buy Lead Replacement Fuel at the pumps,
should
we prefer to use that instead of unleaded fuel. Avoid ethanol-blended
fuel.
Ethanol blend fuel has significantly less energy content available than
conventional fuel. Vehicles with modern engine management system
compensate for
this by increasing the volume of fuel supplied by each injector on the
intake
stroke thus increasing fuel consumption. In older vehicles, you just
push
harder on the accelerator to get the performance you want, which
results in
increased fuel consumption. |
What about pre-war
and early post-war cars?
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There
has been much study of this among Rolls-Royce enthusiasts. Everyone now
agrees
that the early pre and post-war six-cylinder Rolls-Royce engines do not
need
leaded fuel, nor does it need a lead substitute. The problems with
accelerated
valve seat wear pertain to cars with performance camshaft profiles
operated at
high RPM. These two conditions combined cause the valves to go closed
against
their seats with considerable impact, resulting in accelerated wear if
hardened
valve seats are not used. Rolls-Royce cars have neither performance
camshafts
(quite the opposite with the early cars) nor are they operated at high
RPM. |
Storage
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This
is bad news if you don’t use your car regularly. Overseas experience
indicates
that unleaded fuels are less stable than leaded fuel, and will form
varnish
deposits if left to stand for several months. This varnish can cause
valves to
stick, and when that happens the engine usually needs to be re-built.
If you
only drive your car to the club concours once a year, you will have to
drain
the fuel during storage. Try not to leave fuel in the tank unused for
more than
three months. This is one case in point where an additive may be
desirable, and
we will have to wait and see what becomes available on our local market.
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Important
note: At this stage we cannot confirm that this will also be the case
with our
local blend of unleaded fuels, but it is good to be aware of it
nonetheless. |
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More
Information |
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For
more information on the RMI, the Cleaner Fuel Committee and the NAAMSA
Cleaner
Fuel Vehicle Database (non Rolls-Royce specific) see their website
www.rmionline.co.za |
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