216
End
of leaded petrol
Roger
Parker (Green V8 4092) responded to a recent query from Gordon Hesketh-Jones
(Harvest Gold V8 1904) from Cornwall concerning the silent arrival
of lead replacement petrol (LRP) in the pumps during the Autumn of
1999. (Dec 99)
Gordon reported
that he had run his factory built MGBGTV8 on unleaded fuel for seven
to eight years and covered 120,000 miles in doing so without any
problems. When he had lifted the heads out of curiosity recently,
he found the valves were in excellent condition. His use of unleaded
was based on contacts he had had with Land Rover at Solihull when
unleaded first came in some years ago. At that time Land Rover's
advice was unleaded was safe in low compression V8 engines. As many
members of the V8 Register have commented on how four star fuel
has silently vanished from the forecourt during the late Summer
and into Autumn in 1999 to be replaced by lead replacement petrol
or LRP, the subject of using unleaded was raised with Roger Parker.
The remainder of this note is based on his comments.
"The information
regarding the use of unleaded fuel in the V8 comes from Land Rover's
power train engineering team at Lode Lane. The details are that
the specification for the MGBGTV8 engine was developed with an 8.25
to 1 compression ratio and the materials inside the combustion chamber
areas were specified to provide a full unleaded capability. The
engine was tuned to run on UK spec 94 RON fuel, so the 95 RON unleaded
is a higher specification fuel than the engines were built for and
no engine or ignition timing modifications are needed. Incidentally,
all V8 engines from October 1970 were built to an unleaded spec
irrespective of whether they were for a Land Rover product, Rover
car, Leyland Daf van or specialist car maker".
"Land
Rover has always been responsible for the V8 engine production and
still holds production records. The only additional note I would
add concerning the unleaded engine specification is that since the
1970s different, and possibly better, materials have become available
so more recent changes of specification may have further improved
the unleaded resistance of the V8 engine".
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"My
own very early ex-test Rover V8 block and crank (made in 1967) using
1976 SD1 heads with Vitesse valves has used 95 RON unleaded
since it became available with a 4 degree reduction in the ignition
timing specified in the manual. The engine continues to show no
sign of any problems and a continuing rise in recorded power at
the wheels confirms this. Further with a 10.25 to 1 compression
and modified heads that significantly improve volumetric efficiency,
no detonation has been noted, either heard or silently leaving tell
take marks".
"On the
subject of LRP, I worry that there is no UK British Standard for
these fuels. This means there is potential for problems arising
from mixing different brands of LRP in your tank or when mixing
LRP with any of the various brands of lead replacement additives
which may be used. I have heard from some people who have had no
problems with the change to LRP whilst others claim to have had
rough running as soon as LRP was added. At this stage there is no
clear evidence to support the poor running camp's argument, but
I always suggest that people try only small amounts of particular
brands of LRP at a time so if there is a problem, then there is
not a full tank of problems to use up! If after several short fills,
the car runs well, then I suggest that full use of that brand of
LRP can be made in future. What will not have been confirmed from
those checks is what happens when you are away from your home district
and you have to fill your tank with another brand which may be unknown
to you in terms of satisfactory running in your engine?"
"The removal
of leaded fuel has seen the arrival of a wide range of alternative
products or additives all claiming various advantages in terms of
lead replacement or octane substitution over the others. This will
continue to cause confusion. What those additives produce, either
individually or in combinations, in the exhaust gas content does raise
other questions to which I have no answers or suggestions at all".
Copyright
reserved by the V8 Register of the MG Car Club, PO Box 888,
London SW14 7YT
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