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".


"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".

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