Quiller Triumph

Unit 1, White Hart Road, Plumstead, Woolwich  London. SE18 1DF

Tel: 0181 854 4777 Fax: 0181 854 2404   Email: info@quillertriumph.co.uk


Tests performed on fuel additives



The Federation's declared aim is to ensure that historic vehicles continue to enjoy freedom of the road. The FBHVC recognised early on the impact that the demise of leaded fuel would have on the historic vehicle movement and in 1997 set up a sub-committee to protect the interests of member clubs in this respect. Benefits of Lead Lead in petrol has two effects: one is to prevent knock or pinking and thus permit the use of higher compression ratios, the second is to protect against very rapid wear, or recession, of the exhaust valve seats. Valve Seat Recession Exhaust valve seat recession (VSR) is a complex process affected by many factors of engine design and use. Amongst these however, high engine speeds and high engine temperatures are major factors in making an engine susceptible to VSR. VSR is a phenomenon experienced only by poppet valve four-stroke petrol engines. Valve Seat Recession Explained Valve seat recession (VSR) is the name given to a process of accelerated valve seat wear. The mechanism by which this occurs is as follows: 1. The very high temperatures at which it operates (typically between 600 and 800 degrees celsius) causes the exhaust valve to weld locally to its seat. When the valve is then opened a small particle of the iron seat is pulled away. This particle is converted into iron oxide in the hot exhaust gas. 2. As the valve then closes again these particles are imbedded in the valve face. 3. With these hard lumps of iron oxide imbedded in it, the exhaust valve becomes, in effect, a grinding wheel. Thus any rotation of the valve will cause it to grind away the seat. Valves tend to rotate under the action of the valve springs and by engine vibration. Further details can be obtained from a booklet entitled "Valve Seat Recession - Use of Unleaded Gasoline in Older Engines" available from the FBHVC office. A similar booklet entitled "Fuel Problems - Use of Modern Petrol in Older Engines" dealing with other fuel related issues is also available. Booklets cost 6 each including postage. Alternatives Advice on the precise fuel requirements of a particular vehicle should be obtained from its manufacturers, the appropriate one-make club or other authoritative source. Where leaded (4-star) fuel is recommended purely for its anti-knock or octane properties the following options exist: a) Adjust (retard) ignition timing to permit use of standard unleaded (95 octane) fuel. b) Use super unleaded (98 octane) fuel. c) Use lead replacement petrol (LRP, expected to be 97 octane. Further information on LRP later in this leaflet). d) Modify engine to a lower compression ratio to permit use of standard unleaded (95 octane) fuel. Where leaded fuel is recommended to protect against valve seat recession (VS R) the following options exist: a) Fit hardened exhaust valve seat inserts. This is the approach used on modern engines designed to run on unleaded petrol and is totally effective. However it can be expensive and is not possible on all engines. b) Use a commercially available lead-replacement additive in unleaded petrol. More details on page 5. c) Use lead replacement petrol (LRP). More details on page 5. Leaded Petrol Leaded petrol is the name generally given to petrol which tetra-ethyl lead (TEL) has been added and as you would expect unleaded refers to petrol without TEL. TEL was first added to petrol during the 1920's as an anti-knock additive and its function in forming deposits of lead compounds which acted as high temperature solid film lubricants on exhaust valves and seats was not understood until later. FBHVC Lead Substitute Testing FBHVC recognised the impact that the demise of leaded petrol would have on the Historic Vehicle Movement and set-up a sub-committee to monitor developments. It was quickly realised that although there were many lead substitutes available for which great claims were made there was no standard test against which these claims could be validated. To overcome this situation and in the absence of any initiatives from either Government or national standards organisations anywhere in Europe the Federation commissioned an extensive programme of testing at the Motor Industry Research Association (MIRA). This programme represents one of the most comprehensive assessments of the performance of products designed to protect against VSR carried out in the UK. Work started in November of 1998, and by late February 1999 15 tests had been completed -included in these being leaded four-star and unleaded reference tests - bringing to an end the first phase of testing. If there is sufficient demand it may be possible to carry out further tests. Some 40 suppliers of lead substitute products were approached from which 12 products were submitted for test. Each product was subjected to an identical test procedure using a Rover A-series engine run in an engine test cell and VSR measurements taken at intervals throughout the 70 hour test. There is a tremendous amount of interest in the test programme from the motoring press, from the classic car movement and not least from the suppliers of products intended to protect against valve seat recession. The whole concept of evaluating the performance of these products has been rightly taken up as an important safeguard for the membership of the clubs represented by the Federation. FBHVC Endorsements The results obtained from the tests mentioned above were conclusive, showing clearly the differences in performance of the various products submitted. However to ensure the highest standards of judgement the complete data set has been reviewed by an independent technical assessor and moreover the conclusions are further supported by the RAC. The products listed below have received the FBHVC Endorsement: (Test rate details in brackets) Millers VSP-Plus (250ml per 40 litres petrol) Red Line Lead Substitute (8ml per 10 litres petrol) Superblend 12 / Zero Lead 2000 (500ml per 150 litres petrol) Valvemaster (10ml per 20 litres petrol) An additive or device which passes this test, as defined in section 10 of the Test Method (FBHVC 98/02), shall, provided it is marketed in exactly the form in which it was tested, be entitled to carry the FBHVC's endorsement. This endorsement shall take the form of either the FBHVC logo and the words "endorsed by the FBHVC", or "This product has been subjected to a valve seat recession test by an independent test house on behalf of the Federation of British Historic Vehicle Clubs. The results of that test indicate that the level of valve seat protection provided is likely to be adequate for all normal driving, but not including racing or other exceptionally arduous uses." NB: Nothing in that endorsement shall imply any liability on the part of FBHVC or MIRA for any damage or costs incurred following the use of a product so endorsed. Lead Replacement Petrol LRP is, in effect, 97 octane unleaded petrol with one of the VSR protection additives already added by the petrol company. At the time of writing there is no British or other standard for LRP but it appears likely that active components may be at a lower concentration than is the case for the additives tested by the Federation with a corresponding reduction in the protection provided. No LRP was submitted for testing. Precautions 1. The effectiveness of VSR protection additives is dependent on the amount of the active ingredient used; this is governed by the concentration of the product as it is sold and also on the treat rate, i.e., the amount added per litre of petrol. The consumer should ensure that the product is used strictly in accordance with its instructions. FBHVC will monitor the concentration of active ingredient in the endorsed products to ensure consistent quality. 2. VSR protection additives must be used every re-fuelling. 3. There are complex chemical reasons why different VSR protection additives should not be mixed; choose an additive, or LRP, and use it exclusively. Do not use additives with leaded petrol. 4. Whilst outside the scope of the FBHVC testing, there is evidence to show that very high treat rates, whilst giving enhanced VSR protection, can lead to other problems such as valve sticking. 5. There is considerable evidence to show that sodium-based additives can have detrimental corrosive effects, particularly on exhaust valves and turbo-chargers. A paper on this subject was recently published by the Retail Motor Industry Federation. 6. Do not use any additive or LRP in a vehicle equipped with an exhaust catalyst. Such vehicles are designed to run on unleaded petrol and the additive could damage the catalyst. Acknowledgements The Federation of British Historic Vehicle Clubs gratefully acknowledges the assistance of all who have made their programme of lead substitute testing possible, in particular: Rover Group for the generous donation of new cylinder heads and valves for the testing, plus other parts and advice necessary to maintain the engine in good condition. MIRA for demonstrating not only their expected professionalism but also a high level of friendly co-operation. TR Register for providing a congenial venue, refreshments and secretarial services. Members of the Federation sub-committee for their time, expertise and diligence.

Castrol Valvemaster & Valvemaster Plus

"Making The Change": Technical advice on use of unleaded petrol from Department of Transport

Club Triumph Editorial Comments Concerning Unleaded

Federation Of British Historic Vehicle Clubs: Tests performed on lead substitutes


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