|
Home
Up
| |
Unleaded
fuel - the Facts...
This article was written by
lan Coulson Aff.I.M.E. Technical Advisor at Capri Club International.
Engines that were designed and built to run on 4 star leaded petrol, which includes
virtually all Capri engines, will be damaged if run continuously on unleaded petrol. The
reasons are twofold:
Firstly, unleaded petrol burns at a much higher temperature than 4 star and has no lead in
it with which to protect the valve seats. This leads to what is called "Valve Seat
Recession" which is the physical burning away of the valve seat caused by excessive
heat. This, in turn causes the valve clearances, or tappet settings, to close up, which
will then eventually not allow the valves to shut properly. This will cause the edge of
the valves to burn away and this will then lead to poor compression and engine failure.
The second problem is that the Octane rating of unleaded petrol is less than that of 4
star, which has an Octane rating of approximately 98, whereas unleaded only has an Octane
rating of 95. This can lead to detonation, or 'pinking', which is a result of the fuel
being ignited too soon in the cylinder. The sound of the pinking is, in fact, the fuel
exploding violently in the cylinder rather than burning rapidly in a controlled flame
spread. This violent explosion can cause major engine damage and, in extreme cases, hole a
piston.
So, these are the problems associated with the use of unleaded petrol in leaded engines
and, on the face of it, sounds quite frightening and the outlook seems quite bleak.
However, the Technical Department at Ford, have provided some encouraging information.
Firstly, all Capri engines, except the turbo equipped models will run on unleaded petrol
provided every fourth tankful is 4 star leaded. This is possible due to a phenomenon
called 'lead memory'. Lead from the 4 star actually stays within the combustion chamber
and on the valve seat for some time. If unleaded is to be used, the second problem of
pinking must be overcome, and this is done by retarding the ignition timing as follows;
1300cc Kent engines Retard from 6 to 2°
1600cc Kent engines Retard from 6 to 2°
Early 1600 OHC Retard from 6 to 2°
VV carb 1600 OHC Retard from 12 to 8°
2 litre OHC Retard from 8 to 4°
2.8 Injection Retard from 12 to 9°
3 litre Essex Retard from 14 to 10°
From around 1986, Ford started to fit hardened valve seats to a lot of their engines, and
from 1989 all Ford engines were equipped with 'Hard Heads'. It is possible that some of
these found their way into some of the very last Capris. These hard heads have certain
markings on them for identification.
The 1600 OHC with hardened valve seats will have either an 'M', 'MM', 'N', on 'NN' stamped
on the exhaust flange adjacent to number 4 spark plug hole. The 2 litre OHC will either
have a 'P', 'PP', 'R' or 'RR' stamped in the same place and the 2.8 Injection will have a
'D' or an 'E' stamped on the exhaust flange. The 3 litre Essex or 1300 and 1600 Kent
engines were never built with Hard heads, but the Valencia engine as used in the Fiesta
and Escort is very similar to the Kent, and these engines are still used today.
So, what do you do about this unleaded petrol? If your Capri has any of these markings,
all you have to do to run continually on unleaded petrol is to retard the timing to stop
the detonation and the problem is all but solved, apart from the slight loss of
performance you will encounter as a result. You could source the cylinder head from a new
Ford, which does have the hard head markings and fit it to your Capri. If you own a 3
litre Capri, you could have hardened valve seats fitted to your existing cylinder heads
(as you could with any Capri engine), and this would also solve the problem, apart from
necessary timing adjustment that will be required. It has been reported, however, that
under certain circumstances some valve seat inserts have fallen out into the combustion
chamber while the engine has been running, which resulted in engine destruction!
There does seem to be a very easy, relatively cheap and simple solution to this problem,
in the form of a Catalyst that is simply added to the fuel tank. There are two companies
marketing similar products, both of which have been running advertisements in the car
magazines. One is called 'Broquet Fuel catalyst', and is marketed by David Lock and
Associates, and the other is called 'The Fuel Cat', and is marketed by a company of the
same name.
They both claim to allow a 'Lead only' engine to run continuously on unleaded petrol
without the risk of engine damage and without having to retard the ignition timing. Sounds
too good to be true, I hear you say. I too was filled with scepticism, so I contacted both
companies to obtain further information.
I wrote to David Lock first to gain information on 'Broquet'. David then rang me and we
spoke at great length about what 'Broquet' is and how it does what he claims. It would
appear that it was developed during the Second World War to allow Hurricane aircraft, on
loan to the Russians, to run on the very poor quality fuel they had at the time, and this
it did very successfully. More recently, it has been used by the Civil Service Motoring
Association since 1989, and collectively their members have covered in excess of 200
million miles using Broquet with no reports of any engine damage from any of their 10,000
members.
Basically, it consists of a mesh bag filled with predominantly tin pellets, which is
simply dropped into the fuel tank. This causes a catalytic reaction which causes it to
change the properties of the fuel, resulting in much more efficient burning, and this in
turn means that the combustion temperature is significantly lowered to below a safe level
for 'Lead only' engines to operate. This more efficient burning also gives improved fuel
economy, more power and less carbon build up in the cylinders, so a cleaner engine.
Broquet also offer an 'Engine Damage Warranty' that states that if an engine is damaged by
the use of their product, it will be repaired or replaced at their cost.
You can contact David Lock & Associates at:
Swallow Ridge,
Lynwick Street,
Rudgwick,
Horsham,
West Sussex,
RH12 3DG
or you can phone on (01403) 823507
Next I wrote to Fuel Cat, and was then contacted by Phillip Brodie, who is the Managing
Director of Fuel Cat, the company, who was very helpful. His product is fundamentally the
same as the Broquet and it has been on sale since 1991, and again has had no reports of
any engine that has been damaged by the use of his product and unleaded petrol. In fact,
their information pack states that 'the use of Fuel Cat in auto and marine engines is
wholly beneficial and cannot in any way prove harmful to an engine or its fuel system'.
Fuel Cat can be contacted at:
Park Royal House,
23 Park Royal Road,
London NW10 7JH
or you can phone on (0181) 933 2213
These are facts concerning unleaded and our beloved Capri. I'm sure that when the time
comes for 4 star to disappear from pumps there will be an approved additive that can be
poured into the tank when you fill up, as indeed there is in Europe, but this may prove to
be an expensive option in the long run. Having your engine modified with hardened valve
seats would appear to be the safest option, but again this would definitely prove
expensive and not without its problems. So, in conclusion, after looking at all the facts,
it would appear that the cheapest and, indeed, the easiest option, is one of the fuel
catalysts. It is a once-only fitment and both companies offer excellent engine warranties.
It appears to solve all the problems in one foul swoop, but as I personally haven't used
either product myself, I can only pass on to you what the two companies, claim as being
'The Facts'. Contact them today and see for yourself what they have to say.
I hope this goes some way to answering some of the questions that the proposed banning of'
4 Star leaded petrol raises, and I hope that now you are in possession of the facts, it
will put you in a better position to he able to make up your mind on how to deal with this
problem.
[ Back ] [ Up ] [ Next ]
|
web
page is owned