56
STAG OWNERS CLUB TECHNICAL REPRINTS
Unleaded Petrol. Andy Hopper (4787), a
are all giving improved performance on unleaded fuel
partner in Alchemy Engineering of Yeovil,
with Powerplus than they had given previously on
Somerset, wrote:
leaded fuel.
HAVING FOLLOWED with great interest recent
We are convinced that Powerplus and products like it
newsletter articles on the buzzword subject of
are the answer to the unleaded use problem with
unleaded fuel and whether it can be safely used or
Stags and other classic marques. We are now
not, here is another contribution to the melting pot.
supplying agents for Powerplus. The stuff is not
Since January this year we have been testing a product
cheap a Stag costs £72.00 plus VAT to treat,
called Powerplus. It is a cartridge that fits in the fuel
although this includes a Crypton tune.
line anywhere between the fuel tank and the
It basically represents another option for owners who
carburettors, although nearer to the engine is
wish to use unleaded petrol or who are worried about
preferable. It is very similar to the product being
continued long term availability of 4 star. It repre-
tested by Howard Vesey, however, it can easily be
sents a lot less outlay than `green' engines which
removed from the vehicle should it be desired and
seem to be very head orientated anyway. Stellite valve
seats and harder valves are fine in principal but how
fitted to an alternative vehicle.
long will piston crowns survive in the cauldron of
The cartridge releases microscopic particles of tin into
combustion chamber heat greater on unleaded fuel.
the fuel providing the combustion lubricant so
necessary. Its life expectancy is 150,000 miles, in fact
Issue 114 (November 1989), page 13
it is warranted to last this long by the manufacturers
who also are prepared to warrant that the product is
Unleaded Petrol. Mike Bond (15036) wrote
guaranteed not to cause valve/seat/piston damage.
from Texas after reading about a Swiss
We have tested Powerplus in a variety of old Triumphs,
owner running his Stag on unleaded fuel
for four years:
including three Stags, one of which is also fitted with
I'VE BEEN RUNNING mine on unleaded fuel for 14
extractor manifolds and stainless exhaust system.
years, as that's all we can get around here. I have seen
This particular Stag has covered approximately 6,000
no ill effects and certainly no `pinking' whilst running
miles on unleaded fuel including a foreign touring
on 87 octane. That timeframe represents only 14,000
holiday and hasn't missed a beat. We have closely
miles, but all the same . . .
monitored the engine's performance including
Issue 152 (May 1993), page 51
regular compression checks, all of which have
produced manufacturer's specification readings. The
Unleaded Petrol. The Technical Panel
car shows improved mid-range performance
summarised the arguments regarding
particularly noticeable during uphill acceleration.
unleaded fuel in response to a question:
Fuel consumption is marginally improved during
SHORT QUESTION, long reply! There is no easy answer
short or longer runs. The other two vehicles have
to this one, because to provide an authoritative
covered 2,000 and 1,400 miles respectively, both
answer would require detailed research under
drivers reporting pleasing results.
laboratory conditions. However, we do have a body of
Other vehicles treated with Powerplus include three
evidence coming from members and other sources,
Dolomite Sprints, two TR7 Sprints and four Triumph
and the best we can do is pass them on, so you can
2.5 saloons/estates. Moreover, one of these big
make your own decision.
saloons, a 1975 2500 TC has covered nearly 13,000
1. A number of members are running their Stags with
miles on unleaded fuel. It is a hard driven high
unleaded petrol, and say there are no side effects after
mileage motorway hauler with 120,000 plus miles
having retarded their ignition slightly. Some of those
behind it. After 8,000 miles of unleaded use we
people are running `standard' valves and valve seats,
removed the cylinder head purely for reasons of
while others have fitted special exhaust valves
inquisitive interest. The condition of the cylinder
(obtainable from most of the spares suppliers). The
bores after 110,000 plus miles showed expected wear
service life of engines, valves, etc, in this arrange-
the engine had been burning oil under acceleration
ment is not known.
for a while. Removal of the valves showed substantial
2. American Stags have run for many years without lead
valve guide wear, however, carbon deposits were
and the standard valves/seats, but it is believed the
absolutely minimal. In fact the carbon could be
rubbed off with finger pressure a lot like wiping the
fuel has some lead substitute additive. This is known
dust off your sideboard at home.
to be the case in Canada. Presumably once lead is
At the owner's request we reassembled the cylinder
banned in the UK this additive will suddenly become
head and refitted it to the engine without carrying
available, surprise surprise.
out any reconditioning. The car has continued to
3. Lead is not just for valves, it also regulates
rampage along the motorways of the south-west at
combustion by reducing any tendency to pre-ignition
high speed burning lead free petrol.
and also protects pistons and piston rings.
All other vehicles treated, including 4.2 litre Jaguars,
4. Limited tests carried out in the past have shown that
valve wear is very sensitive to engine speed, and an
MGB, Midget, MG Maestro, Alfa Romeos and others,