The Power
Plus © performance
tuning system has been
developed to provide owners of classic
Series 11, 11a, 111
and 90 / 110 Land Rovers fitted with the
2.25 / 2.5 petrol
unit with extra power and efficiency. The system
has been
used on every continent and in every situation Land
Rovers
may be found. The Power Plus © system offers levels of extra
performance
to suit the application and budget of each
requirement without
compromising the legendary reliability
of the Land Rover 4 cylinder unit.
The Power Plus © tuning system allows the
engine to produce
more torque especially in the low to mid range. This results
in faster acceleration, less gear changing and the ability to
maintain
speed on gradients. This makes the Land Rover
easier and safer to drive both on and off the road.
The 2286cc petrol engine was developed for the Series
11 Land Rover, launched in 1958. It featured many common
components and dimensions to the diesel version of
this
engine. This enabled Land Rover to produce both versions
of the engine with the same machine tools and production
line. As a result the petrol version was considerably over
engineered
for its 115 FtLb of torque and 67 BHP.
Over the years remarkably little changed. 1980 Saw
the
introduction of 5 main bearing crankshafts, and
1985 a longer
throw crank shaft raised
capacity to 2495cc The petrol engine
continued in production until
1992, when Land Rover deleted
the petrol unit from its product range. The diesel version
continued
in the form of the 200 and later the 300 TDI unit.
Although Land Rover
no longer manufacture the 4 cylinder
engine, it is still in production
in Brazil. Developed further, now
with a capacity of 2.8 litres and
used in the South American built
Ford Ranger Pick up. From the engine tuners point of view the
2.25
/ 2.5 engine is ideal. The cylinder head design was modern
for the
1950s
and material thickness is generous, allowing the
tuner to raise compression
ratios and reshape the ports to
give great increases in air flow. Manifolding and carburation
is restrictive, and camshaft profile is very mild indeed. This,
combined
with an exceptionally robust design, allows massive
power gains without
the risk of shortening the life or reliability
of the unit.
The cylinder head is the first thing to consider when tuning the 4 cylinder unit, as big gains can be made from this change alone.
When considering performance cylinder heads it is worth specifying 9:1 compression as this raises overall efficiency, yet is still suitable for standard (95RON) lead free fuel.
The airflow efficiency of the inlet and exhaust ports has a direct bearing on engine torque and power. ACR have invested considerable time and resources to develop, using airflow and dynamometer test techniques, the most efficient port designs, with the highest airflow rates possible, yet retain compact port areas, vital to low speed torque and fuel efficiency.
These ultimate port profiles are, on our Stage 2.1 cylinder heads re-created (uniquely in this field) using advanced CNC machining technology on every production item we produce. This completely eliminates all hand working of ports. Solid bronze valve guides, and further CNC machining of valve seats all add up to produce the most advanced cylinder heads available. All our performance heads feature solid bronze valve guides, suitable for lead free fuel. Stage 2.1 heads are specified with 9:1 compression as standard, with the choice of 8:1 or 9:1 on Stage 1 units. 9:1 units are suitable for use with regular 95RON lead free fuel. The 9:1 compression improves thermal efficiency, and is strongly recommended. It is particularly useful with LPG fuel.
All our cylinder
heads are supplied built up, ready to
fit and with a decoke gasket set provided. Available on an exchange
or outright sale basis.
Consider the Stage 2.1 Cylinder Head if using
with other Power Plus © products
Stage 1 8:1 cr + 6 BHP on standard engine
Stage 1 9:1 cr + 6-8 BHP on standard engine
Stage 2.1 9:1 cr + 15 BHP on standard engine
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