A 'boxer' engine is a 'flat' one where the cylinders are horizontaly opposed, as on the VW Beetle, Porsche 911 and Ferrari 512 Boxer and Testarossa! A notable modern day 'boxer' engined car is the Subaru Impeza, although Subaru have also used 'boxer', or flat-4 engines since the early 1970's.
The Alfa boxer engine was used in the Alfasud, the Sprint, the Arna (and Nissan
Cherry Europe), the 33 and the early 145 models.
The Alfa boxer engine first appeared in the Alfasud in 1972. It was originally
1186cc and 63bhp, but over the years grew to 1712cc, and with 16 valves up to
137bhp in the pre-catalyst Alfa 33 16v Boxer and Permanent 4.
Power of the 33 16v engine dropped to 132bhp when fitted with a catalyst from
1992, and down 3 more horsepower to 129bhp, in the boxer engined 145
Later 145 and 146 models were fitted with Alfas in-line four 16v
Twinspark engine as fitted at the time to the 155 etc.
The 'original' style boxer engine was made in 1186cc, 1286cc, 1350cc
and 1490cc capacities. It used a single overhead camshaft per paired bank
of cylinders, with 2 camlobes per valve, and mechanical tappets. These
engines used single carburettors mounted in the centre on the top of the
engine. Some models (usually the 'hotter' TI variants) used single twin
These engines pwer outputs ranged from 63-85bhp.
The' Veloce' version of the 1500 boxer engine appeared in the
Sprint Veloce model from aprox 1981-1982. This engine saw the introduction
of 2 twin-choke downdraught carburettors, made either by Dellorto or Weber,
with a large airbox across the top of the engine. Power output was now up to
95bhp. This engine was used in the Sprint, the series 3 hatchback Alfasud Ti/Tix and Gold Cloverleaf,
the 33 and the Arna.
Veloce engine in 1982 Alfasud Gold Cloverleaf
Veloce Boxer Engine
|By 1983 the 1500 Veloce engine was upto 105bhp, mainly due to the new
camshafts, which now only used one lobe per valve, and shim tappets. This
engine was used in the final Alfasud Ti model (the Green Cloverleaf), the
Sprint and the 33.
The engine was increased to 1712cc in 1986 which gave 118bhp. From around
1988, the engines had new hydraulic tappet heads. Both types of 1700cc engine
were used in the final Sprints and the 33 series 2.
8v Boxer with Hydraulic Tappets
In 1990 the Series 3 Alfa 33s were launched and all engines became fuel injected,
and the final evolution Quad cam 16v Boxer engine was introduced.
The 1300/1400 (aprox 90bhp with CAT) engines used the Weber IAW
static electronic injection/ ignition system. The 1500IE (aprox
97bhp) and 1700 IE (110bhp or 107 with CAT) models used the
Bosch MP 3.1 system with a single central throttle, whilst the 1700 16v Alfa
33 models(137bhp or 132 with CAT) used the Bosch ML 4.1 system with each
cylinder breathing through its own Dellorto throttle body.
The 1994-1995 Alfa 145 was offered with injected boxer 8v engines of 1.3 (90bhp),
1.6 (MP 3.1 injection,103bhp), and the 1700 16v engine with a 'squared off'
intake manifold, and Bosch MP2.10.3 injection (129bhp).
The Alfa 33 4-cam 16v engine
33 16v engine bay
145 Boxer engine bay