- Slant Four
"for the similarly named (but unrelated) engine made by Triumph, see
Triumph Slant-4 engine "The Slant Four is a type of car
engine manufactured byVauxhall Motors and in modified form byLotus Cars . Unveiled in 1966, it was one of the first productionoverhead camshaft designs to use arubber toothed belt to drive thecamshaft from thecrankshaft (an honor shared with the 1966 Pontiac OHC Six), a method developed in 1956 byBill Devin .Vauxhall
The engine features four inline cylinders inclined at an angle of approximately 45 degrees (hence the name), and this is because Vauxhall had originally planned to develop a whole family of engines all built on the same production line. There was to be slant four and V8 versions in both petrol and diesel versions, designed under the guidance of Vauxhall's then chief engineer, John Alden. There is a single overhead camshaft operating two valves per cylinder. An ingenious valve train design incorporating an inclined socket head cap screw, allowed
valve clearances to be adjusted with afeeler gauge and anAllen key . The block and crossflow head are both ofcast iron . The layout makes good use of the cylinder inclination to lower the overall height of the engine, which allowed for moreaerodynamic designs of cars to be achieved by lowering the bonnet line. It also means most of the engine is very easy to access for maintenance, with the exception of the exhaust manifold, which is "underneath" the slanted cylinders.Although prototype engines were fitted to the FC 101 Victor the first production car to use the engine was the 1967 Victor, at capacities of 1599cc and 1975cc. Later, the smaller engine was increased to 1759cc, and the larger, to 2279cc.
Bill Blydenstein racing developed along stroke version with a capacity of 2600 cc, in which form it could produce almost 250 hp (186 kW). Having originally been designed as the basis of a futureV8 , the block is immensely strong and can handle huge increases in power without modification, also the crank was designed to be shared with the diesel version which meant in built strength was assured. The larger capacities are renowned for their immensetorque (having such large pistons), but a downside of this is that they are not very smooth running or high-revving.The engine was widely used in many models of car, and was also developed into amarine engine forboat s and was popular with amateurs due to its great strength, tunability and simplicity. The engine was still being manufactured well into the 1980s for theBedford CF van, and many of them are still in daily use.Lotus 907
It is said that when Vauxhall unveiled its new slant-four engine at the 1966 Earls Court Motor Show its bore centers were exactly the same as those proposed by Lotus for their new all-alloy engine.
Colin Chapman immediately negotiated a deal with Vauxhall to buy some of their cast-iron blocks so that development of Lotus’ own aluminum 907 engine could be sped up.The design became the basis for the Lotus 2.0 and 2.2 engines used in a wide variety of
sports car s, but while the basic block was copied almost unchanged, it was cast inaluminium alloy instead of iron, which made it considerably lighter. The Lotus engine also used a differentcylinder head of light alloy, featuring double overhead camshafts and four valves per cylinder. Vauxhall also developed a 16-valve head for the engine in the late 1970s, which was used on the Chevette HS, but this design suffered a number of problems in use, and the Lotus head was much better - so much so that for the rally cars, Vauxhall substituted the Lotus head, breaking the rules and getting themselves disqualified for one of therallying seasons.
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