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PORSCHE 911
for the 6-throw crankshaft, end thrust being taken by the last bearing on the clutch side. A train of spur gears drives a countershaft underneath the crankshaft; this carries two chain sprockets at its rear end, each of which drives one camshaft via a twin-row timing chain equipped with automatic tensioner. At the forward extremity of the countershaft are two oil pumps, one a large scavenge pump emptying the dry sump and pumping the oil back to the tank, the other, smaller, pump feeding the pressure lubrication system. A thermostatically controlled oil cooler insures trouble-free high speed running. The instruction manual indicates that if all is well 1300 C. (2660 F.) should never be exceeded. We did a lot of miles at nearly top speed on the German Autobahn and never even approached this temperature.
Highly domed pistons and inclined valves working in a hemispherical combustion chamber allow a compression ratio of 9:1. Ribbed cylinder barrels (with cast iron liners) and heads are machined from aluminum castings. Atop each group of three cylinders sits a recently developed triple-choke Solex carburetor type 40-Pt. Instead of an orthodox float chamber, it also has a Sort of dry sump arrangement, with a Bendix electric fuel pump supplying

fuel from the tank and two mechanical pumps establishing a continuous-flow circuit with an overflow at the correct level. This complex arrangement keeps the fuel cool, eliminates any danger of vapor lock and prevents fuel surge during high speed cornering. Between the two carburetors, an alternator and the cooling fan are located on a common, belt-driven shaft.
In spite of the sophisticated design, accessibility is decidedly better than on the pushrod engine. The dry-type air filter, fuel pumps, carburetors and distributor can be reached easily and even removal of the upward-inclined spark plugs poses no problem. Strangely, the least accessible point that the owner will have to reach is t~e oil tank filler neck. Unless one uses a fairly long funnel or removes the air filter (admittedly easy after undoing four clips), it is diflicult to add oil without spillage.
The timed acceleration and top speed figures are excellent for a 2-liter car. The figures we obtained were almost identical, actually a shade better, than the performance claimed by the factory. This engine is not entirely without fault, however. On our test car, it was jerky when running at about 2800 rpm on a trailing throttle, and part-throttle after fullpower acceleration was sometimes accepted with some hesitancy.

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