| The Chevrolet Corvair engine was a flat-6 (or boxer | | | | 164 |
| engine) piston engine used exclusively in the 1960s | | | | The engine was stroked out (from 2.6" to 2.94") |
| Chevrolet Corvair automobile. It was a highly unusual | | | | displacing 164 in (2.7 L) for 1964. Power output was |
| engine for General Motors: It was air-cooled, used a | | | | boosted to 95 hp (70 kW) for the base model and 110 |
| flat design, with aluminum heads (incorporating integral | | | | hp (80 kW) in the high performance normally aspirated |
| intake manifolds) and crankcase, and individual iron | | | | engine, while the Turbocharged engine remained rated |
| cylinder barrels. The heads were modeled after the | | | | at 150 hp for this year. This increase in stroke was the |
| standard Chevrolet overhead valve design, with large | | | | maximum the engine could tolerate, to the point that |
| valves operated by rocker arms, actuated by | | | | the bottoms of the cylinder barrels had to be notched |
| pushrods run off a nine lobe camshaft (exhaust lobes | | | | to clear the big end of the connecting rods. |
| did double duty for two opposing cylinders) running | | | | For the 1965 model year, all engines had the head |
| directly on the crankcase bore without an inserted | | | | gasket area between the cylinder and the head |
| bearing, operating hydraulic valve lifters (which | | | | widened, with a new design folded "Z" section |
| eliminated low temperature valve clatter otherwise | | | | stainless steel head gasket virtually eliminating any risk |
| seen with that much aluminum in the engine, due to its | | | | of head gasket failure. A 140 hp (104 kW) version with |
| high degree of thermal expansion). | | | | 4 single barrel carburetors, and a progressive linkage |
| The flat horizontally opposed ("flat engine") air-cooled | | | | was introduced in 1965 as option L63 'Special High |
| engine design, previously used by Volkswagen and | | | | Performance Engine' and was standard equipment on |
| Porsche as well as Lycoming aircraft engines, offered | | | | the Corsa model. The carburetors consisted of a |
| many advantages. Unlike inline or V designs, the | | | | single barrel primary and a single barrel secondary on |
| horizontally opposed design made the engine inherently | | | | each head, connected by a progressive linkage; in |
| mechanically balanced, so that counterweights on the | | | | addition, the heads featured a 9.25:1 compression ratio, |
| crankshaft were not necessary, reducing the weight | | | | and the cars received dual exhaust systems. Engines |
| greatly. Eliminating a water-cooling system further | | | | supplied with the automatic transmission after spring |
| reduced the weight, and the use of aluminum for the | | | | 1965 were modified with a camshaft from the 95 |
| heads and crankcase capitalized on this weight | | | | Horsepower base engine, and a special crankshaft |
| reduction; so that with the use of aluminum for the | | | | gear that retarded its timing 4 degrees- the former to |
| transaxle case, the entire engine/transaxle assembly | | | | increase torque and smooth idle with the Powerglide |
| weighed under 500 pounds (225 kilograms). In addition, | | | | transmission, the latter to restore some of the peak |
| the elimination of water-cooling eliminated several | | | | HP lost at higher engine speeds by the economy |
| points of maintenance and possible failure, reducing | | | | contoured camshaft with short timing. |
| them all to a single point; the fan belt. As with the | | | | 1966 engines were basically carryover from the 1965 |
| Volkswagen and Porsche designs, the low weight and | | | | models, however Corvairs sold in California (except |
| compact but wide packaging made the engine ideal | | | | Turbocharged models) now featured the General |
| for mounting in the rear of the car, eliminating the | | | | Motors Air Injection Reactor System (AIR), and |
| weight and space of a conventional driveshaft. | | | | emissions control system consisting of an engine |
| Two years after its 1960 debut, the Corvair engine | | | | driven air pump that drew filtered air from the air |
| gained another unusual attribute: it was the second | | | | cleaner, and injected a metered amount into the |
| production engine ever to be equipped from the | | | | exhaust manifolds via tubing to promote complete |
| factory with a turbocharger, released shortly after the | | | | oxidation and combustion of exhaust gasses to lower |
| Oldsmobile Jetfire V8. | | | | emissions. Specially calibrated carburetors and slight |
| Aircraft hobbyists and small volume builders, perhaps | | | | changes to the ignition timing and advance curves |
| seeing the Corvair engine's similarity to Lycoming | | | | were part of the package. The AIR system had an |
| aircraft engines, very quickly began a cottage industry | | | | unfortunate effect of sustantially raising exhaust gas, |
| of modifying Corvair engines for aircraft use, which | | | | valve and head temperatures, particularly under heavy |
| continues to this day. The Corvair engine also became | | | | loads and this was a drawback on the Corvair where |
| a favorite for installation into modified Volkswagens | | | | engine cooling could not be easily improved to cope |
| and Porsches, as well as dune buggies and | | | | with the higher temperatures. Nonetheless, |
| homemade sports and race cars. | | | | performance and drivability were not noticably |
| 140 | | | | effected in most circumstances. In 1968, all Corvair |
| The Corvair's innovative turbocharged engine; The | | | | (and other GM) engines got the AIR system for every |
| turbo, located at top right, takes in air through the large | | | | market. |
| air cleaner at top left, passes it through the sidedraft | | | | The 140 HP engine was officially discontinued for '67, |
| carburetor in between, and feeds pressurized fuel/air | | | | but became optional in 1967 as COPO 9551-B, not a |
| mixture into the engine through the chrome T-tube | | | | regular production option. Chevrolet sold 279 of these |
| visible spanning the engine from left to right. | | | | engines in the 1967 model year, 232 with manual |
| The Corvair's innovative turbocharged engine; The | | | | transmissions, and 47 with Powerglide transmissions. |
| turbo, located at top right, takes in air through the large | | | | Only six were sold with the four carburetor engine and |
| air cleaner at top left, passes it through the sidedraft | | | | the AIR injection system required by California |
| carburetor in between, and feeds pressurized fuel/air | | | | emissions standards. These figures include 14 Yenko |
| mixture into the engine through the chrome T-tube | | | | Stingers and 3 Dana Chevrolet variants of the Stinger. |
| visible spanning the engine from left to right. | | | | Both the 140 HP engines and the Turbocharged |
| The initial Corvair engine displaced 140 in³ (2.3 L) and | | | | engines had many special quality features not shared |
| produced 80 hp (60 kW). The high performance | | | | with lesser Corvairs- Moly insert top rings, stellite tips |
| optional "Super TurboAir" version, introduced mid 1960 | | | | and faces on the valves, a Tufftrided (cold gas |
| with a special camshaft and revised carburetors and | | | | hardened) crankshaft, and Delco Moraine '400' |
| valve springs produced 95 hp (70 kW). | | | | aluminum engine bearings- the quality of the 140HP |
| 145 | | | | Corvair engine for materials is directly comparable to |
| In 1961, the engine received its first increases in size via | | | | the Rolls Royce V8 of that era, item for item. It was a |
| a larger bore. The engine was now 145 in³ and the | | | | fabulous bargain for the $79 premium it commanded |
| base engine was said to produce the same 80 hp (60 | | | | over the basic 95HP engine. Performance of the |
| kW). The new high performance engine was rated at | | | | 140HP engine was better than you might expect, with |
| 98 hp (73 kW). In 1962 the high performance engine | | | | a 5200 rpm peak horsepower output, it offered road |
| was rated at 102 hp (76 kW). The high compression | | | | performance in a Corvair comparable to |
| 102 HP heads were added to the Monza models | | | | contemporary Cadillac models of the day. |
| equipped with Powerglide when the standard engine | | | | The turbocharged engine now developed 180 hp (134 |
| was ordered, giving an 84 HP engine rating. 1962 | | | | kW). Contemporary reviews describe a similarity in |
| engines returned to automatic chokes after a one | | | | power between the turbocharged and four-carburetor |
| year only manual choke on 1961 models. | | | | engines throughout the low and mid rpm range, with |
| The ultimate performance was found in the Spyder | | | | the turbocharged engine being superior only when it |
| model, which became available with a turbocharged | | | | was possible to sustain boost continously. The |
| engine rated at 150 hp (112 kW). The turbocharger was | | | | turbocharged engines long suit was highway |
| mounted on the right side of the firewall behind the | | | | acceleration, flooring the accelerator at turnpike |
| rear seat, fed by both exhaust manifolds; a single | | | | speeds produced ferocious acceleration in the upper |
| sidedraft carburetor mounted on the left side of the | | | | speed ranges as the turbocharger began to boost, |
| firewall fed directly into the turbocharger's intake, with | | | | reaching manifold pressures approaching 15 PSI. No |
| a chromed pipe leading from the turbocharger's outlet | | | | wastegate was used on the Corvair turbocharged |
| to what would otherwise be the carburetor mounting | | | | engine, boost was controlled by careful balancing of |
| pads on the intake manifolds, which were integral parts | | | | exhaust restriction, mostly via the muffler, and intake |
| of the heads. The turbocharged heads received some | | | | restrictions from the smallish Carter YH carburetor |
| valve upgrades to improve durability. Exhaust valves | | | | used. Preignition and knock under boost was controlled |
| on turbocharged engines were made from a | | | | using a novel 'pressure retard' device, essentially a |
| non-ferrous material used in jet engine turbine buckets, | | | | modified vacuum advance device, on the specially |
| called 'Nimonic 80-A'. All other Corvair engines had | | | | curved distributor, as boost pressures built, ignition |
| slight upgrades in valve and valve seat materials as | | | | advance was progressively reduced to preclude |
| well for 1962. | | | | detonation. |