Toyota 5M-GE engines: details and photos
The culmination of fifteen years of development and the production of over 400,000 dual-overhead-cam engines, the 5M-GE engine was introduced in 1982 cars with 145 horsepower, but quickly gained efficiency and power, ending up wiht 175 hp. It was known for instant response, thanks to computer-controlled electronic fuel injection, unique hydraulic lash adjusters that kept valve clearance to zero — the first Toyota use of hydraulic lifters — and other features. The cams were driven by fabric/rubber timing belts.
The 2.8 liter engine had hemispherical combustion chambers, which allowed for a cross-flow head (intake valve on one side, exhaust on the other), and a central spark plug location; the design was similar to the monster Chrysler Hemi engines that had long been discontinued. A standard V6 design, the 5M-GE had two valves per cylinder (in keeping with the hemispherical-head design), activated by dual overhead cams, driven by a belt drive. The engine was only used in the Supra and Cressida.
In 1982, when the 5M-GE was introduced, Toyota was the world's largest maker of DOHC engines. They put the camshafts in the 5M-GE on either side of the engine, directly over the valve system, reducing weight and allowing higher revving and quicker response. The gain in power over the 1981 engines was 25%, a hefty amount. Engine noise was reduced by using timing belts instead of chains. The electronic fuel injection monitored air intake volume, throttle position, collant temperature, air temperature, exhaust oxygen density, injection timing, engine rpm, and engine cranking. Multiple fuel injectors were used to atomize gasoline just before the valve openings; the system was derived from the Bosch L Jetronic system (itself a descendent from Bendix), but using airflow metering.
As with most engines of the time, electronic ignition was used, eliminating points and condensors. A vacuum-advance distributor was used only in 1982; afterwards, advance was controlled electronically.
Rated horsepower (United States figures) was bumped to 150 in 1983, 160 in 1984, 161 by 1986, and 175 in 1987. These boosts were made possible by the 1983 use of electronic vacuum advance, a switch from round intake runners to D-shaped runners, computer control changes, exhaust and emissions system refinements, compression ratio boosts, and other advances. In 1984, the original dual V-belt “fan belts” were replaced by seven-rib serpentine belts; the camshaft belt went from square to round tooths; the compression ratio was boosted; a knock sensor was added to deal with substandard fuel; intake runners were modified; and the oil pan was deepened. The alternator was also dropped from 65 to 60 amps.
The 5M-GE was part of a family of engines known as the “M” engines, starting in 1965 and ending in 1992. They were made in single and dual cam versions, went up to 267 net horsepower and down to 110 gross horsepower, had carburetors and fuel injectors, had turbo models, and ranged from 2.0 liters to 3.0 liters.