bbuss2
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| Joined: 06/11
Posted: 01/01/12
07:43 AM
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Posted: 01/01/12
10:47 AM
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i found this..
In modern times, the Toyota Corolla has used two different engine families (shared with the Celica).
Corollas made from 1993 to 1997 had two engine choices, the 1.6 liter 4A-FE and the 1.8 liter 7A-FE. The 1.8 was used in the GT-S. As emissions laws and tuning changed, horsepower figures moved around slightly, but not enough that the average person would notice: in 1993, horsepower was 110 hp at 5,600 rpm. By 1996, less peak power was available, but you could get it more quickly: 105 hp at 5,200 rpm. Torque went up by two foot-pounds in the same time, from 115 to 117.
1998 models benefitted greatly from a new engine family. Most automakers in the late 1990s were able to create new engine families with more power, better economy, and lower emissions, partly because of new technologies (distributorless ignition, returnless sequential fuel injection, etc.) but also because of computer-aided design and modelling. Some, notably GM and Chrysler, took the same engine blocks and squeezed large new chunks of power out of them, without losing efficiency.
In Toyota's case, the 1ZZ-FE engine combined substantially more power and economy with cleaner burning of fuel. It debuted with 120 hp (at 5,200 rpm) and 122 lb-ft of torque (at 4,400 rpm), which means that it not only makes more power than its predecessor, but does not need to be revved as high to do it. The result is a very fast car that feels peppy at all engine speeds. (Currently, the engine is producing 130 hp and 125 lb-ft of torque, for reasons we will go over later on).
The ZZ is an aluminum block engine which uses iron cylinder liners - a common design now. The deck is open, which saves weight and allows for greater precision in construction, also results in less cylinder strength, really only a problem for those who want to turbocharge or supercharge their engines with a high degree of boost. On the other hand, the bottom end has been strengthened with a full-size main bearing girdle.
Like the ol' Chrysler slant six, the 1ZZ-FE has a fairly long stroke, which is one reason it makes good torque. The bore is 79 mm, the stroke is 91.5 mm. There are two cams and 16 valves (four per cylinder).
The heads are designed to provide knock resistance while keeping combustion efficient. Their tapered squish area design, which forces a mixture of fuel and air at the spark plug, allows for a high compression ratio of 10:1 - on regular gas.
The valve seats, rather than being pressed into the head, are sprayed on, allowing them to be much thinner than standard valve seats - the result is efficient transfer of heat through the valve seats instead of the valve stems. This allows the valve stems to be relatively thin and light, so that the valve springs can be lighter, reducing wasted power and allowing for thinner cam lobes. This also means that the twin cams can be driven by a quiet, compact single-roller timing chain.
The fuel injection is returnless (a technique pioneered by Chrysler), with a pressure regulator in the gas tank, to reduce fire risk and make combustion more efficient.
The exhaust manifold is short, with the catalytic converter very close to the engine. To allow this, the aluminum intake manifold was moved to the front of the engine. Long intake runners were used to increase low-rev power. Toyota uses extruded aluminum, which is smoother than cast aluminum, and made the runners fairly wide.
2000 saw the introduction of the next generation ZZ engine, which includes variable valve technology ("VVT-i" for Toyota, "VTEC" for Honda, and there are others) to raise power by 5 hp while increasing fuel efficiency by about two or three miles per gallon.
2003 saw yet another major advancement, this one in gas mileage. Though the 2003 Corolla added both weight and a little horsepower - another 5 hp, making it 130 in total with 125 lb-ft of torque - gas mileage actually increased, thanks to direct injection. This system, long used by Mitsubishi in smaller engines, is even more efficient than the now-common sequential multiple-port electronic fuel injection, eliminating one more step in the process where fuel can fall out of suspension - essentially squirting it directly into the cylinder. Toyota is the first company to put direct injection into a standard-price "large" four-cylinder engine.
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Posted: 01/01/12
11:09 AM
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