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The famous 4A-GE that the MKI MR2 is so lucky to have. We as AW11 MR2 owners are very lucky to have the engine that we do. Upon the introduction of the Mr2, the automotive world marveled at this little 1587 cc jewel. At the time, a smooth revving, high redline, DOHC, EFI engine was simply unheard of, as many manufactures had problems getting their new 16V 4 cylinders to run as good as the 4A-GE. The block was an updated Toyota design, while the design of the head had been commissioned to Yamaha, a common Toyota practice. While still good today, Toyota at the time had taken the lead in high-tech engines with the 4A-GE along with other models. The 4A-GE is not known for it's Torque, the reason why is because it has none. The engine is definitely likes to make power high in the rpm range. It is a very rewarding car to drive because you have to work to keep the engine power on tap. This makes the car an excellent beginners car, as it will help to educate the driver. While it may seem that you are hurting the engine in the higher rpms, don't worry because it was made to take it, although prolonged high rpm running (6500-7500rpms) over 30 min or so is not suggested. Just always make sure that you have fresh oil in the car! The 4A-GE is used in many different racing applications, and when designed, this was taken into consideration. The 4A-GE is currently used in competition in the Toyota Formula Atlantic Racing series in a heavily modified state. In this series the updated 87+ block is used, as it is a heavier more robust block that can handle greater HP levels. While the original 4A-GE block is indeed a good, light, strong block that is able to handle 190+hp in stock form, it is often the 87+ block that is used for the high-HP engines (200+ HP) . This stronger block was designed with the 4A-GZE in mind although it also became the standard block for the 4A-GE sometime in early 87. Toyota strengthened the block by adding more nickel content along with other physical structural reinforcements. Included along with this were larger crank journals and piston pins so that it would be able to handle the rigors of forced induction. The easiest way to tell these blocks apart is by counting the number of ribs on the intake side of the motor. The older block has 4 ribs whereas the 87+ newer blocks will have 7 ribs. As already mentioned, in early/mid model year 1987 the 4A-GE engine in the US AW11 received the 4A-GZE block along with a few other minor modifications, one of which was the dual spray injector which increased the HP by 3, this engine also having a new ECU and MAF. While not known for sure, it is also thought that sometime in 87 the switch was made to the red cam lettering, which is facing toward the back instead of the front. This is commonly called the "red hat" while the "blue hat" is from the 85-86 and some 87 cars. Currently no one knows the exact date change of the block or the color "hat" for the AW11 NA. My current MR2, which was manufactured in Feb. 87 has the blue hat, but the stronger 7-rib block. While it used to be common practice to say that all the blue hat engines had the weaker block while the red hats had the stronger block, this is not true. The switch to the stronger block was done before the cam cover color change. The G in 4A-GE signifies the type of head the engine has. The G designation stands for the 50 degree valve angle head, which was designed for performance, rather than for fuel economy which was the design goal for the F series head in the 4A-FE. While the F series heads have a more desirable valve angle of 22.3 degrees, the ports are no good for high horsepower breathing. The 4A-GE is a non-interference design meaning that if the timing belt (which is recommended to be changed ever 60k miles) breaks, no damage will be done. This of course will change if the engine is modified to have a higher compression ratio or more agressive cams. The 4A-GE in non forced induction state can be
taken up to around 240 HP as proven in the Formula Atlantic series. These
engines however are not streetable and even though you may want to install
one, it would not work well in an MR2. Current estimates are that the engine
can be taken up to around 200hp and still be somewhat streetable. This
however will be very expensive. For around $3000 though, it can be taken
to approx. 170 hp as proven by those on the MR2 list. If you are
willing to go all the way however, the author would highly suggest taking
a look at
Bill Sherwoods's
fantastic site in which he describes in great detail his streetable
220 HP 4A-GE buildup.
The first version of the 4A-GE was used in the AE 82, AW11, and the AE86. After the AW11 was retired, later versions of the 4A-GE were used in the AE92, AE101, and AE111. The only one of these models available in the US was the AE92 (Corolla GT-S). This engine received numerous changes, the most notable being higher compression ratio, a revised smaller intake port, and no more TVIS. The TVIS was dropped and ports made smaller because Toyota found that, for the street, a smaller port head was a better design, as the air speed of the air entering the engine increased, thus making more power. This engine produced 125 HP. This engine still had the MAF air metering system, whereas its overseas counterparts used a MAP sensor, and had 5 extra HP to be gained from it. Ironically, this small port MAP 4A-GE was indeed used in the US, just not in a Toyota car. It was the engine in the Geo Prizm GSi. When modifying 4A-GEs it is believed that the small port head is the best choice until ~200Hp where the small port head would choke off flow. In 1991 another version of the 4A engine came along, the 20 Valve. This had many different changes most notably the 5 valve head, a new 4 port intake manifold, and a VVT system. This was the first production engine in history with a 5 valve head, this innovation being sourced directly from Yamaha Formula 1 experience. As a result, the power once again went up, this time to a very impressive 165 HP. This engine was used in the Levin/Corolla, neither of which were available in the US. In 1996 this engine received the "VVTi" designation signaling a new ECU. The i stands for "intelligence" which decides the rpm at which the timing is changed. This along the switch from the AFM air sensor to the MAP sensor helped to boost HP by 5. The 5 valve variable valve timing system (VVT) used in the 20V, was similar in scope to the VTEC system of the Hondas, but had a totally different approach in execution. The cam timing is controlled by the ECU and when a certain rpm range is reached, the ECU activates a solenoid which sends pressurized oil into the sprocket causing it to rotate at a more aggressive cam timing. Also thrown into the mix was the 7A-FE engine in the mid 90s. This had a weaker block in comparison to the 4A-GE but had a displacement of 1.8 L, this extra 200 cc of displacement being achieved through a longer stroke. And yes, the G series head has been successfully used on the 7A with the use of a Porsche 924 timing belt. (who would have thought?) By now you may be wondering, "How can I get one of these other 4A/7A engines in my AW11!?!?" Well it can be done, and has been done by numerous individuals. The author knows of successful transplants with both the 130 HP small port "red hat" and the 20 Valve. Also when considering the many different variations of the A series engine, a large number of unique and power combinations have been successfully created for use in the AW11, some including the 7A-GE, 4A-GTE and 4A-GZTE. For those looking for more information on these engine and more, first check the section in the mods section of the page on major engine mods and swaps Secondly a search thought the Mr2 Mailing List Archives will give some more info. For more detailed info on the history of the 4A-GE, see Phil Bradshaw's page: 4A-GE Info If you are interested in the TRD Atlantic Engine, check out the specifications: Atlantic 4A-GE specs Stephen Gunter from the MR2 list has summed it
up pretty good in saying that:
Specifications: 4-AGE:
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