Roizska: 4AGE TWINCAM 16 VALVE

4A-GE (16-valve)

The cylinder head was developed by Yamaha Motor Corporation and was built at Toyota's Shimoyama plant alongside the 4A and 2A engines. The reliability and performance of these engines has earned them a fair number of enthusiasts and a fan base as they are a popular choice for an engine swap into other Toyota cars such as the KE70 and KP61. New performance parts are still available for sale even today because of its strong fan base. Production of the various models of this version lasted for five generations, from May 1983 through 1991 for 16-valve versions and the 20-valve 4A-GE lasting through 1998. The 4AGE shares the same bore/stroke ratio (81mm x 77mm), the same valve sizes (29.5mm & 25.5mm) and similar port designs (In some variations) as the Cosworth BDA

First Generation "Blue Top" (Early Bigport)

The first-generation 4A-GE which was introduced in 1983 replaced the 2T-G as Toyota's most popular twincam engine. This engine was identifiable via silver cam covers with the lettering on the upper cover painted black and blue, as well as the presence of three reinforcement ribs on the back side of the block. It was extremely light and strong for a production engine using an all-iron block, weighing in at only 123 kg (271 lb) - over fifteen percent reduction compared to 2T-GEU. It was also 4 dB quieter.^[19] While originally conceived of as a two-valve design, Toyota and Yamaha changed the 4A-GE to a four-valve after a year of evaluation.

The 4A-GE produced 84 kW (112 hp; 114 PS) at 6,600 rpm and 13.4 kg⋅m (131 N⋅m; 97 lbf⋅ft) of torque at 4,800 rpm in the American market. The use of a vane-type air flow meter (AFM), which restricted air flow slightly but produced cleaner emissions that conformed to the U.S. regulations, limited the power considerably - the Japanese model, which uses a manifold absolute pressure (MAP) sensor, was originally rated at 94 kW (126 hp; 128 PS). However, this was a gross power rating and the engine was later re-rated at 88 kW (120 hp; 120 PS) net. Nonetheless, Japanese cars tested no faster than their American counterparts despite their higher power rating and a lower curb weight.

Toyota designed the engine for performance; the valve angle was a relatively wide 50 degrees, which at the time was believed to be ideal for high power production.^[20] Today, more modern high-revving engines have decreased the valve angle to 20 to 25 degrees, which is now believed to be ideal for high-revving engines with high specific power outputs. The first generation 4A-GE is nicknamed the "bigport" engine because it had intake ports of a very large cross-sectional area. While the port cross-section was suitable for a very highly modified engine at very high engine speeds, it caused a considerable drop in low-end torque due to the decreased air speeds at those rpms. To compensate for the reduced air speed, the first-generation engines included the T-VIS feature, in which dual intake runners are fitted with butterfly valves that opened at approximately 4,200 rpm. The effect is that at lower rpm (when the airspeed would normally be slow) four of the eight runners are closed, which forces the engine to draw in all its air through half the runners in the manifold. This not only raises the airspeed which causes better cylinder filling, but due to the asymmetrical airflow a swirl is created in the combustion chamber, meaning better fuel atomization. This enabled the torque curve to still be intact at lower engine speeds, allowing for better performance across the entire speed band and a broad, flat torque curve around the crossover point.During rising engine speed, a slight lurch can occur at the crossover point and an experienced driver will be able to detect the shift in performance. Production of the first-generation engine model lasted through 1987.

Second Generation "Red & Black Top" (Late Bigport)

The second-generation 4A-GE produced from 1987 to 1988 featured larger diameter bearings for the connecting-rod big ends 42 mm (1.65 in) and added four additional reinforcement ribs on the back of the engine block, for a total of seven. The T-VIS feature is maintained and MAP. It is visually similar to the first-generation engine (only the upper cam cover now featured red and black lettering) and the US market power output was only increased to 86 kW (115 hp; 117 PS). The first- and second-generation engines are very popular with racers and tuners because of their availability, ease of modification, simple design, and lightness.

Third Generation "Red Top" (Smallport)

The third-generation appeared in 1988 and was in production until 1992. This engine has the silver cam covers with the words only written in red, hence the nickname "red top". Toyota increased the compression ratio from 9.4:1 to 10.3:1. To correct the air-speed problems of the earlier generations, the intake ports in this cylinder head were re-designed to have a smaller cross-section, and hence it has been nicknamed the "smallport" head. This change in the intake ports negated the need for the earlier twin-runner intake manifold and it was replaced with a single-runner manifold. Additional engine modifications to extend life and reliability included under-piston cooling oil squirters, thicker connecting rods and other components. Also of note, the pistons were changed to accept a 20 mm (0.79 in) fully floating gudgeon pin unlike the 18 mm (0.71 in) pressed-in pins of the earlier versions. Other internal revisions were made to the pistons. They were slightly modified to make space for the under-piston cooling oil squirters found in this engine version. In addition to this, the piston ring size were changed to 1.2 mm (0.047 in) (top ring), 1.5mm (second ring) and 2.8 mm (0.11 in) (oil ring), this change in size made it difficult to obtain as compared to the earlier 16 valves versions of the 4AGE 1.5 mm (0.059 in) (top ring), 1.5 mm (0.059 in) (second ring), 3 mm (0.12 in) (oil ring).^{[citation needed]} All non-U.S. market 4A-GEs continued to use a MAP sensor, while all of the U.S.-market 4A-GE engines came with a MAF sensor. For US-market cars this revision increased the power to 92 kW (123 hp; 125 PS) at 7200 rpm with a torque of 15.2 kg⋅m (149 N⋅m; 110 lbf⋅ft) at 4800 rpm (95 kW (128 hp; 130 PS) and 14.5 kg⋅m (142 N⋅m; 105 lbf⋅ft) Non US-Market versions (MAP Sensored) Make 8-10hp more at the crank

The 4A-GE engine was first introduced in the 1983 Sprinter Trueno AE86 and the Corolla Levin AE86. The AE86 marked the end of the 4A-GE as a rear wheel drive (RWD or FR) mounted engine. Alongside the RWD AE86/AE85 coupes, a front wheel drive (FWD or FF) Corolla was produced and all future Corollas/Sprinters were based around the FF layout. The AW11 MR2 continued use of the engine as a rear mid-engine, rear-wheel-drive layout, transversely-mounted midship. The engine was retired from North American Corollas in 1991, although it continued to be available in the Geo Prizm GSi (sold through Chevrolet dealerships) from 1990 to 1992. All 4A-GE engines (including the 20-valve versions below) feature a forged crankshaft rather than a cheaper and more commonly used cast version.

Clarification: In the U.S. market, the 4A-GE engine was first used in the 1985 model year Corolla GT-S only, which is identified as an "AE88" in the VIN but uses the AE86 chassis code on the firewall as the AE88 is a "sub" version of the AE86. The 4A-GE engines for the 1985 model year are referred to as "blue top" as opposed to the later "red top" engines, because the paint color on the valve covers is different, to show the different engine revision, using different port sizes, different airflow metering, and other minor differences on the engine.

The American Spec AE86 (VIN AE88, or GT-S) carried the 4A-GE engine. In other markets, other designations were used. Much confusion exists, even among dealers, as to which models contained what equipment, especially since Toyota split the Corolla line into both RWD and FWD versions, and the GT-S designation was only well known as a Celica version at that time.

In South Africa in 1993 the 4A-GE engine was dropped and replaced with the 7A-FE even as other countries moved towards the 20 valve 4A-GE, as South African fuel was not suitable at the time for the 4A-GE 20valve.