4A-GE Big Port Description

Here's a scan of the 4A-GE powerband from a 1988 Toyota Corolla brochure.

Note: The following was taken directly from a Toyota Service Manual.

Here are some cutaways of the 4A-GE as illustrated in the Service Manual.

The 4A-GE engine is an inline 4-cylinder engine with the cylinders numbered 1-2-3-4 from the front. The crankshaft is supported by 5 bearings specified by the inside of the crankcase. These bearings are made of aluminum alloy.

The crankshaft is integrated with 8 weights which are cast along with it for balancing. Oil holes are built into the center of the chrankshaft for supplying oil to the connecting rods, pistons, and other components.

The engine's ignition order is 1-3-4-2. The cylinder head is made of aluminum alloy with a cross flow-type intake and exhaust layout and with pent roof-type combustion chambers. The spark plugs are located in the center of the combustion chambers.

The intake manifold has 8 independent long ports and utilizes the inertial supercharging effect to improve engine torque at low and medium speeds. Exhaust and intake valves are equipped with irregular pitch springs made of oil-tempered silicon chrome steel wire which are capable of following the valves even at high engine speeds.

Both the exhaust and intake cam shafts are driven by a single timing belt. The cam journal is supported at 5 places between the valve lifters of each cylinder and on the cylinder head of the front end. Lubrication of the cam journal and cam is accomplishe by oil being supplied through the oiler port in the center of the camshaft.

Adjustment of the valve clearance is done by means of an outer shim-type system in which valve adjusting shims are located above the valve lifters. This permits replacement of the shims without removal of the camshafts.

The resin timing belt cover is composed of 3 pieces. A service hole is provided in the #2 timing belt cover for adjusting the timing belt tension.

Pistons are made of hihgly temperature-resistant aluminum alloy and a depression is built into the piston head to prevent interference with valves.

Piston pins are of the full floating-type with the pins fastened to neither the piston boss nor the connecting rod. Instead, snap rings are fitted on both ends of the pins preventing the pins from falling out.

The #1 compression ring is made of steel. The #2 compression ring is made of cast iron. The oil ring is made of a combination of steel and stainless steel. The outer diameter of each piston ring is slightly larger than the diameter of the piston and the flexibility of the rings allows them to hug the cylinder walls when they are mounted on the piston. Compression rings #1 and #2 work to prevent the leakage of gas from the cylinder and the oil ring works to scrape oil off the cylinder walls to prevent it from entering the combustion chamber.

The cylinder block is made of cast iron. It has 4 cylinders which are approximately 2 times the length of the piston stroke. The top of the cylinders is closed off by the cylinder head and the lower end of the cylinders becomes the crankcase in which the crankshaft is installed. In addition, the cylinder block contains a water jacket through which coolant is pumped to cool the cylinders.

The oil pan is bolted onto the bottom of the cylinder block. The oil pan is an oil reservoir made of pressed steel sheet. A dividing plate is included inside the oil to keep sufficient oil in the bottom of the pan even when the vehicle is tilted. This dividing plate also prevents the oil from making waves when the vehicle is stopped suddenly and thus shifts the oil away from the oil pump suction pipe.

This is just a table that I threw together. I "tested" each engine in my Corolla GT-S and here's what came out: