Toyota S Engine - 3S - 3S-GTE

The 3S-GTE is an in-line 4-cylinder 1998 cc engine from Toyota, based on the 3S-GE with reduced compression ratio to accommodate the addition of a turbocharger.

There are four generations of this engine, which started manufacture in 1986 and was built until 2007.

The turbochargers used in the 3S-GTE engines are Toyota designs. The first-generation Toyota CT26 utilized a single entry turbine housing and a single wastegate port design. The second-generation Toyota CT26 used a twin entry turbine housing with dual wastegate ports. The third-generation engine uses the (enthusiast-dubbed) Toyota CT20b turbo, which was of the same design as the second-generation but with a slightly improved turbine housing and larger compressor wheel. The fourth-generation engine uses a proprietary, and once again enthusiast-dubbed, CT20b turbocharger, whose exhaust housing is actually cast into the cylinder exhaust manifold, rather than the normal practice of a separate turbine housing after the cylinder exhaust manifold. The CT20b can be used on the second-generation 3S-GTE manifold, but it is not backwards compatible with the first-generation 3S-GTE. The (4th-generation) CT20b is backwards compatible with the third-generation 3S-GTE cylinder head only. All Toyota's turbochargers for the 3S-GTE generations use an internal wastegate design.

Depending on where the engine was intended to be sold the exhaust turbine is either ceramic (Japan) or steel (US and Australia). It was fitted to the MR2, Toyota Celica GT-Four, and the Caldina. Its cylinders are numbered 1-2-3-4, cylinder number 1 is beside the timing belt. The Dual Over Head Cam (DOHC) 16-valve cylinder head designed by Yamaha is made of aluminum alloy. The pent-roof combustion chambers are complemented by a cross flow intake and exhaust layout. Spark plugs are located in the middle of the combustion chambers. A distributor based system is used to fire the cylinders in a 1-3-4-2 order.

On the first and third generations of Celicas, the intake charge was cooled by a water-to-air intercooler, while the second, third MR2, and fourth generations relied on an air-to-air system. Also, the second-generation rally homologation Celica (known as Group A Rallye in Australia, RC in Japan and Carlos Sainz Limited Edition in Europe) used the water-to-air intercooler.

In late 1997, the block casting was revised with added support around the head to prevent block cracking problems.

The crankshaft, located within the crankcase, rotates on five aluminum alloy bearings and is balanced by eight weights. Oil holes are located in the middle of the crankshaft to provide oil to the connecting rods, bearing, pistons and various other components.

On the first two generations the intake manifold has 8 independent ports and benefits from the inertia build up to improve engine torque at low and medium speeds. Due to the design of the intake manifold, cylinder number 3 runs lean under normal operation. Various aftermarket solutions exist all of which require replacing the intake headers or manifold. The first two generations of 3S-GTE engines are equipped with T-VIS. The third-generation uses a normal 4-runner intake manifold, the fourth-generation had 4 runners but the throttle body was located on the end of the intake manifold instead of near the middle like the earlier generations.

A single timing belt drives the intake and exhaust camshaft along with the oil and water pumps. The cam journal is supported on 5 points between the valve lifters of each cylinder and on the front of the cylinder head. The cam journals are lubricated by oiler port located in the middle of the camshaft. To adjust the valve clearance, adjust the shims above the valve lifters (shim over bucket system). This allows for the replacement of the shims without the need to remove the camshaft.

The pistons are made from an aluminum alloy, design to withstand high temperatures. An indentation is incorporated into the pistons to prevent the pistons from "knocking" into the valves. The compression ratio is 8.5:1 for the first, third and fourth generation and 8.8:1 for the second generation. Piston pins holding the pistons in place are locked by snap rings.

The first compression ring and the oil ring is made of steel, the second compression ring is made of cast iron. Compression ring 1 and 2, prevents gas leakages from the combustion chamber while the oil ring works to clear oil off the cylinder walls, preventing any excessive oil from entering the combustion chamber.