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An octane rating, or octane number, is a standard measure of a fuel's ability to withstand compression in an internal combustion engine without causing engine knocking.The higher the octane number, the more compression the fuel can withstand before detonating.
For example, if the static compression ratio is 10:1, and the dynamic compression ratio is 7.5:1, a useful value for cylinder pressure would be 7.5 1.3 × atmospheric pressure, or 13.7 bar (relative to atmospheric pressure). The two corrections for dynamic compression ratio affect cylinder pressure in opposite directions, but not in equal strength.
A stratified charge can allow for slightly higher compression ratios without "knock," and leaner air/fuel ratio than in conventional internal combustion engines. Conventionally, a four-stroke (petrol or gasoline) Otto cycle engine is fueled by drawing a mixture of air and fuel into the combustion chamber during the intake stroke.
Geometrical compression ratio is 12.5:1 The large valve overlap leads to a reduction in cylinder charge and reduced torque and power output, but efficiency is increased. This combination makes the 2AR-FXE suitable for use in hybrid vehicles, where peak torque and power demands can be met by the electric motor and battery. Maximum output of the ...
The 2.0L version is an inline 4-cylinder engine that carries a bore and stroke of 86 mm and a 10.5:1 compression ratio; the engine makes 144–151 PS (106–111 kW; 142–149 hp) at 6,000 rpm and 19.1–19.8 kg⋅m (138–143 lb⋅ft; 187–194 N⋅m) of torque at 4,000–4,250 rpm.
The Toyota GR engine family is a gasoline, open-deck, piston V6 engine series. The GR series has a 60° die-cast aluminium block and aluminium DOHC cylinder heads.This engine series also features 4 valves per cylinder, forged steel connecting rods and crankshaft, one-piece cast camshafts, a timing chain, [1] and a cast aluminium lower intake manifold.
Actually as I remember it, it was: 5-Star = 100 octane, 4-Star = 98 octane, 3-Star = 93 octane, 2-Star = 87 octane, but your figures may be correct. The 5-Star rating was the motor equivalent of avgas and was only used in high-performance cars with high compression-ratio engines, such as Jaguars, etc.
The addition of two milled cutouts [in the head] to extend the volume of the combustion wedge can create a compression ratio of 7.5:1; one milled cutout produces a 9.5:1 compression ratio. The difference between the volume of these cutouts provides a wide compression range without making any changes in the piston or cylinder head.