Mazda K engine

The 1.8 L (1,845 cc) K8 is among the smallest production V6 engines ever; and also the first K-series engine to be used in a Mazda car (in the Mazda MX-3). It was a DOHC 4-valve design with VRIS and a bore and stroke of 75 mm × 69.6 mm (2.95 in × 2.74 in). It produced 130 hp (97 kW; 132 PS) in US trim (sometimes referred to as "K8-DE"), and 135 hp (101 kW; 137 PS) in Japanese trim (the "K8-ZE") on introduction in 1991 and 144 hp (107 kW; 146 PS) and 115 lb⋅ft (156 N⋅m) at its best. The displacement was held under 2000cc to minimize the annual Japanese road tax obligation.

Applications:

• Mazda MX-3
• Eunos 500

• 2.0 L KF - 2.0 L (1,995 cc) 78 mm × 69.6 mm (3.07 in × 2.74 in) bore and stroke - The 2.0 L KF engine was available in various states of tune. The KF-DE produced 140 hp (104 kW; 142 PS) and 132 lb⋅ft (179 N⋅m) and later on 144 hp (107 kW; 146 PS) and 132 lb⋅ft (179 N⋅m). The JDM version KF-ZE engine produced 160 hp (119 kW; 162 PS) and 132 lb⋅ft (179 N⋅m). The Lantis Type R variant produced 170 hp (127 kW; 172 PS) and 140 lb⋅ft (190 N⋅m).

The 2.3 L (2,255 cc) 80.3 mm × 74.2 mm (3.16 in × 2.92 in) bore and stroke, KJ-ZEM was one of Mazda's most technologically advanced engines. It employs the "Miller cycle" which uses a supercharger to increase compression efficiency by decreasing the compression losses (i.e., flywheel energy used to compress the intake charge in the cylinder); and thereby increasing the net power output of the V6. It was used in the T-platform cars. The supercharger used is the twin-screw type with electronic boost control. Power output was 217 hp (162 kW; 220 PS) and 210 lb⋅ft (285 N⋅m). The KJ-ZEM was on the Ward's 10 Best Engines list for 1995 through 1998.

Applications:

• Mazda Millenia S
• Eunos 800
• Mazda Xedos 9

The 2.5 L (2,497 cc) KL family uses an 84.5 mm × 74.2 mm (3.33 in × 2.92 in) bore and stroke. It includes the Japan-only KL-ZE, which produced 200 hp (149 kW; 203 PS) and 165 lb⋅ft (224 N⋅m). Another variant, the KL-DE (also known as the KL-03 outside the US, and fitted to 2.5-litre Ford Probes) was the worldwide version, with 164–174 bhp (122–130 kW; 166–176 PS) in various applications. In 1998 a revised version of the KL known as the KL-G4 was used in the 626. It featured solid lifters, a cast crankshaft to reduce rotating mass and a reworked intake system. The distributor was replaced with a Ford EDIS coil-pack ignition.

Mazda introduced a key technology with these engines, known as the Variable Resonance Induction System (VRIS). A series of two butterfly valves coupled with electronically controlled actuators varied the volume and length of a resonant chamber within the intake manifold. The valves actuate at particular engine frequencies (i.e. rpms) to produce optimal torque/horsepower output at any given engine speed. The valve operates to create three specific first-order resonant frequencies that increase cylinder air charge. All three resonances are used from 0 to 6250 rpm (6800 for the KL-ZE). Above that threshold, the first primary resonant chamber is again used, but at this engine speed the pressure wave from the second-order resonant frequency aids in charging the cylinder.

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