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MAIN SPECIFICATIONS AND PERFORMANCE

Mazda New Lightweight and Compact V6 Engines

Takashi Sakono, Shinobu Takizawa, Setsuo Harada, Tatsuji Ikeda, and Hiroshi Abe

Mazda Motor Corp.

ABSTRACT

Mazda has developed new-generation V6 engines. The new V6 series comprises 2.5-litre, 2.0-litre and 1.8-litre engines. The development objective was to ensure high output performance for excellent "acceleration and top-end feel", while satisfying "Clean & Economy" requirements. The engines also had to have a pleasant sound. Mazda selected for these engines a short stroke, 60° V-shaped 24 valve DOHC with an aluminum cylinder block. Various techniques are adopted as follows:

• Combustion improvement and optimization of control to achieve high fuel economy and low emissions
• Improvement of volumetric efficiency, inertia reduction of rotating parts and optimization of control to achieve excellent "acceleration and top-end feel"
• Adoption of a high-rigidity, two-piece cylinder block and crankshaft and weight reduction of reciprocating parts to achieve a pleasant engine sound
• Material changes and elimination of dead space to achieve a compact, lightweight engine

INTRODUCTION

These days, people are not as concerned with material wealth as they are with spiritual wealth. As for automobiles, there is a growing demand for a vehicle which can be deeply satisfying to drive and is environmentally safe (low emission and high fuel economy). V6 engines are becoming popular for their smooth and quiet characteristics. However, in the "family-use" and "compact-speciality" car classes, conventional V6 engines can not meet the lightweight, compact and pleasant drive requirements. Newly developed K-series engines are small, matching stylish and compact vehicles and appeals to the customer's sensitivity and is pleasant to drive. The K-series comprise 2.5-litre V6DOHC(KL), 2.0-litre V6DOHC(KF) and 1.8-litre V6DOHC(K8) engines.

DEVELOPMENT OBJECTIVES

To achieve drive feeling which appeals to total human sensitivity and as a contribution to the unique "low hood & short nose" styling, the following four major objectives were set in developing the K-series engines:

1. Low fuel consumption, low emissions

2. Excellent "acceleration and top-end feel" and pleasant engine sound

3. Most compact and lightweight engine of all mass produced V6 engines

4. Long-life durability with high performance

MAIN SPECIFICATIONS AND PERFORMANCE

To achieve high combustion efficiency, excellent acceleration and top-end feel, the K-series engines were designed with bore and stroke of 84.5x74.2 mm for KL, 78x69.6 mm for KF and 75x69.6 mm for K8. To contribute to the "low hood & short nose" vehicle style, 60-degree bank angles, which are superior in reducing vibration, noise, and packaging size, were selected. Fig. 1 shows a sectional view of the KL engine and Table 1 shows the main engine specifications.

Fig 1 Sectional view of the KL engine

To achieve excellent top-end feel in the high speed range while ensuring driving performance in normal operating range, high torque was realized in all engine speed ranges. The engine performance curves are shown in Fig. 2.

The following represents the techniques employed in the K-series engines, focusing on the "KL" engine.

Fig 2 Performance curve of K-series engines