Chevy 4.3L V6 Specs

by Vern Hee
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The 4.3-liter Vortec Chevy V6 was the first Vortec engine ever made in 1986 and was used in GMC and Chevy trucks. The engine boasted 155 horsepower when it first appeared. The engine is based on what General Motors calls Vortex technology. The technology produces a vortex or mini-tornado inside the combustion chamber. The idea was to blend fuel and air more efficiently in the chamber, producing more power. This engine is the mainstay of the Chevy line of light trucks and vans.

The Base Engine

Chevy gave its 4.3-liter V6 a numerical designation of "4300." This engine was built as a 90-degree Vortec engine that displaces 4,300 cubic centimeters or 262.3 cubic inches. This engine was based on the 350-cubic inch 5.7-liter V8 small block Chevy engine. The LB4 V6 4300 engine was used only in passenger cars, and then, in 1991, the engine expanded into light trucks.

GMC Syclone

In 1991, the GMC Syclone debuted with the 4300 LB4 engine. The truck boasted 280 horsepower with 350 torque at 3,600 rpm. This was the first use of multi-port fuel injection on the 4300 engine. The LB4 was retired in 1998. In 1992 the engine cylinder block was modified, and Chevy came out with the L35 central port-injected engine, followed by the LF6 in 1996

The Current Engine

In 2002, the 4300 received another facelift as GM went back to the multi-port injected engine and introduced the LU3 and the LG3. The LU3 engine 4300 Vortec version is surviving well in models such as the Chevy S-10 light. The current LU3/LG3 engine is rated between 180 to 200 horsepower at 4,600 rpm with 260 foot-pounds of torque at 2,800 rpm, depending on the model driven. The engine uses a cast-iron block and heads and has a bore and stroke of 4 inches by 3.48 inches. The engine has an overhead valve configuration with two valves per cylinder.

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