Chevrolet LT-1

LT-1
LT-1 air-cleaner decal
Overview
Manufacturer	General Motors
Production	1970–1972
Layout
Configuration	Naturally aspirated 90° V8
Displacement	350 cu in (5.7 L)
Cylinder bore	4 in (101.6 mm)
Piston stroke	3.48 in (88.4 mm)
Cylinder block material	Cast iron
Cylinder head material	Cast iron
Valvetrain	OHV 2 valves × cyl.
Compression ratio	9.0:1, 11.0:1
Combustion
Fuel system	Carburetor
Fuel type	Gasoline
Cooling system	Water-cooled
Output
Power output	255–370 hp (190–276 kW) (gross)
Torque output	379–392 lb⋅ft (514–531 N⋅m) (gross)

The LT-1 is a Chevrolet small-block engine produced by the Chevrolet division of General Motors between 1970 and 1972. It was available exclusively in the Corvette and Camaro and was produced in relatively small quantities. It is regarded today as one of the greatest of the Chevrolet small-blocks, an engine that has been in production since 1955.

Chevrolet introduced the 350 cu in (5.7 L) LT-1 in 1970, making it available in both the Corvette and Camaro. It was an optional engine in the Corvette, and available as part of the high-performance ZR-1 option. Between 1970 and 1972, only 53 ZRs were produced, making it one of the rarest Corvettes. In the Camaro, the engine was available only through the high-performance Z/28 option, replacing the 302 cu in (4.9 L) engine designed to compete in Trans Am racing's 305 cu in (5.0 L) class installed in 1967-1969 cars.

The LT-1 had an 11.0:1 compression ratio, Holley 780 cu ft/min (22 m³/min) 4-barrel carburetor, and solid lifters. For the first year the LT-1 was rated at 370 hp (276 kW) in the Corvette and 360 hp (268 kW) in the Camaro, both of these being brake horsepower (bhp) gross hp ratings. Despite the disparity in these horsepower ratings, there was no difference between the engines.

In 1971, the compression ratio was decreased to 9.0:1 and horsepower decreased to 330 hp (246 kW), then the same in Corvette and Camaro. A net horsepower rating of 275 hp (205 kW) was also given. In 1972, the rating decreased again, then to a net of 255 hp (190 kW). Gross horsepower was not given in 1972.

In 1970, a Nova could also be ordered with an LT-1 via a Central Office Production Order (COPO). Fifty of these were ordered by Don Yenko at Yenko Chevrolet and were converted into Yenko Deuces. Yenko also converted another 125 L65 Novas into LT-1 Deuces.

• * 25 of these were ordered with RPO ZR1.
• ** 8 of these were ordered with RPO ZR1.
• *** 20 of these were ordered with RPO ZR1.
• **** 50 of these were converted into Yenko Deuces.

In 1992, General Motors introduced the LT1, a high-performance 350 cu in (5.7 L) engine based on the Chevy small-block V8 and named as a tribute to the original LT-1. It was offered as a base engine on the C4 Corvette and a variety of other GM vehicles in several states of tune through 1997, including the Camaro Z/28, performance-package Pontiac Firebirds, police interceptors, a number of large luxury cars, and a luxury station wagon.

Its maximum performance ratings (as installed in 1996 Corvettes) were 300 hp (224 kW) and 340 lb⋅ft (461 N⋅m), well above the 275 net hp and 255 net hp ratings for the original LT-1 in 1971 and 1972, and the 300 ft lb (est) net torque for 1971 and 280 ft lb net for 1972, but well below the 1970 LT1 gross rating of 360 hp.

• Holdener, Richard. "1970 GM 350 Small-Block Engine - Clash of the Small Block Titans." In Super Chevy Online. 8 June 2010. http://www.superchevy.com/how-to/vemp-1008-1970-gm-350-small-block-engine/.
• Koch, Jeff. "COPO Gigio - 1970 Chevrolet Nova." In Hemmings Muscle Machines. June 2005.
• Mattar, George. "1970 Corvette LT-1: Best small-block ever?" In Hemmings Motor News. December 2007.