The trend toward computer engine controls and fuel injection in the 1980s allowed manufacturers to design more powerful, efficient engines. Today, it is not uncommon to see engines with compression ratios once again nearing 11:1, particularly in the high output versions.
Guideline performance V8's recurrently had compression ratios environing 9:1 wrapped up the mid 1960s with the grand performance V8's rated at 11:1 or worthier. The complete availability of leaded high-octane fuel permitted these colossal CR's to be canter without engine damage.
1970s
1970 was the extreme year for the colossal compression ratio Chevy V8's for added than a decade. Stringent emission requirements and lower octane fuels created an industry-wide trend toward "cleaner," lower aptitude output engines. Most engines in this Period typically had CR's of encircling 8.5 or 9:1. As an case, the twin example LT-1 Three hundred fifty CI engine in One thousand nine hundred seventy one had a CR of 9:1 as opposed to the One thousand nine hundred seventy anecdote with 11:1.
Modern Engine Design
Chevrolet's V8 engines -- in Industry because One thousand nine hundred fifty five -- carry had many differential compression ratios (CR) depending on the equivalent of performance the engine was designed for. The CR was raised or lowered by designing engines with varying cylinder sense combustion Hospital ward volumes and piston shapes: domed, dished or flat-top.1955 to 1970
The One thousand nine hundred fifty five 265 CI V8 had an 8:1 CR.
