What is the compression for a 1989 Chevy TBI 5.7 in truck?

The compression ratio for a 1989 Chevy TBI 5.7L engine (small-block V8) isn't a single, universally precise number. It varies slightly depending on the specific engine casting and any modifications. However, a generally accepted range is 9.0:1 to 9.5:1.

You should not rely on this general range for troubleshooting. To accurately determine the compression ratio of *your specific engine*, you need to perform a compression test. This test provides a reading for each cylinder, and any significant variations between cylinders indicate potential problems.