How does dropping compression ratio affect AFR's?

[80LS1T]

I just finished up installing a new short block in my service writers 350Z after it "blew up" after installing the turbo kit. The new short block has a stock crank, forged H-beam rods and forged pistons. The stock compression was 10.3:1 but we lowered it to 8.8:1 for the turbo.

 

My question is how does lowering the compression affect AFR's if the PCM's programming is not changed? He had the computer flashed but that was for a stock motor with 8psi boost, now he's running the same programming but 8.8:1.

 

The closed loop is AFR's are right around 14.7 and open loop is at about 11.3:1. The computer was flashed for 8psi to run at 11:1. Now the owner of the dyno that he is going to get it dyno'd at said that dropping the compression should have richened the mixture up. I am just wondering about the theory behind that info?

 

 

Thanks,

 

Guy