More boost with the chiller?
 

I have been running my 10/71 littlefield without a chiller for 2 summers now. I purchased a chiller and I'm having the hatch worked now so everything will clear.

How much boost do I need to add to make up for the restriction in the chiller? I was running 4-5lbs. I'm thinking 8lbs total should be safe????

It should make the same power with the chiller and current pulleys, although boost pressures will drop. The cooled intake charge is denser. You will be able to run more boost now due to the added chiller that reduces the detonation risk and increase power. I would think 7-8 would be safe based on running 4-5 w/o the chiller.

Boost is usually measured under the intercooler, at the intake manifold. Whereas, you probably will see a loss in pressure, if you use the same pulley setup with the chiller. You can add boost with the chiller if your static compression is low enough, and you keep your final compression (with boost figured in) to a reasonable 12.5 to 1; that is using premium gas.
Bawana

How do I figure my compression at 8:1 with 8-9lbs boost?

From the BDS web site. Elevation i smetioned but Cam will also effect CR but this chart will get you close.

http://www.blowerdriveservice.com/techcharts.php

Like I said, keep it safe at 7-8lbs of boost. That should put you right around 12:1 final CR and run 93 octane.