I have a set of PP 5.3 heads milled .040" coming. This would raise the compression to somewhere in the 10.2-10.5:1 range I would imagine. What kind of power boost would come from just the increased compression?

 

shaving .030 will raise your compression .4 higher. Stock compression is 9:4 i think, so since you shaved .040 maybe you'll be near like 10:1

 

These trucks suffer from KR (knock retard) so much that any more compression may (or may not) cause more detonation. My truck "pings" as it is, sometimes even with the good gas, which inturn causes my timing to get knocked back, resulting in lost power. Its probrobally a real fine line where in my opinion it wouldn't even be worth the cost of the head gaskets. (Unless you plan on running 100 octane all the time!)

 

I assume this is for a 5.3 liter truck. Stock CR is 9.5:1 and milling .035 will get you right on 10:1. If the chambers have been cleaned up, the reduction in volume will pull you back below 10:1. I'd guess the TQ / HP increase will be in the 5-10 range from compression alone.

 

I wish I remembered this correctly, but I *think* that each point of compression you raise a given motor, you get somewhere just north of 5% increase in power. This does not include issues you get from increased pinging and pulled timing, which could easily give you a 5% decrease in power or more. This only works up to a break-even point also, probably in the mid teens to 1 compression range.

Anyone know the numbers for 1 point of compression?

Todd