I have 99 5.3 lm7. Im looking to install some heads to really increase horsepower. Any suggestions? Could u give me some knowledge on compression vs. horsepower?

 

4.8 and 5.3 heads are the same with 1.89" intake and 1.55"exhaust valves with 61.15cc combustion chambers.LS1 heads have 2.00" and 1.55" exhaust valves with 66.67cc combustion chambers,both the 5.3 and LS1 the same intake and exhaust volume at 200cc and 70cc.LS6 and LQ9 truck heads use the same size valves as the LS1,but with bigger 210cc and 75cc port volumes.The LS6 head has a 64.45cc combustion chamber,while the LQ9 head has a 71.06cc combustion chamber.Your best bet for a mildly moded engine is probably a set of ported 5.3 heads with larger intake valves fitted,milled to produce a 10:1 compression ratio.

 

Where would i buy some ported 5.3 heads at. Who makes them ported?

 

Try Patriot Performance. They are a sponsor here.