heads swap from ls1 806 heads to a 5.3l heads
02-20-2010, 09:52 PM
#1
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heads swap from ls1 806 heads to a 5.3l heads What gains in switching from stock 806 to 5.3l heads just ported and polish would I see any difference or any gains do I need to changed the valve bigger?? I found out that the flow the same as ls1 heads only difference is that 806 heads are 69cc like 9.6 comp and 5.3l heads are 61cc like put me into 11.0 comp right... Any info would be great to know that there better heads then that I had....
02-21-2010, 04:26 PM
#2
The exhaust port flow is the same, but the 5.3's tiny 1.89" intake valves really do hurt flow, anywhere from 20-40 cfm at .500" lift, depending on whose numbers you believe. Still, the LS1 heads are flowing better by .300", but are about 5.5cc larger combustion chambers. In theory, a .033" cut to the LS1 heads would equalize that, but then the 5.3 heads could be milled to again be 5.5cc smaller. So we're back to the question of if the compression will be more helpful than the airflow. In my case, I'm losing effective compression to the high elevation I live at, so if you're at sea level, our answers might be different. But I do know that just porting 5.3 heads doesn't make them equal to milled but virgin LS1 heads, you need the larger intake valves.
