Quote:
Originally Posted by tim3058
Vortec heads are awesome, I totally agree with drmiller100. I did a a lot of forum reading/research last year when I was building up a 350 V8 for the Z28 - Vortec is hands down best bang for the buck horsepower-wise. The vortecs were designed to flow a lot more (in low-lift conditions, where the valve spends the majority of its duration) than prior heads, and a revamped combustion chamber allowed a faster burn of the mix. This allows us to run less ignition advance and still get the complete burn. Less ignition advance means less time where the combustion has already started while piston is still traveling up to top-dead-center (TDC). Any combustion prior to TDC serves to slow the piston down, decreasing efficiency. More flow, less advance needed, both seem to be a win for mpgs.
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Although I'm not sure the flow numbers are all that great. If you've not looked at one, the vortec intake port resembles a spiral staircase in the bowl area, just under the intake valve. It must really get the air swirling as it enters the combustion chamber, resulting in a fast more complete burn, that produces lower rpm torque at cruising rpm.