Thread: econo horsepower

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Power is a function of moving air into and out of the motor. Eric is saying that the volume of the intake ports in the stock 400 heads is too small to be able to provide the cylinders with a good dose of air on each intake stroke. Sort of like you running and trying to breathe through a straw.

These 400 motors were designed to move Impalas full of people and large station wagons full of kids and junk. The intake runners were cast quite small in comparison to a performance cylinder head because the factory wanted to make huge torque down low in the rpm range to move these heavy hulks. So, they designed them with a long stroke and small intake runners.

Oh, and another thing. These motors were very low compression because they came into vogue during the Arab Oil Embargo. We couldn't get much oil from the middle east and so all the oil was refined into cat piss, low octane pump fuel. The factories had to lower the static compression ratio so the motors would be compatible with the available fuel.