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Originally Posted by Norm Peterson
Quick and dirty, the intake areas are close (not surprising, given that the power outputs are similar and they're both working under the same emissions and fuel economy pressures). What's important is that it takes the OHV motor having a bore about 10% bigger in order for that to happen. IOW, the OHV design has to be bigger at least in the bore dimension in order to get that much valve area into it.
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I don't
have to have bigger pistons, I
want to...
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Side note, that tiny bore is one thing in particular I don't care for about the modular-design Ford motors. I feel that a 93-ish mm bore (3.66") is really better suited to 8-cylinder displacements between about 4.0L up to 4.2L.
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In theory, having the slightly undersquare setup that the Coyote has and 4-valve design would lend itself well to forced induction, as compared to the 2-valve oversquare of the LT1. But it is not ideal for N/A high HP. To be honest, I think the rod ratio is a more important factor here anyway, so I am getting a bit to far down this road...
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Side note #2, there actually have been a couple of pushrod 4-valve designs for the older-gen SBC. The LS would have been a better starting point
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The issue I have with 4-valve pushrod is there is still too much mass to rev high, so the 4-valve is kind of not fully utilized.
Truth be told, what's really holding back the pushrod design in terms of being able to raise the RPM's of peak HP is the emission standards (IIRC cold start emission is tough here). You can buy Chevy's heads and cam for the LT1 and get 535HP right out of the box. Or you can just buy the LT376/535 crate engine right from Chevy. 535 N/A HP with all that low end torque would make a nice replacement in an SS 1LE if that person's engine blew up. That would be a blast at the track!