We'll just agree to disagree.........you're comparing a 5.0 DOHC crate motor to a 4.6 production motor and touting more HP??? Ya think??? Nothing to do with the added displacement.

The larger bearings of a 351 does not decrease HP as much as it super heats the oil. I suppose the added friction robs a little power but you have 49 more cubes. The 347 stroker makes more HP than a 302 all else being equal and a 302 in theory should be able to rev higher there too.


It is known that the current SBC shares nothing with the old SBC........the only point being is heads or not, the smaller bore motors are making more HP. It's not just a simple "bigger valves make more power" and from your writings I know you realize that.

Emissions is the reason for the smaller bores.............BUT lower emisssions can go hand in hand with a more powerful more efficient powerplant. Flame travel, velocity, more complete burn etc........are more important than just the total amount of air you can move............this is the reason the Hemi and to a lesser extent the canted valve motors are not eficient street motors. (I'm not talking about the new psuedo hemi)

Most 4 valve heads, even with smaller bores, will flow waaay more than ever needed for insane peak HP..........it's at the lower RPM that you have to restrict airflow. Either in the intake tract like the old Cobras or with VVT.