Today, dollar for dollar, is the 318 faster than the 340 ???

As far as shrouding the valves between a 318 and a 340, how much is 3.2% less bore diameter really in effect?

If the compression ratio, heads, valve size, cam, intake, exhaust were all the same exactly:
A 340 with 22 more cubic inches at 85% volumetric efficiency is 18.7 HP.

This is based on a 318 Police 4bb @ 165 HP. The 340 with higher CR, bigger valves and hotter cam makes 275 HP, 110 more horses. But, this is NOT an equal comparison.
Many of us have built a 318 with 9.5:1, 2.02 X heads, 340 resto cam, larger 340 size intake and headers.
Except the headers, 'WORKED' iron logs, my 65 B-Cuda 318 (0.030 over) 9.5:1 CR, with ported X heads, a DC Purple 272 cam, Sanborn Oil mods, a 904 (2800 stall and shift kit) and 3.55 SG would slowly walk on my friends stock 340 Duster with 4 speed and 3.55 SG. I'd have him by a door in the 1/4 mile time after time.
My B-Cuda weighed 100 more pounds.

YEPPER, a 340 is FAR superior to a teen. I will leave them to their cult followers. :mob: