Amazing car!!! Amazing engine with a 3.63 bore x 3.65 stroke. I was of the opinion that bore/stroke combination is in violation of the engine God commandments? That same engine in the new Cobra Jets though highly modified and with 13:1 compression , are running naturally aspirated in the low 10s. I expect some comments from you engine builders here on the site!
Yeah it used to be taboo to build under square engines(though Pontiac & Olds had a few approaching under square) plus Ford's 400 was 4.00 x 4.00, and the old FE 410(big Mercuries) was 4.05 x 3.98... I don't build(maybe assemble)... Old school thought that a large piston and short stroke was the way to build reliable HP in the upper RPM range, short rods and crank throws are stiffer and lighter than longer versions... Additionally valves can be larger and are not as badly shrouded by cylinder wall... Now days pistons, crank and rods are much stronger so can be reliably spun to 7500, quad valve heads have flow that easily matches or surpasses the big single(intake & exhaust), of old ( VVT doesn't hurt none either)... Ford had to resort to small bore as the bore spacing of the modular/Coyote is minuscule compared to even a small block, the dual timing chains take up a lot of real estate that used to be occupied by pistons... BTW the 3.65 stroke is shorter than the 390 & 427 3.78... Those old huge rod 427s won a many races spinning 7000-7200 for 500 miles at a time...
If it wasn't moreso about making more chassis room, reducing weights, bettering NVH levels, while simultaneously improving mileage AND emissions.. ALL.. of these 4 valve motors would have bigger bore spacing(and therefore larger bores), taller deck heights and huge displacements. Even 4 valves benefit from larger bores despite shrouding not being nearly as large an issue as the 2 valve stuff has to contend with. Bigger bores can and still do improve airflow efficiency and aid combustion speeds with larger quench areas, dual or full circumferential quench pads, around the entire chamber. Get the bore big enough and the piston can also be designed to incorporate a mirrored chamber area, in the form of a perfectly chamber matched dish, to help further improve power, efficiency, and mitigate excessive compression ratio increases beyond the pump gas detonation threshold allowance. Taller intake systems also allow lower valve angles, in relation to cylinders centerline, and higher intake port entry points. Direct injection helps reduce fuel fallout or centrifuging effects.. but the old rule of "the straighter the shot at the combustion chamber.. the better".. always still applies. But.. that's not the world we live in these days and most guys will instead just toss a blower on em' to cheat more air/artificial displacement into the mix. Or if you want to talk about the term undersquare.. there are guys like Kasse that will just have a custom stroker crank nearing 5" inches of stroke made up to hit 400 cubes. Lack of a cam tunnel and cavernous crankcases make that possible on this OHC stuff.
