Technical Bored and Stroked - No Replacement for Displacement

292 cubic inches can be reached on a 261 Chev. 6 with an offset ground crank. I think this requires the use of G.M.C. rods ​

I think 320 cubic inches on a 302 G.M.C. with a .125" bore.

 

As mentioned, it is easy to get an MEL above 500 cubes by offset grinding the crank down to BBC bearing dimensions. This gains 0.4" of stroke, combine with a 0.050" over bore and you have a quick 510 inch monster that is still fairly oversquare and capable of spinning relatively high RPM's.

The Lincoln Y-Block has a very tall deck height and as such is capable of supporting strokes up to 4.10", perhaps even longer with a bit of massaging. With a stock 4.0" bore 368 block, that nets close to 412 ci.

Jay Brown built a 527 ci SOHC FE for Drag Week. It had a ton of very specialized machining, and was not something that could be done with a factory block. But given the relatively close bore spacing and short deck of an FE, it represents the high end of FE engine displacement (and Jay needed to offset the sleeves to increase the bore spacing to get to 527.)

Packard V8: The Packard V8 has a huge 5" bore spacing and short stroke of 3.5". This means the block is capable of much higher displacements. I don't know of any max effort engines, but theoretically, there is room for a 4.25" bore and 4.0" or 4.25" stroke. That would get close to 480+ ci.

Also, Theoretically, one could take a 337 ci Lincoln Flathead to over 400 ci with offset grinding the crank and max bore. Again I am not aware of any actual engines built to that level.

 

I know of quite a few of 302 Jimmys out to 340" with a 1/4" stroked crank and an 1/8' bore.
Personal opinion only but my favorite SBC are 4.125"-4.165" bore and 3-7/8" stroke. That's a 415-422" they are killers on dirt tracks all over the country and everything is right off the shelf and made in the USA if you aren't going on the cheap.

 

I don't think I would bore a Packard really big. Cylinder walls are thick. But not that thick. Not much iron connecting the right bank to the left bank and almost none holding the lifter bores on. Doubt it would live with serious horsepower. But the heads would never flow enough to be dangerous anyway.

 

In the late 50's we built 3 Ford 60's at 166 ci for midgets. We had 3 cast steel crank billets made.
They were all Offy killers.

 

There haven't been many maximum effort ones done. We did one for a 7 liter boat in the early 60's that did fairly well but it wasn't a "big" engine. It had to be under 427 ci. for the class.