I was not referring to factory stock block....Just looking at somthing to see which way a person would build an engine to a cube inch limit for max power NA....The over riding response seems to be the biggest bore you can get.

Since stock block overbore is limited to 4.400 or less, i assume most of us figured on aftermarket blocks. The best combo might be a 4.560 bore 4.25 stroke for 555 cubes. But not many want to take a good block to the limit if they don't have to.
I became a believer in big bores when my first megablock combo went 8.70s at 3055 lbs with 440-1 heads, and 13.4 compression. 528 cubes, 4.15 stroke 4.50 bore. Cam was only 280/290 @ .050 and .760 lift

Well hell let’s take all those stroker cranks, small block and big block, and throw them in the trash since the BORE makes so much power. I guess the big 3, Cat, Cummins, Offy-Drake, ships, freight trains, any and all got it all wrong.

Unlimited RPM. RPM = horsepower - if you can move the air

None of those run 7k. Or even half that normally.

If you want to do a lot work over a long time, then stroke is your friend. If you want to do a lot of work over a shorter time, then bore and RPM win every single time.

Very interesting topic, I read some of the major race engine builders have always felt that full race it all about the big bore.



One of my bucket list projects for a streeter has been a under square street/light tnt 3.950 bore on a 4 inch crank since they say ... low rpm/high tq.

In this case im not sure if im going to see any drastic changes vs our common stroker builds, but who knows.

They don’t have too rev to make the power to push those heavy loads. One point the 383 and 400, both have same crank but 400 much bigger bore. What’s the difference in HORSE POWER from each? What maybe 5, Negligible

At the low RPM the factory rated those engines it didn't really matter that much. Besides, the factory ratings were rarely correct. The numbers were usually fudged for marketing reasons. Any race engine builder will tell you that bore size makes power in a wedge headed engine. People have known that for at least the last 50 years if not longer. The big problem with making power that way is finding a big bore block. In the old days they didn't exist. These days they exist but they cost a lot so the average racer doesn't mess around with big bore combinations. A 4.500 bore is probably the largest bore size that the average bracket racer will ever get their hands on, especially a Mopar guy. Chevy guys and some Ford racers have the option of larger bores.

as long as the bore on the small bore engine is big enough to not restrict the airflow needed at 7000 RPM then they would be very similar and abiltity to package it is a bigger priority.

A very smart person you never heard of (Dr. F. W. Lanchester) provided an answer over 100 years ago.
Where:
HP = maximum power
B = bore diameter
S = stroke length
N = number of cylinders
C = a constant for fuel quality, materials, construction standards

HP = B^1.65 × S^.5 × N × C

Note that bore to stroke ratio, number and position of cams, valve train design, valve size and number, rod to stroke ratio do not appear.

100 years ago no one understood their respective influence on the internal combustion engine.

limiting yourself to 7k rpms makes it a crap shoot between square, over square and under square Bore Vs Stroke.

100 years ago no one understood their respective influence on the internal combustion engine.

No, 100 years ago THAT person understood their respective influence on the internal combustion engine.

Anybody think this statement is out in left field yet? Works for just about any situation.

That Person was an Aviation and Military Genius, but what we have learned in the last 100 years ADDS a ton more perspective to the OTHER factors that good ole Freddy considered insignificant.

And none of it contradicts what he said.

And I might add there were a ton of SMART people around about that time, telling us how the universe works and all. But the internal combustion engine was to much for them, to hard to understand!
Had to go get the spelling right
Einstein
Curie
Newton
Tesla
Planck
Salk
Bohr
Just name a few from a 100 years ago

Newton didn't try the ICE and fail.
It wouldn't exist for another 200 years.

A good example might be a 413 vs a 400. The extra 13 cubes wouldn't win me over.