the 400 with a 440 crank & 6.76 rods has a 1.81 rod ratio & is the cheapest stroker because you can use stock rods & crank = 451 CI
the 440 with a 4.15 crank & 7.1" rods has a 1.71 rod ratio =500 CI
the 440 with a 4.15 crank & 6.76 rods has a 1.62 rod ratio =500 CI
the 440 with a 4.25 crank & 7.1 rods has a 1.67 rod ratio = 512 CI
the 440 with a 4.375 crank & 7.1 rods has a 1.62 rod ratio = 528 CI
Rdo ratio is important for at least 3 reasons
1] Less side loading on the piston & reduced stress on the con rods
2] increased torque output due to better leverage
3] increased efficiency , the piston stops longer at TDC increasing the amount of fuel burned & it moves away from TDC slower increasing the time the combustion has to push on the piston = more torque , the piston also stops longer art the bottom which can increase cylinder filling
For example look at the GM & Ford diesels both short rod V8 engines with more CI , while the Cummins is an inline 6 with a con rod almost 2" longer , the Cummins get better milage & produces more torque modifed or stock , the same thing happens in Gas engines , the short rod Gm 350 trucks average 10 12- MPG while a 440 can get 18 MPG + with a bigger engine
I will always give up CI for more efficient power , I would not be surprised to see a 500 " engine outpull a 528 or 512 in torque output all other things being equal IE same cam & intake etc
BTW Gm average 1.5 rod ratios
