360ci std vs big bore short stroke

[latemodels4life]

I know back here in Pa. at a certain track both big bore and std. bore motor's are winning at the same track, they both seen to run great on heavy or slick track. this is in a limited 358 late class.

[fastford]

What crank angle does peak pressure occur at?
It is long before the rod and crank throw reach 90 degrees.
This minimizes the effect your speaking of

so your saying a 3.25 stroke will produce more torque than a 3.500 stroke at 6000rpms?

[TBRE]

Perfconn, look on tonybarkerracingengines facebook page, there's a picture of a Mahle Power Pack with those options done to it.TB

[turtle1hp]

Both motors build similar torque curves when built like for like. (compression, cam, heads, intake and carb restrictions) If you are going to put the largest intake valve in the head that will not hit the exhaust valve, then it would be an advantage to open the combustion chamber to the larger bore, to unshroud the valve for more flow. Then you now have the larger surface area of the piston in which the combustion pushes down on. Example: 4.125" bore is 6.47 sq. in. surface area vs 4" bore is 6.28 sq. in surface area. We will just use 1500 psi as our combustion pressure. 1500 x 6.47=9705 psi pushing down on the connecting rod vs 1500 x 6.28=9420 psi pushing down on the connecting rod. Now add the shorter stroke crank and you can have a lighter rotating weight with the even smaller moment of inertia. (the weight is closer to the centerline of the crank) This also aids in the acceleration rate of the given torque applied to the crank itself. But this combination requires different cam timing intervals to aid in the cylinder filling process. The lower piston speeds from the shorter stroke and the rod length have to be taken into consideration when designing the cam. If you have deep pockets, it has its advantages and the dollar figure to go along with it. The amount of extra money spent for the these is questionable. Sometimes it is smarter to keep it simple and spend the money on fresh tires. BUT.... That is just my humble opinion....