New engine on the horizon

[Jac Mac]

Originally Posted by DAVID GAGNARD

Actually all of the Roush/Yates engines used in cup cars use a 3.25 stroke crank......

David

I thought the idea was to start out at ~4" bore & 3.5" stroke then each time the engines were rebuilt to increase bore & reduce stroke to maintain the 355 cu in, hence virtually everything we see for sale is on its 'last' life so to speak, or have they since found the 3.25" stroke & ~4.185" bore is the better combo and now just going straight to those dimensions... the bigger bore does increase the valve/bore distance.

[blykins]

David's right. They generally favor the shorter stroke, but I've seen the smaller bore combination on a few engines, especially if we're looking at "Ebay take-off's."

[DAVID GAGNARD]

Originally Posted by Jac Mac

I thought the idea was to start out at ~4" bore & 3.5" stroke then each time the engines were rebuilt to increase bore & reduce stroke to maintain the 355 cu in, hence virtually everything we see for sale is on its 'last' life so to speak, or have they since found the 3.25" stroke & ~4.185" bore is the better combo and now just going straight to those dimensions... the bigger bore does increase the valve/bore distance.

In NASCAR the cubic inch limit is 358,back in the day they would start out with a 350 chevy or 351 ford and this would allow for a few rebuilds/borings on stock blocks..........that has long since gone the way of the dinosaur,nothing is "stock" in the cars or engines and has been that way for a long time......

They want fast revving short stroke engines now-a-days hence 3.25 inch stroke,depending on the track, they are turning these engines 9500 +rpms and they have to use a solid lifter, non-roller camshaft....These engines only have to last one race,so saving a few dollars is not in the equation.....
Yates has experimented with stroke combos in the 3.10 inch range........

David