Originally Posted by Paul Kane
EE,
I didn't say not to run one; I said that I am not a fan and that I prefer the smaller stroker cranks.
There is little journal overlap with the 4.5 stroker, also they pull the pistons way out of the hole at BDC, then there's the rod ratio, increased cost of building relative to the smaller stroker cranks, etc. But yes, the 4.5 strokers are indeed run with success and will continue to be offered as they, too, are a "drop in" rotating assembly without any crankcase clearancing required, etc.
And they also can make an engine more costly to bulild, as they need more air to breathe, ie more cam (a roller if you really want the BIG HP, but this is not necessary for the engine to run), aslmost always cost more $ to balance, more $ for better heads (ideally), etc. And then with all that power you have this cast crankshaft with minimal journal overlap and thereby minimized structual integrity. A lot or racers seem to be breaking the 4.5 stroke cast cranks at about 1000+ HP or above. That might be a lot of HP for others...but again, for me, I'm just not a fan and would rather go with a smaller stroke deal. Good thing the forged cranks have arrived.
The 4.3 stroker (521/533) makes for a practically "square" engine, which I personally like. More importantly, the 6.8 rodded 521/533 stroker puts the piston pins just .030" lower in the bore at BDC than the OEM 460...which I re-e-e-e-eally like. Great rod ratio. We recently completed a 528 (4.42B x 4.3S) combo that runs on regular ol' pump gas and a single carburetor, and produced 737HP on the dyno, and a diesel flat torque curve that hovered around 655-678 pounds from 4000-6500 rpm (didn't check lower rpms due to the jetr boat application of the engine).
I simply much prefer the 4.3 stroke over the 4.5 stroke deal.
Paul