Question by trondoveac: Which is more reliable a big bore or a long stroke?
Lets say you have 2 engines and both are a 32 valve DOHC 5.0L V8 with VVT but one is a bigger bore with a smaller stoke and the other is a smaller bore with a longer stroke. Would both engines have equal reliability or would one of them be more reliable than the other?. Also both engines are equally maintained very well.
Answer by Small Business Owner in TX
Well, you’re dealing with 2 devils here — big bore means lots of reciprocating mass. Large pistons weigh a lot, and that much mass being accelerated then decelerated rapidly puts enormous strain on connecting rods, rod bearings, etc, which calls for more mass — heavier rods, larger bearing journals which means heavier crankshaft.
Other side of the coin is longer stroke, which means the piston has to travel a long way up and then down, so nasty piston speed at high rpm — again straining capacity of rods, journals, etc.
My vote is long stroke for very high rpm, otherwise big bore.
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