[gotboost_79mm]

Just to add...Someone can correct me if I'm wrong...but doesn't an increase in displacement reduce the engines ability to spin higher rpms, which reduces the top end torque curve and power due to added engine vibration from the stroke. I understand the engine can be balanced through head work, piston balance etc..but wouldn't it make more sense to keep the current displacement and balance the engine to spin higher rpms for more top end torque rather than stroking the engine.

[MartinSTi05]

Originally Posted by gotboost_79mm

Just to add...Someone can correct me if I'm wrong...but doesn't an increase in displacement reduce the engines ability to spin higher rpms, which reduces the top end torque curve and power due to added engine vibration from the stroke. I understand the engine can be balanced through head work, piston balance etc..but wouldn't it make more sense to keep the current displacement and balance the engine to spin higher rpms for more top end torque rather than stroking the engine.

Strokers are typically RPM limited due to their longer stroke. Engine A: 50mm stroke, Engine B: 100mm stroke. Assuming both turn the same RPM the pistons in engine B must have twice the average speed as the pistons in engine A. This increased speed means more force on the bearings rods, pistons etc, which can limit it's ability to rev. If you double the rate of acceleration, the force is quadrupled. So the force on the engine components goes up with the square of the RPM, making it that much harder for strokers to rev high.

Where a stroker makes sense is when low end performance and a broad torque curve are desired, such as street driving. A small displacement engine/cam package that requires screaming RPM to produce horsepower equivalent to the stroker is not what everyone is looking for from a drive ability standpoint.
There are many ways to skin a cat. The application dictates the approach that makes most sense.

[disturbed1]

damn you guys rock. thanks for answering my question and now a get it. i was having a brain fart i forgot about the displacement part of the engine. im gonna stroke out the engine for my K5 blazer. its a 396 big block but in reality it came from chevy bored out to a 402. im taking the block to get bored out .060 more and buy a stroker kit thanks to you guys. i may also run meth in it so i can run a 10.89 comp on 91 pump. maybe in the future ill bore out the STi after the GT35r.

[Neanderthal Racing]

Big Bore Or Long Stroke: Which Is Better? | National Dragster | Find Articles at BNET.com

i've got an overbore to 2.6l.