i was approaching my assertion from a factory tooling standpoint where it might be easier to de-stroke the motor than offer up different bores if the 3.6l and 3.2l engines are built on the same line. i'm kinda guessing at this...maybe bob can shed some light??
It depends upon how much they "de-stroke" the engine. Any change in the deck to combustion chamber ratio, creates issues.
Assuming that every micro-change affects emissions, and may inhibit a stroker engine, I'd still say an engine with a greater stroke to bore relationship, is a better performing engine.
Modern engines are over square because rpms help burn the fuel more completely and frankly because early V6 engines needed to be buzzy to move the vehicle.
The Pentastar (using a modified Hemi/Poly combustion chamber) overcomes this somewhat and produces more torque than any comparable sized Mopar V6.
When I build engines, I care little for horsepower, I concentrate on usable, low to mid range torque, the horsepower will follow. When you accelerate, what you feel is torque, not horsepower.
Engines with massive low rpm torque are fun to drive, get appreciably better fuel economy, but may not be emissions friendly, due to how clean today's engines have to be.
All that being said less bore and more stroke make a better performing engine.*
If you ever get a chance to look at the insides of a V-10 you are going to see relatively long stroke and small pistons, but a lot of them...
* completely dependent upon your intended usage. The old 340 was a high rpm engine, with most of it's torque at high rpm, great for the Trans Am series, poor for a daily driver or truck, yet the same block in 360 form, was just the opposite, a good torque motor, a poor road racer.
Edited by MoparNorm, May 14, 2011 at 08:56 am.