Q: I can see that they would have higher torque delivery, but why would a four-banger with a 5,500 redline not go just as fast as a v-8with the same redline? Links, opinions (supported by FACTS and examples are all highly appreciated.
A: common misconception = red lines are set where the engine cant go any faster, red lines are set for many reasons, some times for engine life, sometimes it is set so a customer cant feel an awefull vibration that occures in the next 1000 rpm, there are cases where a factory set a redline smack dab in the middle of a cars powerband, sometimes its set for fuel echonomy, a 5 leater v8 means that car used 5 leaters of gas vapor to fire all 8 cylinders, where as your 2.5 leaer 4 uses you guessed it half the gas with half the cylinders, so the v8 is generating more power, because of the more power it used longer gearing example = 4 m80s under a coffee can vs 8 m80s under a coffee can witch one is going to hit the ceeling first? and there in lies the other big miscnception = engine equals speed, gearing has as much to do with speed as horse power, if you want to get technical its all about newtons and jules, a bigger engine has more power and torque so it can get through a longer gear, reaching second gear at a higher speed than the 4 cylinder, and every gear you add widdens the diffrence example = no car on the market not the mclaren f1 not the ferrari enzo or even the bugatti veyron has as much power and displacement as even the smallest 18 wheeler semi but it doesnt gear for speed it gears for pulling power, another example is the dodge srt viper and the srt pick up, both use the same engine but the viper is geared for speed and only has enough weight to make it comfterable to drive, the truck is geared for pulling a load and is reinforced with enough steel that the truck can pull what the engine is capable of with out destroying the body