1. The engine is capped at 6800 rpm because that is how Toyota decided to build and tune the engine. My guess is that it could probably handle a higher redline, but it probably wouldn't meet Toyota's ridiculous longevity standards. They could have build a more expensive motor designed for higher rpms, but I imagine that the current setup met their cost goals, while allowing them to position the ISF's power rating comfortably between the M3 and the C63 AMG. Everything in the auto industry ultimately comes down to money. (Also, by building it the way they did, the ISF gets significantly better gas mileage than either the Bimmer or the Benz)Had a couple of questions on the ISF motor
1. Why is the engine capped 6800rpm?
2. Can this engine be modified to generate more torque at higher rpm?
2. You can build/tune a motor in a variety of ways, so nothing is impossible...BUT...typically your horsepower is the only thing that keeps climbing with a higher redline. Your torque tends to taper off well before redline. Also, chances are that if you increased your high-end torque, you would sacrifice some low-end.