| If all you care about is peak power, then yeah bigger is better. Since very little of your driving time is spent there, I've always been more concerned about the power curve on the way there. The reason the correct diameter was important was to do with exhaust gas velocity and temperatures. Same as for a NA car. The thing is, that usually the answer is 'wind up the boost' to solve design issues. With an NA setup you can't do that. The same rules of flow apply to FI, it's just that they usually don't have to worry about reversion as the new intake charge, instead of being sucked in by the negative pressure in the cylinder, is being pushed in by the positive pressure after the turbo. Since it's being pushed in anyway, you could say that you don't need to worry about having a lower pressure area to draw in the charge.
I suppose it's like a NA setup is like a kid pulling a car with a rope tied around the front bumper to move it. A FI setup is like a few guys pushing the car from behind. But ideally, if you could have those few people pushing from behind, AND the person in front pulling as well, even though the person in front won't make much of a difference, it still contributes. Usually the solution is to add more or bigger guys to the back(more boost). Like I said at the start, I was referring to optimal design, not off the shelf of necessarily practical(due to time/money) design.
I didn't have time to go to Dinsdale today, will try tomorrow. |