Of course you're right.
Could we postulate that, at peak power RPM, blowdown is complete by first transfer opening? Wouldn't that be the ideal situation for best power?
Yes, I was mistaken in thinking that Wobbly had said that duct length is usually about 1 x bore. He actually said 2 x bore. In which case my duct is very short, and as you said, must negatively affect washed-through charge.Assuming (and hoping) that your exhaust duct diameter is smaller than the bore, then the duct volume will be a lot smaller than the cylinder volume. And this would imply that part of the washed-through charge makes it into the hot exhaust header before being shoved back by the pipe effects. Not quite what you want.
Should the volume of the duct be related in some way to the capacity of the cylinder? Would the efficacy of the pipe effects also be a factor, since this must affect the volume of washed-through charge?
If I find a way to extend the duct on my (water-cooled) engine, can I assume I must also find a way to cool it?
Thank you for your advice.
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