RE: Cross-Flow with Tuned Pipe?
Mateus,
Please translate your post to English, the spoken language in this forum, so we can all understand what you're trying to say...
JP,
There is absolutely no contradiction between using a tuned-exhaust system and having a baffled piston...
What determines the ability of an engine to 'respond' to exhaust tuning, is what is called 'the blow-down period'...
It is defined as the duration in ยบ between the closing of the intake bypass(es) by the rising piston and the closing of the exhaust port by the same...
It is during this period that the reflected high-pressure wave, pushed the amount of fresh mixture previously drawn into the header by the previous low-pressure pulse, back into the cylinder. The rising piston then mask the exhaust port, trapping a greater mixture volume than the net cylinder displacement.
And yes, it is a rudimentary form of supercharging...
This duration is half the difference, between exhaust port duration and intake bypass duration.
If an engine has no (or a very short) blow-down period, it cannot be boosted by a pipe... Most Cox .049 engines are examples.
Perhaps some older engines also have identical intake bypass and exhaust timing also, in addition to a baffled piston... And this may have brought about your query...