Quote:
Originally Posted by cbinker
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Awesome thanks. So we get:
34,4/18,9 HP/tq factory stock
36,7/19,2 HP/tq Yosh, stock map
38,0/ HP/tq Yosh, tuned map
38,4/ HP/tq Yosh, tuned map w/noise-insert
There's been shift in tuning market where customers are making decisions without adequate background knowledge. People think that bigger pipes is better (which it's not) and aftermarket upgrade suppliers have no choice but to create non-optimized products or lose sales.
I just measured exhaust outlet of my Tyga where it goes into muffler and it's a massive 42mm!!! Plug that into various exhaust calculators and you get sufficient flow-rate for 100bhp!!! No wonder a straight pipe of that size loses power, the pulses and pressure-waves coming back along the edge of pipe of that size would be optimized for 50000 RPM with 250cc engine. Adding some restriction with muffler to slow down pulses and changes optimum scavenging RPM to more reasonable 11000 RPMs.
Ali muffler I got has 51mm inlet and is listed as being useable on a ZX14 with 192 hp!!! So yeah, it's way too big and needs to be clamped down for a 250's flow-rate.