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      10-11-2015, 06:05 PM   #1
onfireX5
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Back Pressure tested the 50i OEM Muffler

Used the same digital manometer that measures down to 0.1" H20 that was used on the intake box.

Very surprised how efficient the big quiet factory muffler is. The large size really helps the flow. Actually tested it over two days with different test hose sizes since the loss was so low. Wanted to verify the tests. Repeated the same numbers.

At 16.2psi of boost and 6700rpm the back pressure peaked at 11" of h20 or 0.40psi. Very low. Last MDX I tested measured 250" of h20 or 9psi....Acura design is very bad.

Using David Vizard's BP chart attached, 0.40psi BP = 97.5% of open pipe flow = 2.5% hp loss at max power.

So 450hp x 0.025 = 11.25 hp loss due to the factory muffler.Extremely low loss for a quiet factory muffler. Add cutouts and you'll get a quick 11 hp plus quicker turbo spool. Up the boost with a chip and the cutout gain will increase as well. For a factory quiet system.....very efficient !
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