Need some help on my first build
My car has some pretty big Maganflow straight-through mufflers. It's surprisingly quiet on idle, a little louder at cruise, and much louder when you really lean into it.
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To estimate how choppy the sound will be, take a cam's duration at 0.050 and its LSA and plug it into this calculator:
http://www.wallaceracing.com/overlap-calc.php
(Yes, use the .050 duration and not advertised duration.)
This will give you an estimate of the overlap at .050. As far as I know no stock cam has any overlap at .050 (they are all negative overlap). Something like +6 degrees overlap will give you decent chop, 9 degrees very choppy.
6 degrees overlap will lower your idle vacuum to about 12 inches; 9 degrees overlap to about 7 inches. These low number might not be enough to let your power brakes work properly!
(I run Hydraboost so that I can run aggressive cams.)
Also remember that "chop" indicates unburnt gasoline is going out the exhaust. This kills your gas mileage and if your state has emission testing, you won't pass.








