Quote:
Originally Posted by mcrews
an added thought on diameter of exhaust pipes.
the chart always refers to the MAX hp. So unless you are a race car you are at max hp MAYBE 1% of the cars life. Remember MAX HP is at aprox 6k rpms. how often do you hold 6000 rpms??????
The other day my scangaugeII recorded 30hp while doing 60mph at 1812 rpms. My car is rated at 340hp V8.
I certainly dont need to 'open up' the stock system to get better 'performance/mpg'
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30hp for a 60mph cruise sounds about right.
Forget about your pipe charts and such, they're wrong and you're looking at the problem the wrong way.
For exhaust systems, better performance and better fuel economy come from reducing pumping losses. It does not matter what the theoretical maximum flow of a pipe is. If you're throwing away energy pushing exhaust through a restrictive system then the energy is costing you gas mileage.
In my experience with V8's big improvements are made with headers. The trick with that unfortunately is keeping the cats hot enough that you're not trading fuel consumption for emissions output.
A lot of the newer PCMs support per cylinder trimming but I'm still waiting for some testing to do cylinder balance - I'm certain this will pick up more efficiency.