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Old 04-26-2009, 10:10 PM   #7 (permalink)
Tygen1
Master EcoModder
 
Join Date: Dec 2008
Location: South Jersey
Posts: 553

Little Blue - '98 Ford Escort ZX2 Cool
Team ZX2
90 day: 44.75 mpg (US)

Big Red - '00 Ford Excursion XLT
90 day: 15.53 mpg (US)
Thanks: 5
Thanked 45 Times in 29 Posts
Avoiding the science, my expirience is going from a 1"7/8 crush bent pipe to a 2"1/4 mandrel bent pipe and didn't really see any noticeable improvement in FE. However, going from a CastIron log style exhaust header to a tuned, tubular, header did make an impact on FE, that is in addition to the larger exhaust pipe. Not a big impact on FE, mostly because of better torque down low has helped to decrease the amount of time in the Pulse phase of the Pulse and Coast routine. Consequently my throttle body is about 2"1/4, however the exit from the header is 2"1/2 back to the flex pipe.
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