Re: Re: Help With Fuel Economy on 4.7L

From: Jon Steiger (jon@dakota-truck.net)
Date: Fri Mar 16 2001 - 15:50:41 EST


zrt800@iname.com ("ZeRTified Cat") wrote in
[...]
>3. Cat back exhaust. So far the only product to make a specific claim
>of better mileage in thier ads. My concern is it also says 'more
>power'. In general you need X gallons of fuel to make X Hp. So if you
>make more power one would think you'd burn more gas. In most computer
>controlled motors they adjust the air/fuel mixture so if you alter one
>side of the equastion by adding more air, won't the computer just
>compinsate by adding more fuel? The only other explanation is that the
>exhaust improves on the efficiency (sp?) of the motor. Are these
>systems louder/noisier than stock?

   Most of the bolt on mods such as exhausts, intakes, etc. make more power by
helping the engine to breathe better. This better breathing will also help out
the gas mileage. While it is true that you need to burn more air and fuel to
make power, when you're not using all that power, you see benefits in gas
mileage. Also, an engine with more power doesn't have to work as hard as a
stock one; a good example is when comparing the gas mileage of V6's towing to
V8's towing the same weight; its not uncommon for the 8 to get better (or the
same) mileage as the 6. Another example, my '96 club cab ran 16.0 and got
about 18mpg highway bone stock; I've added an intake, throttle body, intake
manifold, headers, Y pipe, 3" exhaust, t-stat, computer, and pullies. Now it
runs mid 14s so its obviously got more power but I now get 21mpg highway...
So its kind of a best of both worlds deal; you get more power but if you stay
out of the throttle you'll also get better gas mileage...

-- 

-Jon-

.---- Jon Steiger ----- jon@dakota-truck.net or jon@twistedbits.net ------. | Affiliations: AOPA, DoD, EAA, NMA, NRA, SPA, USUA; Rec & UL Pilot - SEL | | '92 Ram 150 4x4 V8, '96 Dakota V8, '96 Intruder 1400, '96 FireFly 447 | `------------------------------ http://www.cs.fredonia.edu/~stei0302/ ----'



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