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Old June 12th, 2008, 07:27 PM   #1
gadgit0
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Default exhaust question..

i was thinking bout running straight pipe on my truck and was wondering how that would affect my gas mileage? i have a 91 ford f150 5.0. the reason im asking is im only getting like 11mpg. when i first got the truck i was getting about 15-17mpg and had a louder exhaust on it. that muffler broke and i replaced with a $60 muffler which made it really quiet and i thinking that when my mpg went down.. it already has the cat cut off and 3" pipe running from the manifold back.

i have heard that it'll suck gas faster and also that it'll increase it. what is more correct? and what would it sound like if i did run straight pipe, and or cherry bomb in place of the muffler? thanks
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Old June 12th, 2008, 07:30 PM   #2
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straight pipe= LOUD, as there is no muffler at all. a glass pack cherry bomb is basically a straight tho muffler, that quiets the tone down b/c of the packing in it.
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Old June 12th, 2008, 08:44 PM   #3
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also note.... Michigan has decibel laws for vehicles....

restriction in the exhaust will cause the engine to work harder yes..... so, opening up the exhaust will potentially help.... but there are other factors too... such as the general state of your engine... clean injectors, not burning oil, good accessories (alternator ps pump) etc etc...
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Old June 12th, 2008, 09:29 PM   #4
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no back pressure also causes a severe loss of power at NORMAL operating speeds (this isn't a Nascar or top fuel dragster). that results in a drop in fuel mileage.

too much back pressure is just as bad. the engine has to work harder (ie, burn more fuel) to push the air out.

99 times out of 100, a good free-flowing exhaust with a decent muffler will offer better performance and mileage than straight pipes.
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Old June 12th, 2008, 09:47 PM   #5
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I would look into a preformance muffler. Glass pack are the cheapest way to go if you are running a single exhaust get the longest one that you can get melows the tones out nice if you get one it then they get a little louderbut just cruising they are melow almost has quiet has a regular muffler. If you want the quieter muffler then invest in a quality preformance muffler. The other thing is rember just because it's louder just drive normal and your mileage will come up .
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Old June 12th, 2008, 10:33 PM   #6
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I would not run a straight pipe. I'd avoid the cherry bomb also. In the 80's stuff like that was cool, not so much anymore. Just spend a few bucks on a decent muffler.

Go find a decent ford forum and I bet you'll find out exactly what you need.
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Old June 12th, 2008, 11:47 PM   #7
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MRT makes a nice muffler that offers great performance with its straight through design. I'm currently running this muffler and very happy with the sound.
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Old June 13th, 2008, 09:18 AM   #8
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God... i hate when people talk about back pressure.... the only reason back pressure is important is if your egr system has a back pressure transducer valve. Otherwise exhaust velocity and scavenging is the important factors for deciding on piping size. I would say on a 302 2.5" piping is the way to go with some free flowing mufflers.
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Old June 13th, 2008, 09:29 AM   #9
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Quote:
Originally Posted by Fatty Matty View Post
I would not run a straight pipe. I'd avoid the cherry bomb also. In the 80's stuff like that was cool, not so much anymore. Just spend a few bucks on a decent muffler.

Go find a decent ford forum and I bet you'll find out exactly what you need.
aw so purple hornies bolted to the collector arent cool anymore?
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Old June 14th, 2008, 02:14 PM   #10
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thanks guys... prolly goign to go for a better muffler for now
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