This is topic back pressure question.. in forum Tech Talk at Northern California Ford Owners  .


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Posted by gt from 650 (Member # 6717) on :
 
I saw an '07 gt last night. He deleted the mufflers. Just straight pipes after the axle. I'm assuming he had factory cats.

So top end he had more power than me??
what do you guys think? mufflers are not necessary? [Confused]
 
Posted by jaejae (Member # 7958) on :
 
IT DEPENDS WEITHER U HAVE A POLICE DEPARTMENT THAT ACT LIKE FAGETS...THERE NOT NECCESARY N REMOVING THEM MITE FREE UP SUM HORSEPOWER ISS JUS GON BE LOUDER...IT SOUNDS NICE ON SUM CAR N SUMTIMES IT DOESNT...
 
Posted by gt from 650 (Member # 6717) on :
 
I thought w/o proper back pressure. The car might lose power?

In reality on the top end it had more power. I think.
 
Posted by Thirteen Twenty (Member # 7961) on :
 
If he has factory cats then he has plenty of back pressure. I run my truck with just a cat and no muffler but the cats quiet it up so much that mufflers aren't necessary. Usually with cats the only thing a performance muffler does is change the tone deeper, not much in the way of quieting an exhaust. Not so much a matter of proper back pressure as just having some backpressure, the intention of mufflers and high flow cats is that they make power by reducing backpressure, if they were just louder but retained the factory backpressure then they would have no effect on HP.
 
Posted by MAXPSI (Member # 8093) on :
 
On the S197 version of the Mustang, people who removed the mufflers actually would lose some HP for whatever reason. Ford did a great job with the design of that particular muffler. All the after market mufflers are used to gain sound qualities mostly. The biggest gains with aftermarkets were 3-4 HP and some even lost HP.
 
Posted by F8LSN8K (Member # 7080) on :
 
from what i know its, less restriction, more hp. more restriction, more torque.....there are exceptions to both, but thats usually how it goes
 
Posted by gt from 650 (Member # 6717) on :
 
lots of info. thanks guys. I was just curious.

I had flowmasters on mine. Now I'm running magna flows. Then I ran into this guy w/o mufflers. I was kinda trippin'.
 
Posted by BUKSING (Member # 6594) on :
 
check out slp loudmouths for s197's..they're basically muffler deletes.... it replaces the stock muffler with just straight pipe and tips.

ive heard an 06 gt w/o mufflers...didnt sound clean at all.
 
Posted by gt from 650 (Member # 6717) on :
 
yeah it sounded kinda weird. but it definitely got my attention.
 
Posted by porchstang (Member # 7937) on :
 
Mufflers tend to help more with lower RPM ie: torque. He passed you on the top end because since he didn't have any mufflers he was able to flow the exhaust better and there for produced more power up top. Back pressure has a lot to do with were you torque band begins and ends as well has horsepower.
 
Posted by gt from 650 (Member # 6717) on :
 
didn't pass me. til I hit the brakes.
 
Posted by SlowBird (Member # 8106) on :
 
Back pressure is just an old myth. No car needs back pressure to make more torque or more horsepower. What a car needs is a certain amount of exhaust velocity to enhance the scavenging effect and thus make more power. This is the very reason why crush bent pipes hurt performance so much over mandrel bent pipes. Because the compression bends kill exhaust velocity, it also loses some horsepower. Obviously in addition to losing velocity, the crush bends also create more restriction, which of course causes a loss in power as well...
 




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