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Exhaust Make Any Difference?

RumPunch

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Does changing up the factory exhaust make much/any/noticable difference in ANY difference in a 2.9? Be it fuel mileage, low end/high end, response? Mine is functional but not the prettiest. Not sure if I'm at the point to be changing it or not but hey why not start the conversation. Thinking of 2.25" single high flow cat remount 02's and a 60 series muffler. Don't want V6 noise at all just didn't know if I'm replacing it and opened the flow up a little would there be anything noticable. Thanks!
 


RonD

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No, not for performance, but sound can get deeper with larger diameter pipe

Factory exhaust manifold is tuned for mid-range power, thats where changes to the exhaust system can matter, after the manifold as long as you don't put on smaller diameter pipes performance won't be effected either way



Exhaust manifolds(Headers) use exhaust Velocity to Scavenge power, its an ART FORM, these are just the general principles
One thing that has been known since the invention of "pipes" for fluids or air, is that if you run fluid or air at a velocity from a smaller pipe into a larger pipe you can create a pressure difference in the larger pipe, a pressure drop
On a V6 the 3 smaller exhaust port pipes on one bank create a Velocity of air flow to the Collector(the larger pipe at the end)
The diameter and length of the smaller pipes can be "tuned" to the size of the larger pipe
Tuning is when the Velocity creates the lowest pressure drop in the larger pipe, and this pressure drops SUCKS exhaust out when an exhaust valve opens, and this leaves more power at the crank because it didn't have to PUSH exhaust out, so you have FREE Scavenged power added
It doesn't create more power it leaves more of the power already created on the crank, for the rear wheels, lol

And you can tune an exhaust manifold for low range power, mid range power or high range power, but only 1 range
Most put on low range power headers for better "off the line" power
High range are pretty much only used in Racing where high RPMs are used full time

The MYTH of back pressure comes from Factory exhaust manifolds
Car makers have been using Scavenged power since the 1930's if not earlier
People would pull off factory exhaust manifolds and put on "free flow" exhaust, larger header pipes so it can get rid of the exhaust faster
Then go for a drive
"WTF!!!!, I LOST POWER..............WTF!!!???"
"This engine must need BACK PRESSURE"
And the MYTH was born

No 4-stroke engine can run well with back pressure, 2-stroke yes, not 4-stroke, lol
They lost the added power from the Factory Scavenging exhaust, so their result was correct, but the reason was not

Even hotrods or dragsters with short straight pipe on each cylinder have a tuned diameter and length to gain some FREE extra scavenged power
 
Last edited:

rusty ol ranger

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my response wont be as pretty as rons but...

No. You wont notice anything but noise. Bigger manifolds help when you got more air going in (IE forced induction), but on an otherwise stock 2.9 you wont get anything, and may infact lose some power.
 

RumPunch

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Well thanks guys! In short sounds like I'll leave what's on their alone until it falls off😂. @RonD man you really know how to explain stuff and have such a vast knowledge thanks for the explanation!
 

Uncle Gump

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I know if my truck didn't have a new exhaust on it... I would be upgrading a bit for flow and tone. I wouldn't be expecting any gains really but it would have a better note and wouldn't degrade performance to a level you could feel in the seat of your pants.
 

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