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Will my MPG hurt if I install Exhaust?

bmartinez2086

By bmartinez2086
in Engines & Drivetrain

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Jacoby Enthusiast

Jacoby

Posted
Posted
10 minutes ago, bmartinez2086 said:

What cant a person ask a question without getting judged? I just want to make sure I am right about what I already know. Apparently I am wrong because I always thought a exhaust decreases your MPG. My Camaro I do Autocross in has a X pipe Borla exhaust system and at the tank seems like I get more power but my MPG hurts. Use only use 2 tanks per race. Now I use 2 1/2 to 3 tanks.

Not judging.  Im just dumbfounded by the lack of common sense.  Will a cat back exhaust hurt my mpg's?  Oh yeah Ive only ever driven Camaros and Corvettes by the way.  Not sure what that has to do with anything???

Then you go off and some how try to make the ridiculous comparison of your trucks mpgs to a race car that you autocross.  An exhaust system isn't causing your car to use an entire tank of gas more than before, its your right foot.  Or hell maybe it is the cause, maybe the tune on your car is shit because the addition of the exhaust.  Maybe you didn't install the exhaust right and have an exhaust leak somewhere. WHO KNOWS!!!!!!!  Gas mileage averages are scientific and can change from day to day with the weather, amount of traffic, destination routes, added weight being carried, driving habits etc etc etc.

 

It all boils down to your right foot.  Like everyone else has said chances are your mileage may go down and that's simply because everyone who puts an aftermarket exhaust on likes the sound of it so they get into the throttle more than before. 

 

Stay out of the gas and your mileage can increase by quite a bit.  Get on the gas more and watch it go down.  Simple as that.  A muffler isn't going to change any of that

SILVER SLED Senior Enthusiast

SILVER SLED

Posted
Posted

Well technically, the flapper valve is there to help with fuel economy in 4cy mode.  So technically it may hurt cruising fuel mileage.  I'm not saying I agree with it, but just sayin...

KARNUT Senior Enthusiast

KARNUT

Posted
Posted
Well technically, the flapper valve is there to help with fuel economy in 4cy mode.  So technically it may hurt cruising fuel mileage.  I'm not saying I agree with it, but just sayin...

I thought it was there to baffle the offensive sound it makes in V4.


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SILVER SLED Senior Enthusiast

SILVER SLED

Posted
Posted
1 minute ago, KARNUT said:


I thought it was there to baffle the offensive sound it makes in V4.


Sent from my iPhone using Tapatalk

Not saying it doesn't do that, but according to GM that is an emissions device.  Supposedly to increase back pressure in certain conditions helping mileage, which is a whole nother argument.

bmartinez2086 Enthusiast

bmartinez2086

Posted
  • Author
Posted
13 minutes ago, SILVER SLED said:

Not saying it doesn't do that, but according to GM that is an emissions device.  Supposedly to increase back pressure in certain conditions helping mileage, which is a whole nother argument.

Yeah that's my biggest concern because even on stock exhaust on Camaros when you cruise at highway speed of 70MPH when it kicks down to V4 mode the flaps close even in track mode. I pulled the fuse and now with the same highway speed and same run it wasted more gas. So using that logic I was wondering if it will affect my MPG because of the flapper. I mean it is there for a reason right? Removing it will hurt my MPG some is my thought because I no longer have the flap.

bmartinez2086 Enthusiast

bmartinez2086

Posted
  • Author
Posted
25 minutes ago, Jacoby said:

Not judging.  Im just dumbfounded by the lack of common sense.  Will a cat back exhaust hurt my mpg's?  Oh yeah Ive only ever driven Camaros and Corvettes by the way.  Not sure what that has to do with anything???

Then you go off and some how try to make the ridiculous comparison of your trucks mpgs to a race car that you autocross.  An exhaust system isn't causing your car to use an entire tank of gas more than before, its your right foot.  Or hell maybe it is the cause, maybe the tune on your car is shit because the addition of the exhaust.  Maybe you didn't install the exhaust right and have an exhaust leak somewhere. WHO KNOWS!!!!!!!  Gas mileage averages are scientific and can change from day to day with the weather, amount of traffic, destination routes, added weight being carried, driving habits etc etc etc.

 

It all boils down to your right foot.  Like everyone else has said chances are your mileage may go down and that's simply because everyone who puts an aftermarket exhaust on likes the sound of it so they get into the throttle more than before. 

 

Stay out of the gas and your mileage can increase by quite a bit.  Get on the gas more and watch it go down.  Simple as that.  A muffler isn't going to change any of that

I get what you are saying but I have no time on the Camaro. Plus after research I found out the the car flowed more air and as a result of more low end torque and better throttle response was the reason it wasted more gas. But my other issue is the flap that comes with the stock truck exhaust. Because when I had stock exhaust on the Camaro the flap will close at 70MPH when it's in V4 mode. I used 1/2 tank Vegas. I pulled the fuse and the flaps stayed open the whole way in another run to Vegas but this time it used 1/4 tank more. Using that experience with the whole flaps thing. I wonder if the back pressure the flap creates when the truck is in V4 mode if its removed will it hurt the MPG. I does hurt it in my Camaro and I havent test my dad's Cadillac escalade which also has the same flap. Will it hurt the truck. I dont go wild out in the truck I dont dennard starts and I never go full throttle in the truck. I drive my truck like a grandma so my foot ain't a issue.

SILVER SLED Senior Enthusiast

SILVER SLED

Posted
Posted
3 minutes ago, bmartinez2086 said:

Yeah that's my biggest concern because even on stock exhaust on Camaros when you cruise at highway speed of 70MPH when it kicks down to V4 mode the flaps close even in track mode. I pulled the fuse and now with the same highway speed and same run it wasted more gas. So using that logic I was wondering if it will affect my MPG because of the flapper. I mean it is there for a reason right? Removing it will hurt my MPG some is my thought because I no longer have the flap.

Well that's what GM is saying.  Honestly if you just want to hear the motor, just swap to a free flowing muffler or eliminate the muffler, but in either case leave the flapper on. 

SILVER SLED Senior Enthusiast

SILVER SLED

Posted
Posted

You may want to consider an aftermarket intake tube.  I have one, and I modified the stock intake box by opening up the fender side of the box.  It is fairly loud, like interior trim rattling loud at times.  I of course notice it more when pulling a trailer. 

bmartinez2086 Enthusiast

bmartinez2086

Posted
  • Author
Posted
1 minute ago, SILVER SLED said:

Well that's what GM is saying.  Honestly if you just want to hear the motor, just swap to a free flowing muffler or eliminate the muffler, but in either case leave the flapper on. 

Yeah I just need more engine noise not for pleasure but for when I'm going up steep grades fully loaded I like to control my gears my self so I like to hear the engine so I have an idea if I need to downshift or upshift i dont want to blow up the engine up know. But i will have to look into that because I know it has a flap but I dont know where it is. I thought removing the muffler it will also remove the flap like it did in the Camaro.

bmartinez2086 Enthusiast

bmartinez2086

Posted
  • Author
Posted
1 minute ago, SILVER SLED said:

You may want to consider an aftermarket intake tube.  I have one, and I modified the stock intake box by opening up the fender side of the box.  It is fairly loud, like interior trim rattling loud at times.  I of course notice it more when pulling a trailer. 

You got a picture of what you did? I might just go that route instead of putting a new exhaust.

SILVER SLED Senior Enthusiast

SILVER SLED

Posted
Posted
1 minute ago, bmartinez2086 said:

Yeah I just need more engine noise not for pleasure but for when I'm going up steep grades fully loaded I like to control my gears my self so I like to hear the engine so I have an idea if I need to downshift or upshift i dont want to blow up the engine up know. But i will have to look into that because I know it has a flap but I dont know where it is. I thought removing the muffler it will also remove the flap like it did in the Camaro.

Flap is in exhaust line, not in the muffler.  Most are after the muffler,  but I thought I saw somebody say theres was in front of muffler, either way though its not in the muffler.

SILVER SLED Senior Enthusiast

SILVER SLED

Posted
Posted
2 minutes ago, bmartinez2086 said:

You got a picture of what you did? I might just go that route instead of putting a new exhaust.

Would you mind pm'ing your cell #?  It's a lot easier for this low tech guy

bmartinez2086 Enthusiast

bmartinez2086

Posted
  • Author
Posted
1 minute ago, SILVER SLED said:

Flap is in exhaust line, not in the muffler.  Most are after the muffler,  but I thought I saw somebody say theres was in front of muffler, either way though its not in the muffler.

My dad's Escalade has a manual latch where you can turn the flap open and close and it sits roughly at the edge of the exit side of the muffler. There was no way on his truck the keep the flap and remove the muffler.

SILVER SLED Senior Enthusiast

SILVER SLED

Posted
Posted
34 minutes ago, bmartinez2086 said:

My dad's Escalade has a manual latch where you can turn the flap open and close and it sits roughly at the edge of the exit side of the muffler. There was no way on his truck the keep the flap and remove the muffler.

How far away is the flap from the muffler?  I've always seen them at least a few inches from the muffler.

 

I meant on the newer trucks.  Sorry

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