Smashed exhaust section at tunnel cross over.

[Driver72]

Hey all, I know I've brought this up before, but it still kind of bothers me that the driver's side exhaust that meets up with the passenger side has the exhaust smashed down on my 2017 Sierra 6.2 liter.

I can't help but think it's choking up some power even though I've seen the video where they smash the headers all up and not much if at all power is lost.

 

But wondering if anybody has had that section cut out and replaced with a non smashed piece of exhaust pipe?

 

If so, how much did they charge?

 

Seems the pipe may need to be curved a bit as a straight cut out piece won't fully work and eliminate all the smashed part of the stock exhaust pipe section. I'm no expert in exhaust piping but not sure if it's easily possible for an exhaust shop to make a piece that's curved at the ends to meet up with the curved part of the stock exhaust before and after the smashed section, and then weld it in place.

 

Let me know your thoughts.

 

Thanks

[michigan2500hd]

I think I know what you mean. I was inspecting the under carriage and saw how flat the exhaust was on the cross over. ( Y pipe maybe) not sure if the internal size is kept the same. Of course I don't want it lower then the cross member either..idk

 

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[07Softail]

its fine...you wouldn't know the difference if it was reducing power.

 

 

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0ahUKEwiklcD7pLTTAhWJwFQKHYYJAQoQtwIIIzAA&url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DazPKIjxmmdU&usg=AFQjCNEq22dC2YPBR7LhrPEMGtugoVie-w&sig2=CYn1My-tVd1ei_ovvRKiAA

 

 

RT

[diyer2]

Get an estimate.

[Driver72]

its fine...you wouldn't know the difference if it was reducing power.

 

 

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0ahUKEwiklcD7pLTTAhWJwFQKHYYJAQoQtwIIIzAA&url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DazPKIjxmmdU&usg=AFQjCNEq22dC2YPBR7LhrPEMGtugoVie-w&sig2=CYn1My-tVd1ei_ovvRKiAA

 

 

RT

 

 

Yeah that's the video I saw before.

But I don't know about it.

It's like CAI videos and tests. One will show all these gains then another shows no gain.

I bet if someone took a stock car that was built and put it on a dyno then smashed all the headers or exhausts down, then dyno tested again, I'd be shocked if there wasn't power loss.

I mean people all the time put more free flowing exhausts on cars, trucks, etc. and see GAINS, how could you not see loses with smashing the exhaust pipes down restricting air flow??

[Driver72]

I think I know what you mean. I was inspecting the under carriage and saw how flat the exhaust was on the cross over. ( Y pipe maybe) not sure if the internal size is kept the same. Of course I don't want it lower then the cross member either..idk

 

Sent from my E6810 using Tapatalk

Yeah I wouldn't want it to stick down too low either, but looks like it could easily be 1-2 inches lower and not stick down lower than the cross member or frame.

[Rawyzf]

Get headers and Y pipe, problem solved.

 

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[Krusty]

Anyone running true duals and eliminating the squashed cross-over?

[07Softail]

 

 

Yeah that's the video I saw before.

But I don't know about it.

It's like CAI videos and tests. One will show all these gains then another shows no gain.

I bet if someone took a stock car that was built and put it on a dyno then smashed all the headers or exhausts down, then dyno tested again, I'd be shocked if there wasn't power loss.

I mean people all the time put more free flowing exhausts on cars, trucks, etc. and see GAINS, how could you not see loses with smashing the exhaust pipes down restricting air flow??

Right but a daily driver will never notice.

[SScarguy]

GM has been hooked on doing that to exhaust since the 98 Camaro. I don't know why they would do it on a truck, plenty of room under there.

[Driver72]

It's not really a case of whether I'd notice or not, it's just, why?

There's plenty of room under there to have a full exhaust pipe on the cross over, or if anything, if they are worried about clearance, have it step down to a 2" or 2.5" pipe. As it stands being as squashed as it is, it's almost like running a 1.25 inch diameter pipe through there.

No reason to choke up the exhaust that much. Even if it's only 5 hp more, why choke it up?

 

How can the left bank of cylinders breath as well as the right bank when the left banks exhaust has to go through that smashed section of pipe but the right side doesn't? We're talking about 3.1 liters pushing out air through an opening that's at best equivalent to 1.25" diameter pipe.

1.5 liter engines don't have such a small diameter exhaust pipe to push their exhaust through.

3.1 liters would be a huge 4 cylinder.

[Rawyzf]

Oval exhaust, check out Nascar.

[Krusty]

It's not really a case of whether I'd notice or not, it's just, why?

There's plenty of room under there to have a full exhaust pipe on the cross over, or if anything, if they are worried about clearance, have it step down to a 2" or 2.5" pipe. As it stands being as squashed as it is, it's almost like running a 1.25 inch diameter pipe through there.

No reason to choke up the exhaust that much. Even if it's only 5 hp more, why choke it up?

 

How can the left bank of cylinders breath as well as the right bank when the left banks exhaust has to go through that smashed section of pipe but the right side doesn't? We're talking about 3.1 liters pushing out air through an opening that's at best equivalent to 1.25" diameter pipe.

1.5 liter engines don't have such a small diameter exhaust pipe to push their exhaust through.

3.1 liters would be a huge 4 cylinder.

 

 

Maybe it works better than it looks - same CFM or more if it accelerates it like a Flowmaster muffler does.

 

Heck they say you get better gas mileage with the tailgate up - creating a vacuum behind the cab. I know my short box will push a pair of leather gloves left by the tailgate to the front.

 

 

 

[Driver72]

 

 

Maybe it works better than it looks - same CFM or more if it accelerates it like a Flowmaster muffler does.

 

Heck they say you get better gas mileage with the tailgate up - creating a vacuum behind the cab. I know my short box will push a pair of leather gloves left by the tailgate to the front.

 

 

 

 

 

 

Interesting video, maybe you are right.

I know I put a flat bed cover on my truck too, for obvious storing/locking reasons, but they say it's the best way to get the best aerodynamics out of the truck and improve gas mileage too.

Thanks for the video.

[Krusty]

 

 

 

Interesting video, maybe you are right.

I know I put a flat bed cover on my truck too, for obvious storing/locking reasons, but they say it's the best way to get the best aerodynamics out of the truck and improve gas mileage too.

Thanks for the video.

 

 

Gotta be something like the Venturi Effect going on and the other bank drawing it thru - I would bet the driver's side flows better than the passenger side. You have to know GM has studied/tested it to death........