Borla exhaust is out? anyone try it? - Page 7 - Ford Mustang Forum
 
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Originally Posted by THUNDER74 View Post
are the Borla catback systems 3" tubin?

any loss of back presure by goin to 3" from 2.5"?

Does anybody have an answer for the above? I considering the full cat-back system but now wondering about the above.

Also, anyone with the Borla exhaust installed that can post a side view picture of the exhaust tips showing how much they stick out? From one of the videos posted here it almost looks like they don't go past the inner ridges next to the tips on the rear valance but the shot is not quite from a side angle.


2011 Sterling Gray GT Premium, 401a, Manual, Brembo and 3.73 rear.
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Quote:
Originally Posted by THUNDER74 View Post
are the Borla catback systems 3" tubin?

any loss of back presure by goin to 3" from 2.5"?

It's common to think that a larger pipe will reduce backpressure because everyone knows that a larger pipe flows more air. However, in many cases this is a false assumption.

When we speak about exhaust pipe diameters (for bikes, cars trucks etc.) I would say 90% of the discussions involve diameters between 1.25" and 3" and it's very hard to imagine how fluid dynamics are affected by such small diameter changes. However, if we use an extreme example it becomes much easier to visualize and understand. Imagine a constant and consistent stream of water flowing through a garden hose. The water flows through the hose, moving away from the source and out the other end of the hose. Now imagine taking that same constant and consistent flow of water but this time move it through one of those 5' concrete sewage pipes. What will happen? The water will pool up and build upon itself and take much longer to make it out the end of the pipe. As you can clearly see from this example, a larger pipe will not always outflow a smaller pipe, it depends on the amount of air (or in this case water) being moved through the pipe. Another real world example would be putting your thumb over the end of a hose that isn't flowing much water. You decrease the diameter with your thumb and the water exits more quickly.
So, you can actually create backpressure with a larger pipe because you slow down the exhaust gas velocity, making it take longer to exit the tailpipe which inhibits the efficiency of the engine.
Another contributing factor to this phenomenon is friction. Larger diameter pipes have more surface area which creates more friction and friction slows down the exhaust gasses even further.
Pipes that are the wrong size, too big or too small, inhibit the efficiency of the engine. Bigger is not always better.
The one big caveat to this is that at high RPM, when the engine is pushing a lot of air, larger pipes can (not always) create more high end horsepower. However, it's not worth losing all that torque down low to pick up a few HP up top.
Another aspect of exhaust velocity is heat. Exhaust gasses cool very quickly as they move through an exhaust system and cooler gasses have a slower velocity than hot gasses do. If your pipes are too big this just exacerbates the efficiency issue. In fact, many competition race car exhaust systems become smaller in diameter as they get further from the engine (heat source) to maintain a high exhaust velocity.
There's so much more but let's start with this for now.....

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scparts, thank you for the discount on the Borla Sport catbacks, much appreciated!


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Quote:
Originally Posted by david borla View Post
It's common to think that a larger pipe will reduce backpressure because everyone knows that a larger pipe flows more air. However, in many cases this is a false assumption.

When we speak about exhaust pipe diameters (for bikes, cars trucks etc.) I would say 90% of the discussions involve diameters between 1.25" and 3" and it's very hard to imagine how fluid dynamics are affected by such small diameter changes. However, if we use an extreme example it becomes much easier to visualize and understand. Imagine a constant and consistent stream of water flowing through a garden hose. The water flows through the hose, moving away from the source and out the other end of the hose. Now imagine taking that same constant and consistent flow of water but this time move it through one of those 5' concrete sewage pipes. What will happen? The water will pool up and build upon itself and take much longer to make it out the end of the pipe. As you can clearly see from this example, a larger pipe will not always outflow a smaller pipe, it depends on the amount of air (or in this case water) being moved through the pipe. Another real world example would be putting your thumb over the end of a hose that isn't flowing much water. You decrease the diameter with your thumb and the water exits more quickly.
So, you can actually create backpressure with a larger pipe because you slow down the exhaust gas velocity, making it take longer to exit the tailpipe which inhibits the efficiency of the engine.
Another contributing factor to this phenomenon is friction. Larger diameter pipes have more surface area which creates more friction and friction slows down the exhaust gasses even further.
Pipes that are the wrong size, too big or too small, inhibit the efficiency of the engine. Bigger is not always better.
The one big caveat to this is that at high RPM, when the engine is pushing a lot of air, larger pipes can (not always) create more high end horsepower. However, it's not worth losing all that torque down low to pick up a few HP up top.
Another aspect of exhaust velocity is heat. Exhaust gasses cool very quickly as they move through an exhaust system and cooler gasses have a slower velocity than hot gasses do. If your pipes are too big this just exacerbates the efficiency issue. In fact, many competition race car exhaust systems become smaller in diameter as they get further from the engine (heat source) to maintain a high exhaust velocity.
There's so much more but let's start with this for now.....

And Thats why we like having you so involved on the group, Thanks!

Too many car's, not enough time.
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I am VERY interested in the ATAK setup. Will the cat-back setup give me some torque or hp gain? I imagine the axle-back would give very minimal gains if at all. I might go with the full setup if that will help get more gains out of an intake and tune later on.
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Quote:
Originally Posted by scparts View Post
Did the dyno today....video and results coming later today....
any update on the dyno vid?

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S type cat backs sitting in the garage. Hoping to get time this weekend to attempt the install without a lift. Fingers crossed as I've heard it is not easy.
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I just installed my "S" type and it took about an hour, the hangers are somewhat a PIA to work with but otherwise not that bad. If you did not order new brackets then you will have to cut the originals off the original muffler.
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Well, how do you like it? How is the sound? Did you install the cat-back system or axle-back?

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I did the axle backs and so far i am loving the car even more. i had originally ordered the roush axle-backs but when i found out that they only warranty them for 90 days i cancelled my order. The Borla S type has a nice throaty sound under acceleration and is still quiet when idling. I now find I turn down the radio just to hear the roar while driving.

I think I am addicted
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would love to see dyno results if anyone has them. Just read on crutchfield that the exhaust could increase HP and torque 7-10%.

Borla Exhaust System 11790 Fits 2011-up Ford Mustang GT, rear section only (with 5.0-liter engine) — single tips, split rear exit at Crutchfield.com

DELIVERED: 2011 Mustang GT 5.0 Premium, Kona Blue, Black Leather Interior, HIDs, 3.73, Security, 19 inch Painted Aluminum Rims - Roush: Front Valance, Front/Side Splitters

Washington State 5.0 Owner's Thread:

allfordmustangs.com/forums/west-coast/240489-official-washington-state-5-0-owners-thread.html
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Install of cat back s type complete! Can be done on jack stands, but had to undo rear shocks and lower axle to get pipes out. Quality and fit are excellent. Only complaint is clamps for h pipe were too small and impossible to get on. Got some cheapy ones at napa, will have to order better quality ones to replace. Anyone who is considering cat backs and rear suspension upgrades should do at the same time. Sound is outstanding and exactly what I was looking for. Maybe a touch louder than what I expected, but I'm sure I'll get used to it. Question for David, if down the road I opt to switch out the mufflers only to one of your other options, I assume the over axle and h pipe are the same for all three?
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I am planning to do a Borla S-Type on my 11' 5.0 however I am curious if I can do it in pieces and if so what all pieces does it consist of? Im thinking the catback consists of axle backs, x-pipe, and mid section pipes right? so can I do Axle backs now and then later get the mid sections and x-pipe or are they not available seperate..

thanks!

Last edited by FYREANT; 09-19-2010 at 04:27 PM. Reason: grammer correction
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Any dyno results yet?

I'm especially interested in Bone Stock vs. nothing but a cat - back (i.e that cat back was the only change)

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Quote:
Originally Posted by Dr. Spencer View Post
Any dyno results yet?

I'm especially interested in Bone Stock vs. nothing but a cat - back (i.e that cat back was the only change)

Why are those numbers so low? Time to research DynoDynamics vs. ??? A graph would be nice too.

YouTube - 2011 Mustang GT Borla vs Stock Dyno


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