Corsa Exhaust

[david borla]

Are the Borla results fiction?

We'd never survive as long as we have if we posted bogus results. Furthermore, icons like Shelby and even Ford themselves would not be using Borla as their exclusive performance exhaust supplier if we posted bogus results.

We're not pulling a rabbit out of our hat either and we've gone into great detail on this forum with graphs showing the results along with pictures, drawings and editorial demonstrating the differences between Borla and stock, explaining how and why we were able to accomplish these gains.

Also, it's not like we're talking about gains that are not believable. The gains we posted are modest and well within the realm of possibility. We never post the best runs, rather we post the run that seems to be most consistent out of dozens performed over different conditions. You should see what the best run looks like.

db

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[CSL]

Agree, and I appreciate all the tech you provided in your thread....hence the sarcasm in my post about the results of your system.

 

[nastang87xx]

We'd never survive as long as we have if we posted bogus results. Furthermore, icons like Shelby and even Ford themselves would not be using Borla as their exclusive performance exhaust supplier if we posted bogus results.

We're not pulling a rabbit out of our hat either and we've gone into great detail on this forum with graphs showing the results along with pictures, drawings and editorial demonstrating the differences between Borla and stock, explaining how and why we were able to accomplish these gains.

Also, it's not like we're talking about gains that are not believable. The gains we posted are modest and well within the realm of possibility. We never post the best runs, rather we post the run that seems to be most consistent out of dozens performed over different conditions. You should see what the best run looks like.

db

David, are you able to tell us what the primary restriction is? Cats? X pipe? Mufflers?

 

[krt22]

David, are you able to tell us what the primary restriction is? Cats? X pipe? Mufflers?

I cant speak for him but I can see restrictions in both the x-pipe and the mufflers. The x-piple clearly necks to 2.25" on both ends and the opening to the mufflers where the valves are is not a smooth transition at all. Im guessing the "blatty" sound when removing the resonators is partly to do with the mufflers themselves and this transition. Its as if the flow rate builds up just prior to peak torque causing it to transition to turbulent flow and then smooths out and goes back to laminar.

 

[nastang87xx]

I cant speak for him but I can see restrictions in both the x-pipe and the mufflers. The x-piple clearly necks to 2.25" on both ends and the opening to the mufflers where the valves are is not a smooth transition at all.

And just looking, I can certainly tell there are parts of the exhaust that are not the greatest design. I think I need to make it clear too that the reason why I'm skeptical about gains is that know just because a system CAN flow said CFM doesn't mean the engine is taking advantage of all said CFM. Now I know Borla has given a ton of info and in terms of FLOW CAPABILITY, I totally believe it. I had maybe eight different exhaust configurations on my '11 GT NOT including headers + catback and not a single alteration from the cats back did a thing to improve power and torque. The only exhaust modification that uncorked anything was from my long tube system.

Also, none of what we have discussed changes the fact that I still want the Corsa X pipe regardless of power or not.

Im guessing the "blatty" sound when removing the resonators is partly to do with the mufflers themselves and this transition.

Well indeed but I also think the resonators are just directly affecting that in that they're sucking up some of that sound energy in that frequency. Generally, resonators tend to do that. Are the factory resonators packed or reflection only?

 

[krt22]

From what I can tell there is some packing, no louvers. The harmonics of the system as a whole could have been changed by their elimination and they could certainly be damping some of the sound energy in those RPM regions. But either way the fact that the sound is being generated in the first place lends me to believe there is some inherent flow disturbance in the system, but yeah hard to tell if this will have enough effect on the system as a whole to impact flow through the heads

 

[Epiphany]

The power increases was not due to lack of resonators but due to wheel weight rotational mass difference between the R and the Base wheels.

Wheel weight may impact acceleration, no doubt. With respect to the power rating of both the R and the non-R, it was mentioned a couple of times during Pericak interviews on the matter that the R model, with its resonator delete, produced slightly more, but that Ford didn't bother to recertify on that basis. Here's one snippet I could find...

I heard a different assessment.

As above?

 

[CSL]

As above?

Yes, thanks. :cheers:

I didn't have the time to go searching for it. :search:

 

[Zitrosounds]

Wheel weight may impact acceleration, no doubt. With respect to the power rating of both the R and the non-R, it was mentioned a couple of times during Pericak interviews on the matter that the R model, with its resonator delete, produced slightly more, but that Ford didn't bother to recertify on that basis. Here's one snippet I could find...








As above?

Cool! but where's the quote? Seems the rest of the article quotes ford reps just fine except for when it doesn't?

 

[Zitrosounds]

Although I will agree that losing the resonators will free flow and thus make a "teensy bit more horsepower".

 

[Zitrosounds]

And just looking, I can certainly tell there are parts of the exhaust that are not the greatest design. I think I need to make it clear too that the reason why I'm skeptical about gains is that know just because a system CAN flow said CFM doesn't mean the engine is taking advantage of all said CFM. Now I know Borla has given a ton of info and in terms of FLOW CAPABILITY, I totally believe it. I had maybe eight different exhaust configurations on my '11 GT NOT including headers + catback and not a single alteration from the cats back did a thing to improve power and torque. The only exhaust modification that uncorked anything was from my long tube system.

Also, none of what we have discussed changes the fact that I still want the Corsa X pipe regardless of power or not.



Well indeed but I also think the resonators are just directly affecting that in that they're sucking up some of that sound energy in that frequency. Generally, resonators tend to do that. Are the factory resonators packed or reflection only?

I had gains when I installed BBK shorty's and cat delete pipe on my 12 GT and then exiting through Roush cans.

 

[Zitrosounds]

Wheel weight may impact acceleration, no doubt. With respect to the power rating of both the R and the non-R, it was mentioned a couple of times during Pericak interviews on the matter that the R model, with its resonator delete, produced slightly more, but that Ford didn't bother to recertify on that basis. Here's one snippet I could find...

As above?

"Oh, but before you go telling your friends that the GT350R’s engine is more powerful: Don’t. A chassis dyno measures how quickly a car is able to accelerate a fixed mass and then calculates the engine’s output based on that rate of acceleration."
http://www.motortrend.com/news/does-the-shelby-gt350r-make-more-power-than-the-regular-gt350-wvideo/

 

[Epiphany]

Cool! but where's the quote? Seems the rest of the article quotes ford reps just fine except for when it doesn't?

The question has been posed to him on numerous occasions. Suffice it to say he avoided quoting official numbers with respect to any difference in engine output as a result of different exhaust systems. But the point was made.

"Oh, but before you go telling your friends that the GT350R’s engine is more powerful: Don’t. A chassis dyno measures how quickly a car is able to accelerate a fixed mass and then calculates the engine’s output based on that rate of acceleration."
http://www.motortrend.com/news/does-the-shelby-gt350r-make-more-power-than-the-regular-gt350-wvideo/

You are talking about acceleration and calculations based therein. I was talking about engine power, or in essence the engine and each exhaust system. The wheels, be they aluminum or CF, along with changes in tire height (be they 30 or 35 series) introduce yet another variable when trying to compute power numbers via a chasis dyno.

 

[Zitrosounds]

The question has been posed to him on numerous occasions. Suffice it to say he avoided quoting official numbers with respect to any difference in engine output as a result of different exhaust systems. But the point was made.



You are talking about acceleration and calculations based therein. I was talking about engine power, or in essence the engine and each exhaust system. The wheels, be they aluminum or CF, along with changes in tire height (be they 30 or 35 series) introduce yet another variable when trying to compute power numbers via a chasis dyno.

Either way the difference is insignificant and honestly not even worth mentioning.

 

[Lisa@Borla]

As much as I love Borla, I'm hard pressed to believe ANY power gains from a catback alone from any manufacturer. Flow capability is one thing. Actual power gains? Completely different. Yes manufacturers give dyno numbers but we also have no idea what conditions those were under and how many runs were done to produce those results with what deviations.

As David stated before, "We'd never survive as long as we have if we posted bogus results." That said, we always encourage others to do their own testing and share their results. We are confident in the power and sound enhancements that we were able to make, but your experiences should be shared as well. We are always open to feedback.

David, are you able to tell us what the primary restriction is? Cats? X pipe? Mufflers?

I've attached our R&D photos and Testing Results below.

The OEM x-pipe is really not a true x-pipe but rather a stamped piece, and that's not ideal for flow. The Borla is a true x-pipe that maximizes flow and maintains the 2.75" diameter throughout.
The Borla muffler also outflows the stock muffler with the valve open, and closed. Reason: [FONT=&amp]The major area of restriction in the stock muffler looks to be the tailpipe portion where it has a nominal 2.50” valve that has ridges that restrict to 2.25”. There are also complex tight radius bends in the tube. In contrast, the Borla tailpipe [/FONT][FONT=&amp][FONT=&amp]is nearly straight and [/FONT]uses a valve without ridges and therefore no restrictions.[/FONT]

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