[Kracka]

2.25" primary cats? I don't buy that, all 4 cats are 3.0" on the C7.

[TSloper]

I was under my car this morning removing my WB sensor. The inlet pipe is smaller than the outlet pipe on the cats. Oldman is correct.

[Kracka]

Ouch. That surprises me.

[00 Trans Ram]

Originally Posted by cellsafemode

The crushed pipes exist for one of three reasons (or all of them).

Clearance
Tuning the sound
Tuning the backpressure

Regardless of what the reasoning was, it's not going to improve performance by removing it. Even with serious "restrictions", exhaust is still hot and low density and it wont make any measurable effect on performance.
This has been posted before but still good to watch.

Good video. But, I'm a tad skeptical. It's fairly common for a motor to get better on a dyno as it gets run more (obviously, to a certain degree - it'll flatten out at some point). I'd love to know what happened if they removed those dented ones and put a new set back on for the last run.

In other words, did the engine get better as the exhaust got worse, thereby cancelling each other out? Or does it really "not matter".

I do know that when I ran my little KT100 kart motor, tiny exhaust changes had a BIG effect (tube length would move peak HP up and down the RPM range, sizes would increase peak yet lower "under curve" HP or vice versa). Now, comparing a 1-cyl, 2-stroke, 100cc motor to something like the LT1 is comparing apples-to-dinosaurs, but air movement is air movement.

[Tech@Flowmaster]

Originally Posted by oldman

you know what is intresting, the hooker axle back that eliminates the crush bend is stating +15HP, while the flowmaster axle back that keeps the crush bend is stating ZERO HP gain. IMO, I don't think the crush is an issue. Hooker can be ordered with midpipes either stock or to fit their headers that completely eliminated the crush.

I apologize if we hadn't yet posted dyno results for our 2016 Camaro SS systems. All of Flowmaster’s exhaust systems are designed with performance in mind. As such, we do not release an exhaust system for sale until we see an increase in performance over stock. The American Thunder Axle-back and Outlaw Axle-back for the 2016 Camaro SS are no exception. We have seen an increase in performance on both of these systems, as demonstrated by our dyno sheets.

American Thunder Axle-back, part #817744:


Outlaw Axle-back, part #817745:

[oldman]

that some huge gains stp ??? strange HP and I know all dynos are different but 340 stock ??

[SShift]

I dont see any loss of power with the crushed pipes. Look at the autos with the valves. They reduce down to 2.5" and have a butterfly plate. So this crush pipe isnt a big deal.

[EFI]

Clearance
Tuning the sound
Tuning the backpressure

In this case it was because of clearance. Ain't no billion dollar manufacturer *tuning* their exhaust sound by crushing some pipe lol.

I'm sure GM spent a good chunk of time tuning the sound of the exhaust with the use of mufflers and resonators, but the crushing of the pipes was purely for clearance around the components. Anyone else that thinks they got power and/or sound changes from replacing those should pick up a dictionary and lookup the definition for "placebo effect".

[Kracka]

Originally Posted by Nicul15

if they look at the entire mid pipe as a resonator then it would make sense to create a pressure cavity.

read about Helmholtz Resonance.

Makes sense. The factory (and some aftermarket) exhausts for the Honda S2000 had a resonator for that specifically.

[camaro1&6]

The crush pipe definitely is choking the exhaust so is the AFM VALVE

[camaro1&6]

Anytime you disrupt the airflow your loosing power , that's why race cars run open headers , this is a fact car ran 7.71 1/8 mile full exhaust , open headers 7.49 big block , restricted = lose power

[camaro1&6]

Originally Posted by TSloper

That crushed area is so far back the exhaust gases have cooled significantly. It just isn't going to make a difference on a mildly modded engine. Take a look at the pipes going from the manifolds to the primary cats. Beauties they ain't.

mildly modded??? Have you ever looked at the specs on the LT1??, I REALLY beg to differ with you , I have done many different exhaust configurations on gas and diesel engines and the most power is Always made with the least amount of restricted flow. Those crush down pipes are causing a loss of power , I don't care if it's only 1 HP it's a loss . Mildly modded wow ! read the specs on the camshaft, compression ratio, the material used for the Pistons The LT1 is a true performance motor, makes more advertised HP than the legendary Big Block LS6 , don't mean to jack the thread but I'm amazed sometimes when I read these things .

[Shaunsmb]

Bottom line its my car. I didn't like the crushed pipe on there so I changed it. I never said it gained hp from doing this because I don't know. I do know It changed the sound of the car. It doesn't pop while driving or revving like it did. To me I can hear the xpipe better. If it cost me 1 or 10 hp changing the pipes so be it. I'm happy with it.

[camaro1&6]

Lmao! unreal