Weird noise coming from my exhaust. Berk HFC and Magnaflow
03-19-2009, 06:15 PM
#107
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03-19-2009, 09:59 PM
#108
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Hmmm after driving around more i can say that when letting the revs drop i still get a weird sound, but it's not as loud, but i don't have anything on acceleration. here i wrote something on driver
http://g35driver.com/forums/tech-07-...ml#post4033588
http://g35driver.com/forums/tech-07-...ml#post4033588
06-29-2011, 12:17 PM
#109
C2, I just asked the question on another forum and was told an answer I never thought of before but makes perfect sense....
The hiss noise we're hearing on our cars is due to the excess gases flowing through the exhaust. When we add, Test Pipes, High Flow Cats and Cat Delete Pipes to our exhaust systems, we're placing our cars in a situation where a larger volume of air mass is now flowing through the exhaust upon acceleration and deceleration.
My hypothesis:
Under factory emissions regulation, a certain % of air is designed to flow from the motor's exhaust manifold, through the stock Catalytic Converter, burned, cleaned and forced out the Y Pipe, Mid pipe and out the mufflers into the air you and I breathe.
Since G35, 350z, G37s etc are Low Emission Vehicles, the stock cats have a major responsibility of not only burning off harmful carbons, but also controlling excess air mass that could potentially contain harmful carbons which could become potentially released into the atmosphere contributing to global pollution.
This is the reason why stock Cats are ALWAYS restrictive towards performance applications because as we all know the more air you can force into /out of an engine the better it performs.
What does this have to do with us?
Simple:
You, I and everyone who's decided we wanted to upgrade Cats to Higher Flowing Cats, Test Pipes, or Cat Delete Pipes chose to forgo the OEM's recommendation of restricted air mass aka our stock Catalytic Converter.
As a result, we experience more air flowing through our exhaust system and a slight boost in performance due to our now less restrictive exhaust system.
As a result, of the excess air mass that now flows through our Hi Flow Cats/Test Pipes and Cat Delete Pipes, we're hearing the result of that process.
Excess air mass = more gases flowing through our exhaust system.
The system has to regulate itself somehow. So now our HFCs etc are acting like blow off valves for turbo systems.
Relieving back pressure!
This is why a swap of a Y pipe may or may not solve the excess gas hiss sound.
Its also another reason why Dipstix checked and found all his pipes and bolts connected properly. There are no leaks in our systems.
The best way to test this is to have our car on a lift right. Have someone up there in the driver's chair revving the motor while we record and observe the sound the HFC/TP/CDPs are making and write down the area where the hiss sound is coming from.
I'm willing to bet its in the HFC/TP/CDP unit itself. Hope this helps! Feel free to add anything you see fit. We're finally getting somewhere
The hiss noise we're hearing on our cars is due to the excess gases flowing through the exhaust. When we add, Test Pipes, High Flow Cats and Cat Delete Pipes to our exhaust systems, we're placing our cars in a situation where a larger volume of air mass is now flowing through the exhaust upon acceleration and deceleration.
My hypothesis:
Under factory emissions regulation, a certain % of air is designed to flow from the motor's exhaust manifold, through the stock Catalytic Converter, burned, cleaned and forced out the Y Pipe, Mid pipe and out the mufflers into the air you and I breathe.
Since G35, 350z, G37s etc are Low Emission Vehicles, the stock cats have a major responsibility of not only burning off harmful carbons, but also controlling excess air mass that could potentially contain harmful carbons which could become potentially released into the atmosphere contributing to global pollution.
This is the reason why stock Cats are ALWAYS restrictive towards performance applications because as we all know the more air you can force into /out of an engine the better it performs.
What does this have to do with us?
Simple:
You, I and everyone who's decided we wanted to upgrade Cats to Higher Flowing Cats, Test Pipes, or Cat Delete Pipes chose to forgo the OEM's recommendation of restricted air mass aka our stock Catalytic Converter.
As a result, we experience more air flowing through our exhaust system and a slight boost in performance due to our now less restrictive exhaust system.
As a result, of the excess air mass that now flows through our Hi Flow Cats/Test Pipes and Cat Delete Pipes, we're hearing the result of that process.
Excess air mass = more gases flowing through our exhaust system.
The system has to regulate itself somehow. So now our HFCs etc are acting like blow off valves for turbo systems.
Relieving back pressure!
This is why a swap of a Y pipe may or may not solve the excess gas hiss sound.
Its also another reason why Dipstix checked and found all his pipes and bolts connected properly. There are no leaks in our systems.
The best way to test this is to have our car on a lift right. Have someone up there in the driver's chair revving the motor while we record and observe the sound the HFC/TP/CDPs are making and write down the area where the hiss sound is coming from.
I'm willing to bet its in the HFC/TP/CDP unit itself. Hope this helps! Feel free to add anything you see fit. We're finally getting somewhere
Any new updates on this matter?
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SchoonerVanHlmt
Intake and Exhaust
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09-20-2015 01:03 PM
11385, 14385, berk, decel, dipstix is the man, exhaust, fi, hfc, hiss, installation, magnaflow, magnaflow berk, pipe, resonated, vibration
