Speed Engineering Header Drone
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Joined: Nov 2021
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Speed Engineering Header Drone
I’ve had my speed engineering long tubes with a btr stage 2 can and my stock bypassed exhaust. Lately I’ve been noticing a pretty strong drone at about 1600-1700 rpm under load. I’m wondering if something needs tightening after 2000 miles. Any ideas or thought of things to look at when I get the car up on jacks?
Drifting
Joined: Aug 2017
Posts: 1,841
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From: Dayton, OH
Drone, if that is what you are experiencing, is a resonance within the exhaust system. It is usually alleviated by the muffler.
Did it start when the stock muffler was bypassed? By "stock bypassed exhaust" I assume the factory muffler was opened and the internals were modified?
Did it start when the stock muffler was bypassed? By "stock bypassed exhaust" I assume the factory muffler was opened and the internals were modified?
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Joined: Nov 2021
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I didn’t really notice it at first when i did my xpipe and cam last year, but it seems to be getting worse as time goes on. The muffler bypass is the simple inlet to outlet weld a pipe in. Do the clamps on the xpipe need to be retightened so many miles after installation? I’m wondering if things are getting loose.
Safety Car
Joined: May 2016
Posts: 4,633
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From: Erlanger, Kentucky
I’ve had my speed engineering long tubes with a btr stage 2 can and my stock bypassed exhaust. Lately I’ve been noticing a pretty strong drone at about 1600-1700 rpm under load. I’m wondering if something needs tightening after 2000 miles. Any ideas or thought of things to look at when I get the car up on jacks?
Is it possible that the drone was always there but you are now noticing it as you get used to driving the car with the new cam and exhaust?
Only exhaust systems that don't seem to have drone is one that even with headers, has cats and goes into the stock mufflers or similar.
Drifting
Joined: Aug 2017
Posts: 1,841
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From: Dayton, OH
The frequency of the drone is related to the dimensions of the exhaust system and the speed of sound. That is why it will occur/be the worst at a particular frequency/RPM. The speed sound changes with the ambient temperature so the RPM at which the drone is the worst will change throughout the year as the ambient temperature changes.
That is the science behind a drone tube. Google "J-pipe" or "Helmholtz resonator". It is a 1/4-wave pipe welded onto an exhaust system to eliminate, or at least reduce drone. Part of the calculation is ambient temperature.
I studied up on that when I had one of the original Borla S-Type exhausts which droned pretty badly.. I changed to the Type II which got rid of 90% of the drone. It still has some. I added some resonators to try to reduce it more. I will find out in a few days if the help.
That is the science behind a drone tube. Google "J-pipe" or "Helmholtz resonator". It is a 1/4-wave pipe welded onto an exhaust system to eliminate, or at least reduce drone. Part of the calculation is ambient temperature.
I studied up on that when I had one of the original Borla S-Type exhausts which droned pretty badly.. I changed to the Type II which got rid of 90% of the drone. It still has some. I added some resonators to try to reduce it more. I will find out in a few days if the help.
