Stainless Steel Exhaust Drone when Cruising at Speed.

[Rek]

I have a FitzBitz exhaust and headers and the drone at speed gets annoying after a while. Has anyone with a SS exhaust done anything to combat this? I am thinking about experiemnting with some sort of harmonic balancers attached at various places.

 

[HB Chris]

I loved the sound of my FritzBitz except on the highway so I swapped it with my NOS system when I sold the Malaga coupe. Coupeking made a Carrot to insert in the tailpipe when they first made their SS exhausts.

 

[rsporsche]

i'm hoping that improved insulation (sound + thermal) will improve things with the stainless exhaust.

 

[JPB 74]

I get a terrible harmonic between 2800 and 3000 rpm. It's the sweet spot where the car likes to be while cruising. It actually takes effort to avoid it and remain within the speed limit (reasonably within and not well under) on some of my favorite roads! Otherwise, the song my car sings is lovely, especially above 4000.

 

[rsporsche]

i am wondering if it is the metal itself or if it is the mounting. does everybody have all 3 mounts (end of tranny / right side of rear muffler / tailpipe)? do we think it could be improved by better mounting? i have always wondered if the mild steel tubing was better at reducing harmonics vs. stainless. i remember reading something years ago that many aftermarket systems use various gauges of pipe that creates the harmonic issues ... but that's all i have heard

 

[stphers]

I have installed a lot of SS systems on BMW's, Alfa's and Porsches and they all have a bit of a drone to them and sometimes on the decel side, sound a bit " tinny " Have used factory mounts and aftermarket mounts, didn't seem to make any difference Using std steel style exhaust pipe gives off a deeper, throatier sound and the heavier the well thickness, the deeper the sound IMO

Thanks, Rick

 

[Bmachine]

I have installed a lot of SS systems on BMW's, Alfa's and Porsches and they all have a bit of a drone to them and sometimes on the decel side, sound a bit " tinny " Have used factory mounts and aftermarket mounts, didn't seem to make any difference Using std steel style exhaust pipe gives off a deeper, throatier sound and the heavier the well thickness, the deeper the sound IMO

Thanks, Rick

Very interesting

 

[eriknetherlands]

@rsporsche The thing with stainless is that the wallthickness is very low compared to the thickness of mild steel systems such as the original was.
Hence the stainless doesn't have the mass to dampen sounds by itself so much as mild steel would.

 

[TomHom]

This one was installed on my RHD E9.

Made in UK. Does anyone recognise it?
It's on sale for 500€.
I prefer the original Eberspächer. The real sound!
Or Bosal.

This one is on sale for 700€.
Fear I cannot ship them.
Thomas

 

[Rek]

@rsporsche The thing with stainless is that the wallthickness is very low compared to the thickness of mild steel systems such as the original was.
Hence the stainless doesn't have the mass to dampen sounds by itself so much as mild steel would.

This is highly likely. I had a custom made SS exhaust with a thicker gauge steel and it did not drone as much. Some harmonic balancing might be required to stop the reverberation.

 

[eriknetherlands]

I also have an NOS eberspacher system waiting. But now I've changed engine plans to an 3.5 L M90 - would the original system still be enough?

 

[rsporsche]

probably. unless you are building a real fire-breather. years ago, Ray Korman told me that you need to be above 250 hp to really benefit from a bigger diameter header / exhaust system.