Full header back, drone at 1500 rpm on automatic
 

So I recently installed a JDL catted uel header, JDL 2.5in over pipe, a custom fabricated JDL dual resonated front pipe 2.5in, and all of that is mated to a Perrin 2.5in resonated cat back. I mostly drive around the city and back streets, on the highway I experience little to no drone, but when I'm cruising on the streets since I have an automatic my rpms sit at 1500 when I'm light on the throttle and this is where I'm experiencing a lot of drone, is this drone due to the exhaust still being new? I know once it gets coated with soot and carbon it should quite down a bit, but is that the case with drone? Will putting on the stock front pipe alleviate this issue, should I put back on the stock overpipe as well?


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Yep, I agree ...... IMHO, 1,500 rpms for this engine, is on the verge of "lugging" it.


humfrz

Ive been shifting down into 5th to avoid that rpm drone, but when I'm in auto and cruising the rpms always fall into that 1500-2000 drone range. Dont really feel like always shifting down a gear in Manual mode , I'm lazy and that's why I bought an auto :p lol.

Then deal with it if you're too lazy to avoid it. Or spend the money and get another resonator welded in.

Edit: how do you know the exhaust will quiet down once it gets coated with soot/carbon? Do you have factual references for that? Or are you just perpetuating the bullshit that everyone on here seems to spout about that?

Where exactly would I weld in another resonator when I have three already? How bout you read thoroughly before you post. My question was about putting back on the stock front pipe to get rid of the drone anyways, so thanks for your useless input. How do I know the exhaust will quite down, I don't have any factual evidence so sue me, but from real life experience from my previous cars that had axle back/ catbacks, they all toned down after some miles but I'm asking if that apply's to drone since this is my first time getting a full header back. So sorry if this post lodged a giant stick up your bum.

There is no break in, in fact it should theoretically get louder as the fiberglass packing material degrades within the muffler, @Cole is right, you are simply getting used to the sound so it doesn't seem as loud.

There's no way to fix this drone @1500 rpm, the auto is most susceptible to this I had this issue with my berk muffler delete and you simply get used to or drive around it, you said yourself it doesn't drone at any other RPM range. You could attempt to go back to the stock front pipe and weld a vibrant resonator in between the catalytic converter and the exhaust hanger. You've basically run into a problem that engineers spent quite a bit of time tuning out, a specific rpm with a harsh frequency. Where your car sits now is one of the tamest exhaust setups that isn't super harsh

You could try sport mode. I don't know if it will work.

I drive an auto in manual only :bonk: I'm rarely below 2,500 RPM.

So in your opinion would putting back the stock over pipe and front pipe do little to reduce the drone? What are your thoughts on sound deadening? Did you just get used to your exhaust?




Just came back from drive and tried sport mode, helped a little actually lol. What gear are you usually in when cruising in moderate traffic?

You're going to have to spend a lot of time figuring out what area(s) of the exhaust you can reduce drone. In one easy step, you've removed what the OEM engineers spent months trying to reduce/remove: drone from exhaust system.

Adding a resonator, while seemingly easy, is only a fix if you know what frequency you are trying to tune out. A lot of NVH-related stuff is more than just volume of exhaust gas at a certain RPM...

-alex

Which part of the exhaust do you recommend I start with? I'm thinking of switching the stock front pipe back first. What's your opinion on the over pipe in regards to noise and drone?

Front pipe because it has a cat and a resonator.
Or do some math and get a helmholtz resonator.

That would be easiest and least expensive and may knock the drone down to where it's acceptable to you.

Let us know what you decide to do and if it works......;)


humfrz

Full header back, drone at 1500 rpm on automatic
 

Appreciate the input guys, I'm renting out a lift this Wednesday so I shall report back 👍. Also what's yalls thoughts on putting back the stock over pipe?

So in your opinion would putting back the stock over pipe and front pipe do little to reduce the drone?
Overpipe has almost nothing to do with drone, the front pipe however will, put the stock front pipe back on and add a vibrant resonator to it between the hanger it has and the cat.

What are your thoughts on sound deadening?
Sound deadening adds weight, however if you like you can add dynamat to the trunk area, that would help block out some of the frequencies

Did you just get used to your exhaust?
Also I already told you I got used to it if you read my original post>

What gear are you usually in when cruising in moderate traffic?
It's an auto it will essentially force you at slow speeds into a specific gear to prevent a stall condition just get used to it.