Hi guys, I have a 3.5" turbo back exhaust on my BA xr6 turbo. I've noticed that the exhaust sounds totally different when cold compared to when its warmed up. When the exhaust is warm, it sounds nice and deep; but when it's cold (in the morning or 1 hour after being turned off), it sounds terrible in my opinion. The deepness isn't there and it sounds like the engine is missing/spluttering. Hard to explain.

My question is: Do all you xforce owners notice this? It's very noticeable when you stand at the back of the car (facing the tips). I just need to know if this is normal or if I have an exhaust leak that closes up when the exhaust expands.

Generally, what causes an exhaust to sound different when warmed up? Every exhaust modded car I've owned sound the same when cold/hot. Any feedback would be great.

PS: The exhaust note definately changes when the exhaust cools down (not when the engine is cold). Even if I turn off the car for 30min in winter, it will start sounding crap!

Sounds like something with the coldstart tuning side of things .

Edited 20/11/08 11:54 AM20/11/08 11:54 AM by xr6t_ute

My Theory - I have a valiant ute with a 265 hemi in it with extractors and a 3" exhaust. For a while there I had a pretty serious cam in it and it was extremely loud. Attracted too much attention. Then I put a way smaller stage 2 cam in it and now it is much quieter. I reckon when our engines are cold the computer is running a fairly tame cam timing hence softer exhaust note and when they are up to operating temperature the computer is running fairly aggressive cam timing therefore its flowing more gas and creating more power hence it sounds louder.

Comments anyone?

Sounds like something with the coldstart tuning side of things .

+1. Wish I could type faster!

You guys obviously didn't read my post fully.

I said it's not a cold start issue.

The issue is when the exhaust cools down, NOT WHEN THE ENGINE COOLS DOWN.

For example: I drive my car for hours, therefore it's at full operating temperature. I drive home and park it in my driveway. The idle is nice and deep and smooth. I turn off the car, go inside make a coffee. One hour later, I decide to start her up and let her idle. If I stand at the back of the car, it sounds like crap.

I'll say it again, it is not a cold start issue. It is a cold exhaust issue. I believe it's an exhaust leak. Before I go and get it looked at, I just wanted to see if you guys with the same car and exhaust have the same issue.

Thanks

Hows the weather outside

u have a stainless steel exhuast? I know when hot... the stainless expands bigtime.. this could give u that different note in sound..

I have to agree with typhoon freak, stainless steel(if that's what yours is made from) is a lot harder, or denser steel than say mild steel so as it heats up it will absorb a bit more of the sound and make it a deeper note. mine does the same till it warms up a bit

The exhaust has stainless steel mufflers and mild steel pipes.

I have the full stainless xforce 3.5" version and it is very different from cold to hot as per what typhoon_freak and F6_jase said, it expands bigtime so the mufflers on yours will be making a different tone because of the size difference from cold to hot.

With my system I had trouble with it hitting the towbar bracket when it was hot, I kept taking it to my mechanic but everytime I got there and straight away put it on the hoist it had already shrunk by an inch.

No cause for concern though, you could always pull a skid when its cold, I'm sure that will cure the sound!