Exhaust Noise that goes away after warmed up

[FastLane1000]

Guys, I've posted in the overpipe threads but I'm not sure thats my issue. I did have to adjust things to clear the hotckis sway bar but I've taken care of that. I have an exhaust noise which I would describe as rasp. I hear it when the car is not up to full operating temperature. The exhaust needs to be heat soaked before its gone but it does go away so that tells me its not the overpipe hitting. I have the FA20club header and was wondering about the Vband. The noise is under full throttle at 5K RPM or higher. Anyone else notice this sound and found a resolution? Exhaust is FA20Club EL header catted and coated, Motiv overpipe coated, and Motiv Front pipe catted. Rear is stock. Thanks for your input.

[Sportsguy83]

Originally Posted by FastLane1000

Guys, I've posted in the overpipe threads but I'm not sure thats my issue. I did have to adjust things to clear the hotckis sway bar but I've taken care of that. I have an exhaust noise which I would describe as rasp. I hear it when the car is not up to full operating temperature. The exhaust needs to be heat soaked before its gone but it does go away so that tells me its not the overpipe hitting. I have the FA20club header and was wondering about the Vband. The noise is under full throttle at 5K RPM or higher. Anyone else notice this sound and found a resolution? Exhaust is FA20Club EL header catted and coated, Motiv overpipe coated, and Motiv Front pipe catted. Rear is stock. Thanks for your input.

Easy fix, don't go WOT 5+K RPMs with the car not fully warmed up, your motor internals will love you for it.

[FastLane1000]

Thanks, but its doing something it shouldn't. must be a leak somewhere. Motor is fully warmed but exhaust has just cooled off a little.

[Ross]

If there is a leak you should be able to find it at idle. When cold spray with soapy water at your connections before you start it. Then see if you get any bubbles (this is the safer way). I typically will place my hands around all connections making it a point to try and not actually touch any thing to see if I feel any air coming out (the not so safe way). I would also recommend letting your vehicle get up to proper operating temperature before you drive aggressively. Hope this helps.

[qoncept]

Originally Posted by Ross

If there is a leak you should be able to find it at idle. When cold spray with soapy water

That's going to be hard to do at 5k with any load on the engine.

Sportsguy83 said it though. Don't go over 5k when the engine isn't warm. Your engine internals DO hate you for it.

[FR-S Matt]

Betting its the noise of the aggressive cold start vibration in the header, which explains why it goes away when it is warm. There's a million videos of how awful this sound is on un-resonated exhausts with headers that quiet down after warmup.

Don't drive any car hard until it is warm, unless you want to replace it in 50k miles.

[husker741]

I have a header back exhaust that has a lot of rasp on startup. After about 1 minute of driving and letting the engine warm up, it's completely gone. It's just the pipes being cold.

[FastLane1000]

I appreciate the input regarding a solution but I really don't drive the car hard before the motor is warmed. I was trying to explain that the exhaust needs to be heat soaked before the sound is gone. This happens long after the motor is fully warmed. Sounds like the consensus is its header related. Thanks!

[wparsons]

Originally Posted by husker741

I have a header back exhaust that has a lot of rasp on startup. After about 1 minute of driving and letting the engine warm up, it's completely gone. It's just the pipes being cold.

It's not just cold pipes, the ECU runs aggressive amounts of overlap to help heat up the engine faster which also makes it A LOT louder.

It's easily 5x as loud at a cold startup than once warm, even 100% stock.

[FR-S Matt]

Aftermarket headers are thinner and the heat plate on the stock header acts as a muffle too.

[husker741]

Originally Posted by wparsons

It's not just cold pipes, the ECU runs aggressive amounts of overlap to help heat up the engine faster which also makes it A LOT louder.

It's easily 5x as loud at a cold startup than once warm, even 100% stock.

You're very right and I totally forgot to mention this. Thanks for the input.