Too loud

[johnymd]

My exhaust is way too loud inside the car. Its very boomy and I need to do something about it. Engine is a 1jz twin turbo with a 3" exhaust by Haywood and Scott. I've already taken it back once and had a center box fitted so it really shouldn't be this boomy. I've lined the whole of the rear, including quarters, with 12mm closed cell foam. Replaced the noisy rear wheel bearings and should get the diff replaced next week. This should cut down all the rest of the noise and just leave the exhaust to deal with.

I'm no expert on exhausts but there is one thing about it that may not be right. The tailpipe is 3" but the end is rolled back on itself which reduces its size to 2.5". Could this be causing the booming? Any advice welcome as its driving me mad.

 

[Rob Gaskin]

And it's a turbo which I thought were quieter than NA.

3" is big IMO.

Cars don't need to be noisey my 370Z is very quiet but still goes well.

Is it loud outside, if not then it might be mounted too stiffly. It needs to hang loose .

John don't forget that to go on track it will have to meet regulations.

 

[morbias]

Closed cell foam doesn't really do much on it's own as it doesn't absorb much of the vibration in the panels. To stop the metal resonating the best thing to use is Dynamat or Damplifier with closed cell foam on top.

3" is huge! (at least that's what I tell the ladies)

 

[rallymanDP]

Have you fitted Sound deadening pads to the Transmission Tunnel, the front Bulkhead, rear upstand, etc., inside the Cockpit as the Factory did when new ?
And under the Rear Deck Carpet, inside the Doors, the inner sills, and anywhere possible ?

Not expensive , but makes a big difference altogether.

 

[260Z TT]

My 260 has a full 3 inch system, with a small centre box and an Apexi N1 rear silencer with 4.5 inch tailpipe, have never found that too loud !

 

[rallymanDP]

Still boasting about Size, I see, Mark.......

 

[Mr.G]

Have a read of this, maybe you can do something similar:

TwinTurbo.NET: Nissan 300ZX forum - Using Venturi to Cure Low Frequency Exhaust Booming