My Z now makes an air "gushing" noise at lower RPM's during spool/boost. It's coming from the downpipe/testpipe area. I thought it might be an exhaust leak. I removed the testpipes today to make sure that the gaskets that came with my Megan DP's and TP's were holding up and not leaking. They are perfect and so I reinstalled everything and made sure it was plenty tight.

I'm wondering if it's just due to the increased velocity of the air moving through my exhaust now that I've gone to an 2.5" catback, DP's, and TP's. I can't remember for sure if the sound started exactly when I installed the Specialty-Z catback or not. Until then I had the 2.4" Megans slamming into the stock 2" catback from my 2+2. I think I was paying so much attention to the new exhaust note and the fact that I was now boosting 500 RPM's earlier that I could have easily missed the gushing noise for about a week.

It DOES NOT sound like a metallic contact noise. Air inside metal, maybe.

I've read a little here and over at TT.net about turbo rasp in exhaust setups like mine, but for peace of mind I'd just like to see if a few more people experience the same thing.

Before I noticed the noise, all I remember was the clean whistling sound of the turbos. The car boosts fine. No obvious issues.

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If I had a Z, it'd be silver... no... BLACK...

1991 Black 300ZXTT 2+2

Ruler of the Coastal Empire



Edited 1 time(s). Last edit was 2008:08:20:03:39:34.

Boost leak perhaps, the turbos can still reach full boost on some cars with leaks.

It is very localized to the DP or turbo area. I have run a few boost leak tests lately and there are none.

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If I had a Z, it'd be silver... no... BLACK...

1991 Black 300ZXTT 2+2

Ruler of the Coastal Empire

It may be possible that with the increased flow, you could be hearing the wastegate venting through the downpipes. You must have very good ears LOL

do you still have your AIV system? could be that maybe?

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I have Lived and Learned to LOVE... MY Z
Thats like saying that Elvis and I have alot in common because we both took a dump in Tennessee in 1977. ~ Ballistic

Nope. AIV's are gone.

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If I had a Z, it'd be silver... no... BLACK...

1991 Black 300ZXTT 2+2

Ruler of the Coastal Empire

Post a video.

chris, tomorrow morning or sometime tomorrow as i am going to sleep right now, give me a call and see if i can hear the sound over the phone...

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I have Lived and Learned to LOVE... MY Z
Thats like saying that Elvis and I have alot in common because we both took a dump in Tennessee in 1977. ~ Ballistic

Are you certain you are not hearing the stock recircs? The air rush you are referring to may also be known as the illustrious goose honk.

Darn it... I don't have a videotape for my HandyCam. I'll get one tomorrow.

SilverTwinOH... You posts is one of the ones I read over at TT.NET that talked about turbo rasp. As of right now I'm guessing that that is what it is. I've now got the Megan DP's and TP's with a SZ 2.5" catback with H-pipe and the large resonators.

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If I had a Z, it'd be silver... no... BLACK...

1991 Black 300ZXTT 2+2

Ruler of the Coastal Empire