What sound is flutter?

[crimsondragon]

I recently noticed a sound and I'm not sure if it's flutter. When I let go of the gas it makes the sound but it's something like having several washers held in your hand and then you drop each one onto a bolt and time it evenly between each one in quick succession. For those that can't imagine it, then just think of washers in a jar with one shake. It sounds like several clinks, if that's the right word or something loose like a several washers rattling on a bolt.

Is that the sound of flutter or something else? Anyone can provide video links?

 

[crimsondragon]

I can't till this weekend. I left my camera back home. The only reason I think it could be flutter is cause it only happens when I let go of the gas and I have an old style Forge BOV which has the flange epoxied down tight. But when I think of flutter, I think of like...I don't know, birds flapping their wings? So yeah I'm not sure how it sounds.

 

[whiteflash]

does it sound like this:

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MAD's S14a, compressor surge tastic.

skip to 1:00.....

 

[DSM_PWR]

You have some funny analogies

I assume you checked all vaccum hoses, bov adjustment, leaks, etc... Can you hear the "flutter" during idle or just went your gasN it? If so where does it sound like its coming from. Try a few revs during idle and see if you can pinpoint the location

 

[turboglenn]

Those videos let you hear flutter at it's fullest. On a side note..Man what i wouldn't give to go back and start all over with a 240sx and build something that's that much fun to drive. FWD is boring except fighting torque steer. AWD is pretty uneventfull till after 450-500hp (IMO) but RWD's are a blast with a measly 200hp. Maybe it's just me though

 

[throwedgsx]

I was thinking compressor surge. But the washer onto the bolt analogy doesn't sound like that. It's more like you said, a bird flapping it's wings. Anyway check the vaccum line that runs from your blow off valve to your manifold for leaks.

 

[patty AT forge]

I think what you are hearing is the sound that the pressurized air makes as it travels over the concave face of the DV piston.

Is this it?

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[crimsondragon]

That sounds like it. It's definitely not the other videos. It has a metallic sound to it. Thanks Pat. It's nothing harmful right? Mine only sounds when I let off the gas and not when I'm boosting. Also since you are the Forge representative, I've been wanting to clean the old grease off it and put new grease on. Any specific grease you guys recommend?

 

[patty AT forge]

That sounds like it. It's definitely not the other videos. It has a metallic sound to it. Thanks Pat. It's nothing harmful right? Mine only sounds when I let off the gas and not when I'm boosting. Also since you are the Forge representative, I've been wanting to clean the old grease off it and put new grease on. Any specific grease you guys recommend?

We use Mobil Mobilith SHC 220 in all of our valves. Its a fully synthetic heavy duty grease suitable for bearings and the like. But any thing similar should be fine, just stay away from anything with lithium, as the lithium can degrade the o-rings.