R33 Gtr Flutter

[tommis85]

Hi all, I have a bit a complicated question about the induction noises.

I drive a R33 GTR and it's fairly stock apart from a pair of pod-filters that are properly secured with brackets etc. Now, with my old skyline, a R33 GTST S1.5, I used to get one hell of a flutter coming from the pods. I ended up losening off the BOV back then to minimise this sound.

BUT now, with the GTR, I don't get the chopping flutter noise (that's been described as ghey and idiotic and all sorts of stuff haha!) Instead, I have an odd sound. It sounds like a very drawn out flutter or very sick (as in not feeling well) blow off valve woosh. My mechanic suggested to me that this sound comes from the little "balancing" pipe that joins the two turbos??? He is a bit unsure, but he says that when you back off (and blow off too) the two turbos basically see-saw off one another with that linking equalizing pipe???

Does anyone out there, with a GTR that has pod filters, have a similar sound? Maybe it's the twin-turbo's version of "fluttering"?

Please guys, I'm not a noob with what fluttering is. I know what causes it in a single turbo situation and I know how it sounds and what it can do to different types of turbo's.

I've been looking everywhere for an answer and all I find is people asking how to make GTST's flutter....and the replies associated with the nonsense haha!

Hope you can help me! Is this a normal sound, or is something broken?

Edited May 13, 2008 by tommis85

[R31Nismoid]

Its perfectly normal. What your describing is the BOV's going off against one another as there are two.

With a controlled foot you can keep it going for 6-8 i've found

Nothing to worry about.

[tommis85]

Thanks for the quick reply but no no....that's not it boys! Yes, it does make them sounds as well and it's pretty amusing to listen to the two valves chatting to one another when you come over the crest of a hill etc.

This noise comes from the pod filters....and it's generated somewhere between the two turbos. I'm very sure of this - I'd just like a confirmation from someone. It's not BOV sounds as I know the different sounds they make (from the full on woosh to the chitter chatter they do)

The noise is almost a bark or fart...very odd sound. It's hard to describe guys - just wondering if one of you has it??

[R31Nismoid]

Yeah it sounds like air being squeezed out @ different rates yes? Sound changes?

[tommis85]

You see guys, these are the sounds you get from the GTR:

- induction noise caused my turbo spool (sounds great!)

- the twin bov's talk to one another little wooshes that goes "back and forth" between the two valves

- and then finally on a big dump, you get this bit "baaarff!" sounds accompanied by the BOV woosh as well.

Please note that the car only has 70,000km on it and I've been assured that it performs very well and hard

[DRD-00F]

screamer? You're descriptions of a big dump (normally meaning hard acceleration) accompanied with BOV woosh (normally meaning pressure release on deceleration) make no sense...

Any chance you could record the sound?

[tommis85]

DRD-00F, yeh mate I know it makes no sense and it's hard for me to describe. My mechanic is puzzled by it too and I had him check the car over on the hoist for signs of a third bov somewhere that may have been fitted by the previous owner. He also looked for an external waste gate etc but didnt find any.

All he said was that the twin-turbo conversion they did on this V8 engine made similar sounds.

I will have to record the sound for you guys as it's hard to describe (and makes me look like a noob) haha! The mob that services two Falken R32 GTR's is even baffled....so yeh, it's a bit of a dilemma.

Maybe I could ask a different questions to you guys out there with GTR's? Does a twin turbo arrangement flutter? Is it physically possible for them to flutter or would it come out as some jibberish or "baarfff" sound as the two turbines bounch of one another remaining speed and pressure once you have taken your foot off and the system dumps/recirculates the boost.

I'll try to get a recording on my mobile for you - it should come out clear enough on it.

Thanks for the help people.

[GeeTR]

I think you'll find its what Nismoid is describing.

It sound like its coming from the filters.. cus it is

Theres induction noise when your on it, theres a "woosh" when you back off hard, but if you back off 3/4 and then maintain a certain foot position "curve" you can make it sound like a cascading "see saw" type of noise.

I believe its normal comp surge as theres not enough pressure between TB and motor to open BOV's, but you've still backed off, so there air exits the comp covers... giving the normal sounds like its fluttering (with the dynamics of twin turbs and bov's giving the "see saw / tottering" sound.

If you want the full sick flutters all the time, use a blanking plate on the BOV mounts.

Edited May 13, 2008 by GeeTR

[tommis85]

GeeTR....I feel like an idiot trying to describe this! Yeh, I know them sounds too...they're another sounds you can add to the GTR's vocab hehe! I'm sorry, this is frustrating me, but it's not the sound.

Actually, I've just remembered something...back when I was trying to diagnose it I blanked off both of the blow off valves and guess what - it DIDN'T flutter. Explain that one. But it still made that big bark sound.

(not the blow off valve seesawing, not the turbo seesawing, and not the blow off valve dump sound)

Please be patient guys - I'll get down to it. All the sounds that you have to described to me I can relate to my own GTR. It makes all them sounds as well - so that's good in that regard. Maybe it has an external waste-gate that the mechanic missed in his check-over for the sound. I know that them things make quite a racket - but I haven't heard one on a GTR before.

Just going back to the flutter part. What do you think is wrong if the GTR doesn't flutter with both blow off valves blanked off and sealed? Is the GTR hiding something else somewhere as far as recirc goes????

It makes that sounds at about 8 pounds plus.

[GeeTR]

GeeTR....I feel like an idiot trying to describe this!

Yup, its a touchy topic when ever turbos are discussed

Record the sound if your keen.

[SiR_RB]

my brother inlaw has an R33 GTR 98 model and his bovs do sound very different to my gtst. his got apexi pods and its a different sound, and if u play with the throttle while backin off you can actually keep them going for afew seconds....

perfectly normal

[tommis85]

Thanks for the input guys...but I will have to record the sounds for you.

I will record the sound on the way home from work and post it up. Please just be patient till I have the sound posted - it is not the blow of valves or the "wisshwoosh" sounds that you can achieve by throttle foot work ;-)

I'll try to have something on here in about an hour or two. I can guarantee that you will all go "wtf is that!"

I've been given one tip by a guy and that is to take the car for a spin around the block with out the foam muchroom filters. He says that the filters could be making that noise when the excess boost travels back through them. My foam filters are old - I bought them with the second hand elbow pieces.

Do any of you run these - or do you all run the wet/oil type K&N jobs?

Stay cool people....I'll have the sound posted soon. You'll be as stumped as me hehe!

[jenkies]

hey mate, i dont know if this helps at all, but you were comparing the blow off noise compared to your r33 gtst?? big big difference with the way they are plumbed back.. rb20's and rb25's have very short link with the pipe that plumbs it back making a very loud sharp whoosh through the pod filter where as gtr's ahve a very long plumbback pipe across the whole front of the car causing an eco'd muffled blow off noise alot quieter and different to the normal blow off sound coming through the filters

or are you talking bout a totally differnt noise all together?

[tommis85]

Sir_RB....

Yes, mine does that too...it was pretty amusing when I first got the car as you could get the two valves having a good chat with one another....you can make it last for ages especially in 4th and 5th ;-)

"shees-shooo-shees-shoo-shee-shoo" lol...and then it just fades away =P

[R34GTFOUR]

my younger bro has a r32 gtr, and i know what sound you mean, but its defiantely the stock bovs. At first it actually made me lol when i drove his car haha.

The stock bovs dont make the same wooosh sound like the r33, it sounds very different, its hard to describe

Its kinda like a retarded sneeze chhhaaeeeerrrt ??? i dont know.... lol

[tommis85]

Hi Jenkies,

Yeh it made that sound back with my old stock valves. I now run twin Blitz valves but I am thinking of putting my stock ones back on as I don't want to get defected. The stock GTST valves definitely make a much nicer sound...not to mention that the gtst recirc pipe is steel too, and not plastic and oddly shaped like on the GTR.

...But all this is not being used anymore. The plumb back pipe is capped at the BOV side of the car.

As a test I took the valves off completed and blanked it off with cap and hose tie. I boosted it up to around 10 pounds and it made the exact same sound. So, the BOV's have been ruled out as the culprit.

[jenkies]

retarded sneeze sound equils= bvoou

[tommis85]

R34GT4....you're right on the money with that particular sound. Very retarded...and embarrassing.

But I dont run that setup anymore as per above post...Blitz valves venting to atmosphere (return pipe blocked off)

The sound that I'm describing is still made WITHOUT the valves...

pretty frustrating huh?

[quarkgun]

I'm intrigued, make a recording, i want to hear the car barf!

[tommis85]

I've got a recording on my mobile - i'm just downloading some audio converters to make mp3 from the mobiles .amr files

LOL she barf's alright!

Unless you guys have converters and I'll just post up the raw stuff