Gt2860r-5's = Surging & Flutter

[enzan]

Hey everyone, I just finished fitting the GT2860-5's to my R32 gtr and must say they've made a huge difference, the car feels more responsive and comes on boost earlier too. On full throttle it's fine but on really light acceleration and at cruise I now get bad waste gate flutter and surging. I never had this problem with the original turbo's and haven't changed anything other than the turbo's and a bit of metal off the exhaust manifolds.

Any ideas?? Help please!!!

[sky-017]

how much boost are you running? maybe you might need an aftermarket BOV.

[enzan]

how much boost are you running? maybe you might need an aftermarket BOV.

Around 1bar I think (factory gauge). But I don't think it's got anything to do with the BOV's, It's barely seeing any boost at all at very light throttle.

[R31Nismoid]

What BOV's are you running?

Flutter is only associated with a BOV, so it has everything to do with it

[Risking]

I think his actually trying to describe the compressor surge problem.

I had this really bad on my GTR when I first bought it. with the original 2530's fitted it would "chuff" when cruising or light throttle up hill etc.

I bumped the base timing up by 2 degress and it fixed the problem.

[enzan]

Hmm

Edited March 24, 2007 by enzan

[wolverine]

it's compressor surge and the shuffling comes from the return pressure wave. after market BOV's being more heavily sprung will make it worse.

changes to tuning and/or cam gear positions should get rid of it.

edit/correction: it is not the BOV opening and closing, it is the flow of air back thru the AFM/airbox as incorrectly posted.

Edited March 18, 2007 by wolverine

[Swiper the Fox]

changes to tuning and/or cam gear positions should get rid of it.

don't worry it can be tuned out

[enzan]

Ok, I'll start with the basics i.e tune and see how it goes. I went through all the other threads on this topic and everyone is seems quick to point the finger at the BOV's.

[R31Nismoid]

With little baby turbos like that you shouldnt be getting any surge.

If you had big low mounts, then ye. But i suspect something related to BOV operation

[Swiper the Fox]

Ok, I'll start with the basics i.e tune and see how it goes. I went through all the other threads on this topic and everyone is seems quick to point the finger at the BOV's.

its not the BOV's...to prove a point disconnect the vaccum line to them and block it so you don't have a manifold leak, then go for a light throttle drive up a long hill....i bet it still happens. Its the compressed air from the larger turbo's surging back out the intake through the AFM's.

You would not be on the throttle hard enough to generate boost, so the BOV would not even operate.

Ash ive had 2530's chuff so bad the car was almost undrivable....quick tune at Croydon's...magic...all gone!

Stock GTR BOV's are very good ive even seen them on hard tuned Supra's

[enzan]

Alright, well they are a fair bit bigger than the standards so I'm not ruling compressor surge out yet. I'll crimp the vacuum lines to the BOV's rendering them inactive tomoz and see what happens. But I don't understand how different turbo's is going to throw the BOV's out of wack??

[Risking]

Just advance the CAS slighly take it for a drive and my money is on the problem being fixed. Obviously if you have some form of management it can be tunned around but the CAS is a quick check that will work.

[enzan]

Yer I've heard the standard BOV's are really good and I seriously doubt that they are the cause. But I shall test them and the plumbing for them anyway just so we know for sure. First i'll bump the timing up a tad as you suggested and see what happens. I've still only got a mines modified ecu at this stage so tuning is limited, wolf 3d coming soon. Thanks for the advice everyone, I'll let you know what I find.

[bazr33]

i have been told this with my setup that the turbo was producing too much air forcing air through to my afm. causing more fuel and hesitation.

Apperantly only way to fix it (from what i have been told) is if ya get a computer that has an inbuilt map sensor, or move the afm to another location before the TPS.

Bit of farkin around but if thats what has to be done, then thats it.

Im upgrading turbo anyway so i'll deal with it when time comes.

Edited March 18, 2007 by bazr33

[R33GOD]

most pplz like the "flutter" lol. they call it fully sick bro...as ive heard

[enzan]

Yer that's why I'm going for the wolf 3d v5, do away with the afm's all together, bit more expensive but I think the plug n play is the way to go. But for now, unless a simple tweak of the CAS will fix it, it looks like I might just have to deal with it. Oh well, I was looking for another reason to spend more money on her!!

[wolverine]

dirtgarage is spot on, the BOV's are fine.

[enzan]

Well today I blocked off the BOV vacuum lines - made no difference what so ever - still very bad WASTEGATE flutter and surging goin on under there - rules out the BOV's once and for all (and it upset the idle). Advanced the CAS - made no difference either. It seems to occur right on the transition from vacuum to boost, near impossible to drive slow.

[paulr33]

there is no such thing as wastegate flutter

remove the phrase, it does NOT exist, there is no such thing

im curious how the tuning can correct this