Slide Turbo, Induction Noise, Flutter

[TurboX]

Ever seen a compressor map? they're not exactly linear.. what someone was trying to say earlier is that even at 4psi and 2k rpm, the stock turbo is probably still flowing enough air to open the bov. I'm no expert, but that makes perfect sense to me.

I'm no expert either but last time I looked the whole theory of a BOV Blow off Valve was that when it senses VACUUM in the Intake manifold when the throttle is closed between gear changes on a MANUAL,

it dumps the compressed air in the piping from the compressor thru to the closed throttle plate to stop the air backing up on the compressor wheel.

A BOV is NOT actuated by PRESSURE but VACUUM.

A BOV on an AUTO is used to shorten the throttle response by bypassing the longer inlet tract as well as venting after sudden throttle closure when on boost.

My GTS4 AUTO is also experiencing similar symptoms after a new upgraded turbo and I intend to move the AFM to after the FMIC before the TB to see if that solves this issue.

[satanic]

It is very very laggy. On the stock ecu on 11 psi, any gains are not noticeable due to r+r (i.e. power output is probably similar).

It wasn't a direct bolt on, had to bend the lines, and rotate the housings.

Is it worth the money? I'll pm you

1) Get some cams; it'll bring the boost on earlier... or get some cam gears... with my Slide turbo I was making 1bar by 4k RPM so laggy? NO!

2) My turbo sounds like a jet-engine; I would double check all your fittings... want proof?

3) Of course the lines will have to be bent; you're no longer fitting a R33 turbo. Didn't you order the biggest RB25 highflow you could get from Slide? From memory of installing mine, the centres are different.

4) Rotating the housings? I'm not sure if Aaron still does this but I was given CLEAR instructions to tighten the bolts on the comp cover when i got the turbo as he had deliberately left them a bit loose to allow for installation "play". We never had to move it; just tightened it.

[Tangles]

Ive got the basic Stage1 Slide RB25 highflow.

fitted up no probs, used a braided oil line.

very very loud, I have a pod in a cai box with a heap of sound deadening foam in there, very loud tho.

and thats with a restrictive exhaust (muffler), cant go past 14psi as it has too much backpressure

get the blowoff sounds but I dont believe I have any flutter

at 14psi she only has 190kw but goes very very nicely, very happy with the turbo; price / quality / result

[Thunderbolt]

My thoery is, that the flutter has something to do with the plumback. The slide turbo is probably sucking more when you are backing off, so when the bov causes the air to go back to the intake, it causes reverberation hense you get flutter.

That is my theory anyway.

Edited April 13, 2007 by Thunderbolt

[MANWHORE]

1) Get some cams; it'll bring the boost on earlier... or get some cam gears... with my Slide turbo I was making 1bar by 4k RPM so laggy? NO!

2) My turbo sounds like a jet-engine; I would double check all your fittings... want proof?

3) Of course the lines will have to be bent; you're no longer fitting a R33 turbo. Didn't you order the biggest RB25 highflow you could get from Slide? From memory of installing mine, the centres are different.

4) Rotating the housings? I'm not sure if Aaron still does this but I was given CLEAR instructions to tighten the bolts on the comp cover when i got the turbo as he had deliberately left them a bit loose to allow for installation "play". We never had to move it; just tightened it.

You have clearly diverted from the aim of this thread. As you are not the one that installed your turbo or any of your mods, clearly, you are unaware of fitment of the turbo. It is easy to be a backseat mechanic and look at a part and go oh yeh, you undo some bolts, undo some lines, take it off the manifold. Installing it is a totally different story.

My aim of this thread was to attempt to develop theories on the topic. I.e. hoping that information would be shared for the benefit of all to see. However, as the thread keeps getting diverted and people are arguing on other topics, that's fine. I'm going to stop replying to this thread, and i'll discuss this topic over pm. As a result, information is no longer shared.

Edited April 13, 2007 by MANWHORE

[satanic]

As you are not the one that installed your turbo or any of your mods

And you would know this how?

[MANWHORE]

I'm not going to argue with you about this, but, i spoke to the mechanic who installed your turbo about the install?

[satanic]

mechanic"S" matey

[R31Nismoid]

Ok few ideas from this corner.

1) The compressor wheel is larger, and made of different material... (i think the stock R33 wheel isnt steel)

This in itself is going to make a fair difference. Its like going to a plastic or metal casing pod filter. One makes more noise than the other

2) Sounds like the VAC line to the BOV should be increased. Use a larger line so the BOV knows whats going on.

If that doesnt work, just bolt on a GTR BOV (one of the pair), should cost you around $150 at the most.

3) As for the lag, this is due to the stock ECU. So it is relevant that the car needs to be fully tuned

[MANWHORE]

Thanks for the reply ash, I've got a gtr bov down here that I was just about to pop on. I just wanted an explanation of the phenomena experienced.

I know know the reason why. Thanks guys, hvae a good one.

[Gazee]

I've got a GT2876R, standard bov at the moment until i buy inj for tune etc. but it doesn't flutter at low rpm, still makes the pchhtt noise... so this is really weird especially if its happened to more than one person... i'd like to see the explanation of this..

EDIT : I think ash's explanation of the vac line seems reasonable, i changed mine straight away to a 6mm one, maybe thats why i don't get the flutter...

[MANWHORE]

Thanks guys, there have been a lot of good replies in this thread amongst the threads about other things.

Gazee, that's exactly what i'm talking about. Spot on the money.

My aim was to understand what it was about this turbo that does that, whetehr it was compressor maps etc etc. This is not my first turbo change, nor is it my first turbo car. I've actually had more experience with 1JZs, and i haven't seen this (just as a matter of interest). but yeah, that's what i'm talking about - i haven't seen other similar turbos do the flutter at low rpm. I have seen flutter at high rpm - because the stock bov can't release air quick enough, so some goes back through the turbo, but just hadn't seen it at low rpm.

Edit: Gaz, my car came stock with a 6mm one, not the 4mm one. No there aren't any holes in it (if anyone asks)

Edited April 13, 2007 by MANWHORE

[R33GOD]

the flutter is good at low boost..stops me from thrashin my car as i like hearin it lol

im enjoying it alot more now

[MANWHORE]

Haha, I like it too. It's sick. At first, I was wondering whether I had left the vac line to the bov disconnected. hahaha, I was like far out that's sick.

[Gazee]

My aim was to understand what it was about this turbo that does that, whetehr it was compressor maps etc etc.

Do you have one of those modified standard rb25 bov's? that doesn't let it bleed off air whilst coming on boost or something or other?

[Slide]

lol

I don't know where the break down in communication was Chris.

The larger turbocharger is obviously going to have different characteristics to the standard.

As Paul has said the flow rates of the turbocharger are extremely different and the airflow at different boost pressures is also.

You just have to think about this as to where in the rev range it will be different which to my understanding of this thread is not understood by most people, It is different everywhere, It is a larger turbocharger.

It is not a phenomenon, you will find that once the car is tuned it is vastly different again, It is the nature of the beast.

If you do not understand how a turbocharger works there are many aids that can help.

www.howitworks.com

If you want to see how a journal turbocharger is made you can even see that here:

http://www.biagioturbos.com/ing/process2.asp

The standard blow off valves are still useful and not useless.

After market adjustable blow off valves are simply better as they are designed to cope with most sized turbochargers not just the standard one like Nissan intended.

Regardless of the fact it may be working properly or not its simply not up to the task of being able to do so with the new turbocharger.

This is the same for any after market turbocharger.

[Gazee]

Thats all good to say its a different turbo etc, but its stil weird, mine dusn't do that

[Slide]

You have an OP6 Stage 3 Sliding Performance Highflow?

If not then its characteristics will be different as stated, The car is also not tuned and running this size turbo on an untuned car is not only dangerous but also not being used the way it was intended.

[R33GOD]

slide your turbo is awesome. i recomend these to anyone who wants a nice street machine.

going to buy another half a dozen in a couple of months

Edited April 13, 2007 by R33GOD

[Tangles]

slide your turbo is nice

+1