Slide Turbo, Induction Noise, Flutter

[MANWHORE]

Hey guys

For those of you who have been following, I have gotten a slide highflow turbo charger. The turbo was installed properly, and there are no problems. The purpose for this post, is:

1. If you are running a slide turbo and have had the same observations, please say so.

2. If you're a turbo guru, or have researched this area, please comment why this is the case.

Most of you have driven an rb with a stock turbo, stock bov and pod filter. The things that you'll immediately notice are:

1. Massive induction noise when pressing the gas. This sounds like a sucking noise. It's sick, I like it

2. When you release the gas, you hear pssscccht. Even though the bov is plumback, you hear it throught the pod because the noise isn't muffled like in an airbox.

After installing the slide turbo and running 11 psi

1. induction noise isn't as loud. I put this down to the fact that the exhaust has also gotten louder, so I can't hear it as much.

2. I don't hear pssscccht unless i'm up at about 4.5-5k rpm before I release. If I release before then, I hear flutter.

I thought that I mgiht have left cloth in the intake piping, or that the bov was seized, so I took it off, checked it, the vac line wasn't split etc. It was as if, with the stock turbo, if someone had tightened the bov spring.

At low rpm, even if i release my foot when the boost is like 3-4psi or something, it still flutters. I do not believe that the bov can't handle the flow of air, because i've run a stock turbo at 20 psi before for testing purposes, and it didn't even flutter when releasing, just made a massive woosh. surely the slide turbo at 3-4 psi does'nt flow more than the stock turbo at 20psi.

This thread is not for flaming slide turbos, but rather, to gain an understanding of whether it is my particular setup that's doing as I observe, or whether it is the turbo that's different. Just like how nic's thread is the definitive thread about slide turbos on rb20s, I'm hoping that this thread can turn into a FAQ for the other aspects of the slide turbos. Hopefully it will save a bit of time for slide as well, because i'm sure he gets asked this stuff a lot.

Some questions that you guys mgiht want to answer (not all are relevant to everyone):

1. if you have a slide turbo, is this your exact observation? if not, please comment on how it's different

2. if you have experience with another type of highflow, is the induction noise louder or softer than the stock turbo? does it also flutter when you let go at low rpm, and psscccht at higher rpm

3. For you turbo gurus, why is it that the slide highflow flutters when releasing at low rpm, but not at higher rpm?

Edited April 12, 2007 by MANWHORE

[1400r]

found the same thing when I fitted my 2530

[MANWHORE]

1400, can you comment on why that is the case?

I just don't understand why - same bov, same pod, except the bov isn't opening anymore until higher rpm with the new turbo.

[paulr33]

the sympton you have described is due to the bov not opening enough or incorrectly

as a result it surges back onto the compressor wheel and you get the air chop chop / flutter noise.

you could try adjusting the spring on the bov?

[LTHLRB]

a bigger turbo has completely different characteristics to the std one

[silver gts-t]

forget all the sounds etc, all that is irrelaevant at this stage.

pressuming u have a FMIC and boost controller, get your hands on a ECU (if u dont have one) and get it tuned, only then you will take advantage of the hiflows potential

[paulr33]

stock turbo:

a compressor winds up to 3000rpm it has 7psi and 45cfm of air

hiflow:

as compressor winds up to 3000rpm it has 4psi and 25cfm or air

i think the stock bov spring is too tightand wont fire

you could try loosening the spring to make it fire with less air volume/pressure

it needs a certain level to be reached when the throttle body closes.

if the bov doesnt fire it will recirc back to the compressor and chop itself / collision

[paulr33]

dont confuse the bov spring rate vs manifold boost pressure

it doesnt work like that, the bov fires when manifold pressure spikes through the roof

ie: when the throttle body closes, its probably more like 30psi+++ when the throttle body closes and the compresor is still flowing

[drf76]

a bigger turbo has completely different characteristics to the std one

exactly what he said, turbo doesnt spool as hard or as much air as a std one, its what you get when bigger turbos are fitted, if your just after noise you go back to the standard turbo but personly and most ppl prefer more power.

[MANWHORE]

Paul

It is the stock bov. Not adjustible. It is definitely working. I tested the mecahnism, and the firmness is the same as when i had the stock turbo on. It's not siezed etc.

Edit: I just read your later post. I disagree in a sense. Because, going by that theory, ok, if the highflow has only 4 psi at 3k rpm, when the stocko would have had 7, that means that if I released my foot on the stocko at 2k rpm when it had 4 psi, then it should flutter?

You still have the stock turbo. Can you test it? I never had flutter ever on the stock turbo, whetehr releasing at 1 psi, or 20 psi

the sympton you have described is due to the bov not opening enough or incorrectly

as a result it surges back onto the compressor wheel and you get the air chop chop / flutter noise.

you could try adjusting the spring on the bov?

Edited April 12, 2007 by MANWHORE

[MANWHORE]

silver - No offence to you personally, but i'm not some noob who doesn't know that I need to tune it to take advantage of the potential. If you notice, I made no mention of the response, or power. This is not the topic we're discussing here. We're talking specifically about the theory behind

In answer to your question though, it will be getting a z32, increasing boost to 19 psi, injectors and a tune.

That doesn't answer why the bov noise is like this, and even after doing all that, it's still going to do the same thing, as I won't be changing bov.

forget all the sounds etc, all that is irrelaevant at this stage.

pressuming u have a FMIC and boost controller, get your hands on a ECU (if u dont have one) and get it tuned, only then you will take advantage of the hiflows potential

Edited April 12, 2007 by MANWHORE

[paulr33]

i believe the bov is ok and hasnt failed. i believe the stock turbo didnt flutter. i believe what you are saying

im just looking at it logically and dealing with the facts that we have.

maybe its just a case the stocker flowed more air down low (very likely) and it was enough to fire the bov in all situatons.

ie: it was designed around the oem stock turbo flow so its mapped around that level of airflow and pressure.

now that the compressor and exhaust side is different it could be unmatched. i am unsure on the fix sorry

[MANWHORE]

Hey paul, nah nah, it was good of you to comment. please comment more if you have any ideas, that's what I'm looking for, people's theories on why this is like that.

[WazR32GTSt]

how does the turbo drive now?

laggier?

mroe power?

worth the cash?

[MANWHORE]

Waz, i'll just answer this question quickly, so as not to divert the aim of this thread (so other people don't divulge on this tangent):

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.

[MANWHORE]

I'm not after the noise of the stock turbo - otherwise i'd just run the stock turbo. I actually like the flutter, it's sik but that's besides the point.

I'm trying to understand why it's happening, and why the bov isn't opening yet.

exactly what he said, turbo doesnt spool as hard or as much air as a std one, its what you get when bigger turbos are fitted, if your just after noise you go back to the standard turbo but personly and most ppl prefer more power.

[R33GOD]

i just came back from a drive. turbo feels awesome and flutters just like yours under 4,000rpm sounds like a jet taking off when boost pressure increases

[MANWHORE]

yes it definitely does. Can you please explain the difference in characteristics that cause the phenomena I described above?

a bigger turbo has completely different characteristics to the std one

[R33GOD]

this induction noise and flutter attracts chicks lol

[LTHLRB]

spend 900 on a highflow or 2k+ on a hks direct fit unit...

do you know what your talking about? my highflow that i baught of aaron is a straight fit, no rotating housings nothing, but because i want to, im getting braided lines made up so i dont need to drill anything.