Outer Limits 4x4 Board

Was wondering if any one can answer why some turbos whistle and some dont .
I was led to beleive today by a pretty reputable turbo seller that the reason some do is they are not balanced and a good balanced one will not or allmost wont whistle. Weather they run a muffler or not
Any ideas anyone

I'm no guru on the subject, but I've driven enough trucks in the last 11 years to know that has gotta be shite, if a turbo was out of balance it would munch itself at the rpms they spin at. And if that was a fact then almost all trucks have got turbo's that are out of balance. I would say its go more to do with the particular motor, exhaust and/or turbo, and amount of boost being run. I know with trucks a series 60 detroit's turbo is heaps louder than anything else, but maybe because they run heaps of boost on a smaller capacity motor.

i know just about every std ct20 turbo on a hilux whistles but say a denco kit dosnt, maybee its to do with the bearings and water cooling of the ct20 ???

mine whistles without muffler, but you dont hear shit with muffler

As i thought beretta but i have a 4.2 nissan with a swytzer turbo that runs between 9/17 psi boost with 3 in mandrell with no muffler shes got about 180000 ks on both It spools quick makes good boost heaps power/tourque but also friends with standed turbo with almost factory settings have a great whistle from exhaust with a muffler
I know this may seem like a nothing subject but i am very keen to hear other peoples thoughts as i first thought i needed a rebuild of the turbo but from denco have been told not to worry as its a balance thing like mentioned above The boost settings has varied to find a better power curve but as today stand at 10psi which is at the factory setting from switzer ( and how do you spell that properly without reading it off the turbo)
Cheers Jamie H

spazbot as you said the denco kits dont whistle but a friend just fitted a denco switzer based kit to a td42 and with a muffler it whistled its ass off with out tuning a thing ( it was in a shorty though)
And bogged what type of turbo do you run?

not2.8 wrote:spazbot as you said the denco kits dont whistle but a friend just fitted a denco switzer based kit to a td42 and with a muffler it whistled its ass off with out tuning a thing ( it was in a shorty though)
And bogged what type of turbo do you run?

ok there must be something wrong with spazbots denco turbo cos all the schwitzer (denco) turbo i have seen and heard DEFINATLEY whistle helps to have ya muff removed tho

MUSS wrote:

not2.8 wrote:spazbot as you said the denco kits dont whistle but a friend just fitted a denco switzer based kit to a td42 and with a muffler it whistled its ass off with out tuning a thing ( it was in a shorty though)
And bogged what type of turbo do you run?

ok there must be something wrong with spazbots denco turbo cos all the schwitzer (denco) turbo i have seen and heard DEFINATLEY whistle helps to have ya muff removed tho

i have a ct20 not a denco it wistles very nicely

mine is original switzer the second fitted in brissy in 93 and with no muffler has no whistle but still can turn 33s with 4.6 diffs to 90 klws at 4 wheels nothing to brag about but respectable i think but still wondering why the no whistle from it

not2.8 wrote:mine is original switzer the second fitted in brissy in 93 and with no muffler has no whistle but still can turn 33s with 4.6 diffs to 90 klws at 4 wheels nothing to brag about but respectable i think but still wondering why the no whistle from it

must have something to do with exhaust set up? ive heard a 2.8 lux with a switzer turbo and it whistles...not loud but it still whistles

not2.8 wrote:spazbot as you said the denco kits dont whistle but a friend just fitted a denco switzer based kit to a td42 and with a muffler it whistled its ass off with out tuning a thing ( it was in a shorty though)
And bogged what type of turbo do you run?

Denco with Schwitzer snail

so bogged yours is a genuin schwitzer as from what i have leared from denco they use a schwitzer turbo and replace the snail on there brand of turbo?
Correct me if im miss informed but this is from paul from Denco
The way you tell is the snail has denco imbosed on it or schwitzer?

not2.8 wrote:so bogged yours is a genuin schwitzer as from what i have leared from denco they use a schwitzer turbo and replace the snail on there brand of turbo?
Correct me if im miss informed but this is from paul from Denco
The way you tell is the snail has denco imbosed on it or schwitzer?

will look tomorrow cant be fucked at moment....

I think it would be down to sound created by the comp / exhaust wheel tips cutting through the air. Kind of like how helicopter rotor blades make noise. With the wheels spinning over 100,000 rpm at full boost, you wouldn't think they'd be silent.....

so bigpat why would mine be silent but running quite fine?

not2.8 wrote:so bigpat why would mine be silent but running quite fine?

is it an problem?

same as you never hear stock factory turbos whistling

mine at idle you can hear.

I assume from factory ther is a big a** muffler blocking it but from thinking from what bigpat said maybe the non denco but schwitzers turbos dont have as much curve on the exhust wheel blades which i would think they wont spool as quick and wont whistle as much?

I have stock CT-20 running 12 psi. Under boost it whistles from under bonnet, both before and after turbo service / rebuild. When I blew out my muffler I could hear it whistle spooling up, and spooling down out the exhaust . New, full exhaust and it's quiet out the back.

Everything else being equal, a bigger exhaust doesn't muffle noise as much as a smaller one. Exhaust diameter, type of muffler, the amount of restriction of the dump pipe would have something to do with this, trim of the turbo wheels, A/R of the housings all would contribute I would think.

Generally, modded turbos seem to be louder. I noticed the Pro-comp GU Ute whistles LOUDLY as it spools down (Big Turbo, big exhaust). not 2.8,I never said that a turbo has to whistle to be healthy., however I believe if you were to disconnect your exhaust halfway back, you would definately hear the whistle.....

Our standard F250 turbos whistle pretty loud when you have your foot flat to the floor.
My friends 2003 Hilux factory turbo whistles too.

The whistle is to do with the spin rate of the turbo.

You will notice that a smaller exhaust tubine housing allows the turbo to spin up faster, the one's you see that you can hear whistling at low revs are the ones that come on boost as soon as the right foot is used (good for comps and rockwork).

The reason trucks whistle is the same the exhaust tubine housing is small in regards to the size of the motor and remember trucks run around the 20 to 30 psi boost, and that is where they get their power from.

So the best balance is a smaller exhaust tubine housing and a large turbo compressor.

As for the exhaust sound on mine, I don't have a clue, but the engine sound while driving is quiet to start, whistling it's head off at 6psi, then quiet again by 12psi.

So it's spindle vibrating or a blade effect.

100,000 rpm is about 1600Hz. Multiply that by the number of blades on the impeller? 15 blades and you're above human hearing range.

What frequency do you reckon the noise is, and does it rise beyond audible range?

I'd believe the spindle balance explanation. Perfect balance is next to impossible to achieve, and it doesn't need much imbalance to make noise. Certainly less imbalance than would be required for catastrophic failure.

My 2c.

Scott

I couldn't hear any whistle on my Fender TD5 with the stock exhaust.

I wacked on a 3" mandrel with no mufflers and the thing whistles its friggen head off. At idle, through gear changes, and down shifting. Since I did the chip upgrade it is at the point where I am considering a resonator/muffler.

Micka

bogged wrote:mine whistles without muffler, but you dont hear shit with muffler

Mine too and I love it


BJ

The whistle occurs because of a number of things but the main cause is how the air flows over the vains of the turbo. The way the vains of the turbo are cut and angled, the size of the vains, the amount of back pressure from the inlet and exhaust, the exhaust setup. All these things contribute to the sound of the turbo. Not that it really matters. It still sounds horn to hear it whistle.

bogged wrote:

not2.8 wrote:so bigpat why would mine be silent but running quite fine?

is it an problem?

same as you never hear stock factory turbos whistling

mine at idle you can hear.

fark man i work at a servo and when im out on the drive and hear a new td lux or prado take off they wisstle like shit, heaps more than my 2.8 with 2.5 inch mandrel..

[quoPosted: Tue Sep 06, 2005 8:39 pm

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bogged wrote:
not2.8 wrote:
so bigpat why would mine be silent but running quite fine?

is it an problem?

same as you never hear stock factory turbos whistling

mine at idle you can hear.


fark man i work at a servo and when im out on the drive and hear a new td lux or prado take off they wisstle like shit, heaps more than my 2.8 with 2.5 inch mandrel..


I noticed that too.....

As for the theory of small turbine wheel & big comp wheel, there is the danger is inducing compressor surge, which isn't good at all. Turbo places (the good ones) are always careful about this.
[/quote]

[quoPosted: Tue Sep 06, 2005 8:39 pm

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bogged wrote:
not2.8 wrote:
so bigpat why would mine be silent but running quite fine?

is it an problem?

same as you never hear stock factory turbos whistling

mine at idle you can hear.


fark man i work at a servo and when im out on the drive and hear a new td lux or prado take off they wisstle like shit, heaps more than my 2.8 with 2.5 inch mandrel..


I noticed that too.....

As for the theory of small turbine wheel & big comp wheel, there is the danger is inducing compressor surge, which isn't good at all. Turbo places (the good ones) are always careful about this.
[/quote]

As for the whistle and exhaust size mine is a 3in mandrel with 3in dump no muffler but being a wagon i spose the pipe is bloody long.
She does spool up quick but i put that down to 4.6 diff gears and the amount of fuel being dumped in her guts
Allso i gather the internal design and other workings of a schwitzer turbo have developed along way since mine was new in 93 allthough they do look similar with a current new one.

Too true bigpat you have to be careful in matching the turbine to the compressor to big and the exhaust gas will not have energy to spin the compressor and will be sluggish and not reach the boost levels you want, too small and the turbo will respond so quickly as it will be a bitch to drive (there is one Patrol SWB in Melbourne like this a the moment).

The other thing you must put into the equation is where do you what the power.

I have in my Patrol a Denco unit (Schwitzer) the compressor is the standard unit a S2A. At idle you can hear a slight whistle and it starts to boost at 1100RPM and generates 435nm torque at 2000RPM and max power of 183kw's at 3500RPM.

But I wanted better more, so we played. I wanted the boost to come on sooner (at 900RPM) and the torque to max out earlier, what we did was decrease the size of the turbine leaving the compressor the same what we got was started boosting at 950RPM max torque of 450nm at 1700RPM max power of 190kw's at 2750RPM, after the change of turbine at idle you could hear a louder whistle and when you hit it it was like you were killing a cat.

So if you want power from the moment you use the right foot then you need to combine a smaller turbine with the same or larger compressor.

P.S these results were all done on an engine dyno not in the Patrol.