Please explain normal turbo sounds...

[Bluebird]

I want to know what is happening mechanically/physically when the turbo makes these sounds (see signature).



1. The "whistle" sound when accelerating?

2. The "whooossh" when decelerating, especially after getting into the throttle?

3. The "whining" winding down sound when just goosing it a little in 'park'?



I know this may be an ignorant questions, but I guess I am...



Thanks in advance for your replys.

Have a great, safe and insane Independence Day weekend. God bless America!



Patrick

 

[Philip]

The whistle is the turbo being spooled up to operating speed. For most turbo's operating speed is around 100,000 RPM.



That whooshing noise is the turbo spooling backwards to dump pressure when you let off the throttle fast. It is also called turbo bark. This is not good. You should let off the throttle lightely to prevent this from happening.



The winding down whine is normal.



Items 1 & 3 are not anything to worry about. Item 2 is the big turbo killer. Adjust your driving style to avoid this.

 

[dpuckett]

Philip is dead on about all 3, esp bark killing turbos.



Now to expand on #1- As he said, most turbos operate at 100,000 or more RPMs (at full load, anyway; it wont turn 100K just cruising empty down the road making 2-4psi boost). THat means the turbine blades are cutting through the air pretty fast. The whistling noise is just that- kind of like a bullet whizzing by one's head. Put on a 12cm exh housing, and add a 4" pipe and the whistle will nearly split your eardrums at certain RPM/loads.



Daniel

 

[sparks57]

The whistle is a good thing, it's just the resonance from the blades because they're spinning so fast. The faster the turbo is going, the higher pitched the noise.



The hissing on deceleration is similair to the whistle during acceleration, but it's the sound of the turbo slowing down.



Now, when you are shifting hard, you will notice a loud "chirp". This is just the boost evacuating the turbo. But if you here this wierd "woof" noise, that is BAD. That is turbo bark, and is damaging to the turbo. It is the sudden reversal of the impellar as the boost exits the air filter instead of into the engine.

 

[sparks57]

PS: I think philip misunderstood on #2. If you are talking about the long drawn-out woosh, then it's what I said, but if it's a quick woofing noise, then it's bark.

 

[Greenleaf]

CB.......Like this?

Woof! Woof!:-laf ... ... ... ... or



Arf! Arf!

:-laf :-laf



Maybe, ... . more like a coyote howl

 

[Bluebird]

Turbo sounds...

Thanks for all the information good job! I'm just a little confused where CB_Parker states the turbo is just slowing down and what exactly the 'bark' sounds like. And the driving style could use some work-for sure. Regards, Patrick

 

[sparks57]

The "hissing" as you decelerate is just the turbo slowing down normaly, the "chirp" when you shift is normal... a "woof" at the shift is bad... that means you evacuated the boost too quickly. That ussualy happens when you're making a LOT of boost and have a smaller exhaust housing.



Better?

 

[sparks57]

BTW: when you bark it, you'll know it... trust me.

 

[dpuckett]

Personal experience, CB? :-laf

 

[bgilbert]

Patrick, I bet you're not getting much if any bark, since you look stock and intercooled and not pushing big big boost, so you might get the wooosh but no bark bark wooof. . That occurs when there is high boost, say 25+, not for sure, and then the sudden change or let off of throttle and the charged air goes to the easiest exit, and tries to stop the turbo from spinning and then spin it the other direction. With stocker 91. 5+ truck, I bet it'd be hard to hurt a healthy turbo by letting off the throttle quickly under heavy throttle. . yeah thats it.

 

[sparks57]

Actually, even with 40+ psi of boost, I have not yet barked it...



I made 42psi the other day...



But I also pegged my pyro! (just for a split second though).

 

[Bluebird]

Good dog(Ram), no bark!

Thanks bgilbert, I think that's the ticket... PatrickOo.

 

[Jefff929]

I've not heard a turbo make noise in 10 years. :-laf too many years of working on diesel trucks. I go by feel when the hood is up or ask the wife when traveling down the road. I've asked many times is it whisteling? I guess the family will let me know when I have a leak on the pressure side.