turbo spool sound

[hopwoodp]

The sound level generated by any turbo is a function of air turbulence behind the leading edge of the blades. For the same reason you can hear any fan, the blades cutting through the air cause a disturbance. The larger this disturbance, the more noise you hear. I agree with comments about hard piping etc making it louder, but louder isn't better. A 14b is also quieter than most other compressor wheels because of the single height blades. The t-25 makes noise because the angle of the blades is agressive to obtain flow in the small intake hole. If you have 2 identical model turbos and one is noiser than the other, my bet is that the quiet one actually flows more air, but all your ricer buddies won't be as impressed.

Thats some good information. Thanks for sharing. I agree, louder is not always better. I do know that an intake with the least amount of obstruction of flow is what you always want to
aim for.

My 20g is probably the quietest of all the turbos I had on my car. Even at 25psi, it was quieter than my EvoIII 16g at 21 psi. But, the power was much more and it scared me at first because, I didn't think I was boosting right. But, I checked m y boost gauge and it was at 25 psi. Thats when I talked to RRE about it and got the facts.

 

[shadowdrag]

My PTE 3031RE is super quite compare to my brothers evo3 and they are both new turbos. But the PTE pulls alot harder at high end. Kinda miss the winding spool of my t-25 though.

 

[1bad92awd]

My T25 and T28 that I had on my old talon both were very loud when it comes to spooling sounds. All I had for intake was and HKS filter. I thought it sounded really good but thats just me. The filter worked really well for the time I had the car.

 

[Black_Bullet]

The sound level generated by any turbo is a function of air turbulence behind the leading edge of the blades. For the same reason you can hear any fan, the blades cutting through the air cause a disturbance. The larger this disturbance, the more noise you hear. I agree with comments about hard piping etc making it louder, but louder isn't better. A 14b is also quieter than most other compressor wheels because of the single height blades. The t-25 makes noise because the angle of the blades is agressive to obtain flow in the small intake hole. If you have 2 identical model turbos and one is noiser than the other, my bet is that the quiet one actually flows more air, but all your ricer buddies won't be as impressed.

This makes sense, Ive went from a 14b to a evo3 gt knock off chinese 16g to a real MHI evo3 16g and in comparison the 14b spooled an audiable amount but whistled out the exhaust more than anything. This is with an exhaust cutout ( open downpipe ) ...
Funny thing is the knock off 16g gt spooled the loudest by far, i mean that thing sounded like a Boeing 747 about to take off. And then there was thr MHI evo3 which by all means is the quietest turbo out of these three, yet it makes the most power though.... At 15psi i cant even hear the turbo, all you hear is blow off when i shift but never any spool. You wouldnt even think it was turbo. At 20 psi it starts to make some spooling noise but you have to still really listen to it. I have a vid up on street fire of me accelerating 10-80mph in the dsm section and a friend who watched it asked whyd it sound all motor....

A theory I had was that the more Intake resistence the more noise, but maybe this is what you mean by turbulance. But im talking intake resistance thru the whole intake side.
But anyways I believe the air we hear as spool is just air squeezing thru the intake side causing resistence, ( hard pipes just amplifies this noise. ) the more air your intake side can hold the lesser the sound ( i.e. bigger fmic, bigger piping, longer route piping. But for instance, running a bigger turbo and really cranking the boost up you start spooling really loud because your forcing more and more air thru the same amount of space were as on low boost you might not hear anything because the air isnt fighting as much to push forward or escape.

Another example of my theory on my old gst i had 3inch turboback exhaust no cat or muffler and everything on the intake side was stock except cone filter, mass, and it was running 15psi and that thing spooled real loud... Why; because of the small stock smic, small intake piping, small tb elbow. Were as once i got a fmic ( changing nothing else, and never was a boost leak ) the spool noise was almost gone which is same as on my laser which as a fairly big fmic and long route piping to dampen noise. ( Picture blowing x amount of air thru a straw vs thru a pipe for example.) Have you ever heard a muffler with a silencer in it on a car that flowed a decent amount of air, it hisses real bad as the air trys to squeeze out. but obviously the more air your trying to push thru the louder spool will get...

Just my thoughts upon the subject.

 

[Black_Bullet]

Oh and one more thing we all cant really compare who spools louder or why some of us dont spool at all despite having the same turbos or same boost because were all at different altitudes with different type of air, and we all run different set ups, different exhaust, different fmics and pipings so we have a different amount of intake resistence and backpressure. Just my 2 cents. Constructive critism welcomed.