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Turbo.. scream?? , ...myth??

3K views 25 replies 17 participants last post by  96GMC6.5L 
#1 · (Edited)
so,. this truck is new to me,. so far i,ve deduced that it has no vacuum for the wastegate,. so of course i wired the gate closed, (please no rants here i,m only running empty and using it as a toy quite gently) i then removed the snorkle, and swiss cheesed the airbox, but i still don't hear a turbo whistle,.(even at short WOT) and truthfully i don't feel much difference in the sotp when driving it,.i did clear my 36+78 codes and so far haven't got any more,.this is my first turbo dizzle, ('cept my big trucks)
Does the factory air cleaner quieten down the turbo that much?? or do i have a defunct turbo,.(i know, i know, i gotta get the guage in,.but look at weather right now, high winds drifting blowing snow etc,-ffff--ing ccccold.)
nick
 
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#2 ·
Do you have a big exhaust, I think its needed before you get any whistle.
 
#3 ·
I had plenty of whistle with my setup (97+ air filter mod and stock exhaust)...
 
#4 ·
I purchased mine last Sept. 100% stock, added a panel filter thinking it might get a little louder but didn't do much at all. It wasn't till I installed a cold air intake from SS diesel that I heard the turbo. The intakes from the factory are very restrictive, even removing the snorkel helps it, but not a whole lot. It's like breathing through a straw, if the intake source is too small to begin with, there's not much to help it. Haven't heard of people swiss cheesing the air box, so not sure if that's helping or not.
 
#5 ·
your really only gonna hear a good whistle is you have a more open exhaust and you hit over 6 or 7 PSI. The factory exhaust is somewhat restrictive and the turbo will spool slower, keeping the noise down. Also as Tows Alot mentioned if you have the snorkel on there, it quiets things down. The snorkel is a plastic tube attach to the rubber elbow between the turbo and air filter. Yank it out and plug the hole with a proper size rubber freeze plug.

Get at least get a boost gauge quickly, and an EGT when as soon as you can. Look up "step x step" in the search for an easy to make manual boost controller. Look into getting an exhaust, or maybe replacing/gutting your cat converter.
 
#6 ·
You could hear my turbo whine on my 97, the only thing I did was remove the snorkle (silencer air tube), and installed a Turbo Master Boost Controller from Heath Diesel (junked the stupid vacuum pump!). I used the factory style air filter and the air box was uncut, but did not use the top cover on the air box though. I did have the boost jacked to around 10 lbs. though, and stock exhaust...... You could hear it really well, but not as much as my brother's 95 model with the same things done to it, plus 4 inch exhaust.
 
#7 ·
My 94' used to scream. You could hear that thing as soon as it started, pleanty of whine. Now on my 97' I can't get that Turbo to make any noise at all. The only time I heard it was when the intercooler pipe came off. I have the intake muffler removed, foam filter, no box top, 3-4" exhaust, intercooled, & not a peep.......lame!
 
#8 ·
I have a very free flow intake, turbo master equivilent, good downpipe but rest of exhaust is factory and I get zero whistle. The truck still has the original GM-3 turbo, amybe that is a factor but have heard others report whistle on thier 93's.

Phantom have you removed the snorckle in the fender?
 
#9 ·
Turbo scream

Hey Scrufdog,
Are there any benefits to the snorkel? Or is it just to quiet down the turbo?
 
#10 ·
What a lot of people don't realize is the OEM's have to please everybody that would possibly drive something like what we have, be it either 15 years old to 150 years old (haha). So that includes how quiet a vehicle is, interior and exterior. It's up to us to try for more power and noise if that's what we're after, and I believe the snorkel and restrictive intake were put in place to make the turbo as quiet as possible. Plus GM might have been trying to make it as much of a cold air intake from the grill as possible.
 
#12 ·
Phantom, turbo whistle is there just gotta let it out to be heard. you need to build a box and put a big cone filter inside. your 94' has the bigger elbow that attaches to the turbo so that is fine. this set-up will let out some whistle. Add a 4" exhaust and you will love the sound the turbo makes. makes a guy want to hot foot it all the time just to hear it. there goes the mileage but man is it fun.
Below is a picture of the airbox I put in my truck. This box seals to the hood, so no hot air gets sucked in. Whistle starts at 900rpm and at my max boost of 9psi she's screaming.
 

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#13 ·
Mine was loud enough to be heard coming up the road, and inside the truck with the windows up or down, with the stock air box (no top, and a Fram Extra Gaurd filter) and no mods. Mine did have the GM8 turbo, but doubt it would make much difference between the GM6 and the GM4 turbos as far as whine goes. Mine would get louder and louder the more you push the go pedal, where as my brother's truck, you can hear his louder at lower rpms (compared to mine), and the whine just goes away in the upper rpm range, but like I said, he's got 4" exhaust.

Actually mine was around 12-13 lbs. of boost, and all stock....:eek: :D Not really recommended....but mine ran good, like that for 3 years, and it's still running great with 206,8XX miles on it! I just don't own it anymore.
 
#14 ·
Stock air box, K&N flat panel, Banks 3" exhaust (still have cat as it is required in this state if OEM). Whistle? Yes. Screams? No. I wonder if the hole :eek: I cut in my fender made a difference?:D
 
#15 ·
Mine does not have a snorkel the same as some, it's more of a duct that routes air from a hole in the front to a hole in the fender. The intention of each is to get cold air into the air box.

Substituting hot air for the cold air is not good. You need to get more cold air into the air box.
 
#16 · (Edited)
Thanks for all your interesting rplies here, some might need to re-read my post tho,. my truck is 3500 'f' motor with no cat/egr, and i did say i removed the snorkle then swiss cheesed the airbox,.
It would seem these turbo's have no rhyme or reason at the moment,. some whistle, some don't,. very Interesting,.i like your setup bknopp did you build it youself?
Our last caterpillar had a terrific turbo sound to it, (550hp e model) the detroit 60 we have right now is audible at the lower rpm, but goes silent as the revs climb north of 1700,.
I was actually hoping to get turbo sound out of the dually, and yes i will be putting on 4"" exhaust with a better downpipe, probably with a 'fake' muffler,.
We were joking around today, and i help up a 110" 5" chrome straight pipe underneath the running board, it would look wild to have the pair on there,..:D i magine the sound would be unique too,.
i also have scored a gm8 turbo to add on when i do the manual w/g
mebbe it'll be "noisy' ??
Nick
 
#19 ·
i don't hear my turbo until I hit 11-15 lbs of boost and it whines pertty good but not till that point
 
#20 ·
Scrufdog;1575848; said:
your really only gonna hear a good whistle is you have a more open exhaust and you hit over 6 or 7 PSI. The factory exhaust is somewhat restrictive and the turbo will spool slower, keeping the noise down. Also as Tows Alot mentioned if you have the snorkel on there, it quiets things down. The snorkel is a plastic tube attach to the rubber elbow between the turbo and air filter. Yank it out and plug the hole with a proper size rubber freeze plug.

Get at least get a boost gauge quickly, and an EGT when as soon as you can. Look up "step x step" in the search for an easy to make manual boost controller. Look into getting an exhaust, or maybe replacing/gutting your cat converter.
hey budd, that's funny you should mention that snorkel thingy. i'm gonna dump mine and see if my 4 inch and MY mech "step X step" doesn't make my turbo whistle. yup I can proudly say i take credit for that post. anyhow check back here in 24 hours for a new thread, i'll call it poor mans snorkel. it came to me in a dream last nite. Ed
 
#21 ·
cool.

hey phantom, have you actually checked to make sure you dont have a cat? My F engine came with a cat. No idea where the cat is now, but it used to be there.
 
#22 ·
Scrufdog;1577188; said:
cool.

hey phantom, have you actually checked to make sure you dont have a cat? My F engine came with a cat. No idea where the cat is now, but it used to be there.
yes scruffy,. down pipe-flange- almost straight back till the big ugly round muffler, then the t/p.
I think the next test might involve no intake at all, for a short squirt to see if there's any turbo noise,
nick
 
#24 ·
I have a stock 95 air box with K&N. I can hear my turbo singing.

You don't want to spool up the turbo without an intake. There is no place for the boost to build up. Turbo may get damaged.
 
#26 ·
I have the stock 97 airbox with a NAPA filter and I can hear it o.k. when I shut the fan and radio off.
 
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