Where does the sound come from? Does it come from the air filter or do you hear it from the exhaust? I've gutted the kitty, installed a 3" downpipe, removed the muffler, and ran 3 1/2" pipe over the axle and out behind the rear tire just like stock. When I push 3-6 psi of boost I thought I'd hear her whistle but I don't hear much more than the sweet rumble of exhaust... What else can I do???

That's how mine is, and the turbo whistle is very audible. No cat/no muffler = turbo whistle.

turbo whistle is inlet air velocity. opening exhaust allows the turbines to spin more freely there for giving more inlet pressure. get a different air filter or open your original air box. you usually dont hear much whistle till after 6psi...

turbo whistle is inlet air velocity. opening exhaust allows the turbines to spin more freely there for giving more inlet pressure. get a different air filter or open your original air box. you usually dont hear much whistle till after 6psi...

yup, thats it exactly. people have bought a cone filter from auto zone and modified it to fit for more flow. mines extremely loud! have gotten complements from psd drivers.

yup, thats it exactly. people have bought a cone filter from auto zone and modified it to fit for more flow. mines extremely loud! have gotten complements from psd drivers.

any were from 6-8 psi and on mine whistles like crazy. when i was running high boost, it was almost to loud:eek:

yeah, i was kind of wondering the same thing....i have the SS diesel 3" downpipe and a 4" straight through and i can only hear the turbo when i rev the p*ss out of it....yet a buddy of mine has either a 95 or a 96 with maybe a 3 or 3.5 exhaust and possibly stock downpipe and his spool sounds like a cummins.....i want mine to sound like that!

hey cdg what type of filter do you have?

i ordered it from SS diesel supply

so with that filter yours doesnt whistle?

not untill i rev it a lot...not like my friends whose whistles like mad at idle

the 6.5s dont really whistle at idle. you can get some with straight pipe but not much. you do have to rev them pretty good to get them to whistle when youre not driving. your buddy must have a different turbo or something.

My 00 used to whistle pretty good at idle..... then i put on a holset, less whistle at idle but more power up in the higher rpms. Nice trade off.

i have a lil whistle @ idle it starts to get loud when the turbo spools around 1100rpms and extremely loud when i peg her and i hit 13-14psi. i love that sound!:ro) i dont think i could ever get sick of it.

I'm not sure that I got an answer there... Does the sound come from the tailpipe or from the air filter?

turbo whistle is inlet air velocity. opening exhaust allows the turbines to spin more freely there for giving more inlet pressure. get a different air filter or open your original air box. you usually dont hear much whistle till after 6psi...

dieselboy28 already did.

a little of both:D

well, my truck whistles out of the exhaust.... sounds great driving along a barrier w/ a load on very slowly. Nice whistle. Once my truck gets up in the r's, the exhaust overpowers the whistle.

I'm sure Turbine Doc will hammer me within moments of this posting but I've always believed the whistle occurs as a result of airflow shearing as it turns a 90 degree turn which would mean that whistle/whine occurs at both the inlet and exhaust sides of the turbo.

well it does. when youre out side of the truck youre hearing the exhaust side throught the pipes and when youre in the truck and going down the road its the inlet air you hear.

Thanks for the answers... My tailpipe has a slight angle forward, which creates problems because it gets soot on the back fender. That may be part of my problem, if you think about it, the exhaust coming out gets hit with the wind coming around the truck. I know I can't whistle while the wind's blowing in my face.....

That's how mine is, and the turbo whistle is very audible. No cat/no muffler = turbo whistle.

I agree. My truck is set up like that (look at my signature) and all you hear is the turbo screaming off of idle. I also took off and plugged the turbo baffle. I think that's the right name for it.

Mine whistles at idle a bit, you have to be near the tailpipe to hear it. 2-3 psi coasting around town the turbo is very loud out the tailpipe and it stays loud until the exhaust note starts to got loud enough to over power it. You can not hear the turbo intake until 10psi and it gets alot louder with more boost. I should really set my video camera on the side of the road and roll by it so you guys can hear the turbo through the exhaust. The muffler does not seem to cancel the turbo noise but it softens the exhaust pulse significantly.

What does your "turbo baffle" look like P.K.? I have done a bit of work with turbos and i have never heard of it.

When looking at the turbo....It's that plastic tube that comes out of the snorkel, and it bolts up to the front of the block. Its black with a 90deg bend, about a foot and a half long, and plugged at one end. If you need a pic of how to plug it let me know.

95's don't have the baffle. I belive only the trucks that came with the round air filter have those.

My bad i assumed the 95 was the same as my round filter 97. Well disreguard then, sorry.

95's don't have the baffle. I belive only the trucks that came with the round air filter have those.

i think its actually called or has been referred to as the turbo muffler or something like that. but like matt said they were not on 95s and older bc they had the panel filter which just sucked to begin with...or did it not suck...either way there was absolutly no whistle with them!

I noticed opening the air intake (filter) area up makes the turbo most noticable, but I can hear mine from behind the exhaust as well.

I'm sure Turbine Doc will hammer me within moments of this posting but I've always believed the whistle occurs as a result of airflow shearing as it turns a 90 degree turn which would mean that whistle/whine occurs at both the inlet and exhaust sides of the turbo.

This is partially correct. The whistle will change with the angle and degree of the turbine fins. This is why an LLY will change it's note completely at idle going from a TD whistle to a gasser growl.

Powder Keg I'd like to see how you plugged your turbo baffle

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I machined this out of 7075 T-6 aluminum. It has a recessed slot for that hose clamp to fit into. If you want exact dimensions let me know and ill pull it out and get them for you.

Nice, lovin it P.K.

Hey CDG, where did you get your chip, and how much was it? Was it worth it?

I haven't got it yet, its on my list though...the one that i am planning on getting is from SS Diesel Supply

I have seen the odd frost plug jammed in there too. Not sure of the size.

Freeze plug in mine 1-5/8" IIRC liberal application of black RTV to make it visually blend in.

Sorry to tell you P.K. but with OBDII you have to get a reflash, with OBDI we get to by a chip which is much cheaper.

-:t Crap!!!

Powder Keg, I like the plug, great job.... Can anyone tell me what that "turbo muffler" is there for?

i think its actually called or has been referred to as the turbo muffler or something like that. but like matt said they were not on 95s and older bc they had the panel filter which just sucked to begin with...or did it not suck...either way there was absolutly no whistle with them!

That is why I can't hear my turbo?!! I've been trying to figure that out. Thought somethig was wrong.

yep, does the same thing as a muffler on the exhaust does...cancels out the sound. no i know my didnt have one...i dunno if 95 did or not. but for sure i think 96 and up did.

That is why I can't hear my turbo?!! I've been trying to figure that out. Thought somethig was wrong.

partially, you cant really hear the ones without the mufflers either. problem is you dont hear the turbo till about 6psi+ and stock only goes to like 8psi and youre rapped up so you wont hear it anyways. an air intake and exhaust will let you hear it.

well i have a filter and exhaust and i hear that thing spool up @ 900 rpms...man is it sweet!

well i have a filter and exhaust and i hear that thing spool up @ 900 rpms...man is it sweet!

I get almost the Cummins sound from idle to about 900RPM (not near as loud), and if i cruise at like 25 mph its really loud, then it just screams to just below WOT. That all happened after gutting the intake, EGR mods, and plugging that muffler. Ya it was ok with the new exhaust but now its badda**! I have alot of people always asking what i have in my truck!
:cool2:

That is why I can't hear my turbo?!! I've been trying to figure that out. Thought somethig was wrong.

Straight pipe is a must!! :ro) I went with 3" cause i figured that since it was only 3" out of the turbo it would be a waste of money. Looking back iwish i would have gone with 4", it sounds better and looks way cool with a 5" tip on it! :banghead:

Straight pipe is a must!! :ro) I went with 3" cause i figured that since it was only 3" out of the turbo it would be a waste of money. Looking back iwish i would have gone with 4", it sounds better and looks way cool with a 5" tip on it! :banghead:

you d@mn straight it does!:ro) ive gotten a few comments about what i run. theyre always surprised when i tell them its a 6.5l td.

You people with 98's should get back to SS Diesel, they're now offering a filter and replacement plumbing for that nasty old factory intake. It looks sweeeeeeet, and ill let you know just how good it is when i get it.

the 6.5s dont really whistle at idle. you can get some with straight pipe but not much. you do have to rev them pretty good to get them to whistle when youre not driving. your buddy must have a different turbo or something.

File a small notch in one of the inlet compressor fins. or give it a slight tweak. It will whistle like crazy!
Don't laugh, I don't suggest this, but Ihave had more customers show up with it done than I can count;-)

File a small notch in one of the inlet compressor fins. or give it a slight tweak. It will whistle like crazy!
Don't laugh, I don't suggest this, but Ihave had more customers show up with it done than I can count;-)


wow all that for a little turbo whistle?

I took my turbo muffler off and cut off the rounded end (about 1 1/2 inches), then i used that and the factory pinch clamp (from where the muffler connects to the intake) to block the hole. I had to give it a few wraps of electrical tape to get a good tight fit, then i pinched the clamp tight with a set of dull end nip pliers. To finish it all off i took a yellow paint marker and put that 'joe boxer' happy face on it (i had lots of beer that day).

Turbos whistle on both the compressor (intake) and tubine (exhaust) side. Which you hear depends on the turbo design, intake design, engine loudness, load, exhaust design, etc.

On my Suburban, with the 4" exhaust upgrade, I can clearly hear the turbine side whistle out the exhaust at idle and when just spooling up or down, especially if I have the right rear door window down (closest to the exhaust outlet), and the other windows up to isolate the exhaust from the engine sound - then I can hear it easily, especially when first taking off from a stop, and when getting off the accelerator as the turbo spools down. Sounds just like a semi's turbo out the exhaust. :ro)

When I go full throttle, or even part throttle, I can't hear the turbo whistle anymore as the V-8 rumble out the exhaust completely drowns out the turbo whistle. The turbo whistle is still there, but you can't hear it over the roar of the engine roar out the exhaust.

From the compressor side, I can hear it whistle too, but under opposite conditions. I can only hear the compressor (intake) whistle under moderate to high boost, and only with all of the windows up and the radio off. Low boost, don't hear it. I have the stock air filter. I'm sure it makes an intake whistle all the time, but the diesel clatter drowns it out, which is why I can only hear it with the windows up.

My 1983 Thunderbird turbo coupe I used to own had a Garett T-3 turbo that had a VERY loud intake compressor whistle when it would spool up and down. The turbo would really sing. Sounded awesome! But, no exhaust whistle from that one.

File a small notch in one of the inlet compressor fins. or give it a slight tweak. It will whistle like crazy!
Don't laugh, I don't suggest this, but Ihave had more customers show up with it done than I can count;-)

Wouldn't you make things go out of wak if you tweak the the fin?

yeah, i was kind of wondering the same thing....i have the SS diesel 3" downpipe and a 4" straight through and i can only hear the turbo when i rev the p*ss out of it....yet a buddy of mine has either a 95 or a 96 with maybe a 3 or 3.5 exhaust and possibly stock downpipe and his spool sounds like a cummins.....i want mine to sound like that!

Same here I have the 4'' SS exhaust kit and the SS air intake and I could only hear it untill I rev. it pretty high.(about 5psi I beggin to hear it)
That sucks I wish I could hear it sooner. :mad: Censored :mad:

Wouldn't you make things go out of wak if you tweak the the fin?

If it didn't, I would be out there with a file right NOW. I'd be afraid of the balance on something that can spin to 100,000 rpm +.

Same here I have the 4'' SS exhaust kit and the SS air intake and I could only hear it untill I rev. it pretty high.(about 5psi I beggin to hear it)
That sucks I wish I could hear it sooner. :mad: Censored :mad:

put a intercooler on it and youll hear it alot better. it doesnt really start to get with it until 5 psi though

I just put a straight pipe on mine. I can hear the turbo whilst driving but not at idle...which would seem to be normal.

I have the stock wastegate control and it is now driving me nuts (since I can now hear the turbo). The turbo comes in...goes out...comes in...goes out.

My wife thought the police were chasing me as the turbo spooled up and down!

By the way...the 6.5TD with a straight pipe is not as obnoxious as a 350 but darn near. I'm getting a muffler.

I have the stock wastegate control and it is now driving me nuts (since I can now hear the turbo). The turbo comes in...goes out...comes in...goes out.

When mine did that, I needed a wastegate solenoid.

I have OEM exhuast and OEM intake including a typical paper element. When im building boost above 6psi you can baarely hear the turbo whistle. When I threw an open element filter on the front of the turbo, WOW turbo whistle!! (And a got a BOV sound from out of the tuna can too!) However AITs got a wee bit out of control I think with it sucking in hot engine air...

If it didn't, I would be out there with a file right NOW. I'd be afraid of the balance on something that can spin to 100,000 rpm +.

Actually Id guess around 150,000 rpm, but yeah, i cant imagine what that would do to the shaft bearing surfaces! :eek:

Like I said, i would not do it. but I seen it done plenty, even on OTR trucks.
yeah, it hurts the life of the turbo, but from what I have seen not enough to notice. None of the trucks that idiots had done this to were in for turbo overhauls.