Scotty II w/ hole cut turbine whine

[rweis]

The earplugs work WELL!



Drove to work today with windows down. Can hear traffic, had to add a little treble to the radio equalizer, the higher frequency the turbine goes the more it cuts the high frequency sound. At 1600 rpm you can faintly hear the turbine, at 1800 you have to really listen to hear it, over 2000 undetectable. Radio sound is just fine with a little more treble. There is a little attenuation of all sounds in all frequencies.



Scotty II can breathe and I can hear!



Still will work on quieting the turbine, but much less priority now. Not bad for $8. 90 which includes shipping!



Bob Weis

 

[RustyJC]

Bob,



Congratulations! Glad the earplugs work. Still don't think I could sell that as a solution to my wife, though. "Here, honey, just put these in and it'll be fine!"



Rusty

 

[willyslover]

BUTTTTT Rusty it's where she will put them that will get your attention

 

[rweis]

Well she talks about how noisy the diesel is normally and this certainly quietens it down and the $ is right.



I tried to think about from her perspective, you have a LOT less road noise, the radio sounds fuller, my wife reads when we are traveling and I think she will be able to enjoy her reading more, and I had one of the people here at work carry on a subdued conversation with me with the plugs in and it was almost normal volume and understandability.



Tommorrow (friday) I am going to line the Scotty II with the EDAM rubber. I was thinking the sound has to come up the air hose from the compressor, then into the filter and out the sides since the end is capped. If I can reduce the amplitude of the sound waves as they come out of the filter and not disturb or slow down the air flow going into the filter, might have a chance.



I can see your point about the length of the straight inlet needed. We were very careful to guide the air into the turbines on aircraft to keep the compressor from stalling, keep flow directivity, and have a good perpendicular flow for the compressor blade to bite into.



The Scotty II is large enough diameter so I should be able to get my hands and material in there and get it smoothly laid to not disturb the air flow. Should be an interesting project and I will let you know what the results are.



IF that does not work well, then I am going to line the air inlet channels by the windshield with rubber, and build a dam to further isolate the cab cowl opening.



--------------------------

NOTE: I WANT TO MAKE ABSOLUTELY SURE ALL THAT READ THIS THAT THE SCOTTY II DOES AN EXCELLANT JOB AT LOWERING EGT TEMPS. IT DOES EXACTELY AS ADVERTISED AND DOES IT WELL.



I HAVE AN ADVANCED TURBO AND I THINK A LOT OF THE SOUND LIES WITH THE LARGER COMPRESSOR AND SIGNIFICANTLY GREATER AIR FLOW.



I JUST DID NOT WANT ANYONE TO THINK BADLY OF THE SCOTTY II. THIS WAS NOT PROMPTED BY ANYONE, JUST THAT I WANTED TO MAKE ABSOLUTELY SURE WHOEVER IS READING THIS KNOWS THAT SOMETIMES WE GET ON THE LEADING EDGE AND HAVE TO FIGUER THINGS OUT AS WE GO.

---------------------------



Bob Weis

 

[RSnaith]

Originally posted by rweis

The Scotty II is large enough diameter so I should be able to get my hands and material in there and get it smoothly laid to not disturb the air flow. Should be an interesting project and I will let you know what the results are.

I've been reading this thread with great interest, as really the only drawback we have with the Scotty II is the increased cabin noise. Some folks are able to hack it, others can't, some others love the noise. Personally, I found the noise with an HX35 a little tough on the ears (too high pitched), however a larger turbo would relieve it.



Bob, your idea of lining the cowl has some merit, although I believe Scotty gave this a go and it didn't work for him. Maybe the materials you're trying are a little different than his. Be careful with adding any material into the inside of housing. I can see 2 potential problems with this approach:



1) The diameter of the Scotty housing isn't by accident. This particular housing size gives us the best EGT reductions. Going smaller or larger tends to reduce the effectiveness.



2) Please, please make sure the adhesive is a very good one. If the liner peeled off and stuck to the filter, I'd be scared of a filter collapse at high boost.



And I'll throw out one of our customer's mad science experiments as more thoughts to chew on: With his original Scotty I, he scalloped the edges of cowl inlet, like a stealth fighter trailing edge. His truck was significantly quieter in the cabin, and there was no decrease in effectiveness of the unit. He hadn't tried it with the II, as the nozzle of II no longer protrudes into the cowl inlet. It may not work without the protrusion, but you may be able to build a scalloped cap that will nestle inside the cowl hole.

 

[rweis]

I lined about 80% of the inside of the SII with EDAM rubber. I did not line the SII fender side hole. The EDAM rubber is extremely tenacious and stuck very well.



No effect on turbine noise. I did not line the narrow end of the SII as it necks down because ther was a fit issue with the air difuser end cone.



As an experiment I went back to the stock box with the fender port.



Turbine noise reduced by about 75% (ie very significantly, no db meter) Might be because the turbine noise is completely enclosed in a box. This noise level of the stock box is the target level for now.



Tommorrow is another day, will keep updates comming as I get to them.



Bob Weis

 

[rweis]

Went back to the S II covered the cowl end (still have the cowl actual hole) to force draw from the side vent.



About the same as the stock air box.



Tried ear plugs with S II side vent draw only and zero whine.



Took the EDAM rubber lining out from inside the S II. No difference.



Lined the OUTSIDE of the S II with EDAM. Helped a little, but not much.



Tried to fit a 4" 90* elbow in cowl opening to see if I could divert sound, not enough physical room in the air inlet pasages for a elbow.



Company tommorrow, no more expermentation this weekend.



Next is to try an air dam. Thinking of using expanding foam and blocking the S II channel air inlet just to the right of the S II cowl opening as you are looking at the cowl opening from the engine compartment. Will provide for water runoff with a tube interconnect. Maybe then go toward the cab inlet and do a second dam to its left to seperate the two inlet area by some physical distance of maybe 9" or so.



If anyone has any input please jump in here.



So far it seems that lining the inside of the S II had no effect. Lining the outside of the S II has some minor effect. When I do the air inlet dam will line the air inlet channel with EDAM.



Bob Weis

 

[Ram4Sam]

Wonder if this would help....

Look at this link

http://www.dieselpowerproducts.com/tag



Scroll down to the bottom of the page. They claim it reduces the intake noise. Anyboby want to be the guinea pig? I too have a Scotty II sitting on the shelf because of the noise.



Sam

 

[rweis]

Well that is certainly interesting. I wonder if it sort of answers the 5. 5 times the inlet diameter for the length of the incomming pipe for proper air flow.



Any ideas?



What are your thoughts about it really does straighten out the airflow? Would it be better if it filled the entire length of the compressor inlet housing?



What about the NON Holset turbines? ie Garett's etc?



Kurt - your ideas?



Scotty1 - your ideas?



RSnaith - your ideas?



Could be the start of something really interesting. Would any kind of a bundled pipeing insert that fit the compressor inlet do the same? They imply it does not change the compressor characteristics but maybe for the better.



Bob Weis

 

[RJ2]

My k&N 0880 was too annoying out on the road , the BHAF helped reduce the whine to almost nill.

 

[rweis]

As this thread goes along there is one variable that could help in mentioning each time, which turbo each of us has.



As there are several different turbos out there could you please mention which you have ie HY35 or HX35 or HX40 or PDR40 or KS45 or KSB1B or XXXX.



It might make a difference which turbo and the solution or part of solution you did or are working with because different turbos probably have different sound characteristics.



Just an idea.



Bob Weis



KSB1B

 

[JGK]

Ram4Sam,



Re: TAG



Early this spring we had a local dyno-day and one rammer had one of these. He did a run with it out and another with it in. Lost a few HP with it in, as I remember. He pulled it and filed it the "round file".



-Jay

 

[RustyJC]

Originally posted by JGK

Early this spring we had a local dyno-day and one rammer had one of these. He did a run with it out and another with it in. Lost a few HP with it in, as I remember. He pulled it and filed it the "round file".

Yeah, while correct in principle, in this specific application I would wager that the device is too "thin" to be effective. The flow has to be held in the cells for a decent amount of time to remove turbulence. Similar industrial flow straightening devices I've seen with a similar total OD have a length-to-diameter ratio that would look more like a cluster of soda straws.



Rusty

 

[rweis]

Rusty,



If one were to find or figuer out how to get a bundle of tubes (probably stainless steel, and what diameter tubes) bundled together to fit the opening of the compressor (and what general length would they need to be) do you think that it MIGHT help solve the centrifugal compressor noise? by straightening the air flow?



OR



Do you have other thoughts that might bear on the possibilities of reducing the compressor noise?



Just trying to pick your thoughts on some possible avenues of maybe being to reduce the compressor noise some.



Bob Weis

 

[RustyJC]

Well, if I were going to make a test setup, I'd take advantage of all the length available to me (which, with the stock rubber inlet duct, isn't much). I'd have the tubes begin just downstream from the point where the inlet duct transitions from its 180* bend into the straight run into the turbo. I'd hold these tubes in a support plate at each end with that plate OD being just smaller than the duct ID. You could then slip the tube bundle into the duct and secure it with hose clamps placed over the duct to compress the duct onto the support plates.



Even at this, however, we haven't addressed the problem that, due to inertia and the mass of the air, the flow is going to want to hug the outside of the 180* bend. In other words, we might be able to remove a lot of the turbulence from the flow, but you'll still tend to have more flow through the "outside" than the "inside" tubes based on the orientation of the tubes when they pick up the air. You will also see a pressure drop through the tube bundle, but the balancing act is to gain more efficiency through non-turbulent flow than you lose through pressure drop.



It would be an interesting project... ...



Rusty

 

[rweis]

Rusty



With enough head scratching, and enough questions, with all the talent on this board, and a little brainstorming, something is going to pop up.



And if the tubes went the entire length instead of just at the straight section going into the compressor? A bundled tube system maybe replacing the rubber duct entirely? Small enough tubes to keep turbulence down, but large enough to pass the largest percentage of the air.



Sort of like bundled 3/8"? (copper? stainless? tygon?) tubing with an adapter on each end to mate with the filter and the compressor and itself would be the total duct.



The starting pressures would be uniform across the face of the bundle, with the bend etc, would the pressures become uniform across the face of the bundle when exiting?



Could you turn the outside tubes to end up on the inside of the bend, and the inside tubes to end up on the outside of the bend ie all tubes the same length or nearly so?



Wonder what the air flow characteristics would be like?



Bob Weis

 

[RustyJC]

Originally posted by rweis

And if the tubes went the entire length instead of just at the straight section going into the compressor? A bundled tube system maybe replacing the rubber duct entirely? Small enough tubes to keep turbulence down, but large enough to pass the largest percentage of the air.



Sort of like bundled 3/8"? (copper? stainless? tygon?) tubing with an adapter on each end to mate with the filter and the compressor and itself would be the total duct.

The problem will be pressure drop. With the multiple long tubes, look at the ratio of surface area to flow area. The long surface area will generate a lot of drag. You really don't want the flow straightener to be any longer than required for this reason, all else being equal.

The starting pressures would be uniform across the face of the bundle, with the bend etc, would the pressures become uniform across the face of the bundle when exiting?

Basically, yes. The inside tubes with tighter radius would have a little more pressure drop, thus, less flow, but the pressure map across the face of the flow straightener would be better than the stock rubber inlet duct.

Could you turn the outside tubes to end up on the inside of the bend, and the inside tubes to end up on the outside of the bend ie all tubes the same length or nearly so?

I'd have to lay it out and see how the geometries worked out. You could probably get pretty close by putting a 1/2 twist on it.

Wonder what the air flow characteristics would be like?

Good pressure map across the flow face, but somewhat higher pressure drop from inlet to discharge of the flow straightener due to surface drag.



Going back to the idea of just putting the flow straightener in the straight portion of the inlet duct leading into the turbocharger, each tube behaves as an independent inlet duct, so you could pretty quickly calculate the required "thickness" of the flow straightener by using the 5 x diameter formula. If you used thinwall 1/2" diameter tubing, the flow straightener would need to be a minimum of 2-1/2" thick. That's the shortcoming of the aftermarket device pictured earlier in this thread, IMHO.



Rusty

 

[rweis]

Rusty,



2 1/2" depth is not a whole lot and would probably fit inside of what we have (rubber duct) before it starts to do the bend.



I am going to investigate smoothing out the inside of the tube by using something other than the rubber corregated hose. It might be something as simple as PVC pipe (might absorbe some of the sound as well). I think a friend can use a commercial PVC heater bending tool to get the bends pretty right on.



Then if you can straighten the air flow with a 2 1/2" package we probably can figuer out a set screw holding system to make absolutely sure the package does not shift or move.



I'll get a Db meter so I can make accurate measurements for pitch and volume so we know what I do is good or no effect or bad.



I have a KSB1B, you have?



Bob Weis

 

[RustyJC]

Originally posted by rweis

I have a KSB1B, you have?

Just a plain Jane stock HX35W-12 on a lightly-modified (EZ, intake & exhaust) ETH/DEE - our truck is used almost exclusively to tow our 5th wheel. With the BHAF, I really don't have a turbo noise problem. Exhaust drone - that's another matter! Gotta get that resonator from Jerry Jardine!



Rusty

 

[rubberneck]

rweis, i think that the B1 is just a loud turbo. As mentioned before, I love the sound of the B1, the problem was when coupled with the scotty2, it sounded like the turbo was mounted right behind the radio. I just couldn't take it and benched the scotty. I run a Mega cannon now and love the sound of the B1. Nice clean whistle. not too loud, (for me anyway, wife is another story LOL) but you definitely know there is something under there