Re-Silenced, pre-turbo...

[Duck]

After I removed my silencer ring, it took noticeably longer for the turbo to come up to speed. I thought at first that the seat of my pants just needed to get re-synchronized with my ears, but after a couple weeks of driving, some of it towing in the AZ mountains, I put the ring back in and can definitely say the turbo was indeed spooling up slower without it. Sorry CAT



Which reminded me and got me thinking of something I saw on another web page (here ) while looking at the Aeroturbine. It's basically a circular honeycombed piece that is held in place with a silencer ring.



The good news: I can't believe how quickly it spools up now. Feels like it responds faster in any gear. Noticeably faster spool up going uphill with load.



The bad news: The turbo whine is at stock levels. It takes the swirling air and redirects it into a straight stream, distributing evenly over the blades. Thus, the turbo is making better use of the available air which equates (i guess) to less turbo whine.



So, if

more efficient air flow = less turbo whine

then does

more turbo whine = inefficient air flow?



In other words, devil's advocate here, I wonder if removing the X-baffle thingy and the silencer ring is really a good idea?

 

[Vaughn MacKenzie]

Kent Earnest (KEarnest) and I were involved somewhat in the R&D (Kent was more than I was) and we noticed the same thing, quieter operation & less turbo whine with the honeycomb piece in place. The piece seems to do its job at increasing turbo efficiency. It was actually a nice thing on Kent's 98. 5 running the open-element BHAF because the turbo whine was quite loud without the honeycomb piece.



Another gizmo we tried was the deep funnel-shaped "silencer" piece that coned down the airflow & aimed right at the turbine blades. While this made the turbo quieter I didn't see any noticeable performance gains.



As soon as I get a chance I'm dropping by Diesel Power Products to pick up his latest one to try on my '03, but it'll probably be next week. It is an interesting piece of crafstmanship with the ligh-gauge stainless used to construct the thing, which wasn't easy. Dave tried injection-molded plastic but it didn't work out as well being the holes were square and much larger (not much noticeable improvement).



Vaughn

 

[Fireman]

At $129 it had better be good!



Fireman

 

[JBlock]

Dyno Runs

Has anyone run on dyno for real numbers, i love to silence the intake then cut the hole for the Scotty 2, but would want to raise the temperature or lower the power?



JB

 

[Shooter]

I quit reading when it said that EGT's were higher.

 

[Duck]

I asked about that. It's just not written very well. They're trying to say that EGT's were higher without it.

 

[Blakers]

It would be nice if someone had some dyno numbers indicating whether there is a gain or loss by removing the silencer ring.



My truck sounds better and is nicer to drive with it out. I like to hear an engine as it makes it easier to tell the load on it and when to shift.

 

[CATCRACKER]

duck,



mine is in for good. i still want to thank you for the inspiration for 315's and level kit sorry my advice didnt work out so well. sorry to get off the subject but while i have your ear whatever happened w/ your front end?

 

[Duck]

Hey, different strokes for different folks. I like turbo whine as much as the next guy. It's just after towing in the mountains over a weekend it felt like I was always waiting for the thing to spool up. I bought it for towing, so it just didn't sit right with me. It was a blast around town though I'm thinking a Ram Air system and Aeroturbine will bring back the whine.



Front end- They said a torsion bar bolt came loose. They tightened it and I was on my way. Felt kind of silly having it towed in, but it was pitch dark when it happened and I had to leave it at my friend's house.

 

[MLamb]

Wouldn't you think the turbo manufacturer would have designed maximum efficiency into the housing geometry already? If this assumption is correct, then the "clip-on" device many have done away with would serve to return the turbo to original manufacturer design specifications. If the turbo is so much more efficient with the ring in, why isn't the restriction permanently cast as part of the housing? With that said, I am also on the fence with the laminar flow theory which suggests devices which limit the swirling of the intake air help the blades carve up more air and make the turbo more efficient. When the turbo is spinning at 100,000 RPM will it really make that much difference? The diagrams DPP have on their web site show descriptive pictures of bad swirling air without their honeycomb device and good straight laminar air with it. I won't contest the dyno numbers but it all sounds like snake oil to me. Again, if its such an efficiency boost why aren't the manufacturers already building laminar flow mesh screens on their turbo intakes?



Anyway Duck, thanks a lot. You now have me second guessing the xed ring deal and some day when the temperatures drop below triple digits here I will return everything to stock and see if I can tell the difference.



Vaughn, I can't wait to hear your report on the honeycomb flycatcher. If it works and there is solid data supporting it, I will gladly jump off the fence and and join the laminar flow crowd with a check to DPP.



There are enough guys messing with the intakes and silencer rings you would think someone would have documented some before and after dyno numbers but I haven't seen anything.



Interesting discussion.

 

[JHardwick]

Not to be sarcastic, but 100,000 RPM??? Is that at idle?



I'm going to put mine back in to see if I can see a difference in the spooling (have to take it in Thursday anyway), I removed it before I added the boost gauge.



I really can't see how it could effect EGT's or dyno numbers, but it may effect spooling. Mine hits 36psi as quick or quicker than it goes back to 10psi.



Dirty air in may make the turbo work harder, but after it leaves the turbo and goes through the air-to-air, it's still 36psi at the valve and as laminar as it's going to get.



Then again, a turbo that is working harder, may raise EGT's ... ... ... ... ... . I'll put it back in and see what I see, lol.

 

[MLamb]

I just checked howstuffworks.com and they say a turbo will spin as high as 150,000 RPM - how's that for research? My guess is this is on a high reving gas engine, not an inline 6 diesel but just the fact that I had to go to howstuffworks.com means I ain't got a clue -really.



Here's another theory JH and Duck... wouldn't more resistance on the blades cause it spool up SLOWER if presented with a laminar flow rather than a slow spinning stream of incoming air?

 

[Duck]

Guess it depends on which way the air was spinning



But here's my thinking:

I'm thinking the X-baffle thingy was to dampen the turbulent air and make an attempt to straighten out. Probably costs another 30 cents per unit to mfg, so what the heck.



I'm also thinking that the purpose of the silencer ring is to funnel the air toward the blades more efficiently, maybe even increase speed of air by reducing the inlet size pre-turbo. Venturi says higher velocity air = lower temp, so that's another good reason for the ring I'm stretching on that one. If it actually increases pressure, then temp goes up. But I seem to remember that air can go around the ring also, which would stop pressure from building and create a true venturi.



Is "silencer ring" really the technical term for this device, or just a nickname for it in our world? That would be interesting to know. Couldn't find that piece or the x-baffle thingy in the air inlet hose anywhere in the online service manual.



So if you agree with my hunches then you're already on board with the idea, you just don't know it The TAG has the silencer ring, and creates the laminar flow. Does a way better job of the latter since it's directly in front of the blades as opposed to the X-Baffle thingy which is a 90 degree angle away and down the tube.



Long story short, it takes the OEM concepts and exaggerates them. Plus I feel like I'm spooling up faster (I'd actually bet on it). Cheaper than hypno-therapy, which could possibly produce the same results

 

[MMeier]

WTF does "laminar" mean?

Could someone define this new word to me, I do not own a dictionary Thanks Mark

 

[Duck]

"layered", basically.

 

[rbattelle]

Actually, "laminar" means straight, even-flowing air... no turbulence. Perfectly laminar flow contains no turbulence whatsoever.



A turbo is, of course, a centrifugal compressor. When you look into the inlet side you're seeing the impeller portion of the blades. Centrifugal compressors run best with zero swirl at the intake: the air should enter the impellers at exactly 90 degrees and should be as laminar as possible. Adding swirl and/or turbulence to the air (non-laminar flow) increases losses in the flow, and makes the compressor "work" harder to overcome those losses. With swirling, turbulent air you'll achieve lower efficiency and lower pressure ratio. How turbulence would effect spool-up time is not immediately apparent to me, but I imagine it would increase spool up time (turbo takes longer to get up to speed).



Also, since friction drag is lower for laminar flow over a slender body (which we have here), it is preferable to turbulent flow (which has lower pressure drag but higher friction drag).

 

[rbattelle]

Ok, I just read the website about the TAG, and on paper it seems like an excellent idea. What I find interesting is the loss in boost pressure on the highway. I can't help wondering if perhaps the mesh is too close to the compressor. Ideally we want fully-developed laminar flow to enter the compressor. Perhaps there is not enough time for the flow to become fully-developed, and instead of a homogeneous flow field at the compressor face we've got a series of small jets. It seems intuitive that a series of jets would reduce compressor pressure ratio somewhat.



I think the mesh is a great idea, but perhaps it should be larger and mounted farther from the compressor face to allow time for the flow to become fully mixed and homogeneous before entering the compressor. Windtunnels use exactly the same type mesh screen far upstream of the test section so that by the time the flow enters the test section it's laminar and fully-developed.

 

[MLamb]

rbattelle...



What website are you referring to re: TAG?

 

[Duck]

website

Here you go

http://www.dieselpowerproducts.com/dodge

TAG (Turbo Air Guide) is the name of the honeycomb device we're talking about.



Just a warning to people who absorb things as literally as I do. The section on the TAG is filled with grammar mistakes and poorly structured sentences. For instance the last paragraph implies that EGT's are higher but when you call them you find out they meant to say EGT's are higher without it.



I agree with rbattelle about it should be farther away, but you can't go much further back into the tube before hitting that 90.

 

[JHardwick]

Well, now I'm confused.



I put the silencer ring back in, removed the EZ box and clamp from the wastegate hose (going in in the AM for alternator brkt)... ... ... ... ... ... . EGT is 100 degrees higher!!!!



65, unloaded on flat ground is 700 degrees up from 600???



The turbo whine is less noticeable, but I can't say that it spools any faster.



Would sure be nice to see some actual numbers.