Re-Silenced, pre-turbo...

[MLamb]

Could it be that we are all talking out of our back sides



The observations we have made are based on individual perceptions and gut feelings. No wonder we are all over the place.



BTW Duck, higher velocity = lower pressure (Bernoulli's principle) I suppose you could derive lower temp from this as well but the basic principle centers around pressure. I don't think the geometry supports any real venturi effects which could cause the Bernoulli principle to apply anyway.

 

[JHardwick]

a gauge reading either 600 or 700 is an observation rather than a perception

 

[Duck]

Maybe it was Boyle then. As pressure decreases, so does temperature. And since the silencer ring takes an otherwise straight tube and narrows it in the middle, I think Bernoulli would apply.



This is the primary reason for carburetor ice in airplane engines.



I was just grasping at what might be another reason for the "silencer ring". I'm still wondering if that's the technical term for that gizmo.

 

[Duck]

Originally posted by 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!!!!

I wonder if that could be the EZ? When you put it all back in, would be interesting to leave the ring in with the EZ and see if EGT's go back to 600. That would narrow it down at least.

 

[Blakers]

From what I've heard, the silencer ring is just that... . a ring designed to silence the turbo whine. The ring is installed at Chrysler's request and not a normally supplied item in other Cummins engines.



I think there is a lot of truth in the psychological effect of the change in a sound on the seat of the pants feel of anything. I know I have changed exhaust systems and the vehicle feels different. Sometimes one drives slower because their brain is programmed to use the sound to judge speed.



Personally I didn't notice a drop in performance when I removed my ring, but really one needs to go by numbers. Either boost gauge numbers, egt numbers, track numbers or dyno numbers.



Blake

 

[JHardwick]

Duck,



I plan on adding the EZ 1st to see what happens, I thought the exact thing. I 'll let you know this evening.



Kind of a funny deal. Tells you what the informed consumer has over the uninformed.



Scheduled this thing for the alternator bracket, passenger side mirror that shakes badly and 2 bolts missing in the core support (holds the condensor and air-to-air).



They said that they shouldn't have it for more than a day :--)



I said the TSB allows . 3 hours for the bracket and I can't image 2 bolts and a mirror taking 7 hours and 40 minutes, lol.



They said if I was there by 8AM I should be on my way in a couple of hours

 

[rbattelle]

Bernoulli's equation tells us that total pressure is conserved along a streamline... it has nothing to do with whether you have a venturi or not. What I'm trying to say is that Bernoulli applies almost all the time for subsonic flow.



I think the relevant equation you all are searching for is the ideal gas law: P=rho*R*T, where P is pressure, rho is density, R is the universal gas constant, and T is temperature. For incompressible flow (which we have here), density is constant, so a drop in pressure must be caused by a drop in temperature, and vice-versa.



Nevertheless, the honeycomb structure of the TAG will not increase the flow velocity, and so I believe inlet temperature to the compressor will be the same with or without the mesh. The advantage to the mesh is in removing swirl and promoting more laminar (less-turbulent) airflow.



I fail to see the reasoning that the mesh causes a drop in EGT. Are they talking about pre or post turbo EGT?



Ryan

 

[Ladders]

The silencer ring was added at DC's request back in the 1st gen due to the "noise" that some persons were complaining about (along with the heater noise problem). It was put in to "reduce" the turbo whine for those who do NOT like it (some "older" types that use it for towing their full timers - I guess). We, the lovers of the Cummins, like the noise and therefor remove the ring.



Why DC added the plastic tube is probably to silence the noises for the "order window test" that they SAID they did. It probably had a "little" too much noise generated for the order to be heard EXACTLY .



Just another opinion on the 2nd paragraph. But the first is "correct" if you go back to the threads in 98/99 and look up the silencer ring discussions. (or maybe they were lying then??) DC had the rings installed in OUR turbos but Cummins did not install them in other uses of the 5. 9.



Hope this helps to clear up one point, but I guess the jury is still out as to whether or not DC made it "useful" for air flow on the g3's.



SOTSU!!

\\BF//

 

[Duck]

rbattelle, I was speculating whether or not the silencer ring would increase velocity (lowering pressure and temperature), not the TAG. I can talk myself onto either side of the fence What do you think?

 

[rbattelle]

I think it depends on whether the silencer ring acts like a contraction. If, with the ring in place, we have a convergent section (in other words, a decrease in area), then velocity will increase, and pressure/temperature will decrease.



So, the question is, does the silencer make the compressor inlet a throat? When you remove the ring, are there ports behind it where air can get in?

 

[JHardwick]

rbattelle



remember that this air is being sucked in and not forced.



after reading this thread and taking temp and boost readings with a couple of different combinations ... ... ... ..... the ring is a silencer IMO.



mine is lost again ... ... ... ... unless it has to go back to the dealer!

 

[bighammer]

Originally posted by rbattelle

When you remove the ring, are there ports behind it where air can get in?

Yes, there are. (assuming the inlet is done the same way as the older ones)

 

[MLamb]

My ring is out and so is the x-baffle unless there is some data out there that supports putting it back in. My seat of the pants opinion is the difference is only sound.



JHardwick - your post says that you will re-install the ring if returning to the dealer. Is there a specific reason why you do this? Have you heard of others having warranty issues?



Does anyone else feel it necessary to replace the ring prior to a dealer visit??

 

[Blakers]

Originally posted by MLamb

Does anyone else feel it necessary to replace the ring prior to a dealer visit??

It's your truck. What business is it of the dealer's whether you take it out or not? Unless you drop the ring on the floor and dent it and then try to get them to cover it under warrantee.

 

[MLamb]

I agree Blakers, just trying to understand why others feel that it is necessary to put it back in prior to visiting the dealer. I've been to the dealer twice and never thought about putting it back in. Don't think they would ever notice or care.

 

[rbattelle]

Whether the air is being sucked in or pushed in makes absolutely no difference to the flow.



If there are indeed ports behind the ring which allow additional airflow into the compressor face with the ring removed, then I would expect the flow velocity to decrease as it approaches the compressor face, but you could fit more air in there.



In any event, the changes in flow speed we're talking about would be small, since there is a contraction in the pipe anyways, so the flow speeds up with or without the ring in place. It's just that it will speed up a bit more with the ring in place. I'd bet the effect of increased area without the ring would be exactly balanced by the small loss in velocity. In other words, absolutely no performance benefit associated with removing or installing the ring.



But like I said before, I really think this TAG is a great idea, if only it were mounted farther upstream (away from the compressor face).

 

[JHardwick]

the ONLY reason I put the ring in before a trip to the dealer (once so far @ 20K)... ... . is so that they have 1 less reason to say that I am on my own. I've already heard stories of these boxes being detected on both the Chevy and the Ford ... ... ... ... . don't give'm a reason to feed ya to the dogs! It takes like 3 minutes!



pushed air is VERY different than pulled air, it's a totally different animal!

 

[rbattelle]

JHardwick,



I'm sorry but you're wrong: pushed vs pulled air is no different. They are both pressure driven flow: there is greater pressure upstream than downstream. It moves toward lower pressure. They are identically the same thing whether the driving pressure is 1 ATM (and the reservoir pressure is <1 ATM) or the reservoir pressure is 1 ATM and the driving pressure is >1ATM.



The only difference really is the fact that a pull-onlysystem is limited by vacuum: maximum speed is achieved when the downstream pressure reaches 0 unless you then begin to pressurize the upstream end.



To show this mathematically, we can just look at Bernoulli's equation:



P2-P1=1/2*rho*(V2-V1)^2



Where P is pressure, rho is density, and V is velocity along a streamline. This equation shows that total pressure is conserved along a streamline (recall total pressure is equal to Pstatic+1/2*rho*V^2). There is no distinction between a "push" flow or a "pull" flow. Pressure driven flow is pressure driven flow.

 

[JHardwick]

Hey!!!! How about those Buckeyes

 

[rbattelle]

Where are you in Ohio?