tcp_ip_dude
Veteran Member
You're right, a higher pressure reading would be measured in the larger diameter tube in front of the constriction, where the air is moving slower. I'm having flashbacks to my pilots license exam 20yrs ago
Turbo Resonance Dampener Removal
- Thread starter ToeBall
- Start date
bruce846
Veteran Member
Me too, only I wish it was only 20 years agoYou're right, a higher pressure reading would be measured in the larger diameter tube in front of the constriction, where the air is moving slower. I'm having flashbacks to my pilots license exam 20yrs ago
KraftwerkB6
Veteran Member
I got a pic from parts, but will have to wait till i get home to load it up because work comps cant show pics, and iphone fails at work with uploading. So everyone will have to wait i guess
nikhsub1
Veteran Member
Exactly. Performance of centrifugal fans and pumps suffers much more when you restrict the inlet. Many hi pressure water centrifugal pumps have the outlet purposely tapered for increased pressure. Wide open flow on the outlet side of things isn't always ideal.When you block the airflow of a centrifugal fan (which is what the compressor side of the turbocharger is), the RPM's will increase. This is easily demonstrated for instance with an electric air pump for inflatable beds or a vacuum cleaner, turn it on, the block the intake (or exhaust) with your hand and you can hear the RPM's increase.
This is due to the fact the the pump is actually doing less work as the air flow is restricted. Placing an amp-meter on the circuit will also show a drop in amperage (motor is doing less work). It is counter-intuitive, but ask any Physics student or HVAC repairmen, they will be familiar with it.
A more lengthy explanation:
http://hvacrfundamentals.blogspot.com/2009/08/understanding-centrifugal-fan-motor.html
KraftwerkB6
Veteran Member
I lied, raised my car up and took a quick look.
Its actually on the intercooler inlet side of the compressor housing. From what you were saying and looking quickly before it looks like there is another from the intake (plastic) to the actual inlet of the compressor housing of the turbo(metal).
I will have to take some pics tomorrow regarless if i take it out and tear it apart or not. Not enought time today.
Its actually on the intercooler inlet side of the compressor housing. From what you were saying and looking quickly before it looks like there is another from the intake (plastic) to the actual inlet of the compressor housing of the turbo(metal).
I will have to take some pics tomorrow regarless if i take it out and tear it apart or not. Not enought time today.
ToeBall
Veteran Member
The only thing I could find about using flow restrictors or orifice tubes with turbos comes from Bently's Maximum Boost by Corky Bell. It says:
Then it goes on to talk about vent valves and wastegates. What's of interest to me, in retrospect, is the idea that the extra flow will lower charge air temps, cylinder temps, so as a result it stands to reason that it will lower EGT's as well and make the DPF sad. On the other hand, it'll probably be good for the rest of the engine, and also reasonably explains the observed raise in fuel economy.
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ToeBall
Veteran Member
This video is private...
Pelican18TQA4
Veteran Member
The previous thread about this topic that many have referenced was from myself and AudiTTim. Tim and I were working on a piece to replace the flow dampener. After all was said and done, Tim had an actual replacement piece that could be bolted on and the conclusion was, not worth the effort to take the original piece out. Do some VAG-COM logging before anyone believes that this actually improves anything. The placebo effect of a mod like this can easily convince someone that it made improvements. For the most part, the flow dampener functions as a resonance chamber for the air coming from the compressor outlet. The actual size of the compressor outlet opening is very small, deceptively so.
tcp_ip_dude
Veteran Member
I tend to agree with you, abeit w/o having seen any before/after empirical data. It's stated purpose is simply a "resonance chamber" as denoted on page 45 of the VW 2.0 Liter TDI Common Rail Self Study Program (excerpted below)
Flow Damper
"A flow damper is located behind the outlet of the turbocharger in the charge air section. It has the task of reducing disagreeable noise from the turbocharger, such as whistling."
Design and Function
"During full-load acceleration the turbocharger must build up boost pressure very quickly. The turbine and compressor wheel are accelerated quickly and the turbocharger approaches its pump limit. This can lead to burbling in the air flow, which causes disturbing noise that radiates into the charge air section.
The charge air causes the air in the resonance sections of the flow damper to vibrate. The vibration has approximately the same frequency as the noise in the charge air. Disturbing noise is minimized by superimposition of the charge air sound waves with the out of phase vibration of the air in the resonance sections"
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Slo.Mo.Shun
Veteran Member
Fixed.
ToeBall
Veteran Member
Yeah, mine's not that whistlie. It just has the hiss.
Ryephile
Veteran Member
Very cool find! If it's just as well to machine out the damper would a replacement [perhaps aluminum] piece be just to make the concept modular and returnable to stock? I'd love to see any data logging you do, just for fun.
Cheers,
Ryan
Cheers,
Ryan
nikhsub1
Veteran Member
At the end of the day, we really need a before/after dyno of this mod on the same dyno (obviously). We can speculate and theorize all we want, bottom line is if it makes more power then great. If not, it is a potential waste of time.
ToeBall
Veteran Member
Indeed, just makes it and easy bolt on/off part. Also, it might improve airflow slightly as it's really hard to get a smoothly polished plastic surface with a Dremel. To be honest, I'm tempted to just rip out all the intercooler ducting and just replace it with metal tubing and silicone. It may not help, but it can't hurt, and it's not that expensive.
Honestly, I doubt it would make any more power by itself. Diesel engines are, by design, lean running engines. Adding air leans them out more but does nothing for power in and of itself. Since mine is already tuned, rather aggressively at that, maybe I'm noticing a bit of more difference because it's leaning out the engine closer to where it was designed to be originally, maybe I'm imagining it, whatever. The one performance related thing I have noticed is a slight improvement in my instant fuel millage, but that much can be explained away by higher quality fuel, since I filled up while out of town, only time will tell. The other changes, and they are not really practical to quantify, are that I enjoy driving the car more because of the sounds, and it feels like there's less lag. Neither is likely to show up on the dyno, however, to me, either by itself is an improvement in the vehicle and, therefore, not a waste of time to me. It may not be your thing, in which case, leave it alone, or "worry less, drive... whatever". Less lag does suggest, however, better flow. The results of better air flow on a Diesel engine are lower EGT's, lower cylinder pressures and temperatures, and better fuel economy. Again, not something that will show on a dyno. We're talking about a piece of plastic tubing 3" long here, it's not some magical modification that will add 25hp either way!
I really would like to do some VagCom logging and see just what's going on with the engine. Since I didn't run before logs I can't tell you what the difference is numerically, especially since mine's not a stock tune to begin with. So, how about it, anyone in Houston interested?
ToeBall
Veteran Member
Quick Video
Here's a short and not very good video of revving the engine after the turbo mufflerectomy, or whatever. I'll try to get something a bit better later. And in case you're wondering, no, that's nowhere near full throttle.
Here's a short and not very good video of revving the engine after the turbo mufflerectomy, or whatever. I'll try to get something a bit better later. And in case you're wondering, no, that's nowhere near full throttle.
Pillow
Well-known member
I agree and have thought the same... Once the warranty expires, I will be full bore on getting this engine to breath better. Which improves temperatures and increases economy. Diesels love to breathe!!!
KraftwerkB6
Veteran Member
Sorry about pics, been really busy at work this week. I am debating on coming in on sat to do some side work and if i do ill get some pics then.
jml iii
Member
Hey how did you guys access this? I took out my intake box and could not see or get to it. I think I was able to feel it why sticking my hand in behind there but there was no way i would be able to remove it never mind put it back on.
ToeBall
Veteran Member
A couple of extensions and wobble joints wielded by TDIinTexas. If I had to do it myself with my big meaty hands, I'd probably have to pull the cowl and unbolt the ECU cover plate. Plenty of room then. Pretty much my plan for access to the DPF, if needed.
Small problem with this: On our cars, the exhaust gas is turning the fan... on an electric fan the fan is turned by the shaft... essentially the flow of power is reversed from one to the other. SEE?When you block the airflow of a centrifugal fan (which is what the compressor side of the turbocharger is), the RPM's will increase. This is easily demonstrated for instance with an electric air pump for inflatable beds or a vacuum cleaner, turn it on, the block the intake (or exhaust) with your hand and you can hear the RPM's increase.
This is due to the fact the the pump is actually doing less work as the air flow is restricted. Placing an amp-meter on the circuit will also show a drop in amperage (motor is doing less work). It is counter-intuitive, but ask any Physics student or HVAC repairmen, they will be familiar with it.
A more lengthy explanation:
http://hvacrfundamentals.blogspot.com/2009/08/understanding-centrifugal-fan-motor.html
In our car the AIR blows the fan blades. Bigger hole =more air= faster fan speed.
On a centrifugal fan the FAN blows the air. Smaller Hole = less air= less resistance = faster fan speed. (same reason your vacuum cleaner motor speeds up when you plug the hose, but draws fewer amps)
tcp_ip_dude
Veteran Member
With all due respect, you are terribly mistaken on the operating principles of a turbo-charger and perhaps you should also read up on Bernoulli's Law in regard to your comments on orifices and their relationship to airspeed and pressure.
"Air", as in outside atmospheric air, does NOT "Blow the Fan Blades".
By definition a 'compressor' is doing work 'compressing' atmospheric air and therefore requires energy to do so. Waste/heat energy is recovered from the exhaust vis a vis a turbine on the exhaust side of the 'turbo-charger', that energy is transmitted via a directly coupled 'shaft' to the compressor side (centrifugal fan) which in turn charges the intake manifold above ambient atmospheric levels (boost).
The only difference between my original analogy, is that in the case of a turbo-charger, the energy driving the centrifugal compressor is coming from the recovered waste energy via the exhaust turbine, whereas in a vacuum cleaner the energy driving the centrifugal fan (compressor) is from an electric motor which is also coupled via a 'shaft'. Sources of energy not withstanding, my original comment still stands regarding the increases in compressor RPM's when flow is constricted (assuming power to the compressor/CF remains constant)
The basic physics behind a turbo-charger is to recover waste energy (heat), convert it into mechanical energy and use it to force more air into the combustion chamber, either for increased HP output or for altitude compensation in the case of aviation engines.
BTW, "Centrifugal Fans" & "Fans" (aka propellers) operate on entirely different principles and the terms should not be used interchangeably. Fans/Propellars operate on a 'screw' principle which is very different than the 'centrifugal forces' used in the former.
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ToeBall
Veteran Member
No, the problem with your fan analogy, as I understand it, is that you're restricting air on the intake side of the compressor housing (a buddy of mine is doing exactly this with a supercharger with good effect) while this particular restriction is on the output side of the compressor housing. As a general rule, a turbo uses about 10 degrees F per PSI. It makes more sense, however, to build that pressure against the engine rather than an orifice tube. Ultimately, it's not about how much pressure you push out of the turbo, but how much volume goes into the engine, since that determines how much fuel you can burn. Since volume increased, pressure, and therefore temperature, can go down. Lower temperature means you can add more fuel to raise the temp back up and, incidentally, make more power. Of course, that requires a software change, so I don't actually make any more power with just this modification.
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Are you seriously trying to say that a turbo charger uses HEAT to compress air? Have you ever looked at a turbo? It's two fans connected by a shaft - one fan is spun by the exhaust as it leaves the engine and it turns the shaft that is connected to the other fan that spins to compress the air that goes into the intake of the engine.
Don't be an "internet Rambo". While I appreciate you yielding 'all due respect' to me it is not necessary; you are incorrect.
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tcp_ip_dude
Veteran Member
I think not. Please post the science behind your assertions and I'll gladly admit I'm wrong.
But, yes I am saying exactly that, it's the laws of thermodynamics (see link below), there is a direct relationship between the temperature and pressure of a given gas, you increase temp there is a corresponding rise in pressure and vice versa. http://en.wikipedia.org/wiki/Thermodynamics
Exhaust gas is under pressure b/c it is at a high temp, as it traverses the exhaust turbine, heat/pressure are converted to mechanical energy, there is a corresponding drop in temp/pressure proportionate to the amount of 'work' delivered to the compressor side (via the shaft). If you measure the temp of the exhaust gas (EGT) on both sides of the turbine, you will see a corresponding drop in temp/pressure as it traverses the turbine.
As pilot, I see it whenever I fly our turbocharged piston engine aircraft, we have EGT gauges on engine and exit sides of the turbo, there is a direct correlation to amount of manifold pressure you dial in (boost) to the drop in temp on the exit side of the turbine. We dial in more manifold pressure and see an almost immediate increase in the differential of EGT between the engine and exit sides of the turbo (it's a split needle gauge, so it's easy to see).
Same thing in the gas turbine (Allison 250/T63) of the Hughes 500 helo (OH-6A) we fly, you can see a progressive EGT drop across the N1 & N2 turbines as mechanical energy is pulled off at each stage, the N1 turbine is directly coupled via shaft to the compressor stage (i.e. compresses combustion air), the N2 turbine is what picks up the remaining exhaust energy to drive the gearbox that drives the main/tail rotor, the EGT drop across the N2 turbine is huge b/c that is where the vast majority of the mechanical energy goes (to drive rotors), that's why by the time the exhaust gas reaches the exit, it's relatively cool.
So yes, I am absolutely saying 'heat' which has a direct relationship to 'pressure' is what drives the turbine side (exhaust) of the turbocharger.
And yes, I've worked on race car and aviation turbochargers going back to the late 70's, I know them inside and out, literally. .
Respectfully,
MLA
http://en.wikipedia.org/wiki/Thermodynamics
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ToeBall
Veteran Member
Um, a turbo does use heat to compress air. Depending on just pressure to spin the turbo would produce diminishing returns unless it could somehow achieve great than 100% efficiency. Since we can't produce perpetual motion, much less perpetual energy generation, something other than blowing must spin the turbo.
Ryephile
Veteran Member
Yes, that is correct. Turbines are thermodynamic devices and can use either heat and/or fluid pressure/flow to induce motion
Not so fast. A bigger hole, as you state it, means less pressure and less heat. While the total mass-air however may be greater, the wheel speed may not change at all, or even reduce. You'd have to cite specific aerodynamic charts [compressor or turbine wheel efficiency graphs] to say otherwise.PlaneJob said:
I think what's important here would be to measure the delta in pressure ratio between stock and the resonance damper removed. Only then would we have some good initial data to work from.
mattymx
Active member
Dont confuse more pressure with more CFM or air density... Pressure is a measure of restriction, not flow.
mattymx
Active member
I honestly wish there was a way we could measure air mass like we can PSI. But just normal thermal dynamics is as air pressure increases, so does temperature. That's why my trucks stock turbo would throw out 35 PSI, but I would still have black smoke. That added pressure didnt add the air mass the fuel demanded. A swap to a different turbo that was more in its MAP with the fuel I run lowered boost to 30 PSI but bumped up the CFM big time resulting in no smoke at WOT and lower EGT's....