EMP as related to the VNT 17/22

mrchill

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Perhaps he was doing light trucks. They do an easy 50-80 psi boost(modified), so emp must match.
 

IndigoBlueWagon

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OK, so I went back and re-read some of this thread (digressions notwithstanding) and better understand. Now the question is (linked to FUB's), what's ideal? If we have more or less equal IMPs and EMPs, is that good?

And getting back the the first few posts, I don't think anyone asserted that a hybrid would drive lower EGTs. Jeff R. is very careful to always say it's a great street turbo, because EGTs can get high at sustained WOT. But I've got to say after driving my Golf on five different tracks this year you're never at WOT for very long at the track.
 

hatemi

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How much fueling are you guys that have tested it been using? Turbine side of a turbo that is ment for 150hp shouldnt have insane preasures in that power level yet. Ad a bit of fuel and see the needle go up.

For optimum ratios the less preasure in the exhaust manifold is always better. You need a bit of preasure and restriction in the beginning to make it spool but after that less is better. My EMPs peaked at 2.5bar and when the vanes openned they dropped to 0.7bar. They slowly climbed from there and hit 1.9bar with 1.9bar of boost @5k.
 

Fix_Until_Broke

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My fueling is not super agressive: 10mm pump, PP502's, QA voltage holds at 4.5V during a WOT run. Only smokes on shifts and if you get on it under 2K - otherwise clean.

11mm or 12mm pump and R520's are the only ways to add more fuel as far as I know? That or get my friends 8 cylinder inline pump and have a cam ground for it that pairs cylinders. I think it has 18mm pistons in it! :)
 

Rub87

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Ibiza '99 90HP
Mine peaked around bar too spool then falls, between 2000 and 3600 rpm or so boost is greatet than emp.; at 250rpm you have like 0.8ar emp and 1.5 bar of boost.. isn't this a sitaution some valve overlap would be really benficial?

emp @ 4krpm is 2.1 bar, peaks at 4200: 2.3bar os somethin and then backs off as the rev limiter starts decreasing the requested boost and fuel..
 

Fix_Until_Broke

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More info

Some more information on this testing.

I installed a gauge that I have lots of confidence in now (0-60 psi, 2.5" diameter, 270 degree sweep, glyceren filled, calibrated with a dead weight tester at 5 psi increments - it reads ~1psi over actual up to ~25 psi). It's really fast without buzzing. Once I opened the needle valve that I have in to dampen the pressure pulsations, the first time I got on it the EMP gauge swung around to almost 50 psi :eek:! It immedately dropped back down to ~intake pressure but it caught me off gaurd.

I only drove a few blocks after adjusting the needle valve full open so I don't have a good feel for it yet but max PSI's (after the spike) are similar as I described before, just the spikes are much higher than I initially thought.

I now (think?) understand why Street Toys recommended such a high range gauge - dynamics? I was clipping the spike with an orifice and volume after it (a pneumatic version of an R, C circut for you electronic types) in the process of killing the buzz of the crappy guage. If you were getting steady state pressures this high, then I think there might be something wrong.

I'll have more feedback tomorrow night after driving with this for a while. I'll also switch the Intake and Exhaust gauges so I can see if my Stewart Warner boost gauge is at all accurate.

Maybe I'll try and get a video - need to find some willing soul who will sit in the back seat and run the digital camcorder though. Maybe that same person has an ALH with a VNT-15, boost gauge, and EGR Delete we could do the same thing to compare ;).

Hope this helps - more observations as I see them. Any special requests, let me know.
 

Passenger Performance

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jackbombay said:
15's and 17's have been "known" here at TDIclub to be responsible for high EMPs, but it turns out it wasn't true :) . Remember when most everyone here was sure big exhaust did nothing for TSI performance? And big intercooler were pointless? I do, I knew those claims were BS, but I did fall for the high EMP/15/17 folklore, but th emyth has been busted and we can all sleep easier now.

But as usuall you are throwing stones trying to start fights.
Myth is not busted. One tune on one persons car does not prove much if anything at all. Emp's fluctuate with fueling, tune, and especially RPM. Its going to be different for everybody. Which is why when your tuning you should be watching your emps.
 

Fix_Until_Broke

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The gauges used to get the EMP data in post #76 are not accurate!

After driving around for a day with my accurate EMP gauge (described in post #96), the results are a bit different.

Low boost (0-5 psi), low rpm (1400-2000 rpm) EMP's are 4-5 psi higher than IMP's.
100% throttle 3rd gear run has IMP's peaking at ~27 psi and falling to ~24 psi by ~4000 rpm and EMP's starting at ~32 psi and rising to ~37 psi over the same range.
I have not gotten a chance to run it on the highway yet so not much info on mid range boost values. Cursory observations are that EMP's are 2-3 psi higher than IMP's, but the durations are short so it's hard to get a good read on it.

I did swap the gauges so my calibrated one is on IMP and my Stewart Warner is on the EMP. Above I mentioned that the boost peaks at ~27 psi and falls to ~24 psi on the SW gauge. With the other gauge it starts at ~26 psi and rises to ~28 psi. My next task is to now connect both gauges together and see what the differences are at the same time.

All this is getting hard on my MPG's :eek: - this might be my first tank legitimately below 50 mpg since FEB 2007 ~20Kmiles (on pace for ~49 mpg). Not that I'm complaining, just a lot lower than I'm used to.

More info as I get it.

Comments, questions and suggestions welcomed.
 

Fix_Until_Broke

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I'm getting tired of messing with all these gauges, having to add 1 psi here, subtract 1/2 there due to inaccuracies/non linearities, trying to read two different gauges in different orientations of different scales at the same time, etc. I'm thinking of going all out and putting a pair of pressure sensors (0-10Vdc, 0-500 psi is what I have available - they will be calibrated specifically over the 0-50 psi range and I can apply a non linear calibration to the scaling if necessary) and using a portable data acqusition system to record both pressures and it will calculate the differential.

I can read just about any -10 to +10Vdc signal, is there any other signals that I should get as long as I'm at it. I can record up to 8 channels. I'd like RPM as well, but don't think there is an analog representation on the vehicle. The CAN signal isn't J-1939 by chance is it?
 

Passenger Performance

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Fix_Until_Broke said:
I'm getting tired of messing with all these gauges, having to add 1 psi here, subtract 1/2 there due to inaccuracies/non linearities, trying to read two different gauges in different orientations of different scales at the same time, etc. I'm thinking of going all out and putting a pair of pressure sensors (0-10Vdc, 0-500 psi is what I have available - they will be calibrated specifically over the 0-50 psi range and I can apply a non linear calibration to the scaling if necessary) and using a portable data acqusition system to record both pressures and it will calculate the differential.

I can read just about any -10 to +10Vdc signal, is there any other signals that I should get as long as I'm at it. I can record up to 8 channels. I'd like RPM as well, but don't think there is an analog representation on the vehicle. The CAN signal isn't J-1939 by chance is it?
That is a great idea:)
 

hgeittmann

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05 Passat Wagon
Here are some logs I made this summer... the top is w/ my aligator tune, the bottom is stock tune. Hopefully it's legible... I see I clipped the axis labels. y axis is PSIA, x axis is just sample #. EMP/MAP uses the secondary Y axis on the right. I should've used the same colors in both plots... next time. I'll be interested to see how yours comes out. My sample rate was about 10hz, which clearly is too slow to fully characterize EMP, but is probably sufficient for MAP (IMP) and gives reasonable file sizes if you want to capture a few minutes worth of driving. I thought a bit about getting rpm data, and think what I would do is run VAGCOM at same time and use VAGCOM markers to synch my data collecting w/ VAGCOM (trigger markers in VAGCOM using windows messaging from my data collection app).



 
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Rub87

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Ibiza '99 90HP
hmm's emp's are pretty high..


You should make the 2de Y axis the same scale..

I heard that if emp's are above 45psi at high revs you have a pretty big risk of exhaust valve float..
 

hgeittmann

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1) it's absolute pressure, so subtract ambient (12psi where I live)
2) agree, not the easiest to read, maybe I'll clean them up tonight when I'm not at work.
 

Fix_Until_Broke

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I'll have to see if I can run VagCom at the same time as my DAQ software. I can put markers in the DAQ as well and try to syncronize both markers in the data. It won't be anywhere near the resolution but will at least give an idea of what's going on and I can overlay them with a little work. Typical sample rates for are 1kHz with a 200 Hz low pass anti-ailising filter. I can apply various software filtering as well, but typically turn it off. I might lower the sample rates to 100-200 Hz to make it easier to overlay the data. That gives 0.005 to 0.010 seconds between data points which should be sufficient for this.

What VagCom channels - 1, 4 & 11 I assume for RPM, IQ, Mod Piston Voltage, Coolant Temp, MAF, MAP, N75%

If there's something else I should log instead, speak up. I'll probably do this this weekend while the other half is at a book sale :).
 

Fix_Until_Broke

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hgeittmann - That's great that you took some data like this. Can you tell us which car it is on and which kind of driving you were doing? Assume 100% 3rd or 4th gear run?

Any other details, tune, turbo, exhaust, intake, EGR, etc....
 

hgeittmann

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It's a gt1749va turbo on my B4, 3rd gear WOT runs from 1500-4500rpm w/ both stock and Aligator tune. It's a little OT as I don't have the 17/22 hybrid turbo, but this seemed to be a good place to post it, hope you don't mind.

I was going to "borrow" one of the National Instruments pcmcia DAQ cards we have at work, but then decided to go a little more low-tech/affordable so I could keep it at home for future projects. What hardware/software are you using?

I'm not sure which Vagcom channel will be most interesting. They all include RPM if I remember correctly. I would expect N75 duty cycle vs EMP to show the most direct correlation, so maybe once that's verified, it becomes the LEAST interesting data. Hard to say- the more I explore, the less I feel I know.
 

nicklockard

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Fix_Until_Broke said:
I'm getting tired of messing with all these gauges, having to add 1 psi here, subtract 1/2 there due to inaccuracies/non linearities, trying to read two different gauges in different orientations of different scales at the same time, etc. I'm thinking of going all out and putting a pair of pressure sensors (0-10Vdc, 0-500 psi is what I have available - they will be calibrated specifically over the 0-50 psi range and I can apply a non linear calibration to the scaling if necessary) and using a portable data acqusition system to record both pressures and it will calculate the differential.

I can read just about any -10 to +10Vdc signal, is there any other signals that I should get as long as I'm at it. I can record up to 8 channels. I'd like RPM as well, but don't think there is an analog representation on the vehicle. The CAN signal isn't J-1939 by chance is it?
Or, much easier: just hook your calibrated psi gauge up to read the difference in pressure between the two. {EMP-IMP}
 

Fix_Until_Broke

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nicklockard said:
Or, much easier: just hook your calibrated psi gauge up to read the difference in pressure between the two. {EMP-IMP}
I know that I'm not the sharpest knife in the drawer by any means, but how exactly do you do this with a traditional bordoun tube gauge? One pressurizes the traditional port and the other the cavity around the gauge where the glycerine is? That's the only thing I can think of.

Tell me what you're thinking here
 

Fix_Until_Broke

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hgeittmann said:
It's a gt1749va turbo on my B4, 3rd gear WOT runs from 1500-4500rpm w/ both stock and Aligator tune. It's a little OT as I don't have the 17/22 hybrid turbo, but this seemed to be a good place to post it, hope you don't mind.

I was going to "borrow" one of the National Instruments pcmcia DAQ cards we have at work, but then decided to go a little more low-tech/affordable so I could keep it at home for future projects. What hardware/software are you using?

I'm not sure which Vagcom channel will be most interesting. They all include RPM if I remember correctly. I would expect N75 duty cycle vs EMP to show the most direct correlation, so maybe once that's verified, it becomes the LEAST interesting data. Hard to say- the more I explore, the less I feel I know.
Gosh no I don't mind you posting your data here, you're the only other one I've seen who has gone to the trouble of taking continuious data and posting it.

I'm using something similar for DAQ along with some homemade software.

Hopefully I can get everything together for this weekend.
 

hgeittmann

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Hey FUB, I just read your location... I grew up in Port Washington (parents still live there). I bought my B5 from EVS in Menomonee Falls. Funny.

I wrote my own software on the PC side (C#) and the data collection is handled by modified PIC code (C) and sent to pc via usb. We should compare notes. Seems like a simple pressure/temperature logger could really fill the gap between VagCom and the dyno... basically take Corkey Bell's chapter on data collection and do it right.
 

nicklockard

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Fix_Until_Broke said:
I know that I'm not the sharpest knife in the drawer by any means, but how exactly do you do this with a traditional bordoun tube gauge? One pressurizes the traditional port and the other the cavity around the gauge where the glycerine is? That's the only thing I can think of.

Tell me what you're thinking here
Sorry!

I went looking up differential pressure gauges. I couldn't find one for less than $123 and it would take 4 weeks for delivery.

My bad. Wish there was a way to rig yours up with a second port on the vent side.
 

brew1

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Fix_Until_Broke said:
Gosh no I don't mind you posting your data here, you're the only other one I've seen who has gone to the trouble of taking continuious data and posting it.

I'm using something similar for DAQ along with some homemade software.

Hopefully I can get everything together for this weekend.
Matt, I can swing by this weekend to lend a hand and a test car with a stock VNT15, EGR delete and fully restricted stock exhaust. Should be more interesting than sitting 20' off the ground, freezing my a$$ off, waiting for deer to walk past.
 

Fix_Until_Broke

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brew1 said:
Matt, I can swing by this weekend to lend a hand and a test car with a stock VNT15, EGR delete and fully restricted stock exhaust. Should be more interesting than sitting 20' off the ground, freezing my a$$ off, waiting for deer to walk past.
brew1 - Sorry for the short notice, but I'm going to get a data acquisition system and measure both pressures at the same time and calculate the difference. It will be far more accurate than watching or even videoing gauges. We'll be able to do this on your car as well, but I've got to get it setup and working first. Currently working on a high confidence way to calibrate my sensors down in the low (0-10 psi) range.

It will probably be the weekend after thanksgiving before I'm ready to go with it. Thanks for the offer though, I appreciate it.

As long as I'm at it i might see if I can hollow out a glow plug and measure cylinder pressure as well. Would really be most useful if I had crank or cam position to go with it. We'll see what we can find.
 

jasonTDI

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Thanks for the 20!

It's running strong in a clients car right now!

Also, FWIW my turbo had NOTHING to do with RC software and everything to do with 80K miles and sitting for 3 years not running when I bought the car. It was making 10 lbs when it popped.

Sootman said:
I need some more basics on the EMP/EGT thing. Anyone have a link that will give an overview of this subject?
Man, them orange turbos sure are purdy! You should see my yellow block!
[/IMG]
 

Fix_Until_Broke

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Ok - well I finally did some of this IMP/EMP measurement work and also synchronized it with VagCom data. This was much more difficult than just installing the two gauges, but far easier to read and analyze.



The short summary is that the EMP is ~10 PSI higher than IMP's at ~4800 RPM

This is just a print screen shot of a 3rd gear pull from idle, rolling on to 100% throttle by ~1500 RPM, continuing to ~4800 RPM. The Vag data is from groups 1, 3 & 11 (not all plotted, but all available). The Vag data is the blocky, low resolution curves, the analog data is sampled at 0.002 sec intervals (I'll turn this down in the future to 0.005 or 0.010 sec intervals).

EMP=Exhaust Manifold Pressure measured at the EGR port in PSI
IMP=Intake Manifold Pressure measured at the left end of the horizontal part of the intake manifold
TIP=Compressor Inlet Pressure measured at the Vacuum system vent in the Airbox.
IMP-EMP=Difference between IMP and EMP
MAF Actual=VagLog data of MAF Sensor Reading
RPM=VagLog data of Engine RPM

If there's someting specific that you'd like to see, speak up as I've got this setup and I've got a warm place to work on it :). I will make some .pdf's of this when I get back to a place where I can do it. I can add/delete channels and perform calculations as well so let me know if there's something you want to see.

Current mods are: TDI Parts 17/22 turbo, RC4ish tune, 3 bar MAP, 3" turbo inlet tube, 3" downpipe, 4" exhaust and Aeroturbine muffler, PP502's, PD Lift pump, EGR Race Pipe and cooler delete. All other parts are stock (unless I forgot something, 10mm pump, OEM SMIC and piping, airbox,filter, MAF, etc). Lower intercooler grill was removed (tow eye inserted to get me un-stuck).
 
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