[dzlmoose]

Originally Posted by gtp900

TDI, is the clicking sound the wastegate?
I didn't here any "whoosh" sound? Maby mic didn't pick it up?
I would think, (at the track) this new set up would be slower.
Just a question, has anyone considered "building" the tranny? Has anyone ever "broke" their transmission yet from excessive power?

I think the clicking sound is him downshifting with the paddles.

[TDIwyse]

Originally Posted by gtp900

TDI, is the clicking sound the wastegate?
I didn't here any "whoosh" sound? Maby mic didn't pick it up?
I would think, (at the track) this new set up would be slower.
Just a question, has anyone considered "building" the tranny? Has anyone ever "broke" their transmission yet from excessive power?

The clicking was my using the paddle shifters to get out of 4th and into 5th/6th ... and then a couple extra for good measure ... because I wish I had more gears :-)

Also, the sound on this one is a lot lower for a few reasons. On the previous video's I had most of the under covers off, the engine cover off, and the "cold air box" for the AEM dry flow cone filter removed. On this last one I have all those things back on (it makes a big difference in the sound coming into the cockpit). If it was a little above 4F (-15.5C) air temps outside I might have tried opening the windows.

The data I'm seeing would indicate a different impact at the track...

[DWR]

TDI, the boost peak you had before was in a region where the turbos are compounding boost. Both turbos were still operating within relatively safe regions on the compressor maps. Assuming you were already hitting the torque limit for fueling in the DDE, the extra pressure probably was not doing much except keeping the exhaust cleaner. Of course, the high pressure at higher airflow/rpms was the real concern.

As long as fuel delivery is torque limited and EGT is controlled, I think the lowest boost to achieve that will produce the best results. Meaning, the reduction in boost is probably not going to give any relief to your transmission or tires.

I'm glad to see your "last mod" continues to be your latest mod. Thanks.

[TDIwyse]

Originally Posted by DWR

TDI, the boost peak you had before was in a region where the turbos are compounding boost. Both turbos were still operating within relatively safe regions on the compressor maps. Assuming you were already hitting the torque limit for fueling in the DDE, the extra pressure probably was not doing much except keeping the exhaust cleaner. Of course, the high pressure at higher airflow/rpms was the real concern.

As long as fuel delivery is torque limited and EGT is controlled, I think the lowest boost to achieve that will produce the best results. Meaning, the reduction in boost is probably not going to give any relief to your transmission or tires.

I'm glad to see your "last mod" continues to be your latest mod. Thanks.

I strongly agree with the bolded part above.

The way the EWG is configured in the latest video/log is a very simple manifold to lower port config. So drive pressure + boost is pushing the gate open.

Since the EWG is being forced open at lower boost numbers in the rpm range where only the small turbo is in play (as I'm listening/watching the video more it seems I can hear the EWG start to dump at the ~24psi point on the low rpm range), it seems to me the drive pressure is substantially higher in that region. Then at ~2800 rpm where the big turbo path gets switched in the drive pressure seems to be significantly reduced which then requires a little more boost to get to open up again.

Does this interpretation of drive pressure seem accurate based on your experience? I got a little manual boost controller yesterday I could play with if I feel the need to try to increase the boost a little more in 2000-2700 rpm range, but not sure yet if I want to do that.

Regarding sequential turbo setups and how to combine both turbo maps into a combined map ... I had found this presentation from Ford interesting: https://www.gtisoft.com/upload/FordD...gines.2011.pdf

Especially this sequential twin turbo map example where they show both maps and then the combined "curve" they used for the twin turbo setup.

[TDIwyse]

Took some time to play with the boost controller late today. I'm able to move the peak boost down to lower rpm's and keep the benefit of eliminating the ~2800 rpm spike and keep the upper rpm boost in check.

I also noticed that the android Torque MAF based boost calculations are sensitive to temp. Today it was 25F versus previous data's 4F temps. At 25F the android boost #'s are a lot closer to the analog gauge numbers. The analog gauge peak #'s are the same as in the video posted earlier with the EWG, just that now the lower rpm's at ~2600-2700 rpm are higher.

So don't focus on the absolute #'s, just the relative levels vs the rpm and the difference on when the boost is coming on.

[DWR]

That image of the combined compressor maps is more than a little misleading. Let me just point out the obvious. At loads when the smaller turbo shows no contribution, the system pressure ratio is higher than the working line for the single large turbo. How can that be? It can't. The presentation it is taken from is really focused on parallel sequential systems, and not the series sequential we have. I'm guessing no one was looking at it critically.

Regardless, your thoughts on the drive pressure are in the right direction. Under high load at lower rpms, the exhaust is accelerating both turbines. That is the greatest restriction. Boost pressure lags drive pressure and the relationship is nonlinear as you move through efficiency islands. That's why you manipulate the peak up and down the load range.

I'm still wondering if the stock wastegate is undersized for the increased power levels or if the algorithm in the DDE cannot compensate. Did either TDI or Iaknown test with the wastegate disconnected, i.e. completely open and still get overboosting? I'm guessing so, just want to confirm.

[TDIwyse]

Originally Posted by DWR

I'm still wondering if the stock wastegate is undersized for the increased power levels or if the algorithm in the DDE cannot compensate. Did either TDI or Iaknown test with the wastegate disconnected, i.e. completely open and still get overboosting? I'm guessing so, just want to confirm.

I didn't test that.

Multiple tuners had warned of this overboost issue when eliminating too much restrictions in the exhaust flow.

Based on iaknown's findings of porting the internal wastegate and it reducing peak boost numbers, it would seem the stock configuration is beyond it's capacity when the vehicle is modified for more power and the exhaust is opened up and allowed to flow more freely. Seems that little stock wastegate hole can't flow enough to keep up.

[DWR]

I agree the stock wastegate isn't sized for the increased flow in the upper range. However, the "spike" you illustated earlier in this thread was not at high enough flow to overwhelm the wastegate. It is a control dynamics problem. We are really messing around with the pressure differential that drives the turbines.

By logging boost with the wastegate completely open, I believe it would not be too hard to calculate the new size for the wastegate orifice, such that it could be once again in the DDE control loop... hmm, someone already thought of that

I applaud your efforts. EWG is best practice for customized systems. Today control of an EWG is done with PWM in a negative feedback control loop - just how the DDE does it. You have your hands full if you are using springs and manual bleeds. Not impossible, but very difficult if you want that boost curve to slope down at high load, to control rotational speeds. Best of luck.

[TDIwyse]

iaknown might want to comment on testing things with the big turbo wastegate fully open?

I did a little more tweaking and it's actually turning out to be pretty easy to "shape" the boost curve. Attached are 3 configurations showing a slow progression of moving the high boost location lower in the rpm band, and it's still eliminating the big spike. The latest data (#2 setting) is going into higher rpm regions where the MAF is starting to saturate, so the android Torque app is showing more roll off in boost than the analog gauge is showing. But the analog gauge is showing the rolling off as well. So far this setup is demonstrating very good control characteristics across the full rpm range.

NOTE: The link back on post 43 was broken, so I fixed that. It now correctly shows the video of the analog gauge for the pull the android Torque app logged.

[DWR]

TDI, I think I misunderstood what you were doing. Is your EWG before both turbines?

[TDIwyse]

Originally Posted by DWR

TDI, I think I misunderstood what you were doing. Is your EWG before both turbines?

Yes. I'm using the EGR port of the exhaust manifold (as well as part of the EGR cooler tubing) for the exhaust connection. So it's able to vent the exhaust before either turbine.

Attached is a quick attempt to show the location. It's at the front of the engine, and this picture from BMW isn't quite correct as the manifold common point is ~2 ports away from the EGR port instead of showing up in this picture as being between the 3/4 port area.

[DWR]

OK, my bad. My comments would pertain to iaknown and not you.
Very simple (but brilliant) idea. Use the EWG to "scrape" off the peaks. Got it. Thanks.

[Yozh]

Originally Posted by TDIwyse

Something seems out of whack with your readings. Are you using the MAF based boost approach? If so it uses the MAF readings and what you enter for the vehicles engine size, volumetric efficiency, etc. for calculating a boost number. Using the correct engine size and VE should help you get the boost numbers to line up fairly well (it's still off some, but it's within a couple psi of the gauge through most of the operating range when I compare things). To do this you need to edit the vehicle profile.

And at least on the version of Torque I'm using "boost pressure" is reporting "gauge pressure", so it's not including the normal ~14.7 psi from atmosphere.

Hope that helps. 50psi would be deeply sub optimum if it's real.

TDI, now that you have the analog gauge, what VE value you found to be optimal for the Torque to line up with the analog readings?

Also, my understanding, that in torque there is no need to put in the Boost Adjustment unless one lives at a higher altitude.

Thanks.

[DWR]

Originally Posted by TDIwyse

The way the EWG is configured in the latest video/log is a very simple manifold to lower port config. So drive pressure + boost is pushing the gate open.

TDI, just wondering if you are able to log the exhaust manifold pressure using BT. I don't think it is possible in Torque, unless someone has found the PID.

[Yozh]

Originally Posted by DWR

TDI, just wondering if you are able to log the exhaust manifold pressure using BT. I don't think it is possible in Torque, unless someone has found the PID.

It is possible in the BMWhat.

[Mik325tds]

I'm wondering if the overboost is just a problem with a free-flow exhaust or if the DPF delete will already cause the overboost (with the SCR cat still in place). I'll install 2deer's downpipe soon and wonder if I should drill out the waste gate while I'm at it.

[TDIwyse]

Originally Posted by Yozh

It is possible in the BMWhat.

What sensor is it using to do that? I don't see any pressure sensor in the exhaust that would do this. There is a differential pressure sensor that was used on the North American M57 that would measure the pressure differential across the DPF. But I'd love to know how BMWhat is measuring the drive pressure.

DWR, I haven't measured the drive pressure. Just figured I'd be able to figure out the settings with the wastegate and boost controller...

Here's a pic of where I have the boost controller plumbed in. It's where the EGR cooler used to route the exhaust gas into the EGR valve... The vacuum line from here to the EWG is really short.

[TDIwyse]

Originally Posted by Yozh

TDI, now that you have the analog gauge, what VE value you found to be optimal for the Torque to line up with the analog readings?

Also, my understanding, that in torque there is no need to put in the Boost Adjustment unless one lives at a higher altitude.

Thanks.

I've been using 85%. It seems to be fairly close at most temps and mid/upper boost levels. But recent testing has shown that at extremely low ambient temps this causes Torque to under report peak boost values relative to the analog gauge. At 4F it seemed to be low by ~5-6 psi. At 25F it's about 2 psi off. My memory from a couple years ago when doing this comparison was that at summer temps the values were extremely close for most of the rpm/boost range.

Also, at the level of power my car is at the MAF output is becoming saturated at higher rpm levels so this causes some under reporting of boost above ~4000 rpm as Torque is using a calculation that relies on the MAF sensor.

But, other cars may be different than mine in many of these areas ...

[Yozh]

Originally Posted by TDIwyse

What sensor is it using to do that? I don't see any pressure sensor in the exhaust that would do this. There is a differential pressure sensor that was used on the North American M57 that would measure the pressure differential across the DPF. But I'd love to know how BMWhat is measuring the drive pressure.

Number 6 in the below diagram. Mounts onto #1, you can see it if you take the engine cover off. Pipe #9 takes exhaust feed just below the high pressure turbo, M17 banjo bolt.

[Yozh]

One more for you TDI.

[Yozh]

Originally Posted by TDIwyse

I've been using 85%. It seems to be fairly close at most temps and mid/upper boost levels. But recent testing has shown that at extremely low ambient temps this causes Torque to under report peak boost values relative to the analog gauge. At 4F it seemed to be low by ~5-6 psi. At 25F it's about 2 psi off. My memory from a couple years ago when doing this comparison was that at summer temps the values were extremely close for most of the rpm/boost range.

Also, at the level of power my car is at the MAF output is becoming saturated at higher rpm levels so this causes some under reporting of boost above ~4000 rpm as Torque is using a calculation that relies on the MAF sensor.

But, other cars may be different than mine in many of these areas ...

Thanks TDI. Can you confirm that in Torque settings you have left boost adjustment at "zero". Please and thank you. I wish BMWhat would have a boost parameter. Seems weird not to have one.

[DWR]

Originally Posted by TDIwyse

What sensor is it using to do that? I don't see any pressure sensor in the exhaust that would do this. There is a differential pressure sensor that was used on the North American M57 that would measure the pressure differential across the DPF. But I'd love to know how BMWhat is measuring the drive pressure.

I was referring to item 23, in this diagram.
http://www.e90post.com/forums/attach...1&d=1421124967