[HeatherM35d]

Originally Posted by tuikku

.
... About the turbine clipping...

Do any have any evidence, that it will also work in this kind of solution, where engine needs ++2bar (30psi) boost pressure.
For this far, I haven´t seen.
Or can anybody explain why should it give any benefit.

As far as I can understand, that kind of solution (clipping) might give some more flow, if the compressor could reach to so good efficiency area, that extra air is even possible to form. But I doubt.
More flow means less efficiency turbine in this case.

What kind of solution is that, where compressor needs more power and turbine can produce it less.

Not sure I fully understand what your getting at?

[BEWWWM]

I found a fairly old(2003) turbo dodge forum discussion with a dyno comparison showing clipped vs unclipped. The 10 deg clip was performed in an attempt to gain top end power, ended up destroying the bottom end.

http://www.turbododge.com/forums/f4/...o-results.html

[HeatherM35d]

Originally Posted by BEWWWM

I found a fairly old(2003) turbo dodge forum discussion with a dyno comparison showing clipped vs unclipped. The 10 deg clip was performed in an attempt to gain top end power, ended up destroying the bottom end.

http://www.turbododge.com/forums/f4/...o-results.html

In a single turbo arrangement, they may have killed the bottom end. Apples to apples or not? My experience with the x5 doesn't show any extra lag.

[TDIwyse]

Originally Posted by zackz

Yes It seems that they were discussing about the wastegate flap, but I don't remember any test with the turbine bypass flap, will kill the low end boost pressure during the test for sure, but should be interesting in order to know the true stock big turbo turbine/wastegate backpressure/flow restriction in the high end bandwidth.
...

Sorry, I misunderstood. I haven't tested that either, and don't recall anyone posting about this kind of test. Extreme cold is here for awhile (tomorrow's "high" is supposed to be -6F, or -21C) so no more near term testing from me...

[BEWWWM]

Originally Posted by HeatherM35d

In a single turbo arrangement, they may have killed the bottom end. Apples to apples or not? My experience with the x5 doesn't show any extra lag.

It would be really cool to see your before/after dyno.

[TDIwyse]

Originally Posted by HeatherM35d

I'm sure we can run some tests. Bohl Diesel installed the turbos on my x5 for under $3000 with labor. X5 is running a 15 degree clip on both turbines and I believe the 335ds at BDP run more clip than that.

Thanks. I think the boost vs drive pressure info would be extremely helpful in comparing various options. If we could get MAF data along with this then that would be even better... but that takes a lot of fussing around since at these levels the OEM MAF becomes useless.

[DWR]

Clipping is on the exducer side of the turbine. Cutting an exducer down at the root will weaken the turbine. Therefore, material is removed progressively, moving out to the tip. Hence, describing the removal in terms of the angle that is created.

This is an inexpensive countermeasure to excessive drive force. Unfortunately, it does reduce drive force at all flow levels. Therefore it does effect the transient response of the turbo. The R2S turbo system can mitigate some of that by adjustment of the HP to LP transition. To some extent, the software takes care of that automatically.

[zackz]

Originally Posted by TDIwyse

Sorry, I misunderstood. I haven't tested that either, and don't recall anyone posting about this kind of test. Extreme cold is here for awhile (tomorrow's "high" is supposed to be -6F, or -21C) so no more near term testing from me...

Of course I understand!

Anyway, thanks for the information you've already posted here

[DWR]

Originally Posted by TDIwyse

The shape of the IWG power curve showed what I think is evidence of the hot side "choking" at the upper rpm's. Higher drive pressures, higher EGT's and even though the boost was higher, lower peak wheel power.

Choking has specific meaning in a turbomachine, in which air flow velocity is approaching local Mach of 1. The data you show doesn't indicate that is what is happening. Not trying to make a semantic arguement here, just trying to get the nomencature clear for discussion.

Also, what is commonly called "drive pressure" is an incomplete measurement to understand the work going into the turbine. Physically, it is the difference between EBP at the manifold and EBP after the turbine that creates the drive (I'm purposely not including impulse forces). This is exactly what was seen when the DOC/DPFs started coming off and turbo performance improved. The next layer of complication is turbine efficiency, which varies with flow, expansion ratio, and turbine speed. Any "linear" analysis of the dynamics can lead to false conclusions.

So, lets backup and discuss the difference between your IWG and EWG, because I think that is significant.

I'll start with the EWG, because that's easy (well, it's Saturday, and I like to ease into Saturday ) Your EWG is completely out of the flow path of the turbine. It's exhaust does not even return to the main exhaust. Other than an imbalance of EBP at the individual cylinder ports, I can't think of a more effective/efficient setup.

Now, the IWG. It isn't even good for an IWG. First it is not isolated from the turbine flow path. In fact, it interferes with the turbine flow path. Contrary to intuition, abrupt expansion can have greater flow resistant than abrupt contraction. This creates pressure in front of the exducer. For the same manifold pressure, the work that can be transferred to the turbine is reduced. So, to get the same boost from the compressor requires greater manifold pressure to the turbine. I should note that an internal IWG can cause flow disturbances on the inducer side of the turbine,also.



The higher EBP in front of the turbine causes 2 problems. First, it just creates more work for the piston on the exhaust stroke. Energy from the fuel that could have been used to propel the car is being used to push out exhaust. Just to put some magnitude to all this, it will take more than 70HP of shaft power to attain these levels of pressure and flow. Second as the ratio of manifold EBP to boost rises, more residual exhaust remains in the cylinder and potentially a 1% to 2% backflow at the beginning of the intake stroke. If the fuel flow remains the same AFR will drop and EGT will rise.

Now here is an example of a divided wastegate outlet.


And a divided exhaust flange continues the separation and extends the length.


At a minimum, we would like to see the length of the exit duct from the exducer to be 3 times its diameter. Ideally, we'd like to see the expansion take place in a 10 degree flare.


Merging of wastegate and turbine, well downstream of the turbine.


And finally, when an IWG would perform nearly as good as your EWG. Here, the only improvement would be isolation of the wastegate input side from the turbine inducer - just as your EWG does.


Basically, TDIwyse, you have done a very good job integrating your EWG. The OEM IWG configuration cannot compete!

[TDIwyse]

Originally Posted by DWR

Choking has specific meaning in a turbomachine, in which air flow velocity is approaching local Mach of 1. The data you show doesn't indicate that is what is happening. Not trying to make a semantic arguement here, just trying to get the nomencature clear for discussion.

Also, what is commonly called "drive pressure" is an incomplete measurement to understand the work going into the turbine. Physically, it is the difference between EBP at the manifold and EBP after the turbine that creates the drive (I'm purposely not including impulse forces). This is exactly what was seen when the DOC/DPFs started coming off and turbo performance improved. The next layer of complication is turbine efficiency, which varies with flow, expansion ratio, and turbine speed. Any "linear" analysis of the dynamics can lead to false conclusions.
...

Thanks for a fantastic overview and description, and correcting my improper use of terms.

Since you showed those images, I should update that I had that according flex pipe spring a leak, and since went to a solid mandrel bend stainless pipe for the manifold to EWG connection.

Question for those who've done turbo swaps on this platform... if we didn't need the IWG any longer, does that open up any other possibilities for turbo upgrade options? Different hot side possibilities? Or is space so tight, and the integration into the R2S system such, that we are extremely limited on what can be done?

[tuikku]

.
Thank you DWR.

TDI wyse, read carefully the end.

Well, maybe I can tell you so much, that the diameter of the turbine is of course important, but the shape of the turbine wing is other and how much blades there are.
No need to increase the diameter so much, if just take a notice to all these other things also.

[TDIwyse]

Originally Posted by tuikku

.
Thank you DWR.

TDI wyse, read carefully the end.

Well, maybe I can tell you so much, that the diameter of the turbine is of course important, but the shape of the turbine wing is other and how much blades there are.
No need to increase the diameter so much, if just take a notice to all these other things also.

You're so cryptic :-)

Does this image of the M57 turbo on the 535d have an isolated IWG passage like DWR was describing?

http://dencodiesel.com/products/turb...s-bmw-535d-m57

Is the hot side on the 535d different than the 335d?

[AiM]

Hotside in 335D and 535D LCI is technically same. They have different part number and from DWR posts second picture you can see support from block to housing and where brace connects -thats the difference between housings.

Pre-lci 535D is totally different housing but i think turbine wheel is same.

[AiM]

Originally Posted by TDIwyse

You're so cryptic :-)

Does this image of the M57 turbo on the 535d have an isolated IWG passage like DWR was describing?

http://dencodiesel.com/products/turb...s-bmw-535d-m57

Is the hot side on the 535d different than the 335d?

That is just stock housing, no isolated IWG passage. I think you are looking turbine housing inlet, not outlet...

That flap in intake is the flap that is separates small and big turbo at about 3000rpm. That is also the reason why you can't use universal exhaust housings.

There you can find pictures how R2S system operates;
HERE

[TDIwyse]

Originally Posted by AiM

That is just stock housing, no isolated IWG passage. I think you are looking turbine housing inlet, not outlet...

That flap in intake is the flap that is separates small and big turbo at about 3000rpm. That is also the reason why you can't use universal exhaust housings.

There you can find pictures how R2S system operates;
HERE

Thanks.

I suppose it would be possible to form an isolation between the IWG and turbine outlet with a custom made downpipe? Kinda have a shaped section for the IWG flow such that it protrudes into the area where the IWG is located? But it looks pretty tight in there already...

[Works]

Originally Posted by TDIwyse

You're so cryptic :-)

I know the dude from Finnish BMW and MB forums, he has a crap ton of knowledge from engine builds, diesel tuning and turbos, but not the English skills to back them up unfortunately. Hence he reads a bit cryptic at times

Tuikku mate, if you ever need translations help, hit me up!

[HeatherM35d]

Tim does all of the turbo work for BDP, and has a website with good info.
www.timsturbos.com

[iaknown]

Originally Posted by HeatherM35d

Tim does all of the turbo work for BDP, and has a website with good info.
www.timsturbos.com

I can vouch for Timmy, I've been using him for years Great guy and really knows his stuff.

Looking forward to seeing some BDP dyno results.....

[petey_highboost]

Originally Posted by iaknown

I can vouch for Timmy, I've been using him for years Great guy and really knows his stuff.

Looking forward to seeing some BDP dyno results.....

My results with the hybrid units will be on fuel only.. Not a big fan of water/meth

[tuikku]

Originally Posted by HeatherM35d

Tim does all of the turbo work for BDP, and has a website with good info.
www.timsturbos.com

Maybe I am blind, but I cannot see any good info, I just see their opinion about the thing, nothing more.
I´m still waiting the results ...

My opinion is that TDIwyse has proved here many times, that up to ~420hp level, the orig solution with EWG is the best, IWG works, but EWG is better.
My own experience about this is equal.
And I am not talking only for my own car, but I have done few these to other also ...

But, what happens above ~420 level, TurboTim do not know anything about that .

AiM have a good result, very good.
But I´m quite sure, that he could get the same result by only doing the all other improvements he done and nothing to the turbo wings.

For me, the main thing is understand the working principals and change the minimum number of parts, only what is necessary and let the others be there.
I have build many of these by this method - and they work, well.

The only solution, where turbine clipping can work, might be with orig compressor.

Work and AiM, nice to see you here.
Hopefully this don´t become an other Finnish BMW forum ...

[DWR]

Originally Posted by TDIwyse

I suppose it would be possible to form an isolation between the IWG and turbine outlet with a custom made downpipe? Kinda have a shaped section for the IWG flow such that it protrudes into the area where the IWG is located? But it looks pretty tight in there already...

I agree, it is a tricky space. Someone should just figure out a EWG solution, lol.
An insert that blocks the IWG and transitions flow out the exducer to the exhaust pipe might be a nice touch.

[DWR]

Originally Posted by tuikku

For me, the main thing is understand the working principals and change the minimum number of parts, only what is necessary and let the others be there.
I have build many of these by this method - and they work, well.

... nothing more to say.