GTC1444VZ in an ALH

Too bad that a smaller external wastegate wasn't available.It could be tricky to control boost the way you would probably like it to be.I wonder if an AHU egr valve could be reworked to be used as an external wastegate ?

In theory I would try an AHU egr valve (for example).Without any signal hooked up to the valve it could act as a relief as EMP's rise.If higher turbine speed is needed from the high pressure turbo then simply add boost pressure to the egr valve's diaphram using a boost controller.

What is the max HP that you would plan on making with this setup ?

I run 200hp through a 37.26mm turbine exducer with my compounds with no wastegate needed and its being over fueled .

andy2 said:

Too bad that a smaller external wastegate wasn't available.It could be tricky to control boost the way you would probably like it to be.I wonder if an AHU egr valve could be reworked to be used as an external wastegate ?

In theory I would try an AHU egr valve (for example).Without any signal hooked up to the valve it could act as a relief as EMP's rise.If higher turbine speed is needed from the high pressure turbo then simply add boost pressure to the egr valve's diaphram using a boost controller.

Click to expand...

I was using a cast iron ford EGR valve as a sorta wastegate on an unrelated project for a while. It worked for a while, but then the pipes to it broke, so it didn't get too many miles on it before it was tossed in the bin.
My only concern was that the diaphragm on them is pretty close to the body of it, and it would probably get pretty toasty.

As an aside, the ford one had about an 11mm port through it, would the AHU one flow a bit better? Looking for a higher flow EGR valve is surprisingly difficult, short of walking through the junkyard and actually taking the parts off of cars for a look.

I should probably start a separate thread on this...

Andy - do you mean a manifold like this?


I might be able to put the wastegage like you say and see if I can figure out how/where to put the LP turbo and save all the manifold fabrication...at least in the short term.

I'm aiming for a very driveable 200 WHP from 2600 RPM on out (400 ft-lbf) and holding 400 ft-lbf as low as PCP's will allow.

It's possible that an egr valve might not take Higher EGT's for too long.It depends on how long that higher EGT's would be traveling through it.

I think that the AHU manifold would do the job at 200whp.A cast manifold does the best job of keeping available energy to the turbine.

The passat with AAZ (1.9TD/Canada) used an EGR with two different exhaust manifolds depending on which turbo/year used.One of these manifolds might even work better for you.I think I have an AAZ passat k03 manifold that I could take a pic of.

andy2 - could you post a picture of the manifold you're talking about?

This has me thinking (being lazy, I mean efficient ) about putting the wastegate on the EGR port of the manifold I'm already using and seeing if I can cram the LP turbo up in there somewhere. Then it's a lot less fabrication

Heck, even just adding the wastegate only on the EGR port might make the 1444 work better at higher RPM's as the EMP's get pretty high at a relatively low RPM.

wastegate on the egr port alone will not bring much to the EMPs unless the 1444 is creeping (when using 1444 alone without LP turbo). the turbine needs this energy to built the boost. if you unlash energy through the gate. the vnt will just close more in able to extra same energy to provide the boost (as the compressor is way out of efficiency range)

+1 on what Ruben said

Wastegating while running the GTC1444VZ as single turbo will force the vnt to act like a smaller A/R housing to be able to reach the requested PR, EMP will actually be higher

Alcaid said:

+1 on what Ruben said

Wastegating while running the GTC1444VZ as single turbo will force the vnt to act like a smaller A/R housing to be able to reach the requested PR, EMP will actually be higher

Click to expand...

we had this problem on our compound build, we had to map around it, but doing this on a single turbo setup would not work well as said before, unless the turbo is doing 2x too much boost with the vanes fully open at higher RPM already!

Pictures of the passat AAZ k03 exhaust manifold.







When force feeding a turbo (staged) it does help regulate the high pressure turbo's shaft speed.A wastegate is only needed if the shaft speed can't be controlled within reasonable limits while the vanes are fully open.You would have to ignore EMP's and focus on shaft speed at that point.I havn't bothered with a shaft speed gauge but it would be neat to see.

I've only ever messed with a wastegate to control a high pressure turbo as it was fixed geometry.

You can have the manifold and just pay shipping.

andy2 - thanks for the offer, I'll let you know if it's something I'm interested in but I don't think that manifold will have much advantage over the manifold I currently have (see post 1 or 63). Off topic - is that an organ/piano it's setting on in the pictures?

Regarding the EMP's and a wastegate on this turbo, I think there's some benefit to be had. See between 7 and 15 seconds of this video

https://www.youtube.com/watch?v=2NVA339cuss

Notice how boost is 25 PSI and falling slowly, EMP's are 45 PSI and rising slowly and the VNT vacuum is zero? The vanes are wide open (start motion at ~3inHg) and the turbo is fixed geometry at this point I agree that you can't take away so much energy that it won't drive the turbine anymore else the ECU will close the vanes as Alcid mentioned, but I don't think that it takes 45 PSI to drive the turbine at 3500 RPM.

If I put a 5 or 10 psi spring in the wastegate and fed boost into the same side of the diaphragm it should open when EMP's get 5 or 10 psi over boost.

Fix_Until_Broke said:

If I put a 5 or 10 psi spring in the wastegate and fed boost into the same side of the diaphragm it should open when EMP's get 5 or 10 psi over boost.

Click to expand...

Issue with that is that the EMPs spike up pretty high when initially spooling the turbo. Mine went to 80 PSI or so when completely stock with a VNT-15.

So, the VNT won't spool quite so violently as it will without a 'gate in the picture.

Not if you're tune/stop screw/actuator is adjusted properly in my opinion

You have very small turbo is normal you have high EMP at high rpm, clearly the turbo are far away of efficiency zone.
A simple wastegate on mecanical boost controler plug on exhaust manifold make EMP pressure limiter.




Dieseleux

Fix_Until_Broke said:

Not if you're tune/stop screw/actuator is adjusted properly in my opinion

Click to expand...

I have since adjusted the stop screw (along with a lot of other junk), but this was as it came from the factory.

Fix_Until_Broke said:

Notice how boost is 25 PSI and falling slowly, EMP's are 45 PSI and rising slowly and the VNT vacuum is zero? The vanes are wide open (start motion at ~3inHg) and the turbo is fixed geometry at this point I agree that you can't take away so much energy that it won't drive the turbine anymore else the ECU will close the vanes as Alcid mentioned, but I don't think that it takes 45 PSI to drive the turbine at 3500 RPM.

If I put a 5 or 10 psi spring in the wastegate and fed boost into the same side of the diaphragm it should open when EMP's get 5 or 10 psi over boost.

Click to expand...

When vanes are fully open and you are not seeing boost creep, the only thing you will accomplish by wastegating to lower EMP is a boost drop. Only way to lower EMP at the same boost pressure with open vanes is to increase the turbine choke flow ie. bigger exducer turbine wheel and/or bigger A/R turbine housing....

Ahh - that makes sense now that you explain it and I think about it more. Something felt a bit weird with the boost continuing to drop as EMP's went up. I don't have any turbine maps, but I'm guessing that they would show this phenomena just like a compressor map would.

Might this actually work as a benefit in a compound setup to keep the shaft speed in check and force more exhaust across the wastegate to the LP turbo?

Yup, that's what a turbine map will show:



Past a certain peak, when the vanes are wide open, further increasing shaft RPM will actually result in the corrected mass flow declining! Wastegating will reduce the mass flow and simultaneously the EMP, RPM (and boost) will readjust to lower values.

Also note that turbine efficiency is worst at wide open vanes (~45%); the peak efficiency occurs somewhere along the middle of the working range of vane opening (~65%). For authority boost control and best efficiency, you want never to let the vanes fully open but go up to about 70-80% opening max.

Wow, that's really cr*p turbine efficiency!

For a small (39mm) turbine.

In any case, I've never seen best-point efficiencies exceed 72% in ANY automotive-sized turbine.

Fix_Until_Broke said:

andy2 - Off topic - is that an organ/piano it's setting on in the pictures?

Click to expand...

Yeah I think its both.

Alcaid and TDIMeister are explaining it better.

From my experience it will require higher EMP to drive an undersized turbine wheel/housing to get the boost required.So while limiting the EMP seems like a good idea it can actually be slowing the turbo down too much to get the compounding effect.

Having the vanes open 100% on the high pressure turbo for compounds can be ok as long as the manifold boost is where you want it while the low pressure turbo is contributing enough.

Basically the vanes won't need to be in the "optimal" position as the low pressure turbo will make up for it.This will also keep EMP's at their lowest.

TDIMeister (or anyone else) Could you explain that turbine map a little for those of us who are not familiar with them?

I assume the x axis is pressure ratio? On that assumption if I turn the plot counter clockwise and look at it in a mirror, it starts to look like a compressor map

Choke on the top (right), RPM curves, I'm guessing that there isn't really a "surge" on the bottom (left).

What are the 1.2% and 1.5% and 1.8% on the RPM curves - % of what?

http://www.scientificbulletin.upb.ro/rev_docs_arhiva/full7406.pdf

https://www.dieselnet.com/tech/air_turbo_vgt.php

http://www-control.eng.cam.ac.uk/Homepage/papers/cued_control_17.pdf

http://repository.up.ac.za/bitstream/handle/2263/40415/le_guyader_back_2014.pdf?sequence=1


Some information found on Google for turbo turbine efficiency...




Dieseleux

See post 5 for dyno data. The numbers are not likely accurate, but the shape of the curve is nice for an engine design that's 15+ years old.

More to come

Now that my new ALH engine is breaking in (7K miles on it, give or take) I'm back to enjoying how responsive the stock VNT-15 is with RC3+ ASV, 11mm pump, and PP357s. Smoke free, and accelerator response is immediate. Small turbos have their benefits, especially in daily driving.

Finally was able to get a tank of fuel in where I wasn't pulling a trailer, didn't have snow tires on, it wasn't -5F so idling all the time, etc with my RC6 tune.

559.5 miles on 10.64 gallons for 52.46 MPG. This is with my 17" wheels, driving 50% 60 MPH and 50% 70 MPH and about 30 miles or so of misc in town driving. Thermostat holds at 188-190F, 5w40 engine oil, GM Synchromesh in the trans.

We'll see if it repeats (filled up at the same station, same pump facing the same way 3 days apart within an hour of the same time of day, clear fuel to the top of the neck, etc).

I finally replaced my axles this weekend, and while I was under there, I clocked the center section/compressor housing just a little bit so that the turbo outlet hose would stop rubbing on the axle. I also replaced the turbo outlet hose (see post 43 - been driving with it like that for 2 years now).

And, while I was there, I decided I'd try and see if I could make the 17/22 actuator that I cobbled together work a little better (see post 2 for why I ended up doing this in the first place).

I was able to move the actuator "in" a little bit which helped the geometry. Same actuator and bracket, I just drilled another hole in the bracket which puts the actuator can more or less touching the compressor housing. Pretty simple, it used to be in the right hole, now it's in the left



This makes the actuator able to move the vanes farther since it's more perpendicular to the arm. Before it was only able to move the actuator 2/3 of it's travel and now I'd say it moves it ~90% of the travel.

Here it is full open


Here it is at full vacuum (~20inHg)


I wasn't quite sure where to set the actuator preload since it ran pretty well before and I was worried about really big EMP spikes with the vanes being able to close even further.

The actuator starts moving at ~5inHg (was a bit hard to tell since the vacuum pump I was using wasn't very good - had a leak in it so had to continuously pump it) and was at the end of it's travel by ~18inHg.

I was not prepared for how significant of a difference this made in almost every aspect of how the car drives and responds to throttle inputs. It was a more significant change than switching from a VNT15 to a VNT17/22. The turbo just does everything better* - it spools faster, it has lower EMP spikes and lower running EMP's both at low and high RPM's, it handles mid throttle transitions better. * The only compromise is that it's a bit smokier on tip in at low RPM - it used to get down to 14:1 or so if you got after it "under" the turbo, and now it's 10:1-12:1 which is pretty smokey. For reference, when I say low RPM I mean 1200-1400 RPM and more than 50% throttle suddenly applied. If you roll into it at low RPM's or stab it at 1800 RPM or above, it just takes off and pulls hard all the way until ~4000 RPM where the EMP's hit ~50 PSI and that's the end of my gauge.

I'm still running my RC6 tune for a 17/22 at this time - It's MAF based so it does a really good job of maintaining AFR levels regardless of ambient temps, turbo spool up, actuator settings, etc. Requested boost is pretty significant at low RPM's (I think this is to get the 17/22 spooled up?), but this smaller turbo will deliver those boost pressures and the N75 PID must be setup well enough that it works. It's definitely an experiment on my part, I just threw it in one day (see post 44) and it works really well and now it works even better with the actuator changes.

I'll try to get some VCDS boost logs to compare with the data in Post 3 and maybe a dyno curve to compare with Post 5, but it's really quick in terms of transient response - you touch the pedal and it's almost "right now" response. I've got a video that I need to get off my iPhone somehow and then I'll put it on YouTube and put a link here.

The actuator adjustment ended up being really easy - I wish I would have done it a couple years ago.

The YouTube app alloys for direct upload from your iPhone. It'll help you trim it too if you didn't do so previously. That's how I uploaded my last ones.

I haven't followed or read this entire thread, so sorry if this has been discussed. Without the VNT lever being allowed to pull the VNT control arm to the stop you are giving up the key spooling/tip-in region of the mechanism's dynamic control range. It seems to me this is greatly negating the greatest benefit of your turbo choice.

Have you looked into shortening the VNT control arm like we have to do with the GTB turbos?

Video of "Dash DAQ" https://youtu.be/3JNAKcuDCxI

A5INKY - You're absolutely correct, however this turbo is small enough that even with the vanes wide open (no actuator at all, it spools almost identically to a well tunes 17/22. The issue is a geometry related, not stroke length related. The actuator is barely perpendicular to the arm when it's wide open and flattens out the more you close the vanes so it gets to the point where it just can't move any farther. Posts 2 & 3 show all this so you don't have to read the whole thread.

Alcaid said:

When vanes are fully open and you are not seeing boost creep, the only thing you will accomplish by wastegating to lower EMP is a boost drop. Only way to lower EMP at the same boost pressure with open vanes is to increase the turbine choke flow ie. bigger exducer turbine wheel and/or bigger A/R turbine housing....

Click to expand...

So, just for grins this weekend, I threw my 32mm wastegate on the EGR port just to see what happens. To no surprise, all you guys were right. Any leaking exhaust gas across the turbine makes a noticeable difference in performance.

Also, somewhere along the line, my understanding must have gone astray because some simple math and areas didn't really line up. The diaphragm has a ~2.65:1 area ratio to the poppet on the wastegage and the downstream is effectively atmosphere.

I started with just teeing in the N75 actuator vacuum to the bottom side of the wastegate thinking that it would hold it shut until exhaust pressures got too high. Well, that didn't work so well - it hit about 10psi boost/EMP and the wastegate was wide open, AFR was 10:1 - back to the shop.

I then put full steady vacuum on the bottom of the actuator and that helped a bit, was able to get mid-high teens out of it before the wastegate opened - back to the shop again.

I then put N75 vacuum back on the bottom and boost on the top - better again, could get 20 psi out of it, but that was about it.

Full vacuum on the bottom, boost on the top and it was reasonable finally. It would open the wastegate right at 50 psi EMP, hold boost at ~20 PSI and run 13:1 AFR under wide open throttle.

The downside to all of this was that at it's best with the wastegate active, there was a significant softening in the low RPM transient response along with a reduction in AFR and more smoke. Even with that compromise, you couldn't limit EMP's much below 50 PSI without limiting boost to ~20 psi and lots of smoke at high RPM's.

So, in short, loss of transient response, no benefit at high RPM - kind of a lose/lose situation.

I made a mechanical stop that is screwed in from the top and holds the poppet shut which restored the low RPM transient response. I do have a selection of springs that I can put on the top side of the diaphragm, however it may make the transient response better, however at the cost of even higher EMP's at high RPM.

I guess on the plus side, the wastegate is installed and I've got a little bit of experience in tuning it so when the HE221 goes in I've got a little bit of an idea of where to start.