Mechanical VNT Control - Page 3 - PeachParts Mercedes-Benz Forum

libbybapa · #31 09-05-2011, 02:28 PM

Quote:

Originally Posted by Marvelicious

Meh, it might crack eventually, but I wouldn't lose any sleep over it. When welding cast, preheating with a torch helps big-time! What makes cast so tricky is that it expands a lot when heated. As counter-intuitive as it would seem, stainless is a better match, because of its expansion rate. Use some 309 welding rod and it will bond with both materials.

I did pre and post heat and let it cool quite slowly. I am not concerned about it.

winmutt · #32 09-06-2011, 10:34 AM

Quote:

Originally Posted by libbybapa

Here's a photo of the modified manifold. Everyone would be encouraged to resist the urge to tell me that welding on the cast manifold will crack. It has been a daily driver for 3 or 4 years and driven on longer trips (e.g. to Vegas, baby) without any issues whatsoever.

Are you the guy that posted up on TDIForums or one of the other VW sites? If so we have spoken before.

I made a t3->t25 adapter this weekend that is removable using 2x3/8" steel plates and a variety of counter sunk bolts. I will be posting it up later this week when everything is mounted. I went with a HY30W, after much musing I decided that the VNT was more trouble than it was worth and wouldnt work to well with an uprated pup.

Its nice to see other manual control options for the VNT. My favorite is still the one that uses the VCV. Also there are a few electric control solutions on STD using the stock Hella actuator.

libbybapa · #33 09-06-2011, 01:45 PM

I have posted on various sites, but rarely on the TDI Club.

I can see how two plates bolted together would work. I might go that route if doing over just for the ability to return things to stock, if desired. At this point I am happy with this solution.

I would be interested in links to other controls. I am not familiar with the VCV control. Most of the functional standalone electronic controls I've seen close the vanes fully any time operating less than max boost which, IMO, is the wrong approach causing unnecessary excessive back-pressure. Closing the vanes proportional to the demand for power is the way to go.

Having used VNTs on various vehicles I would not opt for a wastegated turbo ever again on a vehicle I intended to keep. VNTs are so incredibly worth the added work of a functional control.

Marvelicious · #34 09-06-2011, 02:32 PM

Quote:

Originally Posted by libbybapa

I did pre and post heat and let it cool quite slowly. I am not concerned about it.

I figured, since it has lasted. I was just throwing it out there as a FYI for anyone who decides to copy what you have done.

winmutt · #35 09-06-2011, 04:00 PM

Quote:

Originally Posted by libbybapa

I have posted on various sites, but rarely on the TDI Club.

I can see how two plates bolted together would work. I might go that route if doing over just for the ability to return things to stock, if desired. At this point I am happy with this solution.

I would be interested in links to other controls. I am not familiar with the VCV control. Most of the functional standalone electronic controls I've seen close the vanes fully any time operating less than max boost which, IMO, is the wrong approach causing unnecessary excessive back-pressure. Closing the vanes proportional to the demand for power is the way to go.

Having used VNTs on various vehicles I would not opt for a wastegated turbo ever again on a vehicle I intended to keep. VNTs are so incredibly worth the added work of a functional control.

AH yes I remember the nick distinctly now. Good to see the weld held up. I tracked down a hard to find euro manifold for my om603 so I wanted to make sure I could go back if it was too small. Here is a link to the hella actuators :

http://www.superturbodiesel.com/std/Thread-Garrett-712120-VNT-Hella-6NW-008-412-actuator?pid=7425

http://www.superturbodiesel.com/std/Thread-Electronic-variable-vane-control

moon161 · #36 09-06-2011, 04:36 PM

Quote:

Originally Posted by netboy

MEANWHILE,BACK AT THE FARM............ So are you saying that you removed the stock turbo and this V-DUB turbo bolts right up. And do you have intercooler pics? By the way it is an aviation concept. All new axial flow turbine engines use variable vanes for more efficient air flow across the compressor blades.

New? In in my propulsion class in 97 or 98 we pulled the covers off of a GE J79 that had been donated to the school, and I could pick out the variable stator system and read up on it. Has to be 50's or 60's technology at the latest.

turbo97se · #37 09-06-2011, 09:55 PM

I looked at this stuff and remember the link posted quite a long time ago. I was wondering if any one can tell me where I can get of these electronic actuators reasonably priced? I saw some on Ebay about a year or so ago but wasn't sure which way to go at that time and now have difficulty finding them. If I can't find these, then I will go mechanical actuator and use PWM controlled solenoid or Idle control stepper with arduino ... just learned how to program these things .. very useful!

Quote:

Originally Posted by winmutt

AH yes I remember the nick distinctly now. Good to see the weld held up. I tracked down a hard to find euro manifold for my om603 so I wanted to make sure I could go back if it was too small. Here is a link to the hella actuators :

http://www.superturbodiesel.com/std/Thread-Garrett-712120-VNT-Hella-6NW-008-412-actuator?pid=7425

http://www.superturbodiesel.com/std/Thread-Electronic-variable-vane-control

libbybapa · #38 09-06-2011, 10:23 PM

Quote:

Originally Posted by winmutt

AH yes I remember the nick distinctly now. Good to see the weld held up. I tracked down a hard to find euro manifold for my om603 so I wanted to make sure I could go back if it was too small. Here is a link to the hella actuators :

http://www.superturbodiesel.com/std/Thread-Garrett-712120-VNT-Hella-6NW-008-412-actuator?pid=7425

http://www.superturbodiesel.com/std/Thread-Electronic-variable-vane-control

Thanks for the links. I skimmed the Hella actuator thread and it didn't seem like anyone has actually gotten it working on a vehicle. Also the overly simplistic control parameters described of having the vanes fully closed whenever less than max boost is certainly not how I'd do it. They should only close based on load. Might as well just add a boost can to the vanes. When I have some more time I'll read through both threads more thoroughly. I actually have one of the actuators and would be most interested in seeing it working.

turbo97se · #39 09-07-2011, 03:26 AM

Hmmm . I think you have a point there .. but wastegates operate on boost signal for the most part .. better for performance, may be not so good for economy. Could use a MAP sensor, RPM, IAT and TPS to make load based calculations .. all of a sudden your method looks simpler LOL!

Sorry ... forgot to give you props for coming up with a rather ingenious method of control and sharing it with us. I am still trying to understand parts of it

.. I am more of a bit banger than mechanical.

Quote:

Originally Posted by libbybapa

.... They should only close based on load. Might as well just add a boost can to the vanes... .

libbybapa · #40 09-07-2011, 10:29 AM

Quote:

Originally Posted by turbo97se

Could use a MAP sensor, RPM, IAT and TPS to make load based calculations

IAT is probably more useful at determining fuel quantity and because the mechanical injection pump ignores IAT, it probably wouldn't be particularly useful. The sensors I would use if designing an electronic control would be MAP, Drive Pressure, RPM and TPS.

I considered adding an RPM input to my mechanical control. The only functional difference I would want from it would be to alter the vane closing map based on RPM so that at low RPMs the vanes would be fully closed in the first half of accelerator travel and at higher RPMs the vanes would be fully open until the second half of the accelerator travel. Functionally that would not change max acceleration rates for the car, it would just give it the feel of more power with less push on the accelerator, probably reduce smoke off the line a little and slightly reduce cruising back-pressure. I came to the conclusion that it would be more effort than it was worth.

scottmcphee · #41 09-16-2011, 10:46 PM

Brand new VNT25 on ebay, with new spare parts, did not sell for opening ask of less than $300.. Hm.

Just been relisted and has one bid at the moment for the $295

http://cgi.ebay.com/ebaymotors/GARRETT-VNT-25-Brand-New-Turbo-ULTIMATE-PERFORMANCE-/110745097019?pt=Motors_Car_Truck_Parts_Accessories&hash=item19c8ec133b

winmutt · #42 09-17-2011, 07:36 AM

GT2552V

libbybapa · #43 09-23-2011, 12:20 PM

Here are some concept diagrams to assist in easy understanding of how the control works. They are based on one of the VW controls I built so the boost can is in a slightly different position, but the concept is the same.

Group49 · #44 10-04-2011, 04:29 PM

That system only controls how fast the turbo spools up to maximum.
It needs to control pressure based on engine load. This is how every vehicle manufacturer in the world controls it.