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+--- Thread: VNT/VGT mechanical vacuum control (/showthread.php?tid=348)
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RE: VNT/VGT mechanical vacuum control - Atli - 11-13-2010
Hi
Is this setup still up do date and how is the last year experience of it?
Is the vacuum site connected to the vacuum pump? (not transmission site)
Is the vacuum pump on Mercedes diesels as mine OM603 constant vacuum? or does it variable with rpm?
Thinking of trying this setup and will be grateful for all the help I can get.
Do anybody know if there is any electronic VGT control close or workin allready?
Regards Atli
RE: VNT/VGT mechanical vacuum control - tomnik - 11-13-2010
Hi Atli,
still no progress over here...
I also prefer the electronic actuator. I ordered a LED dimmer that has a poti to manage the PWM output. Important here: 140 Hz.
The dimmer cost me 7 EUR incl. shipping.
Then it needs a PID unit with an analogue output to replace the dimmer and it could work, so my ideas as a non electronic.
There is a guy on VW TDI forum with a nearly complete solution but he is very busy and can not give a schedule for a "plug and play" sell-able solution.
I failed with my mechanical set up because the vac is too weak in sense of flow. Boost comes fast and acts the vanes but then the vac is too slow to move the vanes for rebuild boost. Have to admit that it made some fun driving with this set up (but only to be the clown on the street).
It was like boost-no boost, boost-no boost,...
The last thing I will try is to link the vanes directly to the pedal in an adjustable way regarding movement, then push back the vane lever with up coming boost. The pedal linkage is spring loaded to the vane lever so the boost actuator can push the lever back although the pedal is depressed. Could work but also might end up in the scrap bin.
Tom
RE: VNT/VGT mechanical vacuum control - ForcedInduction - 11-13-2010
(11-13-2010, 07:03 AM)Atli Is this setup still up do date and how is the last year experience of it?Yep, I enjoy the hell out of it. The only thing I've done is fine tune the boost pressures of each stage and adjusted the timing of how much throttle until the second stage comes in. As the balls seated in and started sealing better the pressures drifted upwards 2-3psi.
Quote:Is the vacuum site connected to the vacuum pump?Yes. It is connected to the first nipple of the main line and shares with the shutoff circuit (it would also share with the door locks and CC, if they still existed). I also drilled out the orifice at the main line nipple to 1/16", not sure how small it was before. The second nipple (closest to the check valve) is for the transmission alone.
Quote:Is the vacuum pump on Mercedes diesels as mine OM603 constant vacuum? or does it variable with rpm?MB's vacuum pumps always work to pull maximum vacuum. At my altitude that works out to 15"Hg but sea level that can be as high as 22"Hg.
I've run all the way up to 12,000' and the system has operated the same as it does at home (5280').
Quote:Do anybody know if there is any electronic VGT control close or workin allready?Only functional one I'm aware of requires a CAN equipped vehicle to operate.
I agree electronics are the way to go for best performance, I'm just not equipped to build or program for it.
Quote:I failed with my mechanical set up because the vac is too weak in sense of flow. Boost comes fast and acts the vanes but then the vac is too slow to move the vanes for rebuild boost. Have to admit that it made some fun driving with this set up (but only to be the clown on the street).Mine doesn't do that, it goes to boost and stays there. The only real variance is at low loads where it will run between 3-5psi, which my water injection system depends on to cut off water flow during deceleration.
It was like boost-no boost, boost-no boost,...
With the dawes valves you're not limited only to vacuum. Boost can pressurize the actuator to make the vanes open quicker if, for example, the actuator spring isn't strong enough to overcome the exhaust pressure or the system is setup to build boost very fast.
Quote:The last thing I will try is to link the vanes directly to the pedal in an adjustable way regarding movement, then push back the vane lever with up coming boost. The pedal linkage is spring loaded to the vane lever so the boost actuator can push the lever back although the pedal is depressed. Could work but also might end up in the scrap bin.That method has been popular in the VW world. I don't like it though, it doesn't have any way to limit/vary boost pressure with engine load/throttle. Throttle movement only changes how quickly the turbo spools up to maximum boost (and the actuator pushes against the throttle force).
RE: VNT/VGT mechanical vacuum control - Jambo - 11-16-2010
All looks very interesting, must keep an eye out for this thread.
@ ForcedInduction
What is the orange unit in the breather line? Can you give some details.
RE: VNT/VGT mechanical vacuum control - ForcedInduction - 02-15-2011
Bump for MTUpower.
(11-16-2010, 05:57 AM)Jambo What is the orange unit in the breather line? Can you give some details.
Crankcase vent oil separator.
New idea; A normal "boost controller" (like used with wastegates) but instead of an adjusting screw to set spring tension, a plunger that can be depressed to increase spring tension with increased throttle. That would give linear boost:load response like the opposing-actuator method without the drawbacks of carbon buildup. The boost curve would be easily tuned by altering the cam ratio, spring pretension and/or spring strength. This would eliminate jumpy boost "stages", the two blocking valves and the spider.
Anyone know of such a device? Maybe a plunger that could replace the bolt adjuster in a normal controller?
:Lightbulb:
Fuel pressure regulator. That would allow the use of the stock VCV to control boost bleed into the actuator line with no mechanical connection to the throttle linkage.
![[Image: 2636_12lo.jpg]](http://us1.webpublications.com.au/static/images/articles/i26/2636_12lo.jpg)
Now I just need to find one that regulates to ~1psi at full vacuum, 16psi at zero vacuum.
RE: VNT/VGT mechanical vacuum control - ForcedInduction - 03-18-2011
I added an exhaust brake function.
All it consists of is an emissions valve from a 90's Volvo. Its wired to the output of the brake switch to activate. It blocks the 1st and 2snd stage boost valves to make the turbo put out up to 16psi boost during deceleration, good for around about 30psi backpressure at 4500rpm and 10psi at 2000rpm.
Air output from the valves enters the top (coil end) of the solenoid. Non-energized, the flow is unobstructed between the ports. Energized, the flow is completely blocked (capped end).
The only thing left to be added is a relay to automatically disable the water injection during braking. This will also allow me to set the 1st stage injection a few psi lower since it will no longer be tied to low boost for it to shutoff during deceleration.
RE: VNT/VGT mechanical vacuum control - George3soccer - 03-18-2011
Does it sound any different during deceleration.
RE: VNT/VGT mechanical vacuum control - ForcedInduction - 03-18-2011
The exhaust quiets down a bit and the turbo whistles pretty decent. It surges some under 2000rpm, but at that speed it won't damage anything.
RE: VNT/VGT mechanical vacuum control - George3soccer - 03-19-2011
Does the whistle sound like it would be under full load.
RE: VNT/VGT mechanical vacuum control - Syncro_G - 03-19-2011
(02-15-2011, 11:27 PM)ForcedInduction :Lightbulb:
Fuel pressure regulator.
I'm working on making a variation on FI's setup - I wanted to smooth out the steps that the switching system creates and I think I've got something to report back with.
Assuming it works, it would greatly simplify the system - one valve, no cam lobs and switches on linkage. it's ugly but once proven, the body could easily be machined from billet and just transfer the guts over.
It's a variable pressure spring ball valve - derived from the dawes valve that FI uses and it uses off the shelf plumbing parts and a few servilite parts that you can find at a better hardware store (springs, bronze bushing, ball bearing). As is, it goes from 0-15 lbs pressure with 1/2" travel
I've ordered a shaft seal from Grainger and a collection of springs from Century Spring to refine the travel and reduce the blow by around the actuator exit.
The idea is to put it where the cruise control servo would go and use that linkage. boost enters at the ball end, passes the piston (turned bolt on drill press) and exits through the side port of the tee fitting.
All is 1/4"NPT, ball is 3/8" dia, spring rate and overall length is a work in progress. I did some minor work to shape the ball seat and piston head.
I'm still working at a glacial dad-with-toddlers pace but have been making lots of progress lately.
RE: VNT/VGT mechanical vacuum control - ForcedInduction - 03-19-2011
(03-19-2011, 11:56 AM)George3soccer Does the whistle sound like it would be under full load.
Airflow is airflow, so yes. Only the exhaust sound is different.
Great work Syncro_G! I haven't made any progress on the idea, I can't find any existing vacuum controlled regulators with the required working range. With existing ones the variable regulator would only work as the first 0-10psi stage since my vacuum system only makes 16"Hg (7.9psi).
RE: VNT/VGT mechanical vacuum control - Syncro_G - 04-08-2011
I have been slowly evolving my valve design - the goal was to get it to pop from 0 to 15 psi with an actuator movement of 1-7/8" so that it can be directly connected to the cruise control cam.
I got the basic system working with plumbing parts but it was sticky. I started to worry about that. If it's going to be attached to the throttle linkage, it better be smooth and durable. So I've been iterating to get it hiccup free.
first picture is of the assembly mounted on the valve cover. from that, I found that the lateral forces on the actuator rod was a big problem
so I decided to replace the long carriage bolt I was using with a precision ejector pin. That was way better but would still bind because the bearing surface wasn't long enough. So I then added a slide block as you can see. now it's really smooth and doesn't bind with moderate side pressure. I also decided to use the dawes valve - I drilled out part of the casing so that the long spring could pass into it - this was really so I could make use of some precise parts using my not-so-precise tools. The whole thing has been a fun exercise in managing errors and of careful assembly. the whole thing would be fairly cheap except that for every piece I'm using, I also bought 4 or more other sizes of that thing before I got it right.
(shown with the first plumbing version)