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Syncro's mechanical VNT project - Printable Version

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Syncro's mechanical VNT project - Syncro_G - 07-23-2013

Hi,
Life has largely kept me absent from STD for the last two years. However, I've had a back burner project that is now nearly finished and is in need of a little advice.

background:

Some of you might recall me trying to improve on Forced Induction's (vacuum controller). Instead of using three fixed pressure dawse valves controlled by vacuum switches on the throttle linkage, I came up with a variable pressure valve that is directly controlled by the throttle position.

However, to keep things interesting, I also replaced the automatic transmission with a 5-speed manual gearbox (Getrag 717.421), replaced the head gasket, and pulled out a pile of vacuum control devices and the wiring harness that were put in to support the automatic ('85 722.4) transmission.

problem:

Engine appears to idle fine but dies after a little while. idle doesn't seem to be that consistent.
Engine also dies if I give it too much throttle. as if it's fuel starvation. I don't think it's the controller. I can remove it completely from the vacuum system and engine still dies.

Here's a clip on Youtube

descriptions of system:

VNT controller overview
(seems straight forward enough)

vacuum system overview
(this shows my assumptions - are these correct?)


RE: Syncro's mechanical VNT project - OM616 - 07-23-2013

What pump are you running?

Did it die while you were increasing RPM, or did you "snap" the throttle and it died when the throttle was returned to the idle position?


RE: Syncro's mechanical VNT project - Syncro_G - 07-23-2013

(07-23-2013, 04:09 PM)OM616 What pump are you running?

Did it die while you were increasing RPM, or did you "snap" the throttle and it died when the throttle was returned to the idle position?

it's an MW pump. in that video of it running, I still had the throttle up when it died.


RE: Syncro's mechanical VNT project - OM616 - 07-23-2013

Is this something it just started doing all of a sudden?

I assume you have checked the tank vent, (no vacuum in the tank), also the filters, (not plugged), and the post lift pump pressure?


RE: Syncro's mechanical VNT project - Syncro_G - 07-23-2013

(07-23-2013, 04:20 PM)OM616 Is this something it just started doing all of a sudden?

I assume you have checked the tank vent, (no vacuum in the tank), also the filters, (not plugged), and the post lift pump pressure?

Engine has been out of the truck for about 5 months.
I hadn't checked the tank vent yet. It's an unlikely problem on the G-wagen but I can remove cap to be sure.
both fuel filters are newly installed.

when I operate the primer pump, I see plenty of fuel rushing through the pre filter so I don't suspect a blockage problem (at least yet).

It looks like I found the problem - main fuel filter bolt wasn't on tight enough!

in the meantime, I broke the vacuum check valve - I'll need to replace it before I can do much more


RE: Syncro's mechanical VNT project - offroaddieselhu - 07-23-2013

Hi
https://www.youtube.com/watch?v=u74Ofbgjaoc

https://www.youtube.com/watch?v=8KzaMJkrWmg


RE: Syncro's mechanical VNT project - offroaddieselhu - 07-24-2013

(07-23-2013, 03:33 PM)Syncro_G Hi,
Life has largely kept me absent from STD for the last two years. However, I've had a back burner project that is now nearly finished and is in need of a little advice.

background:

Some of you might recall me trying to improve on Forced Induction's (vacuum controller). Instead of using three fixed pressure dawse valves controlled by vacuum switches on the throttle linkage, I came up with a variable pressure valve that is directly controlled by the throttle position.

However, to keep things interesting, I also replaced the automatic transmission with a 5-speed manual gearbox (Getrag 717.421), replaced the head gasket, and pulled out a pile of vacuum control devices and the wiring harness that were put in to support the automatic ('85 722.4) transmission.

problem:

Engine appears to idle fine but dies after a little while. idle doesn't seem to be that consistent.
Engine also dies if I give it too much throttle. as if it's fuel starvation. I don't think it's the controller. I can remove it completely from the vacuum system and engine still dies.

Here's a clip on Youtube

descriptions of system:

VNT controller overview
(seems straight forward enough)

vacuum system overview
(this shows my assumptions - are these correct?)

Hi,

Can you writte me what kind of turbo you have?
What car it's on?
What pressure do you want to use it?
What is th e aim? (to use for...)
I try to help you if you writte me the basic data.

Offroaddieselhu


RE: Syncro's mechanical VNT project - Syncro_G - 07-24-2013

(07-24-2013, 03:24 AM)offroaddieselhu Hi,
Can you writte me what kind of turbo you have?
What car it's on?
What pressure do you want to use it?
What is th e aim? (to use for...)
I try to help you if you writte me the basic data.
Offroaddieselhu

Thanks! The problem turned out to just be air in the fuel.
The controller isn't sorted out yet. I still need to tune spring pressure and orifice between the device and the vacuum source. I also need to verify I'm getting the desired pressures at the actuator.

This is a GT 2256V turbo. I'm planning to operate it at 1 to 1.2 bar range when under load at full throttle with a stock MW pump.

My initial goals are simply to improve on the stock Garrett turbo without tearing apart my engine compartment.
  • a little more low end torque
  • better economy at lower throttle positions
  • a little more hp at higher speeds
  • preserve reliability
  • smoother boost curve at low speed

Once I have that figured out, I will likely be tempted to add fuel.


RE: Syncro's mechanical VNT project - offroaddieselhu - 07-24-2013

(07-24-2013, 05:58 AM)Syncro_G
(07-24-2013, 03:24 AM)offroaddieselhu Hi,
Can you writte me what kind of turbo you have?
What car it's on?
What pressure do you want to use it?
What is th e aim? (to use for...)
I try to help you if you writte me the basic data.
Offroaddieselhu

Thanks! The problem turned out to just be air in the fuel.
The controller isn't sorted out yet. I still need to tune spring pressure and orifice between the device and the vacuum source. I also need to verify I'm getting the desired pressures at the actuator.

This is a GT 2256V turbo. I'm planning to operate it at 1 to 1.2 bar range when under load at full throttle with a stock MW pump.

My initial goals are simply to improve on the stock Garrett turbo without tearing apart my engine compartment.
  • a little more low end torque
  • better economy at lower throttle positions
  • a little more hp at higher speeds
  • preserve reliability
  • smoother boost curve at low speed

Once I have that figured out, I will likely be tempted to add fuel.


Hi,

How big the engine? (cm3)
The turbo would like to work on min. 1,4 bar not on 1 bar if your engine can bear it.
The air is for free you should trade on it! And your car will go better!

Offroaddieselhu


RE: Syncro's mechanical VNT project - Syncro_G - 07-24-2013

(07-24-2013, 06:09 AM)offroaddieselhu How big the engine? (cm3)
The turbo would like to work on min. 1,4 bar not on 1 bar if your engine can bear it.
The air is for free you should trade on it! And your car will go better!

it's an OM617A. (3L)

I will definitely play with higher boost pressure. at one bar, I can test out the controller without fear of damaging anything.
(thanks for your interest)


RE: Syncro's mechanical VNT project - Syncro_G - 07-24-2013

Just took the truck for a hill climb. it feels nice though is only making about 4.5 psi (3.1 bar).

I tuned the valve for 17psi in atmospheric environment. However, since the valve has 20mmHg vacuum on the other side, I need to compensate with more spring pressure.

next step is to have a new exhaust made and fit an air cleaner.


RE: Syncro's mechanical VNT project - AlanMcR - 07-24-2013

(07-24-2013, 12:04 PM)Syncro_G Just took the truck for a hill climb. it feels nice though is only making about 4.5 psi (3.1 bar).

I tuned the valve for 17psi in atmospheric environment. However, since the valve has 20mmHg vacuum on the other side, I need to compensate with more spring pressure.

next step is to have a new exhaust made and fit an air cleaner.

Correction: 3.1 bar is 45psi.


RE: Syncro's mechanical VNT project - raysorenson - 07-24-2013

Not sure if this makes any difference because I don't know exactly how that part works or what it does, but the green thing is not what I understand to be a vacuum restrictor. Dieselgiant calls it a transmission vacuum dashpot. The restrictors, which are color coded by size look like this:
[Image: IMG_7115.jpg]

Thanks for sharing your idea with us. I think it rawks. Did you have the block the dawes valve threads into fabricated or is it an off the shelf thing?


RE: Syncro's mechanical VNT project - Syncro_G - 07-24-2013

(07-24-2013, 12:56 PM)AlanMcR Correction: 3.1 bar is 45psi.

oops yes, decimal in wrong spot. it's .31 bar

(07-24-2013, 02:52 PM)raysorenson Not sure if this makes any difference because I don't know exactly how that part works or what it does, but the green thing is not what I understand to be a vacuum restrictor. Dieselgiant calls it a transmission vacuum dashpot. The restrictors, which are color coded by size look like this:
[Image: IMG_7115.jpg]

cool thanks, - I'd rather have one of those than that green pot.

update:
everything appears to be going well - my controller needs a stronger spring to make the boost I need.
down pipe is now in -- good enough to get to drive to the exhaust guy at least.
and still need to figure out an air cleaner solution. the stock G can doesn't work.

(07-24-2013, 02:52 PM)raysorenson Thanks for sharing your idea with us. I think it rawks. Did you have the block the dawes valve threads into fabricated or is it an off the shelf thing?

Thanks - the black aluminum thing is an off the shelf air manifold. There are better choices out there but this one was sitting in front of me.
The guts of the thing are custom and are what makes it work. Once I get things dialed in, I'll be happy to pull it apart and describe what I did, springs used, piston, etc.


RE: Syncro's mechanical VNT project - AlanMcR - 07-26-2013

(07-24-2013, 04:49 PM)Syncro_G ...still need to figure out an air cleaner solution. the stock G can doesn't work.

Consider putting in 463 fender liners and using the area behind the headlight and between the fender liner and the fender. There is quite a bit of room. On mine that area is used for the fan-driven oil cooler.


RE: Syncro's mechanical VNT project - Syncro_G - 07-29-2013

(07-26-2013, 05:02 PM)AlanMcR Consider putting in 463 fender liners and using the area behind the headlight and between the fender liner and the fender. There is quite a bit of room. On mine that area is used for the fan-driven oil cooler.

I decided to go with a Donaldson G082525 filter system like Inkblots used on his 460. It looks like it will fit by just a hair and was really cheap on Ebay.
(The whole thing with filters was cheaper than the replacement filter for my stock G air filter.)


RE: Syncro's mechanical VNT project - Syncro_G - 08-02-2013

quick summary -

I had to chase down some other issues with vacuum supply that were getting into the way. now with new check valve, I'm getting 12 psi boost on heavy load (WOT, steep hill). That may be for a couple reasons.
not enough fuel or not enough vacuum signal to the VNT actuator.

I am suspecting the latter. so I think I need to rethink the actuator and install real slider seals. it currently relies on a simple bronze slide bushing to stop wasted vacuum.

In the meantime, VNT is coming out again and stock Garrett is going back in.


RE: Syncro's mechanical VNT project - Syncro_G - 08-05-2013

Does anyone know what the proper vacuum levels are needed to move the actuator?

this is a GT2256V garrett from a T1N sprinter (before they switchted to the hella actuator)

measuring with a mightyvac, I see the following:
0 to 5 mmHg does nothing to vanes
then 5 - 17 mmHG moves vanes to maximum.
is this normal?


RE: Syncro's mechanical VNT project - AlanMcR - 08-05-2013

(08-05-2013, 11:16 PM)Syncro_G Does anyone know what the proper vacuum levels are needed to move the actuator?

this is a GT2256V garrett from a T1N sprinter (before they switchted to the hella actuator)

measuring with a mightyvac, I see the following:
0 to 5 mmHg does nothing to vanes
then 5 - 17 mmHG moves vanes to maximum.
is this normal?

If you are saying that it behaves in an on/off manner, then that desn't sound right to me. Maybe the mechanism is just sticky? Try the test again while shaking/tapping the housing.


RE: Syncro's mechanical VNT project - Simpler=Better - 08-06-2013

(08-05-2013, 11:16 PM)Syncro_G Does anyone know what the proper vacuum levels are needed to move the actuator?

this is a GT2256V garrett from a T1N sprinter (before they switchted to the hella actuator)

measuring with a mightyvac, I see the following:
0 to 5 mmHg does nothing to vanes
then 5 - 17 mmHG moves vanes to maximum.
is this normal?

Sounds like sticky vanes. Time to open 'er up and start cleaning


RE: Syncro's mechanical VNT project - Syncro_G - 08-06-2013

(08-05-2013, 11:38 PM)AlanMcR If you are saying that it behaves in an on/off manner, then that desn't sound right to me. Maybe the mechanism is just sticky? Try the test again while shaking/tapping the housing.

No, it moves roughly linearly from min (5mmhg) to max at 17mmhg

But I'm wondering if it should reach max displacement before 17mmHg

Either way, I'll disassemble it and clean parts.


RE: Syncro's mechanical VNT project - Syncro_G - 10-28-2013

it's been a while - I have the VNT project on hold again.
But for those interested, I found out my vacuum check valve was busted.
So I wasn't getting the vacuum needed to make the system work.
That's fixed but unfortunately, I didn't discover the problem until all the VNT related mods were removed.


RE: Syncro's mechanical VNT project - atypicalguy - 10-31-2013

That was a lot of work to let a little vacuum check valve stop you! Sounded like it might actually work.

I am thinking the same idea on my 85 300tdt. It goes OK now but I actually had a Sprinter and the VNT/intercooler was sooo nice. That motor would be sweet in a Gwagen or a regular wagon. All kinds of torque pretty much on demand.


RE: Syncro's mechanical VNT project - cjcosta - 10-31-2013

Lot of guys use the sprinter motor in the Gwagen.

I am also curious about the VNT controler.


RE: Syncro's mechanical VNT project - atypicalguy - 10-31-2013

(10-31-2013, 06:17 AM)cjcosta Lot of guys use the sprinter motor in the Gwagen.

I am also curious about the VNT controler.

Anybody put one in a wagon?

Ill probably buy one of those myna pumps, an intake, a big turbo and try to inter cool it somehow. But it's fun to dream.