1.1.81 boost control

[AVP]

without anytrim i have it set to 85 up to 3600 then 80 to 3900 then 76 to 4300 and 77 thereafter. this curve gives me a stable boost even though later spool.

i have tried 90dc or more and it spikes

[gunni]

I meant cause he´s upped the spring, he could have put boost on top of the wastegate as well as bottom to force the valve shut for longer and then control boost with the solenoid. This way I have been able to use weak springs make steady strong boost.

Can you clarify how resulting force to W-gate valve stem changes if pressures on both sides of membrane are equal?
In 20VT OE case it atmospheric pressure in both chambers. In old MC variant - boost pressure in both chambers.
Real way is to use two opposite solenoids or 4-port solenoid. Then it is possible to keep upper chamber pressurized, but vent bottom chaber to atmosphere.
Another way might be using very soft spring. And connect just upper chamber. I never seen such setting.

If you have the same pressure on both sides then you have zero pressure acting on the diaphragm + spring pressure holding it down.

Like so.

[GintsK]

So and where then is difference between plumbing like 20VT OE versus plumbing on this drawing? Both will give same pressure.

BTW MC 10VT top side was fed from manifold. May be it gave little help for boost reduction on partial throttle.

[AVP]

what gunni is suggesting is that when the top chamber is pressurised and you have a stiffer spring, it will be the spring itself adding to the improved spool because it will allow more gasses to go through the turbo.

[GintsK]

But it is no matter how to plumb 2 or 3 port solenoid: to top or to bottom. When DC is at 100% the only forces comes from backpressure to valve area and spring to opposite direction. So max boost is limited by spring. Not by connection type.
 At least until bottom chamber has no significant leak trough valve stem. This is why Audi put big port N75 comparing to MC engine.

[AVP]

well im off to try a few more things today.

a bit of timing reduction on the spark map, as well as possibly some anytrim playaround.

[GintsK]

No need to try anytrim. It do not work also on default config. I just wrote report in IRC.
set it to 100% and temporary forget about it.

[AVP]

ok, thanks

i just wrote to marcell as well.

im going to try the ignition table reduction, as well as the speedsensor which marcell explained a few things more about it.

[AVP]

Back from the tests

i managed to get the boost up to 270ish kpa at 4100rpm on 3d gear which is a big improvement as its only 30-40kpa away from the goal which is the 305kpa i had on megatune

i used pid: 110/10/28 and tested increasing P and decreasing D without any better results.

I have to try more on the P value though.

i also decreased the timing as well as increasing the fuel in those areas which i think also helped.

when i used someone's values of 220/70/60, the boost spiked all the time even with reduced DCref.

[AVP]

here are the 2 turbosmart options of connection:

1) this is what i use now




2) this is what i can try




this last connection apparently is for maximal boost, but does not say if it is for faster as well.

[AVP]

does IAT have anything to do with spool and lag as well?

[Jamo]

in a few weeks time im going to try a 4port solenoid to use in the same configuration as turbosmart eboost. if this doesnt work as well, then im not sure what else i can try, other than going to an electronic boost controller.

by the way, which is the setting that controls rpm on vems? i want to make sure this is not something silly like rpm signal being read wrong and therefore the log is off on the rpms....

This is my setup Vas, 4 port mac solenoid to upper and lower wastegate.

For Gints it's not the same as putting in a stiffer spring, the boost response is better with the top and bottom configuration when you use a 1.9 absolute spring over the 1.4 absolute spring

[AVP]

so you are using 4 port and 1.9bar spring?

i must say i did not see any spectacular improvement regarding the 1.9spring a couple of days ago

[GintsK]

here are the 2 turbosmart options of connection:

1) this is what i use now



2) this is what i can try



this last connection apparently is for maximal boost, but does not say if it is for faster as well.

Are you sure about you use method 2?
It looks funny!
Connection can't work as controller: There is no way to bleed pressurized chamber somewhere out while turbo gives boost! It should give hard overboost and then go to high boost as we usually see at 100% DC.
Because at first top chamber being pressurized from turbine housing (means hard overboost). And each solenoid cycle transport some portion from top chamber to bottom. Finally both chambers are just filled with no any sense.

All working kinds of connection reserve way to bleed chamber to atmosphere during regulating. Not this. Think about it!

[mattias]

GintsK : the solenoid vents to atmosphere, as written in the picture so it works as you want it to.

"method 2" is the method used in 99% of cars with external wastegates that I'm involved in.  In some cases we use 0-2 bar air pressure regulator, instead of an electronically controlled 3-way solenoid.