boost control

[pug106]

i bougth vems with all harness and sensors like knoc, map, vs. but there is no boost selenoid, does any one knows a selenoid works with vems?
and am i control the boost firt gear 0.7 bar second 0.8 ..........
or do you advice buy a hks evc 6

[rob@vems.co.uk]

VEMS has boost control, but no way of sensing which gear it is in.  We use a 40€ 3 port valve:


The information for its connection is in the UserGuide

[pug106]

i bougth the selenoid whic shows in picture, but i did't fix it.
Please give me the installation of this selenoid.

[rob@vems.co.uk]

http://www.vems.hu/wiki/index.php?page=MembersPage%2FPhatBob%2FUserGuide
Section: Connecting A Boost Control Solenoid

[BenFenner]

Can someone explain if the recommended method using that solenoid allows for the prevention of premature wastegate creep? What I mean is, the turbo dodge crowd have put valves in their wastegate lines that prevent the actuator from seeing any pressure until the desired boost pressure is reached. They've been doing this for some 10 years. The idea is, the pressure slowly opens the wastegate as it rises, providing a smooth transition from no boost to full boost. With this valve in place, full boost is achieved markedly sooner. Here's a quick explanation of the process:

http://www.gusmahon.org/html/boostcontrol.htm

Do we get the same benefit? Or should I plan on putting one of these valves in addition to the solenoid?

[multiplex]

we can do the same thing a number of ways.

what firmware are you currently running?

I'm using a similar valve as shown above - actually its the GM valve alot of the MS people use.

boost pressure line is t'd and one side goes to the front of the wastegate. the other goes through the valve and to the back of the wastegate.

the valve is then set to always be open so that both sides of the wastegate see the same pressure.

vems has a setting "actuator off below this pressure". this is the setting you are looking for.

anything under that value, the valve is open. once it hits that value, the valve starts to bleed off pressure to the back of the wastegate allowing it to open.

in my situation, i found if my target boost is 210 kpa, i need to set my "actuator off below pressure" to around 160kpa. Otherwise you get a nasty boost spike before it settles out.

I'd like to find a way to move that value up though.

[BenFenner]

I'm not running any particular firmware just yet. VEMS will be going in this weekend or next. I was just asking for my own knowledge. It seems the way you describe it, that no "quick spool" is employed as in the link I posted. As far as I know, with the "grainger" valve method, there are no boost spikes.

[BenFenner]

Now that I think about it, the methods I'm talking about assume there's a spring holding the wastegate closed. The way you describe it, it seems you're using boost pressure instead of a spring. That could have a lot to do with what's going on.

[multiplex]

no, its is in a sense duplicating the 'grainger' valve.

unless i'm misunderstanding, that valve is just a pressure adjustable check valve. it doesn't open up until a certain psi. thats what vems would be doing in a programmable sense.

i'm using a 9 pound spring in my wastegate, so there is a spring in the system.

do you know what psi they typically set the 'grainger' valve to?

[BenFenner]

So you do have a spring? I see....

You understand the grainger valve correctly. It prevents any pressure in the line until a certain pressure is met, then it lets that signal through. The dodge guys set this check valve to what ever boost setting they want to achieve. The valve is adjustable. it takes a little practice, but you can set it anywhere from 7-30 psi (or more).

It was designed at first to be applied to stock cars. The stock wastegate spring is for 7 psi, but starts creeping open at 0 psi, as most wastegates do. Instead of slowly creeping open from 0-7 psi, they want the valve to slam open. They want it to stay shut until 7 psi (or what ever setting) is met, and then open quickly to stop boost creep. The idea is that boost comes on much quicker. I've ridden in a car before and after this modification, and the results are tremendous.

From what you're saying, I still don't see how you get the same effect, as you said yourself you need to set VEMS at 160 kpa if you want to see 210 kpa. That just isn't right. =]

[rob@vems.co.uk]

If you look at the UserGuide you'll see that there are two ways of fitting these Pierburg valves, one using a t-peice and the other using the valve as the T.  There is a 3rd way, but its not recommended becuase of the lack of control if there is a solenoid failure, where the boost pressure is fed to the Common Open (CO) port, and the wastegate is connected to the Normally Closed (NC) port.  While the boost is building the actuator "sees" no pressure until the desired boost pressure is reached and the NC port opens and bleeds pressure through the CO port.
Of course if the solenoid fails to open you get to sweep your engine up with a dustpan and brush...  Which is why its not recommended;D

[jadzwin]

I use the pierburg valve such way that by default (no current on valve) the actuator see full pressure,
and when there is a current, actuator see the atmospheric pressure (or even lower if the one of valve tubes is connected before turbocharger). 

In my device that control boost,  there is a 3D map that defines valve DC in fuction of RPM and MAP.
When the pressure is lower than required for about 0.2bar the valve DC is 100% making the westgate fully closed to help build the boost quicker. Editing this map we can perfectly control boost in RPM function. Moreover there can be several maps depending on gear and VSS based boost correction to prevent wheel spin.
This method give me very good result and it is quite safe.

Jadzwin

[multiplex]

If you look at the UserGuide you'll see that there are two ways of fitting these Pierburg valves, one using a t-peice and the other using the valve as the T.  There is a 3rd way, but its not recommended becuase of the lack of control if there is a solenoid failure, where the boost pressure is fed to the Common Open (CO) port, and the wastegate is connected to the Normally Closed (NC) port.  While the boost is building the actuator "sees" no pressure until the desired boost pressure is reached and the NC port opens and bleeds pressure through the CO port.
Of course if the solenoid fails to open you get to sweep your engine up with a dustpan and brush...  Which is why its not recommended;D

perhaps in my situation my boost is raising too quickly. so if i set the number to 210 the system can't react fast enough to keep the boost at 210. system being wastegate, turbo, etc. 

i've read in other boost controller manuals (eboost2) that this is a typical, and they talk of having to set the number lower than your boost target.

maybe i'm missing something though 

[BenFenner]

Of course if the solenoid fails to open you get to sweep your engine up with a dustpan and brush...  Which is why its not recommended;D

What about VEMS or MegaTune? Isn't there a setting you could use to cut fuel or spark once charge air pressure gets over a certain limit to prevent the dustpan/brush result?

[rob@vems.co.uk]

Fuel cut above N kpa would do it.

But you do it at your own risk because its fail unsafe, rather than fail safe, if you get me