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TCV max boost

petercz

Member
Joined
Sep 24, 2011
Location
Czechia
What is max boost I can achieve with stock TCV (Pierburg) from T5? I?m using it as on/off valve for my two stage boost control, but it can?t flow/bleed enough air for more then just about 0,2bar more, then with just first MBC. If I remove the TCV, I can run much higher boost.

for example:
tcv off - 0.7 bar
tcv on - 0.9 bar max
no tcv, just both MBCs - whatever I want

bstcntrl.jpg

_
940 b230fk, 16T, Kinugawa wg actuator with 0.6 bar spring
 
I don't understand what you're trying to do. The TCV is just supposed to vent boost when you close the throttle. It should have it's own unobstructed separate vacuum line to the intake manifold. I don't see how to incorporate it into a boost control scheme.
 
I want two boost levels. Low boost is set with the first MBC (ball and spring type). Then I can switch on the TCV - open (I have no pwm control, so just like open/closed valve) and bleed another air, so I can run high boost (which is adjust with the second MBC).

I have the left port blocked, other two connected like on the scheme.
images
 
I want two boost levels. Low boost is set with the first MBC (ball and spring type). Then I can switch on the TCV - open (I have no pwm control, so just like open/closed valve) and bleed another air, so I can run high boost (which is adjust with the second MBC).

I have the left port blocked, other two connected like on the scheme.
images
Sorry I was thinking the pierburg blow off valve, still no help here.
 
I think the issue is in how you have it plumbed. With the setup in the first diagram the WG is still seeing boost pressure from the left most MBC regardless of TCV position, the slight increase may be because some of the boost is bleeding into the pre-intake piping.

Ide plumb red (off position) to the low boost MBC, Blue (On position) to the high boost MBC and yellow to the wastegate, with both MBC seeing pressure from the compressor housing.
<a href="https://imgbb.com/"><img src="https://i.ibb.co/gMTBxn5/TCV.jpg" alt="TCV" border="0"></a>

Note the colors in my diagram are different then the picture you posted, Low boost-OFF high boost-ON so if the wiring goes out your not stuck at higher boost levels all the time
 
The steel pipe is the pressure inlet port from compressor side normally this should be connected.

So you should connect from intake to the steel tube and then yellow one to wastegate and blue one to intake pipe before TC and after AMM.

Once it's powered it will let air from wastegate(yellow) to free air (blue) and blocking air from T/C (red), without power it's connecting T/C (red) to wastegate (yellow) like in a direct T/C to WGA setup.

Trying to think with you, you should put the two setups in parallel.

n1LKnkJ.png


Like above...

So the low boost system will bypass the high boost system once without power, also being failsafe, open circuit = low boost.
 
Last edited:
I?ve tested some more setups and ended up with parallel one like below, which works best for now =>
Maybe I will change the bleed mbc also for ball and spring type, but I haven?t got another spare yet.
I also tried some restrictor pills with the first setup, but 2mm hole, which worked, was too small and boost was unstable (spikes etc.).

bstcntrl2.jpg
 
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