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Thread: The basics of boost control, wastegates and how to turn up the boost.

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Posts: 41-50 of 53
2012-07-03 13:09:13
#41
We had to buy a $5 pack of maybe 100 assorted springs at Lowe's and sort through them for ones that fit. I'm sure there is a better way, but that's how we had to do it.
Boost ranged from wastegate pressure which was around 8-10 on the various setups to 21-25 psi on the various setups. There wasn't ever a time we wanted more boost that we couldn't get it.
2012-07-03 13:13:22
#42
K thank you just looking for 15-18psi. Thanks again
2012-07-04 02:29:18
#43
Originally Posted by benfenner
i like to build them exactly like the ones sold here: http://www.sr20-forum.com/turbo/35182-come-get-your-mbcs.html

that varies a little bit from most directions because it eliminates a piece, and removes the tapping requirement.
It can be a bit tricky to find the right ball and spring. You may have to get creative.
do not forget to drill the tiny bleed hole in the main housing. That is important, and make sure you do it in the right spot so you don't have a constant tiny vacuum/boost leak.


+100000
2012-07-09 03:43:42
#44
I haven't read this entire thread and I apologize if this has been covered...with the wastegate only wanting to see boost before the throttle plate, why is it that tial says to Tee into the BOV as a source? A source which also sees vacuum? that has always boggled me.
2012-07-09 03:53:31
#45
Originally Posted by 93specv
I haven't read this entire thread and I apologize if this has been covered...with the wastegate only wanting to see boost before the throttle plate, why is it that tial says to Tee into the BOV as a source? A source which also sees vacuum? that has always boggled me.



Not here it doesnt
http://www.tialmedia.com/documents/w3_tial_wginstall.pdf

Says pre-throttle here too.
http://www.tialmedia.com/documents/MV-Install-Guide.jpg
Last edited by unijabnx2000 on 2012-07-09 at 03-55-53.
2012-07-09 09:13:49
#46
Hmmm....now I'm searching trying to find where I read that.
2012-07-09 11:25:41
#47
Ok, I think I found what I had read. Sorry, it was a long day yesterday. I was tired, lol!

What I had read was installation instructions for a MBC that say to tee from the wastegate into the BOV which would then be putting the WG on a boost/vac line.
2014-05-28 18:13:13
#48
Originally Posted by BenFenner
Vadim clued me into this type of manual boost control for those with dual reference (two input) wastegates.



The intake charge pressure works against the wastegate spring like normal, but some of that pressure is redirected to the top of the diaphragm to help the spring. This makes the pressure on the top side of the diaphragm higher, so it will take more boost pressure below it to open. If you set the pressure regulator for 1 psi, it will add 1 psi of helping pressure to the spring so it should take 1 psi more to open the wastegate than normal. Set the pressure regulator higher to obtain higher boost levels.

It's a really elegant solution that helps retain a stock-like wastegate opening speed (slow) if that is something you desire.

Edit: I've been told this is the way some older turbo Porsches are set up, even having the regulator dial driver-accessible for quick boost level changes on the fly.


To use this type of setup,
im guessing you have to start with the MBC set on full tight
slowly loosening the screw... to get the boost level desired?
2014-05-28 18:23:20
#49
^^ Wouldn't full tight on a manual screw in type controller be the opposite?? My thought process is full tight means the wastegate is not seeing any vacuum hence it won't get pulled open (given correct spring pressure preventing it from opening from exhaust)??

I could very well be opposite in correct thought however
Last edited by Boostlee on 2014-05-28 at 18-24-22.
2014-05-28 18:30:48
#50
the wastegate doesnt use vacuum to open

the top port still sees atmosphere pressure b/c of the bleed hole in the MBC
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