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Preferred location for mounting underhood MBC
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Fasteddie313  



Joined: 29 Sep 2013
Posts: 1912
Location: MI

PostPosted: Tue Jun 16, 2020 4:07 am    Post subject: Reply with quote

What I have noticed with a couple top port regulator setups I have tried is that it takes a couple times getting into boost before it starts to get enough pressure on the top port for the boost to start to climb.. Maybe just my crap regulators fault..

I've been doing something more similar to a CO2 boost controller but with a hand pump, and I find that it works splendidly, just like having a heavier spring in there I imagine..
Constant top port pressure completely independent of whatever the engine is doing..

Maybe I'll make a prettier one eventually, or possibly even a serious one that my MS can control..
Who knows..
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bureau13  



Joined: 07 Sep 2017
Posts: 239
Location: South Florida

PostPosted: Tue Jun 16, 2020 4:35 am    Post subject: Reply with quote

At all the way closed, you will have either spring pressure or max pressure, depending on how you have it connected. If you have connected it in between the compressor and your wastegate (i.e. in the original control line) then all the way closed will give you max boost. If you have it connected to the top of the wastegate, then all the way closed gives you spring pressure, or the minimum boost setting. In any case, I agree with the below, in that if you're getting about 7 psi it seems like you have an unrestricted line to the bottom wastegate port and no pressure going to the top. If you remove the MBC, turn it all the way closed and then blow through it, what happens? Can you?

chuck21401 wrote:
poor-sche wrote:

I installed a turbonetics MBC over the weekend similarly to what you show in your picture but it doesn't seem to work. No matter the adjustment, 7 psi is the max boost I see on the in cabin gauge.

The strange thing is that previously it was set to 10 psi with a small spring loaded valve that worked fine. Since I couldn't get the turbonetics MBC to work, I reinstalled the previous setup, but now adjustments don't work on that one neither.

Any thoughts?




If the WG is opening at 7psi that tells me that the line is not being restricted and that you don't have leaks in the control line...enough air is pushing the spring up to open the WG.

When I first connected the turbonetics MBC it didn't seem to work. I cranked it all the way UP (+) according to the +/- on the dial....and still had stock boost. It took me a while to figure out that turning the knob down actually increases the boost...turning it down restricts the flow. I turned the knob all the way down (-) and the boost went to the moon...I let off the gas as I saw the boost gauge heading to 12psi in a hurry. From there I was able to adjust it to 9/10psi. As I mentioned above...a 1/4 turn makes a big difference....so it might take several runs to dial it in.

Can you remove the MBC and test it to make sure that air is being restricted? If you turn it all the way down...no air should pass through it. Of course make sure the air is flowing the right direction. If you connect it backwards it might not work correctly.






Quote:
The strange thing is that previously it was set to 10 psi with a small spring loaded valve that worked fine. Since I couldn't get the turbonetics MBC to work, I reinstalled the previous setup, but now adjustments don't work on that one neither.


That doesn't make sense. Not sure what is going on there.

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1982 931
1986.5 Silver 928S
2007 Hummer H3 (Daily Driver)

Past lives (I miss them all):
2004 RX-8 (Wrecked)
1993 RX-7 (Sold)
1987 RX-7 Turbo II (Sold)
1985 RX-7 GSL (Stolen)
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bureau13  



Joined: 07 Sep 2017
Posts: 239
Location: South Florida

PostPosted: Tue Jun 16, 2020 4:37 am    Post subject: Reply with quote

I haven't noticed that, but it's interesting. I'm not sure I would have noticed it, given the testing I've been doing. I will look for that next time I drive it.

Fasteddie313 wrote:
What I have noticed with a couple top port regulator setups I have tried is that it takes a couple times getting into boost before it starts to get enough pressure on the top port for the boost to start to climb.. Maybe just my crap regulators fault..

I've been doing something more similar to a CO2 boost controller but with a hand pump, and I find that it works splendidly, just like having a heavier spring in there I imagine..
Constant top port pressure completely independent of whatever the engine is doing..

Maybe I'll make a prettier one eventually, or possibly even a serious one that my MS can control..
Who knows..

_________________
-----------------------------------------
1982 931
1986.5 Silver 928S
2007 Hummer H3 (Daily Driver)

Past lives (I miss them all):
2004 RX-8 (Wrecked)
1993 RX-7 (Sold)
1987 RX-7 Turbo II (Sold)
1985 RX-7 GSL (Stolen)
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poor-sche  



Joined: 06 Jan 2017
Posts: 73
Location: Los Angeles, CA

PostPosted: Tue Jun 16, 2020 11:55 am    Post subject: Reply with quote

Yup, that was it. Started by turning the valve completely counter-clockwise and then made adjustments turning clockwise. Approximately 2 complete turns clockwise got me back to 10psi.

No idea why the previous setup didnít work when I reinstalled.
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chuck21401  



Joined: 20 Feb 2005
Posts: 240
Location: Annapolis, MD

PostPosted: Wed Jun 17, 2020 2:46 am    Post subject: Reply with quote

poor-sche wrote:
got me back to 10psi.


Welcome back. Once you've turned up the boost it's difficult to dial it back.

So I've heard.
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poor-sche  



Joined: 06 Jan 2017
Posts: 73
Location: Los Angeles, CA

PostPosted: Wed Jun 17, 2020 4:12 am    Post subject: Reply with quote

chuck21401 wrote:
poor-sche wrote:
got me back to 10psi.


Welcome back. Once you've turned up the boost it's difficult to dial it back.

So I've heard.


Yeah, it's not much but you can definitely feel the difference.

-Shee Sed
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