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Old 07-25-2002, 10:07 PM   #1
WRC WRX
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Question New boost control method?

I know someone already did this


but any way when reinstalled my stock lines after i took the boost controller off i had lost the ristrictor in the line that gos from the turbo to the T so i could only get 8psi so i tryed to use a smaller connector but i could only get 11psi so what i came up with is I used the mbc as a ristrictor on the turbo side of the line so now i can slow the signal to the wastegate and get like 15.5 psi without the partial throtle problem .



is there something im missing?


i know someone did this before me and found a kink .


help me out is it safe?
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Old 07-26-2002, 10:58 AM   #2
Eric Kovacs
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We did the same thing on my friends wrx and its been working great so far....... oh wait it was you

my bad

bump ttt
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Old 07-26-2002, 11:09 AM   #3
KwanDDS
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Hey I just started a thread about this today before you.
http://forums.nasioc.com/forums/show...hreadid=220731
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Old 07-26-2002, 11:39 AM   #4
KwanDDS
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In any case, do you get a solid increase in boost without spiking thru-out the whole TPS range?
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Old 07-26-2002, 12:34 PM   #5
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Lets see:


Compressor ----- Variable restrictor ----- tee ------ Wastegate
----------------------------------------- !
----------------------------------------- !
------------------------------- Factory solenoid

And it works good, huh?

Kevin

-----------------------------------------------------
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Old 07-26-2002, 01:31 PM   #6
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yeah i press the gas half and you get half boost no spiking that i can see and you go wot and then you get 15.5



so far works pretty good
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Old 07-26-2002, 06:03 PM   #7
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So your peak boost at middle RPM's is about 15.5 lb, in what gear is that? What is your boost like at high rpms in 3rd gear? How about your 1st and second gear boost?

I'll venture a guess about why this works. By causing a big pressure drop in the line off the compressor, there is nothing the factory boost control can do about WOT boost. The solenoid remains closed, and the MBC/needle valve creates the all the pressure drop that the wastegate sees. As rpms increase, the system of the compressor/valve/wastegate actuator will maintain a pressure equilibrium, but actual boost will roll off because of the increasing pressure drop through the intercooler and piping.

At part throttle, you have a nice big throttle plate making a nice big pressure drop throught the intake track. You're getting plenty of pressure off the compressor though, which gives the ecu plenty of pressure to control the wastegate with.

But I could be completely wrong...ack

Kevin
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Old 07-26-2002, 06:44 PM   #8
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Default Read this thread:

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Old 07-27-2002, 09:24 AM   #9
wrxspeed
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Default ????????????????

Does this method decrease/increase/remain the same in regards to the factory boost spool time?
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Old 07-27-2002, 01:13 PM   #10
KwanDDS
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What boost level are you getting at part throttle? Are you getting stock levels (ie .5 kg/cm2 or 7 psi)?
I'm looking to increase part throttle boost to 8 or 9 psi. That shouldnt be a big enough incease in boost to run lean at part throttle.
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Old 07-27-2002, 06:31 PM   #11
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I had tried an experiment with gate valves at one point and my results are at the bottom of this page:

http://forums.nasioc.com/forums/show...ighlight=valve

Mike Robinson
2002 WRX Sport Wagon
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Old 07-28-2002, 01:28 AM   #12
VetteVert
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Default Re: New boost control method?

Describe more how this is different than any MBC setup please If it is a ball-n-spring MBC, then regardless where in front of the wastegate it is, you are still held by it's pressure (and partial throttle boost is the same). If it is a bleed type MBC, then it shouldn't matter where in the setup you put it. At pressure all the lines are a system, and if you put a bleed anywhere in the system, the results will be very close. Post a diagram if you have time.

VV

Quote:
Originally posted by WRC WRX
I know someone already did this


but any way when reinstalled my stock lines after i took the boost controller off i had lost the ristrictor in the line that gos from the turbo to the T so i could only get 8psi so i tryed to use a smaller connector but i could only get 11psi so what i came up with is I used the mbc as a ristrictor on the turbo side of the line so now i can slow the signal to the wastegate and get like 15.5 psi without the partial throtle problem .



is there something im missing?


i know someone did this before me and found a kink .


help me out is it safe?
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Old 08-18-2002, 04:10 PM   #13
KwanDDS
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Ok, not sure if this thread is still alive anymore.

I installed this setup and here are my observations.
I placed my TurboXS MBC (bleed-type) in line as in the diagram.
I set the MBC to increase boost by 1 psi.

I noticed a slight increase in spool rate. Part throttle boost remained at .5 kg/cm2.
WOT on resulted in the 1 psi increase as set by the MBC. But in 4th and 5th gears, I'm getting a boost spike of about 2 psi.

From what I gather, the part throttle boost remains stock because this is limited by the wastegate. Spool rate is increased by the MBC, but retains stock levels. I assume that the stock solenoid stays out of the picture until you go beyond a certain TPS setting.
Once that TPS setting is reached, the stock solenoid(FBC) activates.
I think the boost spike occurs because the FBC turns on but doesnt shut down fast enough to control the spike.
Any other opinions?
Attached Images
File Type: jpg mbcsetup.jpg (11.5 KB, 490 views)
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Old 08-18-2002, 04:16 PM   #14
KwanDDS
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Also with stock settings, the ECU sets the FBC a couple of psi lower than its full potential.
Maybe at WOT it briefly activates fully, creating a spike, then goes back to stock settings.

BTW, that diagram is from the Boost Monkey installation instructions.
Once I get my new monkey in the mail, I'll hook it up with that setup. Hopefully it wont give me a boost spike since I can control the FBC with the Boost monkey. Who knows? I'll post after I do that.
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Old 08-19-2002, 01:22 PM   #15
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Default Bam....

I'll go out and try this tomorrow......

Kwan...are you running the stock restrictor in the solenoid line, or have you done the 3/16's mod? I would think going back to the stock restrictor might help reduce the spike.

Kevin
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Old 08-20-2002, 09:00 PM   #16
KwanDDS
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yup, I put the stock one back in there.
I was getting a smaller but similar spike with the 3/16th connector alone, before the MBC.
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Old 09-28-2002, 01:01 AM   #17
'93PGt
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Bump...

Has there been any additional finding on this topic? WRC WRX, do you still have the mod installed, or have you removed it? What about the removal of the 3/16", did it aid in the reduction of spike? Thanks
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Old 10-02-2002, 08:27 PM   #18
KwanDDS
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Well, I've been running this setup for a while now.
I have an increase in boost as expected. No part throttle issues since it follows a similar curve as the stock setup, just a bit higher throughout the range.
Only drawback is that there is a boost spike on 5th gear(sometimes 4th also) at WOT only. The spike is about .05 kg/cm2. in magnitude at Full boost.
This is forcing me to be a little conservative in setting the boost because I dont want to overboost.
I did notice faster spool, but I have no way of measuring this, other than my judgement.
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Old 10-02-2002, 08:28 PM   #19
KwanDDS
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By the way, the Boost monkey turned out to be a scam. I never got the repaired boost monkey, but thats a different thread....
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