BCS Restrictor Removal vs MBC

[psychbiker1966]

Im starting to mod my second 2g DSM.This one is a 5 speed manual.. much better than my Auto gst which I sold the day I bought the stick. I did the basic tune up and now have a boost gauge , 1g Bov,MBC, and Ebay Injen Style Intake. When stock my boost was at about 12 dropping close to ten at high revs. (I have a slight throttle body shaft seal leak to fix.. I found during my boost leakdown test.) Now to the point. After changing to the 1g Bov and installing the intake ,I installed the MBC. I have it set to boost to 15 ,but by the time I hit 4500 rpm , my boost falls rapidly to 10. (Just like my previous DSM).. Last night I took off the MBC and did the BCS Restictor removal. Now I am boosting to 14.5 and the car holds 12.5 now to redline! Seems to me that the MBC is just not as good at regulating the boost and will not be going back on the car anytime soon. My question is this a common experience? At this point I am much happier without that huge boost loss. Also when I go to a 3 inch exhaust with a cat delete downpipe, (My next mod), will I get too much boost without a MBC?

 

[Doubleot]

You shouldn't buy why wouldn't you want to just leave the MBC on?

 

[Talonfiend]

Keep the BCS restrictor and install the MBC.

 

[JAYFRESSH]

Do you have a pic or example of style MBC you are using ? Might just be junk if it acted the same way on 2 different cars.

 

[95redturboawd]

Why does it matter if the BCS restrictor is in or not? Don't you bypass it with the mbc?

 

[EclipseTical]

Why does it matter if the BCS restrictor is in or not? Don't you bypass it with the mbc?

2Gs are known to throw a CEL when you unplug the BCS. Leave it plugged in but cap off the vac lines when you install the MBC.

 

[OEM]

Im starting to mod my second 2g DSM.This one is a 5 speed manual.. much better than my Auto gst which I sold the day I bought the stick. I did the basic tune up and now have a boost gauge , 1g Bov,MBC, and Ebay Injen Style Intake. When stock my boost was at about 12 dropping close to ten at high revs. (I have a slight throttle body shaft seal leak to fix.. I found during my boost leakdown test.) Now to the point. After changing to the 1g Bov and installing the intake ,I installed the MBC. I have it set to boost to 15 ,but by the time I hit 4500 rpm , my boost falls rapidly to 10. (Just like my previous DSM).. Last night I took off the MBC and did the BCS Restictor removal. Now I am boosting to 14.5 and the car holds 12.5 now to redline! Seems to me that the MBC is just not as good at regulating the boost and will not be going back on the car anytime soon. My question is this a common experience? At this point I am much happier without that huge boost loss. Also when I go to a 3 inch exhaust with a cat delete downpipe, (My next mod), will I get too much boost without a MBC?

My 2g is doing the exact same thing. I have a hallman in cab mbc, I was going to remove it tonight and put it back to stock to see if I wouldn't loose so much boost, before the mbc I never lost any pressure, well not till close to redline.

 

[psychbiker1966]

My 2g is doing the exact same thing. I have a hallman in cab mbc, I was going to remove it tonight and put it back to stock to see if I wouldn't loose so much boost, before the mbc I never lost any pressure, well not till close to redline.

OK...Thats what I wanted to know. This is my second MBC ..The 1st one acted up on my other car even though I bought a different type (Ball and spring).
So ..
Conclusion: A MBC tends to lose boost VS my stock solenoid (Restrictor removed).. Therefore if I get the same boost and it holds it better..Why would I use /need a MBC? At this point i would loose boost and high end HP!

Once I get my 3 inch pipe with Cat Delete.. I think I might need it since I believe I might start to OVERBOOST right?

 

[MidShipCivic]

The rise to 15 is a boost spike. Something is delaying the pressure to the wastegate actuator.

 

[tmil1]

The rise to 15 is a boost spike. Something is delaying the pressure to the wastegate actuator.

x2
I think that this is probably right. You probably have the MBC actualy set to 10 psi not 15. It spikes to 15, MBC are kinda know to spike, then the boost settles down to where it should be, i.e. where you have it set at.

To test this increase boost with the MBC and notice where the boost settles to. Note RPM and boost levels, note all spikes and lows.
set it for a different boost level and take notes again.

 

[lyonswm]

i got a 1g dsm. if i remove my bcs restrictor are there really any risks?

 

[9!'clipseDOHC]

i got a 1g dsm. if i remove my bcs restrictor are there really any risks?

x2. I'm working on my turbo wire harness and need to know if I can remove the BCS plug or if I need to keep it so I can plug in the BCS and just cap if off. I will be running a Hallman MBC. I was under the impression that when you got a MBC you could completely remove the BCS but after reading this I need some more clarification.

 

[gringo72884]

No, you do not take off the BCS, you leave it connected through the harness and cap off the vacuum entrances. Also, psychbiker1966 where did you have your mbs mounted? inside the car or in the engine compartment?

 

[ttetzner]

Im starting to mod my second 2g DSM.This one is a 5 speed manual.. much better than my Auto gst which I sold the day I bought the stick. I did the basic tune up and now have a boost gauge , 1g Bov,MBC, and Ebay Injen Style Intake. When stock my boost was at about 12 dropping close to ten at high revs. (I have a slight throttle body shaft seal leak to fix.. I found during my boost leakdown test.) Now to the point. After changing to the 1g Bov and installing the intake ,I installed the MBC. I have it set to boost to 15 ,but by the time I hit 4500 rpm , my boost falls rapidly to 10. (Just like my previous DSM).. Last night I took off the MBC and did the BCS Restictor removal. Now I am boosting to 14.5 and the car holds 12.5 now to redline! Seems to me that the MBC is just not as good at regulating the boost and will not be going back on the car anytime soon. My question is this a common experience? At this point I am much happier without that huge boost loss. Also when I go to a 3 inch exhaust with a cat delete downpipe, (My next mod), will I get too much boost without a MBC?

I noticed a 1-2 psi gain when i installed my turbo back and injen intake

 

[9!'clipseDOHC]

No, you do not take off the BCS, you leave it connected through the harness and cap off the vacuum entrances.

Is this just for 2gs or is it the same for 1gs? Can I toss it or do I have to keep it and cap it?

 

[LiquidX]

Leave the BCS plugged in and remove the lines from it. You don't need to cap it off at all. You keep it plugged in so it doesn't throw a CEL, that's all. The MBC will act the same way the BCS will as they are both boost controlers. One is set manualy the other is ran off of the ECU. It's possible you have a bad MBC and is leaking which can cause the boost to drop an extra 2 psi over the BCS. Also, the boost will drop before you hit redline on the T-25 because it's just too small to boost good over 14psi.

How did you tap your MBC into the vacuum lines (which lines did you use)? The overboost problem you are referring to for the future, you can only go as low as the wastegate will allow. If you over boost then you have a very free flowing exhaust and you'll either need to do some porting on the wastegate or go external.