DIY dual stage MBC

[mwreed]

I hope this is in the right forum.

Sorry for the long post, but, I think this is pretty cool. I hope you find it useful

I needed a boost controller and since I am a tight wad, I decided to use the plans for the DIY MBC. It seemed simple enough and was logical to me in functionality. At any rate. I also wanted to be able to switch between boost settings as well. I was looking at the dual stage boost controllers and doing some research and found that to switch between stock and high (or whatever you want) you just need to be able to make the flow go from the source straight into the wastegate actuator and your MBC to set the resistance of air flow. After looking around and doing searches here and on the web, I found a design that gave me an idea. I don't remember the link, but, I think it was the poor mans profec. Not sure. If I can find it again, I will link it. So then my quest led me to looking for an air switch. I then realized that, wait, I already got one. The BCS. It will not be used with installation of the MBC, so, why not use it. So, after a little planning, I figured out a way of utilizing the BCS to create a dual stage MBC. The important thing to realize is that the BCS is closed when there is no power to it. We want it to be open by default and closed when we want boost. I figured that I would use the standard automotive relay, you know the one used in audio installations? The idea is that you supply power by default and the move the switch to turn off the power to the BCS. Really, that is a simple task, but, I like lights. I got a lighted switch. So, I wanted the switch to light up when I had high boost and off, when I am at stock boost. Hence the need for the relay. My original plan was the hook the relay up where, when you flip the switch to turn on the relay, it would open the circuit to the BCS and turn on the light on the switch. Pretty easy, really. To my suprise, the switch I used made this possible without the relay. The switch the I used supplies power to the ACC when it is off and turns off the power when the swich is on. I guess you can hook it up different ways, but, I found that this option worked great for me. Another very important thing to realize is that you need to make sure that your power source is only available when the car is on. Fortunately, I have a turbo timer and could tap right into the ignition lines right near the switch. I mounted the switch in the coin holder. Will supply pics later. Let me know if you have any questions and I can explain more. I just thought this was a good way to control boost in a relatively inexpensive way. I will tell that it does work. I was testing it last night and flipped the switch. It jumped to 20psi... not good on my small 16g. I then experience fuel cut, however, I was watching my boost gauge and flipped it back as soon as I saw it hit 20. I am still adjusting the setting on the MBC. The point was, that, because of the swich, I was able to immediately open the wastegate and reduce my boost and did not have the complete experience of fuel cut. Nice safety device.

Michael

I found the links I used.

MBC - http://www.geocities.com/chmwatson/FAQs/mbc.html

Dual stage setup
1 - http://pages.cthome.net/gus/pictures.html - helpful
2 - http://www.xmission.com/~dempsey/perform/recipe_b.htm - this one was the best help.

 

[jake98gst]

Really cool idea. But instead of using the BCS and stock boost as one and the MBC for high boost. Couldn't you use 2 MBCs for two boost levels of choice and then have a valve that switched pressure between the two MBCs? I dont know. Just a thought.

 

[mwreed]

Absolutely. I just opted for standard boost for daily driving. It's a simple flip of the switch when that sooped up honduh thinks he's got you. I did think about the dual mbc, but, you would still need to use some kind of solonoid to switch between, and you can still use the BCS. It's only acting like a switch in this configuraion. No input from the ecu at all.

 

[dsmturboawd]

why is this needed?

 

[jake98gst]

I dont understand what your questioning. Is what needed? Some people like a 2 stage mbc because they want two different boost levels of choice: high boost and low boost.

 

[MNGSX]

If you want some good DIY boost control articles.

http://www.autospeed.com.sg/cms/article.html?&A=0028

That is probably the best for a DSM. The writer likes it on his skyline.

Keeping the factory BCS in line is a good idea. The level is increased yet the ECU has control over it and can decrease boost if excessive knock is detected. It's good protection.

You need to have a knock sensor in good condition and clean or revised lifters so phantom knock wont trip it. Getting those to work right is cheaper than a new engine.

DSM link if you get that later will firm up the boost control a bit. If you use a valve inline like the article it still will be above stock but the curve will be the same shape. The factory ecu sort of softens up boost a bit in the RPMs in which the OE turbo really starts to spool. On dsm link site it says removed bcs flicker between 2k and 3k or so. I think it just reshapes the boost curve to be more progressive. One of those things mfg's do like quiet intake tubes with weird mystery boxes in the name of refinement.

Just get a evap purge or egr solinoid from even a NA car or another brand even. Since that is a three way valve one valve position can bypass the aftermarket control and the other use it.

You must be logged in to view this image or video.

Out BCS sits between a T and the intake as oposed to being the T to the intake and the valve. But it works the same. For a two level system plumb a 3 way EGR solenoid between to compressor housings boost port being sure that it is connected to the common port on the solenoid.

One outlet goes to the new adjustable valve.

The other gets connected to a T on the backside of the new valve.

So you are T ing both outlets together then going into the T between the WGA (wastegate Actuator) and the BCS.

 

[dsmturboawd]

Originally posted by jake98gst
I dont understand what your questioning. Is what needed? Some people like a 2 stage mbc because they want two different boost levels of choice: high boost and low boost.

my question is why. why would you need high boost and low boost? give me an example of when youd use low boost. then give me an example of when you'd use high boost. then explain to me how youre going to make proper fuel adjustments for each boost level. help me understand here. i just dont get it.

if you want less boost, just dont put as much pressure on that pedal with your right foot as you normally would.

 

[mwreed]

Does this clear it up?

I drive in the city 98% of the time. There is no need for full boost most of the time. I like to know that I have the power there if I need it. Traffic here is horrible thanks to the many invaders from other states and very unpredictable. (personal experiences) It may be a lot easier to control you pedal in a suburb than here, I would assume. So, let's say, when I am ready to go to the track and see what I can do. I can then switch over to the high setting for the track. I am running an MBC. I don't have to guess what the value will be by the amount of turns, because I already have it set. Granted, temperature will play a role in amount of pressure. The other purpose for the switch is, let's says your BC fails. It is a mechanical device or even a electronic device... It can fail. Your boost can increase to bad levels. I can switch it off so that I am back to stock boost and not blow my engine. So, why are TurboXS, Dejon Tool or MMi Racing making dual stage boost controllers? I assume they are doing it for the same purpose.


As far as the fuel control issue. I looked this up on Apexi's website. I do not have this yet, as I am mostly stock and gradually increasing my power.

Copied from Apexi SAFC 2 manual

¡Storing two patterns of setting data in the memory
Two patterns of setting data including air correction factor, throttle opening, air correction engine revolution speed, deceleration air upper limit, etc, can be stored in the memory. There are two files that can be stored in the memory. The setting data can be selected in an instant according to each driving stage such as circuit driving, town driving, and winding driving. When driving on the same stage, two patterns of setting data can be compared. These patterns of setting data can be used for various purpose.

I hope this helps.

 

[dsmturboawd]

a failed mbc results in the boost giong to what the WA is set at. a possiblility of a failed mbc is no reason to justify this mod.

i guess you'd have to be running a safc2 for this to be cool. will you be going to the track enough to justify doing this? i mean adjusting a mbc is hardly difficult or a pain.

im in the detroit area, there is traffic here. not being able to control the gas pedal due to traffic is rediclous.

this mod makes sense to me i guess, but it just seems dumb. im still failing to see a good reason to do this.

So, why are TurboXS, Dejon Tool or MMi Racing making dual stage boost controllers? I assume they are doing it for the same purpose.

youre assumptions are incorrect. they sell them because people buy them, to make money, etc. not for the reasons youre thinking of. same reason companies sell turbo timers and grounding kits and other useless shit... because people buy them.

 

[bigjangin]

I am considering making my own dual stage boost controller. I dont think its useless, but I wouldnt pay alot of money to buy a premade unit. I run 20lbs all the time right now, but I think it would be fun and cool to throw a switch and switch for 15 and 20psi. The way dsmturboawd talks makes it sound like this thread is about how to install altezza's. C'mon, wouldnt you like some form of in car boost control for cheap?

 

[mwreed]

Let me add a cost here. $20 - $25. I think it is a smoking deal. Do a search in the forums for dual stage. You will see what purpose they serve.

Remember, my car is a work in progress, it is just begining to unlock power. I am still getting a feel for it.

 

[jbillakdsm]

You can make your own for a little more that runs off the idea of two MBCs connected. I made two MBCs on one piece of aluminum and use a electric hydraulic switch to change from the cabin. The idea of having two different levels of boost is mainly for the FWD crowd that is having trouble getting traction off the line. THis way they can run enough boost to get traction at low speed and then really turn it up once they get to speed. It doesn't help much on the AWD cars, but I have fun with it and it helps me save gas on longer trips.