Hey guys, could you BCS boost gurus do me a favor? What do I have to change in the maps to make my BCS bleed the max amount at 5500RPM and above? I want it to be max open, no matter what. This means I'll leave the target load 319or whatever I have it at now, and I don't want any error correction. I want the BCS to be a simple on/off switch, if you will.

I'd like to know because it is my new theory that boost drops off w/ my MBC because the Hallman has a static (or at best, linear) bleed, when what I need is much more exponential at higher RPM due to high manifold pressures and an 11 psi (OE) WGA spring.

I know I need to leave my load targets 319, I know I need to make the WGDC maps all 0 before 5500 and 100 after, but what about error correction and is that the MAX I can get it to open?

pix are worth 1.3billion words

Also, one other thing: Which nipple on the BCS goes to the boost source and which one goes to the WGA? I looked at the other How-Tos, but the picture was too small and poor quality to make out those labels. I took that thing off like 3 years ago and now I don't remember... Guess I'll try to check the service manual too.

 

It doesn't matter which BCS nipple goes to boost source.

If you zero your error correction table, it will go by MWGDC only... so if MWGDC is set to 100, you don't need to make any other changes (including load target)

Do you plan on bleeding away the output of the Hallman?

If you're on the stock turbo, I would suggest logging lb/min, because my stock IX couldn't flow more than 37lb/min... at this point (25psi, 5500RPM) the engine is using air faster than the turbo can pressurize the system, and boost drops... this is normal and there's not much you can do, although I do agree the stock BCS can hold boost much better than any MBC

 

I've logged the stock 9 turbo at up to 39lb/min. Airflow mods go a long way...

 

Thank you very much. I log through ECU+ and configurable MUT parameters are almost ready. What is the math required to log it in lb/min? I'll poke around the 2-byte airflow threads a bit.

To answer your question, yes I plan on bleeding away above 5500ish where I think the hallman is too "steady state". Dunno if I should do it pre or post Hallman. Hmmm... now I'm thinking about it.... I think pre would be more advantageous because the resistance of the MBC would cause more of the air to rush out through the BCS when open. If the BCS were between the MBC and WG it would only be able to bleed off what comes through the hallman. lol, I don't know... I'mma give it a shot.

Sure the solenoid doesn't care which side? The Mitsu repair manual is specific in which side you are to check, but it doesn't exactly say which side goes to where. Anyone know offhand?

Sorry, another addtion, I just re-read your post: I realize that there is a ceiling for airflow, its just that I'm sure that I'm not at it because I see these BCS boost curves an mine is nothing like it. With the hallman I'm hitting 30psi, but it quickly drops down under 18. I'd be happy to keep over 20 by redline. I've already tried the "Wastegate spring mod" where you add an aditional spring to increase WG spring pressure... all that really did is made me have to turn down the MBC some. Maybe a pic will help...

 

So, will this work like I've intended? Will it basically keep the BCS open 100% until 5500RPM, where it becomes closed (as close to 100% as it gets)?

 

yup thats it

 

cool, thanks. I'll give it a shot tomorrow.

 

Just thought about something else... currently (installed/tuned but not tested) I have it so that the "boost" comes out of the turbo nipple through the BCS, to the MBC, then to the WGA. This way I'm effectively using the BCS to "stop" the airflow to both the WGA and MBC by using 100% WGDC at 5500RPM and above... but what if:

I Teed the BCS into the line between the MBC and WGA and inverted my settings so that I have 100%WGDC BEFORE 5500RPM and 0 WGDC at 5500RPM and higher? I would take the output of the BCS and run it back into the intake, post MAS. Then I would change the BCS from "stopping" the airflow to bleeding it off.
My only issue is this: My guess is that at 0%WGDC the BCS is NOT fully open and at 100%WGDC the BCS is NOT fully closed. Especially if it works on modulation rather than position.

 

lol, lots of interest ey? Ah well. Testing is delayed a bit... seems I didn't turn down the MBC any and I must have gone over 30psi because my GM 3Bar maxed out and then my upper IC pipe blew off (probably saving my motor). It's been pouring here so I'll tinker today and maybe test tomorrowish.

 

100% WGDC is venting 100%, or attempting to keep the WG 100% closed.

0% WGDC is not venting at all and allowing the WG to see full manifold pressure. this attempts to keep the WG 100% open.

Basically, 100% is maximum possible boost and 0% is least possible boost.

Is that what you needed to know?

 

Yes, I needed to make sure I was understanding correctly. I was, thank you.

I have new issues.
I took it out today with this configuration:


Okay, boost wanted to go way above 30psi. So... that didn't work.

So at lunch today I took the MBC out of the loop so that it went:
boost source--BCS--WGA (I've got none of the stock "pills")

The outcome: 23ish psi tapering to 15ish. I didn't even bother logging. Now keep in mind I added that extra spring to the WGA (WGA spring mod)... so I think that raised it some.

Question: If you remove both pills and enter "0" for all of your WGDC tables you should typically get 11-12psi, correct? I need to make sure that I'm getting that increased boost because of the spring.

Plan: take off spring, see if I get 11-12psi. If so, switch the order of MBC and BCS, see if that helps.

All input welcome.... this isn't working... lol and my oil cap blew off and dissapeared... anyone got a really cheap one they can get me in less than a week?

 

Found an oil cap at advance I'll pick up after work. Testing will continue! Please guys, let your brains spill out here, I think mine alone is not powerful enough to tackle this. What are some of your thoughts?

 

I'm not so sure I agree with your setup of BCS before MBC... the MBC is designed for a more smooth transition of pressure, and if you are rapidly changing it's source boost you might find a tough time tuning that.

I would run the turbo outlet to the MBC, and the MBC outlet to the factory vaccum lines (as if the MBC outlet was the turbo outlet in the factory setup).

Then start with 0% WGDC and go up until you get the desired boost.

I certainly wouldn't have jumped straight to 100% man, you're just asking for overboost. Take it slowly in 10% increments

 

Remember, I'm using the MBC to set my boost curve below 5500RPM, so the BCS shouldn't affect it. I'm only "changing the MBC's source boost" between 5000RPM and 5500RPM, where the solenoid should "close" as much as possible. This shouldn't create overboost since I'm pretty sure that at 5500RPM and above the baby 16G turbo isn't able to overboost. The idea is that I'm trying to shock the WGA closed at this RPM. I'm hoping that the BCS will cut down pressure on the MBC at 5500RPM enough so that it can no longer overcome the spring pressure in the MBC and the MBC effectively bleeds ALL air between it and the WGA, causing highest possible boost above 5500RPM. I'm spiking near 30psi... for goodness sakes, I should be able to hold more than 19 at redline.

Now here are my findings so far...
So yesterday I removed the spring 'mod' and went with the OE config of: Boost source--BCS--WGA, where my maps were 0%WGDC up to 5000RPM and 100% from 5500 up. This produced what one might expect. I got ~15ish psi spike quickly dropping back to 11-12ish and holding with a bit of creep up top. This was a good sign.

So... this morning I put the MBC back in the loop. I put it in the same config as in the above pic, and my tables have still never changed from the beginning (0%WGDC<5500RPM)

Result: Boost was controlable via MBC up to 5000-5500 range where it DROPPED DRASTICALLY!!!! Exactly the opposite of what I wanted. Here's a pic:


So... either:
A. I'm totally wrong on what 0% and 100%WGDC mean (I don't think so)
B. Some other dynamics are going on between the BCS and MBC
C. I have the inlet and outlet on the BCS mixed up

I'm going to test out C. first because it is the easiest. It has been claimed that it doesn't matter what order, but the mitsu service manual tells you to check port "A", but doesn't tell yout to check "B". See below:


lol, this is why I need more people theorizing with me... I just made things WORSE! lol!

I have to say though... boost up to 5K was really smooth.

So my question is this... I have the boost source going into nipple "A", and the output (nipple "B") going to the input of the MBC. Someone please verify for me the order that the airflow goes through the BCS on the stock system by going out and looking at it for me! I'll likely be making my next changes during lunch.

 

Hey mate,

I do believe you have a setup that cannot work, and I'm trying to be 100% constructive in what I'm saying and in no way mean to be anything otherwise.

1st thing i'm thinking is that the combination of two items in line or at least the BCS in line with the MBC would have some effect on the flow of air through the hoses and give you a larger boost spike... but not to 30+ psi.

By sending your BCS to 100% open above 5500 rpm's you now have both the MBC and the BCS venting air at much more than the turbo wants especially to do anything smooth, which is why i think you have that giant spike to 30psi.

To make it work i would say you should hook it up the first way you tried and got a giant spike, and only open the BCS a little at a time as you see the boost start to drop off and increase the amount the BCS is open until you get the level you want.

The other option i'm thinking of is something i don't think will work, but i'll think about it longer before i try and explain it.

Hope this helps,

E