The factory Mitsubishi system uses a connection from the compressor housing to the wastegate actuator and the boost control solenoid (BCS) valve. There are two pills in the system one on the line from the compressor housing to the T (primary pill) and one on the BCS line.

I have heard people that uses a smaller pill in the compressor housing line for higher boost applications and control with the ECU using the stock solenoid valve with the stock secondary pill in the system.

COBB in their Access Port application keeps the primary pill and remove the secondary pill for ECU controlled boost programs. I am not sure what WORKS does with their Brain Flash.

Which is the better method to control boost using the stock (Not a 3 port GM) solenoid valve.
1) Change the primary pill for a smaller one and keep the stock secondary pill
2) Keep the stock primary pill and remove the secondary pill (none at the BCS side).
3)Any other options?????

My plan is to run 22-23 PSI on 93 octane pump gas and try to keep it as flat as possible til redline. I already bought a Hallman MBC but I am not sure if ECU controlled boost is a better option. Anyone?

 

#1, but there's no need to keep the secondary pill.

You can also get a JDM MAP sensor and use direct boost control (psi based) rather than load based.

From another one of my posts:

The stock wastegate actuator has a 10.5 psi spring. If you connect your turbo outlet vac. line directly to the WGA you will get 10.5 psi.

There is a restrictor pill in the turbo outlet vac. line which reduces the amount of air the WGA gets. Also, the stock boost control solenoid bleeds air back into the intake, further reducing how much air the WGA gets. This vac line also has a restrictor pill to reduce how quickly the solenoid can bleed air

With these vac lines in their 100% stock form, and with the solenoid bleeding as much air as it can (100% Wastegate Duty Cycle) you will run 20-21psi

If you remove the pill on the solenoid side, it will be more responsive at bleeding air, and you will run 22-23psi.

If you use a smaller, more restrictive pill on the turbo side, then you can run very high levels of boost, because the WGA is only getting a fraction of what it was before with the stock pill. These pills are typically referenced by the size drill but used to create them... #60 and #65 being the most common (#65 being the smallest I've seen used, therefore the most possible boost).

 

Are you saying there is third pill on the connection from the BCS to the intake pipe? This is the rear connection nipple on the BCS if you look from the front of the car? Is this the one you are referring as the vacuum line?

Where can I get more info on the JDM MAP sensor to use direct boost control (psi based) rather than load based. Is there a tutorial on that? Will I loose any of the safety features of the factory system by changing to a psi based boost control? Is this similar as using a MBC?

 

#1 is the best solution if you want to keep the stock solenoid. #65 pill works well.

 

Razorlab,

Does the #65 pill works also with the EVO VIII? I saw a pill at GST but it is under the EVO IX section. Is it the same for both? Or is it only for the IX? This is to run 23 PSI on pump gas.

 

Yes works for both Evo 8 and Evo 9

 

Another option is to keep the stock pill at the compressor, remove the pill before the BCS, and install a bleed hole to atmosphere in the hose just before the BCS. I've been using this for over a year. Works very well for me. I've always been interested in comparing to the option 1 method, but have never taken the time as my setup works as well as I could hope.

 

Or you can use the GM 3 port solenoid and not have any pills.

Actually you could further limit the WG signal on the 3 port by putting a pill in the line from the solenoid to the WG. This might help boost at the top end if really needed. Maybe a #58 or #60

mrfred or razorlab have you tried this to help the stock actuator hold say 23 psi up top ?

Milburn

 

The #65 already does a pretty good job of maxing out the stock actuator at the top end. Past that you really need an upgraded actuator to keep the wastegate closed up top.

The problem with adding yet another pill or restriction is that the system won't react quick enough on spool or fast throttle changes. I have tried pills with even smaller holes in them and that problem starts to show. On race gas, it's not really an issue but on pump it can be.

In my testing of a ton of different pill sizes, the #65 is the best solution for pump with enough headroom for race gas.

 

Alright, so I've been thinking about all of this.... (yep, here goes my .02)

Okay so I'm broke now (babies being born tomorrow, just repaired the lancer and put on fresh rubber) and I have a hallman MBC. I want to hold more boost up top but I'm convinced that this manual won't let me no matter what.

A) I have peak boost cranked up to like 29.5
B) I've done the "WGA spring mod" and added an extra spring

No avail. I still taper to around 19ish by 7K and worse by 8K. From what I'm seeing you BCS guys would be able to hold something like 23psi or more by 7K if you were to hit 29psi max. So I'm thinking this:

(If I can find it) can I hook up my OE BCS back up in combination with the MBC? I would use 0 for values before 5500RPM and likely ramp up to 100% duty cycle hoping to keep boost from tapering up top. Does that make sense?

Reasoning: I think that I'm getting such bad taper because my "bleed hole size" is static.... right? I mean the MBC is set so the bleed capacity is set, but then when backpressure gets high (upper RPM) the weak stock WG spring that "bleed amount" is insufficient.

I'd like to keep the "on the fly" boost adjustment... and I'm really not all that fond of load based boost control w/ all that error craziness and such. I can't afford a JDM MAP so psi based isn't an option. I'm really more curious on you guys' thoughts on my idea. Could it work? Using the BCS simply to prevent taper by giving more bleed only when necessary.

 

Your idea is basically the same as what Mrfred is running. Basically, restrict or bleed the pressure pre solenoid via a MBC. It will work.

 

Even with a TBE, I'm still only able to hold about 20 psi by 7000 rpm. From what I've read, getting more boost at that rpm requires making the intake and exhaust system as free flowing as possible, e.g., cone air filter, LICP, FMIC, maybe UICP, O2 housing, test pipe.

 

I'm not hitting 23psi @ 7K (more like 19.5-20) with the direct boost control setup and AEM solenoid.

 

What stops us from just putting a stronger spring in the stock wastegate actuator? Like a 20 psi spring

 

I'm able to hold 21.5 psi @ 7500 in cooler weather with a smaller pill (not sure on the size ... I made it with a Dremel bit set and tapered it by hand) and the WG spring mod.