Manual Boost Controller vs. Aftermarket EBCS

[Mindspin311]

So here's my story. Get the car tuned this weekend, but the car wont hit the targeted 19psi the tuner is shooting for. He explains that the factory EBCS just isnt cutting it and it wont hold closed till the targeted 19psi. He says a simple solution is to go with a MBC. So we install that and continue on and finish the tune.

 

Now, my question is, should I stick with the MBC? Ive read tons of good things about the GrimmSpeed BCS and it being so cheap, I figured I would give it a shot.

 

My concern is the various values in the map that control the solenoid and the rest of the boost control systems. I am moving out of town in a few weeks so I really dont have the opportunity, nor the money, to go back on the dyno. Should my tuner be able to adjust the map to work with the new BCS without actually putting the car on the dyno? Im hoping he doesnt need to get the car back on the dyno because once I move, Im looking at full costs for tuning since Top Speed in Atlanta wont be able to edit the tune I just received.

[Th3Franz]

http://legacygt.com/forums/showthread.php?t=113792

Not intending to toot my own horn but I am really thrilled with the boost response when using an MBC with a BCS upgrade in parallel. It's a pretty simple system but if you insist on keeping the stock system, you can just do a BCS upgrade by itself. The tuner should be able to adjust the map for a new BCS but you might need to do some data logging afterward. Are you running an open source tune?

[rao]

Personally Ithink your tuner is full of sh!t , but to answer the question you can use any solenoid that you want and the tune can be modified to deal with it. The bad news is that the stock BCS is just fine and you don't need to change it

[Spec B]

On the stock turbo the stock system works fine...just get a smaller restrictor pill.

 

And to answer the OP question...Yes. Boost can be easily tuned without the Dyno.

[Mindspin311]

Personally Ithink your tuner is full of sh!t , but to answer the question you can use any solenoid that you want and the tune can be modified to deal with it. The bad news is that the stock BCS is just fine and you don't need to change it

 

I dunno, the car wasnt hitting 19psi for whatever reason. Added the MBC and everything worked.

[rao]

Then keep the MBC

[Mindspin311]

If tuners could access other tuner's maps, we wouldnt have this problem haha

[subaruski]

i'm going in for a tune in a couple weeks also. my tuner suggested getting a mbc of a ebcs also. on a stock turbo trying to hit 19psi is the stock ebcs really not in adequate?

[biz77]

19 psi should never be a problem for the stock system, unless there is a mechanical issue. If the tuner is unable to hit target boost they should first check the WG solenoid and make sure the arm is adjusted correctly. The next step would be to try a different pill.

 

Using a MBC in place of the factory BCS invites all sorts of problems, including defeating failsafes the ECU uses to protect the engine and drivability issues.

[Legend]

19 psi should never be a problem for the stock system, unless there is a mechanical issue. If the tuner is unable to hit target boost they should first check the WG solenoid and make sure the arm is adjusted correctly. The next step would be to try a different pill.

 

Using a MBC in place of the factory BCS invites all sorts of problems, including defeating failsafes the ECU uses to protect the engine and drivability issues.

 

+1

 

I've used and tuned both the VF40 and VF52 with the stock bcs and it works great (23psi sea-level equivalent) using the smaller-than-stock 1.0mm pill.

[Mindspin311]

Yea Im not sure, all I know is that the car wouldnt hit 19psi..

[dudeondacouch]

...just get a smaller restrictor pill.

 

[reid-o]

I think MBCs are great when they're paired up with external wastegates because external wastegates are able to regulate boost easily due to the sheer size of the valve.

Paired with internal wastegates, however, they can sometimes need adjusting depending on weather conditions and especially load conditions (like a long hill in 4th gear).

 

You have to be careful and watch your boost gauge (if you dont have one, you shouldnt be using an MBC) such that you account for creep and/or spikes that may occur on long hills.

It's not that I think MBCs are bad; rather they sometimes are unable to work consistently because the internal wastegate is just not an efficient mechanical way to regulate boost, so under some conditions it works, and then under others, the setting may not work.

 

The stock boost control system, paired with a stronger and faster acting solenoid, is able to compensate better for more conditions with an internal wastegate.

 

 

Bottom line, if you have an MBC, you need a boost gauge, and you need to watch it when you're in high gears for extended periods.

Don't discount this.

[Mindspin311]

All I know is that my tuner said sometimes the solenoids cant handle it and wont hold. Says it doesnt happen often, but it still does on occasion.

 

Ideally, Id like to get a GrimmSpeed BCS and be done with it. The thing Im worried about is how the tables for WGDC and the other boost related tables are currently set. I am leaving the region my tuner works in so it would be real hard to get the map edited since no tuner where Im going can edit the map.

 

Guess Ill have to call them up and see if the map already has the proper settings if I were to ditch the MBC and reinstall an EBCS.

[biz77]

I think MBCs are great when they're paired up with external wastegates because external wastegates are able to regulate boost easily due to the sheer size of the valve.

Paired with internal wastegates, however, they can sometimes need adjusting depending on weather conditions and especially load conditions (like a long hill in 4th gear).

 

You have to be careful and watch your boost gauge (if you dont have one, you shouldnt be using an MBC) such that you account for creep and/or spikes that may occur on long hills.

It's not that I think MBCs are bad; rather they sometimes are unable to work consistently because the internal wastegate is just not an efficient mechanical way to regulate boost, so under some conditions it works, and then under others, the setting may not work.

 

The stock boost control system, paired with a stronger and faster acting solenoid, is able to compensate better for more conditions with an internal wastegate.

 

 

Bottom line, if you have an MBC, you need a boost gauge, and you need to watch it when you're in high gears for extended periods.

Don't discount this.

 

The BIGGEST drawback to using a MBC on a smaller turbo, like the stock unit on the Legacy is that you have no way to request tapered boost as RPMs rise. Best case scenario the little VF40 is going to be able to run 12-13 psi near redline and that is already pushing the abdiabatic efficiency of the turbo to its limits. With a manual boost controller if you request 19 psi, then you are requesting that 19psi all the time. This means that at the upper RPMs the turbo will be running to it's absolute physical limits, asked to deliver 19psi, but only able to belt out 12-13. It also means that above boost threshold when at part throttle you certainly have the chance for partial throttle/full boost, which IMO makes for a poor driving and jerky car. Some people mistake this for responsive or fast spool.

 

I don't discount the use of MBCs, however I feel they have no place on a car with a turbo capable of quick boost onset that typically occur in RPMs spent during normal cruise driving and/or turbos that are not able to maintain the set boost point on the MBC throughout the entire RPM band.