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Discussion Starter #1
Does anyone know the differences between the Hallman, TurboXS, and GFB Atomic MBCs? If all I want to do is to leave it at the stock boost level, would you prefer one over another? Thanks!
 

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Discussion Starter #3
To increase the area under the boost curve. Even though the peak boost is the same, there is more boost across the rpm. Thx.
 

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Gotcha.... thats kinda what I was thinking, but I guess if it was me and I was already putting in a boost controller, I'd want to increase the boost. :)
 

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I am not sure what you mean, are talking about quicker initial spool?
I don't know how you could get more boost across the rpm, with the same amount of boost?

At any rate the hallman or Joe P. style MBC, which TurboXS markets along with many other companies, is a very simply ball and spring valve. It basically just regulates air pressure the wastegate will see.
Electronic controllers use solenoids that open and close to regulate boost and can be controlled from inside the cockpit, however more people are switching to the manual type for ease of use, cost, and beleive it or not they seem to work better to.
 

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I had a TurboXS dual stage on my WRX and it worked like a charm :) Never had a problem with it :D, the only disadvantage is that you have to get out of the car to adjust it, and is harder to fine tune.

-d
 

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Discussion Starter #7
Isn't it correct that a boost controller set at the stock level (or any level) will try to raise the boost to that same level at all rpms? Thx.
 

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Sti_Time said:
I am not sure what you mean, are talking about quicker initial spool?
I don't know how you could get more boost across the rpm, with the same amount of boost?
The stock boost controller uses purposely restrictive vacuum lines to help control boost levels. This causes lower boost levels at low RPMs, but still allows the same peak boost pressure. Adding the manual boost controller alone and setting it at the stock boost pressure will create substantial power and torque gains in the lower range RPMs, while keeping peak performance the same.

For instance, on my wife's 04 Forester XT 2.5 Turbo, max boost is set at 11 psi from the factory. But she could only manage 6 psi before 2500 RPM. With the JoeP MBC, I set the boost still at 11 psi peak, but she is able to boost the 11 psi at 2000 RPM. HUGE difference in low end torque. For some reason that stock BC will restrict boost at the low range.
 

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That sounds really strange, almost the exact opposite of what you might expect. Why would you want to limit lowend power? This is when you want the car to give everything its got.

Why Subura chose to do this, if in fact this is what's happening, is beyond me.
Anybody running a boost guage that can confirm this?



P.S. With the EVO 8, Mitsu did the exact opposite, allowing 19psi initially and then slowly tapering off to 16 psi by redline.
 

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Sti_Time said:
That sounds really strange, almost the exact opposite of what you might expect. Why would you want to limit lowend power? This is when you want the car to give everything its got.

Why Subura chose to do this, if in fact this is what's happening, is beyond me.
Anybody running a boost guage that can confirm this?



P.S. With the EVO 8, Mitsu did the exact opposite, allowing 19psi initially and then slowly tapering off to 16 psi by redline.
Yeah this is correct. However, they also run the car at like 14:1 A/F in the lower RPMs to get the turbo spooling faster (higher EGTs = faster exhaust gas velocity). 14.5 PSI as soon as the car can deliver it, and at partial throttle, is not necessarily optimum driveability. On the track, you will be WOT most of the time and with the 6 speed, you should be able to keep the engine above 5ks RPMs all the time.

BTW - Once it hits peak boost, it will taper towards redline.

-st
 

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Sti_Time said:
P.S. With the EVO 8, Mitsu did the exact opposite, allowing 19psi initially and then slowly tapering off to 16 psi by redline.
The stock boost controller is not causing the boost to taper off on the EVO. It is the size of the turbo that does not have enough airflow at redline. What you have to realize is that 19psi @ 4000RPM does not equal 19 psi @ 7000RPM. You could close the wastegate shut and you still wont be able to get more boost at redline.
 

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jeffsti said:
The stock boost controller is not causing the boost to taper off on the EVO. It is the size of the turbo that does not have enough airflow at redline. What you have to realize is that 19psi @ 4000RPM does not equal 19 psi @ 7000RPM. You could close the wastegate shut and you still wont be able to get more boost at redline.
Are you simply guessing or can you back up this statement?

First off the EVO 8 doesn't even have a boost controller in the conventional sense.

Secondly it's the ECU that limits boost according to rpm, this is so you have a safety margin built-in and do not blow your motor.

Third, I installed a MBC in my friends EVO 8 and we set it at 20psi, guess what? it hold rock steady right to 7000RPM!

The turbo on the EVO isn't some little hairdryer you find on another cars, its a real turbo, and its size looks almost aftermarket.

With regards to initial boost and A/F ratio, this is exactly when you can get away with a leaner condition, at low RPM. Hardly anyone has ever blown their motor between 3-4K, its almost always lets go much closer or even after redline. Thats why you want to make as much power (torque) as possible at low RPM's, because you can get away with cranking the boost here.

Come to think of it, since it doesn't flow very well in the upper RPM regions, thats exactly what I would do in the STi.
 

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MBCs work good. With my wrx it made a nice difference and that difference is called "partial throttle, full boost"

With the stock ecu you can't get full boost at part throttle, with an MBC you can.

There's a lot of people paranoid about using an MBC though, they claim it causes too high of egts and lean conditions, neither of which I've experienced on my wrx. I believe this is because the wrx is so rich from the factory that even if an mbc did lean it out it doesn't hurt.

No signs of detonation or high egts.

You'll notice a nice kick from low-midrange with an mbc, and im my wrx at least, the mbc doesn't spike a FRACTION as bad as the stock ecu controller does.

Also try lowershores performance they make a great and cheap mbc that has dual controls, I'd stay away from anything other than brass internals if you go with a ball and spring the aluminum can corrode against the metal spring and ball and cause it to stick.

Lower shores is ball and spring and some type of bleed valve combo made of brass/doesn't corrode and is only like 35 bucks and comes with a nice mount.

No I don't work for them, just happy with the great product for cheap price.
 

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thanks

I should put a hair dryer on my escort, that'd be what, 4 HP? :lol:
 

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The Hallman units seem interesting.

My Sti is stock (2 cat deleted * Prodrive axle back)

Has anyone installed a Hallman in a stock Sti that can report on results?
 
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