I don't have a turbo, but I'm just trying to educate my-self. How do you control how much boost is applied.

Do you add a mechanical part to your turbo that lets out that much air, or is it only electronicaly controled?

 

either or.

wastegates are applied to allow exhaust gasses to bypass the turbine fan. the wastegate can be controlled electronically or by a diaphragm activated control mechanism

the latter is basically a loaded spring with a diaphragm attached. once your boost hits X amount, the diaphragm will pull back, opening the wastegate. The unfortunate side effect of this type of wastegate is that it bleeds into full open, so some of the energy that could have been utilized is diverted too early.

electronically controlled boost uses a sensor to detect how much boost is currently being run and opens the wastegate vie a mechanical lever arm. this setup is the best IMO because you have no leakage in the wastegate prior to max boost.

where you set up the wastegate's vacuum line is up to you. Mine is setup to activate after the IC, so I can account for losses in the IC. The unfortunate side effect of this setup is that I have to remember that my turbo is running 1-2 PSI more than what I"m reading or what my wastegate is stopping at.

 

Great answer!! This part tho..I kinda wondered about what you sadi about MBCs bleeding off: There is nothing that has been found that a MBC is any less affective than an electronic one. It is really hard to determine the diference between the 2 when tuning. There are no performance gains from either...that is just an electronic controller manufacture claim. NOW the electronics do have great features and this IS where they rule..features and use of switching boost levels on the fly. A MBC suffers at this and can only do one thing...control boost but can do it's job very well. The downfall of the Elec. ones is that they can fail where a MBC is almost fail proof. The crappy thing I dont like about the MBC's (yes i have one too) is the driving down the street stopping getting out adjusting it drive some more and so on. Once you have the boost set to where you want it tho...leave it and forget about it

 

Let me ask a question about wastgates. If a Turbo like a 14b has a internal wastegate is that as good as a external wastegate and would you still need a BOV.

 

Let me ask a question about wastgates. If a Turbo like a 14b has a internal wastegate is that as good as a external wastegate and would you still need a BOV.

 

Nope an external wastegate is going to be better tha a stock internal wastegate. The trouble with internals is that they can be easily out flowed when when you start pushing lots of boost/power. Thats why it is common for people to port out the wastegate. You will always need a BOV or what mitsu's use is really called a CBV. The BOV is used for releasing pressurized air in the system when the throttle plate closes. It is the turbo's last line of defense when this air comes back downstream towards the turbo. This valve purges this air. If it was not there the turbo would get what is called compressor surge. Actually causing the compressor to turn backwards.

 

MBC's aren't completely fool proof. They have diaphragms that can rip, melt, or get out of whack and cause them to fail.

There is no performance gain between either an electronic actuator or a manual actuator, but it's more in how fast does the turbo spool. Since MBC's lead into full open, exhaust gasses are wasted by being vented around the turbine even though the turbo may not be spooled up to speed. an electronic boost controller on the other hand will wait till max boost is reached before opening the wastegate, saving a bit of crucial exhaust energy for faster spooling and increased turbo response.

 

the major problem with compressor surge is that it will damage the compressor blades. the compressor is turning in one direction, and now air is coming back at it, wanting to go in another direction. what happens is the compressor vibrates, causing the shaft to vibrate and possibly damaging the bearings (being either ball bearings or bushings)

 

Hallman Boost Controllers have a dual stage MBC, as well as others probably, but they also have a MBC that can be controlled for the drivers seat, never used it I can't say how well it works. And why are you selling your spyder?

 

There are at least 2 major types of MBC: ball/spring type and bleeder type. Bleeder type is basically just a controlled leak, while a ball/spring type holds boost till it pops the ball up against the pressure of the spring, thereby pressurizing the line to the wastegate diaphram and opening it. The TurboXS HPBC actually integrates both of these mechanisms in one controller, so you can set the ball to pop at a certain psi, and let the adjustable bleeder take over easing the boost curve and reducing spiking. The characteristics of the bleeder type are considered to be the less desirable because of the aforementioned point unless used in conjuction with a ball/spring type. Basically, if the spring has 22psi of force seating the ball, it's not going to move till it starts to see 22+ psi.

And about EBC's not leaking before full boost: Actually an advantage of "smart" EBC's is that you can start a controlled "fluttering" of the wastegate near the boost you want to achieve to minimize boost spikes. That is actually how the stock ECU operates, along with units like Apexi AVC-R. If you hook up an LED to the boost control solenoid signal from the ECU you'll see what I'm talking about, it will flash off & on at certain RPM's to tame the curve.

 

Yes you are right Hallmans does have this for an extra 50 I believe...but I have no experience with it myself but have hear it works great. For most poeple I believe that buy a MBC dont purchase it. It's a kinda set it and leave it for me. The reason Im selling the spyder...basically it's taking up room and I never drive it. I put less than 7k miles on it a year.....plus I have 2 other vehicles.

 

No MBC arent completely flawless, anything can breakdown. But a MBC can outlast a EBC IMO, there are less fail points with an MBC than a EBC, with the MBC being a much simpler device. I also agree as to what the other poster stated..there are two diferent types of MBC's and you are only refering to bleeders, not ball and spring. Most manufactures, Hallman and what not, use ball and spring controllers. As to what you are saying about the spool up please refer to MachV.com They have a wonderful write up that goes way in depth on the pros and cons of boost controllers. After their testing they could not see a difference in spool time between and MBC and a EBC. I think they woud be more experts on this than either one of us due to the fact that they have tested this in a controlled enviroment with dynos and such. All in all it is just a matter of money and prefrence when purchasing a boost controller. I dont fiddle with the boost..I set it and leave it therefore the $50 halmans was good enough for me for you it could be different.

 

i have a question that might be off topic...is the boost on a supercharger controlled the same way?

 

They are controlled by what pullies you are using.

 

so you have to change pulleys if you want to upgrade your boost?