boost controller

[gotta_learn_1st]

Hi, i'm kinda new to all of this, and I wondering if someone could explain to mean how to use a boost controller??

[turbo2nr]

a manual boost controller works by bleeding off access boost untill desired boost level works it splices in between the wastegate and compressor nipple. its cheap, and can be made for $6 form home depo or you can buy one i bought mine for $43.. disadvantages of mbc is boost creep and boost spike and you have to adjust from under the hood..

electronic boost controller uses the signal going to the boost selonid (i think) and regulates the psi for their i belive.. not to sure on that one tho.. its better and expencive.. you can control it form inside your can and you get no creeps or spikes.. its aslo more pricy starting at $350 is your lucky..

what car btw..
welcome to a/f.

[gotta_learn_1st]

what does the "boost ratio" mean?

[gotta_learn_1st]

o yeah, I have a 1995 Mitsubishi 3000gt vr4

[Skyline_R32_Canada]

learning how ebc's are kinda difficult...but i'll try to explain it my best:

theres a solenoid (valve) that connects the intake and wastegate and wastegate to the atmosphere, and let's say you want to run 14 psi so when boost reaches 14.1 psi the solenoid will connect the wastegate to the intake which causes the wastegate to open letting the excess boost fly off...when it gets to 13.9 psi the wastegate closes so the boost builds. So just think of it as the wastegate constantly closing and opening to maintain the 14 psi. sorry if im confusing lol

now most boost controllers figure out the duty cycle, which is basically the time the solenoid connects to the wastegate vs connecting it to the atmosphere and its all directly related to the desired boost.

[Thourun]

Welcome welcome! Always good to have another 3000GT lover on the forum! I reccomend the 3000GT forum, it's where you'll fit in best http://www.automotiveforums.com/vbul...splay.php?f=44
We'd love to see you over there and we will be more helpfull because we have the same cars!

[gotta_learn_1st]

thanks ill check it out

[LandoAWD]

Originally Posted by turbo2nr

disadvantages of mbc is boost creep and boost spike and you have to adjust from under the hood..

its better and expencive.. you can control it form inside your can and you get no creeps or spikes..

Uhhh, no. Creep has ZERO to do with a BC.

[JekylandHyde]

Wow, there is a lot of completely wrong information in here.
The facts:

Wastegates
The wastegate vents exhuast gases NOT boost pressure.
Exhaust spins the turbine which in turn spins the compressor whihc makes pressure.
The wastegate is a valve placed before the turbine to vent exhaast gases around the turbine so it stops building more boost.

The wastegate has a spring rated for a certain pressure, when the compressor side of the turbo builds enough boost (pressure) to open the WG against the spring, the exhaust is vented.
So if you have a 10 psi spring in your wastegate, when you build 10 psi of boost ... the WG should open and you should maintain boost.
___________

Boost Controllers
A boost controller is a device that inhibits air flow to the wastegate so that you can build more pressure than what the wategate spring allows.

MBC (manual boost controller) ~ These are usually ball-n-spring designed. As you "adjust" the MBC, you increase the tension in the spring which will then require more boost to push the ball out of the way ... once it pushes the ball out of the way, it rushed to open up the WG. So you are basically adding interference in the line and by adjusting the spring tension, you change how much boosr pressure is needed to get past that interference.

EBC (electronic boost controller) ~ Same principle as the MBC, but there is an electronically controlled solenoid in the system instead of a ball-n-spring. You electronically set at what PSI you want the solenoid to open.

[JekylandHyde]

Boost Spike
This is when you nail boost so hard and so fast that there is a brief moment that boost pressure builds beyond what your boost controller is set at. This happens because boost builds faster than the boost controller can respond to. This is almost non-existent in the MBCs since they are physical. It is more common in the EBCs since they need a split second for the electron to comprehend what just happened.

This can also happen in a systme when the wastegate is too small to run a prefered lower boost setting. This is more likely to happen with internal wastegates since they are inhibited in how big they can be.

Boost Creep
This can happen in any set up. This is when boost starts to build beyond the set point. This happens when the wastegate is fully open, but can not flow enough exhaust to control boost pressure. As it gets over run (it's at capacity) boost pressure will start to build higher than what you wish.

This is caused by an insuffienctly sized wastegate.
.

[JekylandHyde]

Originally Posted by gotta_learn_1st

what does the "boost ratio" mean?

EBC's do not actually work on PSI ... they work on ratios since every turbo set up will require a varying amount of wastegate opening to control boost at a given PSI.

On the Blitz DSBC that I use:
0 on the ratio is your wastegate spring. Basically the controller is not doing anything.

100 is the controller keeps the wastegate closed forever and you make inlimited boost until your engine blows up

So you need to find what "ratio" in between 0 and 100 will give you the boost setting (psi) you want.

[youngvr4]

that sounds about right

[gotta_learn_1st]

so wat is the maximum ratio that I can set on a 3000GT whithout risking detonation

[gotta_learn_1st]

Also, what is the most boost that a 3000GT can Handle

[duplox]

Well done JekylandHyde, saved me a whole lot of typing . Another few terms you should know if you're planning on modifying a turbocharged car:
Wastegate Creep: On a car without a MBC or EBC, where the wastegate is directly hooked to the manifold(most production turbo cars are set up like this), when boost pressure is less than max(say at 5psi with 8psi wastegate setting), the 5psi will be enough to push the wastegate open a bit. This causes exhaust gasses to be vented even though full boost has not been achieved. Basically, this causes a slightly slower spool. Even if you're not interested in increasing boost, a MBC would be a good idea just to eliminate wastegate creep.
Not really a term, but many OEM wastegates cannot hold much pressure. They're designed to be used on factory boost settings, and therefore, the same ammount and pressure of exhaust as stock. When you increase boost, you increase the ammount of energy(heat and volume/velocity/pressure)exhaust coming out of the motor, which exerts pressure on the face of the wastegate valve. When exhaust pressure gets high enough, it'll merely push the wastegate open, regardless of the boost pressure. I've seen this happen on a turbo dodge of some sort. The owner fixed it by riggin up a vacuum can to the wastegate. When the engine is at idle, it produces vacuum, which is stored in a can(much like a vacuum resevoir for power brakes). The can is fitted with check valves so it will never leak the vacuum back to the manifold. When not at maximum boost, the vacuum is applied to the wastegate via a solenoid valve, which helps pull the wastegate valve shut. When maximum boost is achieved, the solenoid switches to manifold pressure, and the wastegate opens. Works very well, I think the car achieved 22psi on a stock turbo. Then again, with that kind of boost, you shouldn't be running a stock turbo.

As for the highest boost a 3000gt can handle... I have no idea. Ask in the 3000gt forum, you're more likely to get a good answer. We can give you good general info here(even though its off topic), but for specifics, seek people who deal directly with the car you have.