Before any of you run out and lay down as much as $200 for a boost control solenoid it is nothing more than a standard MAC valve with their label and harness. They cost be tween $8.00 and $15.00 nearly anywhere.

MAC Part number is 35A-AAA-DDBA-1BA


With the solenoid, 2 Bar Map sensor, and a SPDT relay you can build your own EBC.


Cole

In my early days, being the cheap bastard that I am, I build an EBC using a solenoid and $12.00 adjustable pressure actuated switch. Calibrated the switch with 13.0 psi off my air compressor, and hooked the switch in series with the solenoid. The air pressure line for the switch went to the same source as my boost gauge. Of course, the solenoid went in-line between the IC and the WG...delaying the boost signal and achieving 1.0 bar boost in the end.

Gimp,

Weak minds frequent the same gutters.

You don't need no stinking $400 EBC's.

Cole

I used to have an adjustable boost controller and finally just went for a 1 bar spring. Much simpler.

I took an even more "German" engineered (translation= over engineered) approach and made mechanically variable wastegate. I can vary the boost mechanically from the wastegate housing and lock it down before driving off. The range of adjustment is roughly between 0.7 and 1.0 bar with my current design. This removes the temptation to keep adding more boost from inside the vehicle when the red mist starts taking over. The adjustment has to take place at the wastegate housing with a couple of wrenches, which gives you time to think about it.
Called upon some friend that is an expert machinist to make the parts that I designed on my Proe cad workstation.http://forums.pelicanparts.com/uploa...1288048700.jpg
http://forums.pelicanparts.com/uploa...1288048714.jpg

And that's why he's called the "Fredmeister"

Cole

Welll now, you wanna see grossly engineered? Take a look at this, my all-in-one homemade EBC...complete with pressure switch, solenoid, fused link, and one-way return bypass valve ( to let the pressure back out of the WG diaphram after boost is gone and the solenoid closes...otherwise the WG would stay open from residule pressure). Self contained, just had to hook power and ground and splice into the WG line. A real piece of crap, but when stuffed back behind the engine for nobody to see...who cares?
My warped mind comes up with the strangest Rube Goldberg stuff sometimes. Worked just fine when I was using it. Function over form, I always say.
(It's ok to laugh, give me crap, flame me....I don't care, I have broad shoulders). It was fun designing, but I've since locked into the spring of my choice in the Tial).

http://forums.pelicanparts.com/uploa...1288060264.jpg

Gimp,

Got to give it to you buddy, simple, cheap, and functional, no one ever said it had to be pretty. Really cool !!!!!

Cole

I ordered that exact same solenoid a week ago and with the fittings and filter it was $35 from ebay. I will use it with my split sec AIC with the second injector map to control boost.

Busman,

Good move!!!!!

Over the years I've found if you take the time to look into things a little deeper to gain an understanding of exactly what they do and how they work you can save a lot of money. On the other hand if I had not misspent my youth I wouldn't have to care what it cost. But God, I had a great time getting here.

Cole

fredmeister 8.00 dollars ebay
BLACK Manual Turbo Boost Controller with Hardware: eBay Motors (item 110533728442 end time Nov-11-10 12:07:28 PST)

If your car already has a wastegate spring installed, and an overboost/fuel injection cutoff, what purpose is an adjustable wastegate? For running 87 octane, and running something like 0.4 to 0.6 Bar? If your wanting to go the other direction in boost, the results may be less than desirable.

If your car already has a wastegate spring installed, and an overboost/fuel injection cutoff, what purpose is an adjustable wastegate? For running 87 octane, and running something like 0.4 to 0.6 Bar? If your wanting to go the other direction in boost, the results may be less than desirable.

Manual boost controller on e-bay= $8
Designing and fabricating one yourself= PRICELESS

To each his own I guess. I just like the fact that mine is truely mechanical and not subject to failed inexpensive pressure relief valves.
I like doing things my own way, keeps me sharp and its a unique approach.

Anyone know where you can buy these factory types? Even if I didn't connect it I'd want one for it's aesthetic value!!! :cool:

Basically you are delaying the boost MAP signal to the wastegate spring -so as goran states,you can only harden it up over the spring stock setting. You can do it manually by putting the simple ball/adjustable spring type unit in the line. I've seen them set in the engine bay - so you cant suddenly fiddle with it. I have an EBC with a low spring rate (0.7) and have it set to run at 0.8 - I use the 0.7 in the wet - ie turn the EBC off. Alternatively, the EBC has two programmable settings - so really I could run at 3 rates - off (base spring rate) and two higher rates.
And guess what - my EBC failed to work at one point and my safety shut the engine down.
DO NOT disconnect the safety. In fact, verify it is tripping out at 1.1bar.
You can do this by pulling it out, hooking some gas pressure to it with a gauge teed in the line and an ohmeter across the body and terminal. Make sure it trips as it is supposed to. Mine failed after tripping out twice on the track - but I had put the car away at that point and picked it up checking everything over - mine melted internally for reasons I dont figure.
So, I tested my new one before installing too. It is pretty crude internally - I pulled mine apart.
Alan

Although any of the previously mentioned methods will allow you to adjust for higher boost there is more to be gained by using an EBC Electronic Boost Controller than meets the eye.
A standard wastegate has a simple valve and valve seat connected to a diaphram with a boost spring setting on top of it. Boost pressure is directed under the diaphram and as pressure builds the diaphram expands and pushes against the boost spring untill it overcomes the boost springs pressure, When the diaphram is fully inflated the valve stem that is attached to the diaphram has lifted off it's seat and exhaust is diverted out of the wastegate outlet pipe.

Standard wastegate:

This is your wastegate with the spring cup unbolted. Note the spring setting on top of the diaphram and you can see where the valve stem end comes through the top of the diaphram cap and a nut fastens it to the diaphram cap. So as the diaphram is inflated by boost pressure the valve is pulled up with inflation and lifis the valve off the valve seat. As soon as the valve starts off the valve seat it allows exhaust to start bleeding off through the wastegate outlet pipe. .2 - .4 bar of boost is escaping out the outlet pipe while the diaphram is fully inflating. This bleed off slows the time it takes to reach full boost.

http://forums.pelicanparts.com/uploa...1290835229.jpg


Exploded View:

Shows all the internals of the standard wastegate.

http://forums.pelicanparts.com/uploa...1290834659.jpg


Boost Springs:

Here is a .43 bar 924 Turbo boost spring ( left ) compared to a stock .8 bar
930 boost spring ( right )

http://forums.pelicanparts.com/uploa...1290835515.jpg


Wastegate Diagram:

Nice illistration of a wastegate and components as well as flow paths.

http://forums.pelicanparts.com/uploa...1290835338.gif


EBC Solenoid:

A small comment about the failure of a inexpensive pressure releif valve or boost solenoid. The solenoid valve is a normally closed valve and if it fails for any reason the boost simply exhausts through the exhaust port as it normally does when no power is supplied and the boost is controlled completely by the stock boost spring.

http://forums.pelicanparts.com/uploa...1290836081.jpg


EBC hook up and how it works:

Run the vac line from the compressor housing nipple to the bottom WG port. Then, cut that line near your EBC solenoid and put a T in there and run a line to the COM port of the solenoid. Then, put the brass fitting on the solenoid onto the NC side of the solenoid. Then run that to the top WG port.

This is the most commonly used and recommended method. The solenoid, when at rest (closed) in this configuration blocks flow to the top of the wastegate so no pressure reaches the top. This means the full boost pressure will work against the bottom of the diaphragm and the system will maintain a boost level based on the wastegate spring. If the solenoid is opened with an electrical signal then the pressure at the top and bottom of the wastegate diaphragm is equalized. With the pressures equal the wastegate spring is easily able to hold the wastegate closed so the wastegate will never open. This would allow for uncontrolled boost.
What happens then, is that the solenoid is opened and closed very quickly (60-250 Hz or there about) but it spends more time in the open position than it does in the closed position. This creates a situation where you can vary the amount of pressure provided to the top of the wastegate to "help" the spring. If you have a 7 psi wastegate spring and you want to run 8 psi with this method, the controller needs to open and close the solenoid in such a way that only a little bit of pressure makes it through to the top of the wastegate. If you want to run 30 psi the controller needs to spend a lot more time "open" to allow more pressure to the top of the wastegate to "help" the spring keep the wastegate shut against the pressure.
This method is fail-safe. If the solenoid or control method fails the solenoid will close the pathway to the top of the wastegate and the boost level will return to that dictated by the wastegate spring pressure. This method equalized the pressure in both chambers so the ebc can maintain a constant boost level while holding the wastegate shut, at the selected boost level, until the gas pedal is lifted.


A manual boost controller would be plumbed exactly like this but using a manual pressure regulator in place of the solenoid.

http://forums.pelicanparts.com/uploa...1290836267.jpg

EBC OPERATION (Quoted)

How does a electronic boost controller work?
First, let us understand how a turbo works. A turbo simply consists of an exhaust wheel and a compressor wheel connected together, exhaust gases from the combustion turns the exhaust wheel which in turn spins the compressor wheel. The compressor wheel then crams more air into the intake, creating boost pressure.
If left alone, a turbo would just keep spinning faster and faster and could result in too much boost, which would cause engine components to fail. To regulate the amount of boost, wastegates are equipped on all turbo-charged cars. The purpose of the wastegate is to divert some of the exhaust away from the turbo (so it won't spin the exhaust wheel). A wastegate is simply a spring loaded valve, this valve opens when the intake pressure reaches a certain pressure and diverts some of the exhaust away from the turbo. Suppose the wastegate is designed to open at 7PSI of boost, then when boost reaches 7.1PSI, the valve opens and the exhaust from the cylinders are diverted away from the turbos, and the turbo starts to slow down. When the boost drops to 6.9PSI, the wastegate closes and the turbo starts to speed up again. This happens rapidly and keeps boost regulated nicely at 7PSI.
The pressure at which the wastegate opens is the base boost pressure, installing a boost controllers will allow you to run higher boost. An electronic boost controller usually works using a solenoid (electronically controlled) valve. A solenoid valve would have 3 ports (sometimes 1 is hidden inside the housing), and 1 port goes to the wastegate, the other port is hooked up to the intake, and the last port is left open to the atmosphere. The solenoid can switch between connecting the wastegate port to the intake port, or connecting the wastegate port to the atmosphere port.
Suppose you want to run 14PSI of boost, then a electronic boost controller should do this -- when the boost reaches 14.1PSI, the solenoid will connect the wastegate to the intake, causing the wastegate to open (since 14PSI is higher than the 7PSI required to open the wastegate)... the turbo will start slowing down, when it drops to 13.9PSI, the boost controller will then switch the solenoid and connect the wastegate to the atmosphere. This causes the wastegate to close since the atmosphere is 0PSI lower than the 7PSI needed to open the wastegate, and the turbo will start speeding up again. This happens rapidly and keeps boost regulated nicely at 14PSI.
Most boost controllers accomplish this by figuring out what percentage (or ratio) of the time the solenoid would connect the wastegate to the atmosphere vs. connecting the wastegate to the intake. This ratio is often known as the DUTY CYCLE, the duty cycle is directly related to the boost level.
Now this is the main function of the boost controller, but there is another benefit to running a electronic boost controller, and that is it will allow the turbos to spool up a faster. How does it do this? Well, a wastegate might be designed to open at 7PSI, but it usually cracks open a little even before the pressure hits 7PSI. This will slow down spoolup of the turbo, causing it to hit 7PSI a little later. A good electronic boost controller would keep the wastegate shut for as long as possible, by using the solenoid to connect the wastegate to the atmosphere (0PSI) till the turbo gets really close to hitting the boost you want, only then it will start switching the solenoid back and forth according to the duty cycle. To determine how long to keep the wastegate shut, most electronic boost controllers use a number known as GAIN. If the gain is set too high, the boost could spike (the wastegate is held closed a little too long causing overboost), but if the gain is set too low, the spoolup is not as optimal as it could be. Getting the correct gain setting will give the optimal spoolup of your turbos.

On a Personal Note:

To allow more boost flexability and safety I choose to put the .43 bar (6.23PSI) 944 Turbo boost spring in my wastegate and run an EBC so I have a boost range from as low 6.23PSI to as high as you want to gamble. I also run a Water Methanol Injection System on the car and can run 1.2 (17.4PSI) bar safely and as much as 1.4 bar (20.3PSI) for short blasts. Now if your going to do this safely you need to know if something fails you can instantly cut boost back to the normal wastegate spring pressure of
.43bar (6.23PSI). By using map inputs I monitor the EBC, WMI Systems and if any failures are detected boost solenoid power is cut and it fails to it's normally closed state which defaults it back to standard wastegate operation and the .43 spring pressure and the timing is retarded back to 14o.

Hope all this helps clear up some of the confusion and misinformation that normanly follows our search for how all this comes together.

Cole

Thanks for the tips :):), it was very helpful :) i appreciate it

Yes thanks for that Cole, even a mechanical dimwit like me can understand that :)

It seems to me the problem lies with gas escaping from the diaphragm before the level dictated by the spring is reached. That contributes to turbo lag. So a manual boost controller won't solve that. All it will do is to increase the top end of the boost by allowing a higher boost level? Is that right?

If it's right then an EBC is the way to go because it not only allows you to raise the boost level, it also ensures the boost is kept within the top and bottom range with no early wastage.

Basically the 930 wastegate has a design limited by the available technology in the 70s or do modern ones still use a spring?

Stu,

That is exactly the big advantage to the EBC. The pressure on the top side of the diaphragm provided by the EBC solenoid line holds the valve tightly against
it's seat until the set point is hit. Then the solenoid cycles on and off (hundreds
of times per second) to keep the pressure at that set point and only allows the valve to open when you let off the gas and the boost pressure on top of the diaphragm is diverted back through the exhaust port of the solenoid. And it is perfectly safe because if the solenoid or EBC fails the solenoid fails back to
its normally closed state and exhausts any pressure through the exhaust port of the solenoid. And with the EBC no longer in control the system defaults back to normal wastegate spring control.

With a manual boost controller all you have control over is the amount you can raise the pressure over the level provided by the original boost spring. A Manual controller allows you to add more boost pressure to the top portion of the wastegate on the top of the diaphram plate. By doing this you effectively increases the amount of boost pressure it takes to fully inflate the diaphram and open the wastegate outlet. The inflated diaphram is no longer just trying overcome the boost spring pressure but that of the the boost spring and the additional pressure added by the manual controller. There is no way to reverse this other than turning down the manual valve and you can not do that fast enough to prevent serious
damage if something goes wrong.

Cole