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Boost control advice needed.
https://www.slantsix.org/forum/viewtopic.php?t=48877		 Page 1 of 2
Author:  Sam Powell [ Tue May 22, 2012 7:28 pm ]
Post subject:  Boost control advice needed.
I wish to add an adjustable boost control. This is the model I found on the internet. http://www.boostcontroller.com/index.ph ... egory%3D97

Is there any opinion about this out there? Is this type of control the best, simplest, surest, or any other adjective you can think up? Are there serious weaknesses to this type? Is there something out there that is just as effective but cheaper? This seems pretty cheap to me, if it works.

I should add I am trying to limit upper level of boost, not when it starts. It comes in fairly early now, and goes higher than I wish it too for now. The turbo is a stock Grand National unit from 1987, and I have added a turnbuckle to the actuating rod to adjust it some, but am actually unsure of how this effects things. It has been years since I made that mod. It was from an article on a Grand National forum. Thanks.

Sam
Author:  Joshie225 [ Tue May 22, 2012 8:18 pm ]
Post subject: 
A boost controller like that can only raise the boost level as they reduce and possibly hold-off the signal to the wastegate. If you want to reduce boost then you can change the wastegate actuator or add a spring helping boost pressure open the wastegate.
Author:  Dart270 [ Wed May 23, 2012 2:40 am ]
Post subject: 
I like Josh's last idea - cool.

Lou
Author:  Sam Powell [ Wed May 23, 2012 4:26 am ]
Post subject: 
Thanks. This is an internal wastegate, so it is hard to tell what is going on by looking. I can lengthen the actuator rod with the turnbuckle, which would open the wastegate sooner. I am not sure where the spring is located. Is it in the control pod itself,or in the wastegate? If the spring is not easily accessed, am wondering if it is possible to buy another control pod for lower boost, and put the controller on that one to raise it back up to whatever was needed or wanted later.

Obviously I do not understand the theory behind how these parts work. It came to me disassembled, and I put it back together, not even sure where the various hoses hook up. I am pretty fuzzy on how this works. Boost comes on early, and strong. It will come in as low as 1500-1800 RPM pulling up a hill, and maintain 5 pounds for awhile and then slowly climbs up to 9-10. I would like to keep it at 5 for now.

I could go on a GN forum and do a search, but it has been awhile since I participated here, and wanted to get back in the flow a bit.

I found this unit on another merchant's site. http://www.cottonsperformance.com/prodd ... -25&cat=95

It says it can control the boost from 0-25. But if Joshua's comments are correct, then I do not see how it can make it less than what it is now. It simply looks like a standard pressure regulator you can buy at any Home Depot, which could limit pressure, but not raise it from what it is now. Would a larger hose, or fitting raise pressure on the wastegate? By the way, I did find out that lengthening the rod lowers the turbo boost pressure. I can try that first. Now I am glad I added that when I put it together the first time, even though I did not know how it worked. I just read it was a good idea on the GN forum.

Sam
Author:  75customdart [ Wed May 23, 2012 7:14 am ]
Post subject:  factory wastegate
I'm not sure what your factory wastegate actuator looks like but most look relitivly close to this.
Image

The way it works is boost pressure is applyed from the Turbo cold side outlet to the top of the diaphragm which moves the rod and opens the wastegate door inside the exhaust housing. By what you said it takes around 9-10 Psi to overcome the spring and open your wastegate completely. The way the cheap boost controllers work is by adding a controlled amount of boost pressure to the opposite side of the diaphragm. So if you add 1 psi to the spring side of the diaphragm your boost pressure should increase by 1 psi.

Now if you adjusted the rod length to be longer the wastegate should start opening sooner and be completely open soon lowering Max boost pressure. So give it a try, but you might find that the internal wastegate can't flow high enuff and cause boost creep at higher rpm. Hope this helps, Cory
Author:  Dart270 [ Wed May 23, 2012 7:16 am ]
Post subject: 
Just is suggesting, I think, that you go to the hardware store and buy some extension springs and just loop one around the actuator rod to put tension on the diaphragm. Tune spring tension by driving car, observing max boost, and adjusting spring tension (diff spring, or lengthen/shorten spring). No internal mods required.

Lou
Author:  Rust collector [ Wed May 23, 2012 8:12 am ]
Post subject: 
I think that is a good way too :wink:
I am not sure about yours, but if you adjust the rod too much, you can end up with a gate that never close completely (would make it spool up slower), or never open all the way (maybe get boost creep), depending on what way you turn it, obviously.
Author:  Sam Powell [ Wed May 23, 2012 3:28 pm ]
Post subject: 
Quote:
Just is suggesting, I think, that you go to the hardware store and buy some extension springs and just loop one around the actuator rod to put tension on the diaphragm. Tune spring tension by driving car, observing max boost, and adjusting spring tension (diff spring, or lengthen/shorten spring). No internal mods required.

Lou
That sounds good. As you might suspect, I was trying to make it more complicated. :wink:

Sam
Author:  Sam Powell [ Wed May 23, 2012 7:10 pm ]
Post subject: 
I went and looked at the waste gate. It looks like the rod extends from the actuator to open the wastegate. Since I put a turnbuckle in the rod to lengthen, or shorten it, I could put a compression coil spring between the actuator and the turnbuckle to apply opening pressure. I would have to buy different strengths and lengths and try them to see what worked. I have no idea how much pressure the actuator pot applies to open the waste gate. Thanks for giving me some direction here. I will let you know what happens.

Sam
Author:  Rug_Trucker [ Wed May 23, 2012 9:55 pm ]
Post subject: 
In the "old days" didn't some people use a knob in the dash operating a cable?
Author:  Rust collector [ Thu May 24, 2012 8:50 am ]
Post subject: 
Quote:
I went and looked at the waste gate. It looks like the rod extends from the actuator to open the wastegate. Since I put a turnbuckle in the rod to lengthen, or shorten it, I could put a compression coil spring between the actuator and the turnbuckle to apply opening pressure. I would have to buy different strengths and lengths and try them to see what worked. I have no idea how much pressure the actuator pot applies to open the waste gate. Thanks for giving me some direction here. I will let you know what happens.

Sam
Yep, like this:

http://www.youtube.com/watch?feature=pl ... ogCn4AJYsY
Author:  Sam Powell [ Thu May 24, 2012 4:14 pm ]
Post subject: 
Wonderful! Thanks so much. I am out there tonight to do this.
Sam
Author:  Sam Powell [ Thu May 24, 2012 6:52 pm ]
Post subject: 
Done! But, I could not test drive it because it is raining AGAIN. So, I have no idea if this is not strong enough, or too strong. I was annoyed that Home Depot drove the real hardware store around here out of business, and they sell springs only in packs of 3 or 4 each. Now I have extras that may or may not ever be used for anything.

Does anybody know what the 2nd hose to the actuator does. It is vacuum on one side. But it seems thatboth sides would see boost and cancel each other out. :?

Sam
Author:  Rust collector [ Thu May 24, 2012 7:09 pm ]
Post subject: 
If it goes to the "other" side of the diaphragm, you could...... use boost pressure in stead of the extra spring, I suppose... with a cheap boost control valve-thingie. :lol:
Author:  Sam Powell [ Thu May 24, 2012 7:30 pm ]
Post subject: 
There is vacuum on the side of the pot towards the wastegate, and boost reference signal on the side away from the waste gate. It seems there must be some kind of check valve on the vacuum side,as it would become boost at the same rate as the rest of the induction system, would it not?

Sam
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