HOW TO: Automatic dual stage boost controller by 91cavgt

[punkrokdood]

As requested for the last couple of months, here are the detailed instructions of my custom made dual stage automatic boost controller.

But before you say "I can buy one just like it with a button to control high and low boost". Well, no you can't buy one like this. My design(scottmech also had the same idea and built his exactly like mine without ever seeing mine) lets the factory computer control boost to an adjustable level(say 11 psi). Then, above that set boost level, the boost controller takes over. Everything happens automaticly with NO input needed from the driver.

Why is this soo much better than a typical boost controller? Well, as we have all seen, our computers are VERY sensitive to too much part throttle boost. Just look at ANY dyno out there. The ones letting the computer control boost are getting torque REALLY coming on hard at only 2500 rpms while the ones with any kind of boost controller don't get good torque going till 3,000 rpms. My personal dynos show this as well. Why is this? I'm going to go out on a limb here and say because of retarded timing even though I have no iron clad proof of it. This type of boost controller with also prevent compressor surge when using a boost controller.

So, how does it work? Well, scottmech made a nice schematic of how everything is plumbed in and wired up so I'll post it.

http://www.srtsyndicate.com/attachments/Automatic dual stage boost controller by 91cavgt/scotmech.JPG

You can see his write up on the next post*

Now Scottmech used junk yard parts to build his. I used parts from NAPA and a Chevy dealership. Here are those 2 part numbers;

NAPA #701-1575 Hobbs adjustable pressure swicth $27.49
Chevy #1997152 Boost selenoid $21.86

I also used a 16 gauge piece of wire about 1 foot long that is fused with a 3 amp blade type fuse. The wire runs from the + side fo the battery to the Hobbs switch, then out of the Hobbs switch to the Boost selenoid, then out of the boost selenoid to a ground point(on my car it is a strut tower bolt). My system is EXACTLY the same as Scottmech's accept that I am not currently using a bleed port as my manual boost controller has it already on it.

Now here is how everything works. While cruising if you start to get on the gas just a bit the car responds just like it does when it is bone stock. The boost comes up to 5 psi and stays there! No 15 psi of boost at part throttle!! Amazingly, and I've talked to some other people that say the same thing, the car accelerates as quick, if not quicker at factory boost levels at part throttle then it does with 15 psi of boost when you have a boost controller connected!! Now, once you stab the gas, the boost rises like normal. However, once boost hits the boost level that the Hobbs switch is adjusted to, the boost controller takes over and your boost then raises to the level you have set it to.

Now here are some cool advatages to this design. You can now have traction in 1st gear like stock(9-10 psi) and then when you shift to 2nd gear, your boost goes up to your level that the boost controller is set to!! Instant traction control! Not only that, but let's say that you got a bad tank of gas and your computer decides to retard timing and boost down to 5 psi. No problem. Since the computer has 100% control over the boost below the set level of the Hobbs switch(11 psi) then your boost controller will NEVER control the boost so you no longer have to worry about blowing your motor from a bad tank of gas!!

Alright guys, let's here some feedback on this. There are other things that can be done with this system. With slight changes, I think it could work with you Stage 1 guys that are running an upgraded wastegate actuator!



* edited for format, no information has been changed

[punkrokdood]

By scottmech:

Just got done with some testing of a junkyard dual boost controller. Seems to be working great and best of all I only have $40 in it. Here's some of the background and details.

I have s1, mopar bov conversion and the AGP wag. I don't go to the strip so for me drivability is more important than anything, but I still want to boost 17 on the street.

I first hooked up the wga to the green line bypassing the wga solenoid(workrd best for my car). Boost seemed to rise to quick in part throttle situations and it seemed the pcm was having a hard time adjusting for the early boost. Power was great but drivability suffered. Not to mention trying to launch the car was a pain in the ass.

I then hooked it to the stock line and adjusted to 17 psi. Loved the power delivery. Smooth but still had great punch up top. But after a couple of days the pcm started relearning and adjusting boost. So started the quest for a boost control system that would keep stock activation of factory solenoid up to a pre set psi or wot, then shift over to a second system that would bypass the stock solenoid, and do it cheaply.

Main system components are an adjustable pressure activated Hobbs switch for $25 (also used for alcohol water injection systems found at NAPA), 2 ea. 3 port solenoids (with connectors) that can be found at the junkyard for $2 to $3 each and an mbc of some sort. Other misc items are vacume hose (3/16 and 5/32), wire and connectors.

The solenoids are almost identical to the 3 located on the top of the air box, operate in exactly the same way and use 12vdc for power. They can be found on Shadows and Dusters on the pass side engine compartment fwd of the wheel well.

While the solenoids are unpowered I routed the air such that the air flow still went through the stock solenoid thus retaining pcm boost control. At about 14 psi, The Hobbs switch closes and allows power to go to the 2 solenoids. One routs air around the stock solenoid, the other was used as sort of a shuttle valve to keep air from backfeeding into the stck solenoid. It also isolates the mbc from controlling boost during pcm boost control. Currently I'm using a needle valve found at ACE Hradware for bleed control (works well actually). Will be ordering a ball and spring type next. I have it set to 17 psi.

Another option for system activation would be a switch on the throttle so it would ony work at wot, or a toggle in the interior. Once I have more time I will look into fabricating a bracket to do this (throttle actuation). Right now the Hobbs switch is working well and it was easy to install.

The next step is to replace the AGP WGA with the stock one and retune the high boost. Hope to do this tonight when my daughter goes to bed.

Another good piece of info I found out while testing concerns the surge valve. I put a meter on the surge valve solenoid connector and found that at no time during wot runs was the surge valve commanded open. And this was done with the boost set at 17.5 psi (by the gage in the car).

Let me know what you guys think.

[punkrokdood]

I jsut did this mod, and some things that should help out a bit:
1. the diagram shows the top nipple on the stock solenoid as the WGA, but it should actually be hooked up to the turbo (green line.) The center nipple should go to the WGA.
2. If you use the GM solenoid (the supplied part number) there are 3 nipples on it. one on one side, 2 on the other. with the wires on top, on the side with 2 nipples, the left nipple is common, the right is normally closed, and the one by itself is normally open. That being said the GM solenoid should be hooked up as follows:
COMMON= turbo (green line)
NC= MBC's input
NO= Top nipple on stock solenoid #2 (stock green line location)

the rest of the diagrams can get it installed correctly.

When you take it out for the test drive, take it easy. it is VERY easy to hook it up in such a way that the WGA is completely disconnected from a boost source which will cause you to boost 30 psi almost instantly, so just be careful :thumb:

[cooper232]

on my 03 i no longer use the solenoid with the red/white lines. would this be ok to use with this set up? if so all i need is some vacuum line and the hobbs pressure switch, correct? awesome how-to!

[punkrokdood]

on my 03 i no longer use the solenoid with the red/white lines. would this be ok to use with this set up? if so all i need is some vacuum line and the hobbs pressure switch, correct? awesome how-to!
you could use that solenoid, but you'd have to cut the wires to it, and re-route the power signal. i don't know if removing one or more of the solenoids completely like that would cause a CEL or not

[cooper232]

for my MBC would the needswings in-cabin mbc work ok? and also i read on the forums how someone said they needed check valves to make this work. is this true? also i currently have an AGP wga installed but i am thinking about taking it off and selling it and returning to my stock wga for this set up. how much can i hold to redline with the stock wga and this set up? i am thinking if i can sell my wga for a good amount i will have enough money to buy all these parts and still have a few bucks left over plus a more factory look under the hood.

[cooper232]

ok the post previous to this one was just a joke trying to get someones attention but it didnt even work. so i got these parts from someone used and am doing this setup but the question i have is... which way is which when adjusting the pressure switch? if i turn the screw clockwise and tighten it down it adjust for more or less pressure to activate it? some help please...

[gudeman00]

Im thinking about trying this per philly's recommendation. I am sick of PTB.

[Eulers Ghost]

I think its going to help. The design idea is sound and it would probably improve driving.

[gudeman00]

Punkrok said it didn't do much for him but he never messed much with the hobbs switch to try and change anything.

[blackbird]

It should work fairly well if you dial it in. But any time you use a very strong spring tension (such as with an aftermarket WGA) it's going to be harder for the factory boost control solenoid to regulate boost. It might need a little time to learn. The best thing would be to run as little tension/pre-load as possible for the amount of boost you want in conjunction with this. There's other things like the vacuum line diameter, length, and source, restrictors, and the solenoids you use (stock or aftermarket) that can influence boost control.

It's nothing new and similar setups have been proven for many years. You can check out some of the following links for other ideas such as making it multi-stage, combining with a WOT switch, etc.

http://www.thedodgegarage.com/ : "Turbo Database"

http://www.xmission.com/~dempsey/ : "Got Boost"

http://www.gusmahon.org/ : go to the mirror (http://www.gusmahon.org/index_main.htm) link and scroll to the bottom.

http://minimopar.knizefamily.net/perf/index.html


Also do a search for turbo Volvo (or 'turbo bricks' as they're called), turbo Buick/GN/GNX, turbo Ford/SVO Mustang, and turbo Saab web sites to get some other ideas.

[Eulers Ghost]

wow those are some good spots to check out.

[Stage2BlackSRT4]

Going to do this but have questions.

So:
Bought a GM solenoid, MBC and an on-off-switch

Have:
I have a PTP WG, SST
SFAC 2
W/I
All the supporting stuff: 55mm TB, ported everything else (EM, IM), full 3” exhaust, ect, ect
Stage 2 with toys with smaller bleed at the stock solenoid mod. So that dab (0=15psi, 1=17spi, 2&3=20psi) even with the WG and SST because the stock solenoid can only bleed of so much with a tiny hole for a bleed.

My idea: have a switch in cabin so that normally I’m stock boost with dab control but flip the switch and I run though the MBC so I can have 26-27PSI when ever I want.

My Question:

Will this work? *(lots of boost..)
Do I need to change anything?

Thanks for any and all help guys.

Regards,
Andrew

[blackbird]

It should work as long as you get the vacuum routing correct. Just make sure at first you leave the MBC engaged and set the boost on the low side. Then slowly turn up the boost to the max level you want to run while ensuring you have a good safety margin (for higher loads, heat soak, water injection failure, etc.). Then you should be all set to switch back to factory boost control and have high boost for when you want it.

[Stage2BlackSRT4]

Thanks Blackbird, I was wondering if there would be anyprob because of higher then stock boost...thanks for the reply.

Same Blackbirdr/t as srtfourms? If so I think I've read every single one of your posts lots of great info in them (info I would trust to). :0)

[blackbird]

Yep, I haven't posted over there "for a while" now. But I'm on other sites all over the internet like a bad rash on a two dollar... :lol: