Delima: I want to electrically control the boost from the driver seat without spending $300+ on a digital boost controller and without running vacuum lines for the cheaper manual boost valve

Objective: To be able to go from low boost to high boost (and vise versa) at the flip of a switch from the driver seat for as cheap as possible (less than the manual boost valves).

I think I'm gonna go with my own homemade boost controller. I'm sure I'm not the first person to think of this but it makes sense and it's cheap (I like cheap things). I hope this works like I think it will. Please correct me if you see any issues with this setup.

Here are the cheapest prices I've found so far. If you can find any of this for less, please PM me and I will edit this list.

Required Parts:
12V 2 wire Boost Solenoid - $5-10 at your local junkyard
(2) 12V Adjustable Boost Pressure Switches - $30 shipped for both on ebay - http://motors.search.ebay.com/boost-...h_W0QQfromZR40
(2) SPDT 12V Switch - $2.29 Radio Shack (I have one laying around) - http://www.radioshack.com/product/in...entPage=search
(3) Diodes - $1.79 Radio Shack (I have some laying around) - http://www.radioshack.com/product/in...entPage=search
Vacuum adapter tee adapters - $4.29 NAPA (I have some laying around) - http://www.napaonline.com/MasterPage...ption=Hose+Tee
about 5' of vacuum line - $6.25 ParagonPerformance (I have some laying around) - http://www.paragonperformance.com/Silicone%20hose.html
(3) Tri-Color LED's - $2.98 Radio Shack - http://www.radioshack.com/product/in...entPage=search
(5) 330 ohm resistors (for LED's) -$3.96 Radio Shack (I have some laying around) - http://www.radioshack.com/product/in...entPage=search
about 35' of wire - $4.99 Radio Shack (I have some laying around) - http://www.radioshack.com/search/ind...4.00+-+%245.99
(5) Ground spades - $1.69 Radio Shack (I have some laying around) - http://www.radioshack.com/product/in...entPage=search

So grand total if you were to purchase everything from scratch - $65.44

My cost since I have a lot of this already - $37.98 (the $30 pressure switches being the biggest expense)

As far as I know, this could be the cheapest way to electrically control boost. Best of all it's a homemade kit.

Like I said, if anyone can find cheaper prices on any of these items, let me know and I will update this thread.


Here's a diagram of the Vacuum lines:

Basically, instead of running the line from the intake manifold to the external wastegate (or manual boost valve for you guys that have them), it gets tee'd off and runs to the two pressure switches and to the boost solenoid. Then from the solenoid to the wastegate. Pretty basic and it can be done with less than 5' of vacuum line and some tee adapters. Each pressure switch is adjustable from 4-25 PSI. I figure one can be set at about 8 PSI for daily driving and the other around 12 PSI for those "spirited" driving moments. It follows the usual wastegate operation. The wastegate will stay completely closed because it will not see any pressure in the vacuum line until the solenoid is activated. The wastegate I have is a 35mm external set to 7 PSI. Anytime the solenoid is activated and supplys the wastegate with 7 PSI or more of pressure, it will open and vent the extra exhaust pressure. Once the solenid closes, the wastegate closes and stays closed until the next time the solenoid is activated.

Here's a diagram of the electrical connections:

Basically, there is a manual switch that allows you to chose from one pressure switch (8 PSI) or the other (12 PSI). Depending on which pressure switch is chosen determines what boost level I can hit (pre-set switches) There are three LED's that can display 3 colors each. One is a power indicator and will light up green if the 12V source feeding the entire circuit is good, or it will light up red if the circuit fails for some reason (uses the relay to do so). Another LED is for Hi/Low boost indication and will light up red if the low boost pressure switch is selected or it will light up green if the high boost switch is selected. I'm choosing red for low and green for high because at the track it will always be in high boost and I'd rather have all the LED's lighting up green so that incase the power cuts out, the red LED will stand out more to alert me of an issue. The third LED (does not have to be tri-color) is simply used as a wastegate activation notification. Anytime the boost solenoid is supplied with voltage (activated) the LED will light up using the relay to isolate circuits. (I have a blue single color LED laying around so mine will light up blue any time the wastegate gets activated). That's basically just another safety precaution. If at any point in time the boost gets higher than the set level and the blue LED does not come on, I know something is wrong whether it's a pressure issue, wiring issue, whatever.



Overall layout inside the car:
No pictures yet. I'll update this thread when I actually get around to doing this.
The hi/low switch is going to be mounted in a custom panel below the radio (where the cubby pocket is).
T he 3 LED's will be mounted at the top of the gage cluster for easy driver viewing and also hiding them from others.
The two relays will be bundled together for ease of installation and to make troubleshooting easy and they will be placed behind the dash/center console area.

Overall layout under the hood:
Again, no pictures but I will update later.
The pressure switches will be mounted in fairly close proximity to the manifold for accuracy.
The boost solenoid will be placed within close proximity to the wastegate but away from the turbo heat.


That's pretty much it. It's not a digital controller, but it is an electrically selectable boost controller that will change between pre-set boost level at the flip of a switch and provide the driver with visual feedback about what the system is doing. I'd personally reather spend $37 on this setup instead of on a manual valve.

Like I said, I can't be the first person to think of something like this, but I have not seen it posted anywhere so figured I'd take the innitiative. Let me know what you guys think, possible problems, and any info you can give on this setup. I will be doing this in the near future and will keep you updated. PLEASE FIND CHEAPER PRICES ON THESE PARTS! This kit may be do-able for less than $45 with the right prices on parts!

 

The Honda MAP outputs a variable voltage to the ECU. Something like this:
http://www.pgmfi.org/twiki/bin/view/Library/MapSensor
or
http://www.robietherobot.com/storm/mapsensor.htm

We could maybe just take a simple comparator like a LM311, and use it to compare the voltage the sensor is outputting, to some reference. This reference could be set by a ****, or buttons. Once the output of the MAP goes above the reference, it turns on the Boost Solenoid (or whatever else).

Let's assume we are using the numbers from the GM sensor table. Let's just set the comparator's reference to 3.47v. The Boost Solenoid will be off until the MAP registers 6PSI (3.47v), and then it will turn the Solenoid on. Once the MAP drops below 6PSI again it will shut the Boost Solenoid off. That should work, right?

This site has some good general info on comparators. http://home.cogeco.ca/~rpaisley4/Comparators.html

 

Here is a quick diagram I made:



LM311 chips are under $1 each, the stock MAP can probably be used too.

Edit: Using some Op-Amps we could probably figure out a way to convert your referance voltage directly to Millivolts, and display it on a cheap ($10) LCD Voltmeter. So say, 3.47 V could show up as 6 milliVolts, which you know means 6 PSI. As long as the MAP sensor's output is linear (it looks like it is), it shouldn't be too hard to do.

The Comparator + Map basically make a variable boost pressure switch.. The only problem I see is the circuit could maybe get into some sort of feedback loop, where it keeps trying to open and close the solenoid to maintain a certain level of boost. I am not sure how it would work in practice. Worst case there would maybe have to be some stuff to smooth the output to the solenoid.

 

I've personally never messed with comparator chips before so bear with me if I don't get it right away.

Yes, the MAP is linear. Using a Motorola 2.5 bar....but the ref. voltage is +5V, not 12 so I don't know if that affects your kick-*** diagram with the 12V dirty source.

To make sure I understand it correctly...


I'd feed the same ref. (dirty) voltage to the chip and the MAP. Map ground goes to ground and signal wire goes to the chip. Without the **** installed and set, the chip would bsasically do nothing. With a **** installed and set between 1 and......11 lol it determines when the 12v goes to the solenoid. So, is the solenoid getting the 12v clean source feeding the ****? And the dirty source is only for MAP.

I'm gonna do some more research on this and see what I can come up with. The LCD display is a kick-*** idea but let me get the controller part of it down for now before gettin all fancy and ----. Thanks a lot for the ideas!

 

here's an internal diagram of the chip....I think lol



So if this is right, then
V+ gets the 12V
Output goes to the solenoid
Input+ goes to adjustable ****
Input- goes to MAP signal
Gound goes to ground

So if the MAP signal is ...say....3.4V, then the solenoid would not be triggered unless the **** was adjusted to a voltage of less than 3.4V. Seem right?

Also any particular **** recommended?

 

Ok, I ordered 10 LM311N chips.

I also ordered this meter to use as spare parts for the "boost" LCD.




I'm having issues finding a **** that will adjust voltage. Do you know if I could use something like the LM317T voltage regulator with a simple potentiometer used to adjust resistance? Or got any better ideas?

 

In my picture I was just saying that everything would need a clean, regulated power source (like with a LM7805 for 5v or LM7812 for 12v) . This stuff can't be hooked up directly to the battery.

Now, I have never used a boost controller (Actually, I haven't even gotten my car turbo'ed yet, still working on that). I am into electrical engineering, and that is how I got into cars.

From my understanding, this is how wastegates work in different situations:

Stock:
Wastegate is stock set to 5PSI
As Actual boost hits 5PSI -> Wastegate slowly opens all the way, keeps opening wider as needed.
As boost drops below 5PSI -> Wastegate slowly closes

DIY boost controllers:
Wastegate is stock set to 5PSI
DIY controller set to 9PSI
Actual boost hits 9PSI -> Wastegate attempts to open all the way immediately, boost drops
Boost gets below 9PSI -> wastegate attempts to close all the way immediately, goes up
Repeat until you let off the gas (Would wastegate flutter?)

The speed that the wastegate would open or close would control whether the system would be stable with the feedback, I am guessing it is slow enough to keep it smooth. Probably acts kinda like pulse width modulation. I have never heard of any problems like this with home made boost controllers, so it must work out OK.

Apex-i AVC-r:
Wastegate is stock set to 5PSI
Fancy Boost controller set to 9PSI
Actual boost hits 9PSI -> Boost controller cracks open solonoid, keeps opening it more as engine RPMs go up. Watches current PSI and adjusts as needed too. This would/could reduce unwanted movement of the wastegate.
Boost gets below 9PSI -> Boost controller closes solenoid, keeps closing it more as engine RPMs go down, also watches actual PSI.

From what I can tell the Apex-i AVC-r does PWM of the solenoid, meaning they open and close it really fast to simulate being half open, or a quarter open. It looks like they take information from the engine RPM to calculate how much of a duty cycle to run the solonoid at (how far to "open" it). It calculates the correct distance to open the wastegate, and guesses it pretty close, then checks the actual boost level and adjusts as needed. By adjusting the ammount of feedback, (basically how fast it guesses, and how much its guesses can change the PWM), you can make its responce look more like A or B:

Something like would probably be easiest to make with some sort of microcontroller (a PIC).

All solutions would probably work, the "best" would probably be something with a PIC.

Here is another simple solution I came up with for a 2 level boost selector, probably others have done it too:

Here is the DIY manual boost adjuster http://www.geocities.com/chmwatson/FAQs/mbc.html

Edit: To make a voltage reference, I would just make a voltage divider, http://hyperphysics.phy-astr.gsu.edu...ic/voldiv.html (look at the stuff for open circuit voltage). Pick up some resistors at radioshack, and make one of the two resistors in the divider a variable resistor.

Edit Again: This picture describes the responce I would be worried about (flutter in red):

 

OK, correct me if I'm wrong. I know wiring but I'm fairly new to electronics....

To create PWM, you need a sine wave or modulating signal and the sawtooth wave or carrier signal and then use another comparator to create the modulated pulse width.

So couldn't a PWM setup be made for fairly cheap using another comparator with RPM as the sine wave and MAP signal as the sawtooth wave?

It would basically use your first diagram with the addition of the PWM.

Like I said, I'm new to this ---- so I may be way off. Could it be done for cheap?

 

You could maybe make the PWM that way, out of op-amps and comparators, but if I was going to do something that I would just buy a PIC chip, they are only a few dollars, and make a program for that in assembly. That way I could easily change numbers and work with the data.

Any design without RPM sensing relys on the motion of the wastegate (and the rest of the system) to handle the feedback. I have never heard of problems with this approach, so its probably OK.

Oh yeah, ignore the text about the "scramble" button in the graphs, it was just the best graph I saw in their manual. I guess its some button that you can hit that bumps the boost up. The same stuff in that graph should apply for entering normal boost.

 

Acclude are you Midnightmechanix on ebay? I noticed you sell chipping parts. It also seems that you use Xenocrons pictures to do your advertising?