Two-setting boost controller options?
 

Currently, I have one of those ebay ball and spring boost controllers with the adjustment knob sending signal to the internal wastegate on the TD04H. To be honest, I absolutely love it. With the vac source for the boost controller coming from post-intercooler, the turbo holds a given psi right up to redline with at most .5 psi of taper.

However, I will soon be getting a water injection kit, and I want to turn things up to a solid 14 psi.

This presents a problem because I am also gearing up for a lot more track duty for this car, and I am a novice. I want to use the 14 psi for autocross where I am comfortable and could use the power and on the street where on-ramps and the occasional M3 must be taught a lesson...

For track though, I want a bit less power so I can focus on building my driving skill, and to go easy on the motor and transmission since the track is the most abusive environment for the car - somewhere in the 180 whp range.

With the adjustment knob on this boost controller, there is no way to know just how much to turn the knob for a given psi - in my experience you must adjust it a bit, do a few pulls and datalog, adjust a bit more, and repeat till you find the right psi... not ideal - I would like to be able to flip a switch and go from one psi setting to a second - no need for two maps or anything fancy with MS.

I had my eye on the Greddy Profec B (not type 2) boost controller but used they go for over $200, and I'd like to put as much of my extra money towards track days as possible, so what are the options out there for being able to switch between two boost levels? Anything more affordable than the Profec B?

Thanks!
-Ryan

You could simply run 2 MBCs and a switching valve. You'd only need the valve to shut off the output of the lower pressure MBC.
--Alex

Two MBCs and just swap between them.

http://www.boostedmiata.com/gallery2...-1/ebc_mbc.jpg

put a switch inline to the signal back to MS.

use open loop boost table set to 100%.

when the MS is controlling boost, it's set to your MBC.

when the switch is off, it's set to your wastegate level. (if you want more than wastegate, put another MBC before the tee.)

adjust your wg actuator to your lower desired boost level, and get a switching solenoid that can switch between that and your MBC. http://lh4.ggpht.com/_ScASycO1DOk/Sv...4/s720/EBC.jpg

this is my old setup. the new one only differs slightly

brainy beat me to it

I'm sorry to hear about your dual thumb amputation which precludes you from turning the boost controller knob.

^ hahahahaaha

Ok really though, turning the knob just isn't precise whatsoever. I'd like the simplest affordable solution to be able to just quickly switch between two different boost levels.

This idea you guys have proposed sounds really great, I may even just go with Savington's suggestion - set one MBC to 9 psi, and another one to 14 psi, then just pop whichever one on that I want. It's two vac lines, and requires no testing because each is set.
Brain, your method makes almost complete sense to me, but not quite - what is the point of having MS do anything (it seems like you are saying to use EBC but at 100% then have the MBC set the psi)?

-Ryan

Two MBC’s and one EBC type solenoid wired to +12 with a toggle.

Boost signal T’d to each MBC, plumb normally open port in the solenoid to one MBC, and the normally closed port to another MBC. On / off at the toggle to choose which MBC. Probably use the off [normally open] port for whichever you think you’ll use more often.

I guess you don't need the MS...just run the switch to ground. BUT, I also fill in my table so I don't get full boost at part throttle...anything under 75% TPS might only be 50% DC, get it?

Right, I don't have a TPS so that would probably not apply to me..

So I am beginning to understand this - I never quite knew how the EBC solenoid thingy worked. Quite honestly, the MBC has been so solid and reliable that I love the idea of just running two of them instead of EBC. So, if the EBC solenoid is switched off, vac signal will run through the normally open port of the solenoid?
What about when it is 'on' - which I assume is when it is grounded? If I do as you say brain and don't connect it to MS and simply give it +12v and switched ground, it then acts like it is being told 100% DC?
Also, in your schematic you show the top port going to the MBC and the bottom one going to just wastegate pressure, now yes I'm wanting to run an MBC on both lines, but on the DIYautotune website I'm looking at the EBC solenoid and it says the bottom of those two lines is the one that operates when it is 'on', so I'm just wondering, does this basically act as a switch - when it is 'off' is sends the vac signal through one port and when it is 'on' it switches, doesn't send signal through that port and instead sends it through the other port?

I think running the higher boost setting on the port that is active when the solenoid is 'on' may be a better idea - this way if it ever has a failure, default 'off' is the low boost setting, no?

I appreciate you guys helping me flesh this idea out in my mind sorry for all the questions.
Thanks!
-Ryan

it's a three way valve:

With no power it will fail to the bottom port on my diagram and completely block the top one. This means boost will flow right through the valve into the wastegate.

When given 12v the valve will go to 100% DC and open the top port while completely blocking the lower on my diagram. So boost will flow through the MBC before going into the wastegate.

if you want more than wastegate boost level, put a second MBC on the lower port that's tuned to the level you want for low boost.

to hook up the solenoid, run the 12v source off the blue connector near the headlight. then run the ground back into the cabin into a switch and then to a ground.

And if you want something in between, you can just flip the switch back and forth really fast! :)

--Ian

Magnificently awesome solution. Thanks brain and swimming108. This is literally a quarter of the cost of a used standalone EBC and I get to continue to use the bulletproof and simple MBC design to control the boost, instead of fancy shit that likes to have mood swings depending on the temperature and fail when you need it most...

I will get to work on this soon.

Can I get one of you guys to verify that this is exactly the thing-amabob that I need?
http://www.diyautotune.com/catalog/e...kit-p-285.html

Thanks!
-Ryan

That solenoid is what you want. I think it's a bit overpriced, but I'd also buy this: http://www.diyautotune.com/catalog/p...kit-p-160.html at the same time. Then you have lots of options. You can use manual boost controllers and just switch from a high or low boost OR you can let Megasquirt PWM control the boost. I have no experience with Megasquirt doing this, so it may be buggy and horrible, but that's what that board is for.

the PWM code in MS-I doesn't work well. The PWM code in MS-II an MS-III works well.

I know DIYAUTOTUNE is an awesome vendor, but...

If you want to save a few pennies the valve can be found here: http://airinc.thomasnet.com/Item?cid...7&assetid=spec

but you still need three 1/8" fittings and you don't get the mounting bolts. I also think the fittings in the DIY kit are too small on the hose size.

If you change your mind I have a Gizzmo electronic boost controller for sale in the buy/sell section that has 5 different settings. Changes with a hit of a button.

This is why I have stuck with the MBC. It has been very reliable and offered me no reason to want to get rid of it and search for another method of boost control, except that I would like this ability to quickly switch between two settings. Problem solved!

Now about the hose size you mention - I have always been under the impression that it is ideal to run the absolute smallest inner diameter vac line you can from vac source to boost controller to wastegate as there is therefore the smallest internal volume to fill and the quickest wastegate response... I see in swimming108's pic that he is running what looks like almost small fuel lines for the vac - wayyyy larger than what I'm currently using. Is there a reason for using such large hose for this? A drawback?

-Ryan

never heard of this... curious.

Brain's way is best on a budget.

But just so you know, that Profec you mentioned will give you three boost levels. You would have wastegate, low, and high. And if you adjusted low to be around where wastegate level is, it gives you the same boost but onset is much crisper because the WG isn't cracking open during spool up.