Hey gang, I was just tooling around ECS Tuning and saw some manual boost controllers and had a question or two! First, my friend has a 2004 WRX with a standalone ECU. He has three tunes, an aggressive 20psi, a moderate 14psi and a no boost. The no boost affords him amazing MPGs in his 2.2L. I thought this was genius, but I can't afford a standalone. Chip companies dont offer this, so I had another idea. Could I use an MBC on a chipped car to manually turn off the boost? How easy is it to dial back in to a set level? Since my car is chipped to hold at a certain level, would I just screw it full open? How safe are they? (i.e. can you easily overspool/overboost?) and finally, installation. I want to install it in-cabin. Easy?

 

BAD, BAD IDEA! To quote Monty Python and The Holy Grail... "Run Away!!! Run Away!!!"

MBC is possibly the easiest way to blow up an engine. (even with a chip I imagine) There are a lot of chip companies that will do what you want to anyway. Look into APR chips, they have switchable modes, so you can press a button and (for example) have the ecu tuned to 93 octane (High power), 91 octane (stockish), and a special valet mode which wont make much boost (and net you more MPG). I'm sure there are other companies that make switchable chips as well, just shop around. but whatever you, no MBC!

 

Any other opinions? I know the APR doesn't offer quite what I'm looking for. GIAC and APR both have valet, but its a modified speed limiter at 40.

 

Ive ran mbc's on a couple of my other cars that I have owned before the a4. They are super easy to use and very easy to adjust. You will get a feel of the dial and will be able to set it in just matter of seconds (open hood, turn, close hood). You might want to look into an ebc for the sounds of what you want. I wouldn't try to crank it up past what you have it tuned for but adjusting it to around stock level (8 psi ish) will be just fine, try driving at 0 psi and see how it feels, you wont like it. Its also pretty easy to control the boost with the gas pedal. Even though my car is set at 18-19 psi, it doesn't see it unless I want it to go full boost. But since you will be adjusting it, either get a quality mbc or maybe a greddy ebc.

The same ppl who think a mbc will blow up your car are the same ppl who pay the dealer $150 to change spark plugs that take 5 min....

 

If you want to do this you will want to install the MBC in parallel with the N75, this will add a 2nd path for the pressure to reach the WG actuator. This will allow you to decrease the boost pressure but not be able to increase it since the N75 valve will still be used.

So basically you cut Y both hoses to the N75 and put the extra hose on each Y to the MBC.

Now if you really want to decrease boost just pull the 2 lines off the N75 and put them together, this will force the car to make no more then 5psi. Just make sure to loop the 2 nipples on the N75 when you pull the lines off.

 

Thanks for all the know how mike! But I was thinking an easy no boost/boost switch. Could I put an MBC in the cabin and still run it parallel to the WG?

 

i dont think it will be worth the time/money to make what is basically a limp mode switch...unless you have some shady people driving your car. if you have a boost gauge, you can always just drive it like a baby and do some hypermiling techniques to save gas

custom limp mode switch = dust collector

it makes sense if you have a big turbo with agressive tune etc., but with stock turbo and chip...?

 

You could just put in a valve that is either fully open or fully closed in place of the MBC in the setup I put up in my other thread with the dual Y lines. Then when you open up the valve the wg will get full boost and the turbo wont make more then 5psi.

 

wanna know how to boost 0psi and w/o a mbc? this is a complete secret so dont tell anyone else (really, im serious. this is pretty serious stuff). ready...... Take your foot off the ******* gas pedal!!! how simple is that? when your boost gauge reads zero psi, dont press on the pedal any more. you use a lot more gas in boost than out of boost. crazy concept, i know, more air equals more fuel needed, but hey, theres a lot of crazy stuff in this world. (sorry if that was a bit harsh but the answer is pretty obvious)

 

obvious yes. So obvious that every other response on this thread took that knowledge for granted. No ****! That was a bit harsh, but jeez, if I know enough to want to try an MBC install then I hope I understand the concepts of forced induction and its relation to engine RPMs and how these both correlate to my fuel efficiency. So yes, I roll in neutral and I shift into high gears to stay out of boost when I want good MPGs, but I was looking for something that would NOT ALLOW boost to pass. Christ.




In response to Mike, do you have a link to this setup? This sounds perfect for me. Could I just get this valve at a plumbing store or home depot? Or does it need to be a beefy automotive grade? Finally, I'd like to put it in the car for on the fly switching; possible?