Thread: installing MBC with an external wastegate question

i have had a mbc for a while not a fancy one but just your average generic ebay style one, here are some directions i found online however these are for a internal wastegate setup

Generic eBay Manual Boost Controller install on SR20DET: SR20DET Forum (rear-drive): Nissan Forums / Infiniti Forums - NICOclub

my question is with a externl wastegate can i run the top nipple to the top wastegate port and the botom nipple to the compressor housing. i read that you dont have to use the T off. is this true, i feel like a newbie asking suc a stupid question but i donno gimme some help

Im thinking, with that MBC because the ball and spring is inside the "T" it will need to be hooked up. The other piece is probably a needle valve or something to regulate flow for inside the car adjustment. I wouldnt have it inside the car though, i think that would lead to boost spikes or crazy lag either way, you want everything as close to the wastegate as possible.

Point the arrow on the T to the bottom nipple on the wastegate. Leave the top nipple open.

Correct me if im wrong guys. I was just going through this with mine. My MBC is a little more simple though.

Yes, MBC's are very simple by design. One in, and one out. The out to wastegate, and in from boost only source. The MBC simply fakes the amount of boost that the gate sees, which makes the gate open later, allowing more boost. MBC's even at gate pressure allow better response since the gate won't creep open when boost starts to push the spring. Instead, it opens rather quickly since the checkball remains closed in the MBC until the right amount of pressure is achieved.

Run the signal from the MBC to the bottom port on the gate. Top should be to atmosphere.

Sorry if that was a big block of text, typing on the iPhone.

Why not just run a boost controler off your EMS ??

well i would, initally i was trying to keep things really simple and just use wastegate springs, but i really hate taking the gate apart, so right now im running 1bar big yellow and small green, i picked this boost controller up really cheap so i decided i would run with it and see what was up.

i would love to run boost off the ems however its just too much money for me at the moment, i think my local tuner said like 350 for a install of the sensor/wiring and tuning the onboost map for it.

so its just not the thing i need to do right now i would love to have it setup like that though

although these are cheapo boost controllers i hear some reviews of them being decent to use, i just really want to have a quick on the fly way to adjust the boost so keeping it pretty simple

I did that way from the begining....so I am not noticing the cost , but I will I am spending as much to finish mine up as some people are selling theres for on the forum

well i kinda like the simplicity of the mbc they are ALMOST failsafe, where as you might get a wiring issue or mechanical failure with a sensor device used to mediate boost pressures. this isnt always true that a sensor would fail, nor is it true that a mbc is 100% failsafe, you could get spike, but i just want some instant grad as i have been running 1bar for a while now, and the g2871rle just starts to wake up at 1bar so 22lbs sounds good to me

deos anyone know what the consensis if for these style mbc's as far as how many turns or clicks is 1psi of boost gain? right now i havent turned it up, i just bought another boost gauge as my last mechanical one took a ****, i was just curious as to weather or not anyone knew how many turns is 1psi or what not

That's going to be highly dependent on each controller. The ones we build take about 1.5 turns for 1 psi but that is not going to reflect all controllers.


This installation method can be replicated with an external wastegate setup simply by installing it the same way but instead of the connection to the internal wastegate, you connect that line to the bottom port of your external wastegate.


However that installation method is new to me, and initially I feel it's overly complicated.
You could certainly ditch the "T" portion if you'd like. The way it is set up in the picture above it seems like the boost controller is being used as a controlled pressure bleed.
There's pros and cons to each setup.

If you do it like they picture above you will retain stock boost onset.

If you ditch the "T" and just use the boost controller on it's own connected between the boost signal and the wastegate port then you'll get "quick spool" boost onset and have a simpler system. However, the body of the boost controller needs to have a built in tiny bleed to prevent holding the wastegate open in certain situations. If it doesn't have that then you might be better off installing it with the "T".

Frankly, I'd just have got a more typical boost controller.

See the "breather hole"? That's mandatory.


If I got sick of making my own I would buy something like this for cheap:
Amazon.com: NXS Motorsports Manual Boost Controller: Automotive

so you think the bost onset will be slowing with the t setup verses not using the t setup i have it set up with the t right now how much slower do you think the onset will be with the t setup