Manual Boost Controller Basics

Manual Boost Controller Basics

Courtesy Turbosmart

The boost controller is an integral part of your turbocharged vehicle. Without it, your vehicle or turbo kit may run unchecked or fail to build boost at all, which could prove detrimental to your engine health. There’s no doubting the effectiveness of an MBC, which is why it’s still one of the most popular forms of boost control. Covering the manual boost controller basics today, we’ll cover what makes it work and how to make one.

As part of our ongoing series of turbocharger guides, today’s topic will answer the “Which boost controller is best” question. Of course if you are looking for directions on how to install a boost controller, you can check our FAQ section for any number of our How To guides.

Mitsubishi Eclipse boost controller install
Mitsubishi Eclipse boost controller install

Of course when you are installing any performance part onto your vehicle, it’s a good idea to take it to a mechanic if you are not comfortable working on your turbo vehicle. Any time you change or increase your boost, it should accompany the proper engine tune as well.

Engine failure could occur, so it’s a good idea to take things slow whenever you want to install a manual boost controller. If you are in the market for a boost controller, make sure to check out our page.

Manual boost controller basics – How does it work?

Turbocharged engines produce boost and pressure, which is created from the turbo. The turbocharger is a component of both the exhaust and intake of your engine. It uses the exhaust gases to produce positive pressure and more performance from your engine. Want to learn more? Check our our beginner guide on turbocharging.

Below is a diagram of the basic turbocharger setup. You’ll see the blue manual boost controller depicted inline with the vacuum system. This is a simple and easy to read manual boost controller basics diagram that will show you what’s going on.

Manual Boost Controller basics

As the exhaust side of your turbo spins, it builds positive boost to your engine. In order for your turbo wastegate to properly function, it looks for a signal to begin working. This bleeds off pressure and can also allow you to increase boost further than your factory or stock wastegate spring setting.

manual boost controller basics 1
Perrin makes one of the best manual boost controllers today. Image – Perrin

If you reference the image above you’ll see how the manual boost controller begins to work. The blue manual boost controller shown will work as a “ball and spring” style mechanism. The internal spring is set to a specific pressure, and when that pressure is exceeded it will signal your wastegate actuator.

Manual boost controllers come with a dial that cranks down the pressure and increases the amount of load this internal spring can take. This allows you to run more boost and get more performance out of your turbocharged vehicle. It’s also great for instances where you want to use E85 or race fuel at the track.

This means that the manual boost controller basics setting is vital. Your wastegate won’t open unless your boost controller tells it to. This will actuate the wastegate flapper of your exhaust housing, allowing exhaust gases to bleed off and relieve pressure.

Don’t forget to dyno tune your vehicle after any major engine modification.


How do I adjust the manual boost controller?

Once the controller is installed and secured, you can turn the adjustment dial down.  This is typically the process in which the internal chamber of the manual boost controller forces more pressure on your spring.

As your vehicle builds boost, it will continue to do so to your new manual boost controller setting. Make sure to take things slow and keep an eye on your boost gauge however. It’s one of the steps to manual boost controller basics. You don’t want things to get out of control, which could end up damaging your engine.

The boost controller is mounted inline of your turbo wastegate vacuum piping, and will control the amount of boost desired. If you happen to own an electronic boost controller, the servo or black box would be mounted inline. This is the typical “ball and spring” style of manual boost controller, or the more popular one at least.

Think of it as an internal piston that cranks down on the internal spring, or lifts up to relieve stress. The more you turn it the more boost your engine will run.

What good will a manual boost controller do for me?

If you own a turbocharged vehicle, chances are you stumbled across this guide to learn about raising boost. By increasing boost, you are increasing the amount of positive pressure that is entering your engine at any given time.

By eliminating your stock or factory boost control and installing a manual boost controller, you can raise your vehicle boost. Never attempt to increase boost without a boost gauge or pressure gauge to measure. Installing and adjusting a manual boost controller basically blind to the real time boost levels in your engine is not a good thing.


What is the difference between manual boost controllers?

There are typical two different styles of manual boost controller. The most popular one is the ball and spring style, which I just described and the bleeder style of boost controller.


Bleeder style boost controllers slowly meter out pressure to the desired pressure. Because of this reason it’s not ideal for turbocharged performance vehicles. Who wants to increase turbo lag without increasing horsepower? In this application, one can safely say that bleeder style boost controllers are a boost leak.

Meaning a failure or breakdown of the system, which again makes them unpopular for modification. Contrary to popular belief, there is no single one style of manual boost controller however. There are many people that believe their ball and spring MBC uses a vent system via the holes in the side of the housing.

These are designed as blowback holes, and only when the boost pressure is achieved will it leak. This does not change the fundamental operation of the ball and spring manual boost controller.

Need to find some of the best manual boost controller on the market? Want to find the manual boost controller basics and components? Check out our store or one of our favorite bang for your buck boost controllers. Want a simple guide to building a manual boost controller? Check it out here.