GrimmSpeed Electronic Boost Controller EVO User Manual

GrimmSpeed 3 Port Boost Control Solenoid

Installation Instructions

Mitsubishi EVO 8/9/10

***Image above is a generic GS photo, your EBCS may look different***

All GrimmSpeed products are intended for Off-Road use only.
Park your vehicle on a level surface. Fully engage the parking brake and put wheel stops on
the front and rear wheels to keep the vehicle from rolling.

Warning (read before installing):

Before moving forward with the setups outlined below, insure that you have the experience
and confidence to properly tune your car. If not, please consult a tuning professional.
Without a proper tune you can overboost and damage your engine.

Under no circumstances is the GrimmSpeed Solenoid to be used in any applications where
failure of the valve to operate as intended could jeopardize the safety of the operator or any
other person or property.

Note! You must tune for this hardware! Using stock or off-the-shelf EM with a 3-port solenoid

installed in interrupt mode will result in overboosting!

A. Purpose

The benefits of this upgrade are faster spool, ability to hold higher boost, and better control
over boost. A side benefit of the improved boost control is the ability to reach higher target
boost levels in the low (1st and 2nd) gears.

G

rimm

s

peed

1

B. Technical Background

A BCS is a binary device – i.e. it is either on (energized), or off. In the context of the
Mitsubishi device, when the BCS is energized, air is allowed to pass through the device, while
when it is off, the air flow is cut.

There are two modes of boost controller operation, at least in this context: “bleed” mode,
which is the mode that the stock BCS operates in, and “interrupt” mode, which is the mode
that a 3-port BCS can operate in. Note that a 3-port BCS can also operate in “bleed” mode,
depending on how it is connected.

Despite being digital in nature, these devices perform a very analog-like task, which is to
control the boost level. In order to do so, the ECU opens and closes the solenoid at varying
speeds, from 0 Hz (closed) to (effectively) ∞ Hz (open).

C. 2-Port Operation (Stock) Review

The stock solenoid is part of the stock bleed-based boost control system. See figure 1. When
the solenoid is off (closed), pressurized air from the compressor is fed straight into the
wastegate control. Any increase in compressor pressure beyond the rated pressure of the
wastegate control results in the wastegate being opened, preventing buildup of boost.

When energized (opened), air is allowed to bleed off the compressor-to-wastegate line by way
of a “T” connector (in stock vehicles, this air is vented back into the intake post-MAF). This
prevents the wastegate from seeing the full compressor pressure, allowing boost to build.

While the stock system operates adequately, it can lead to problems at higher-than-stock
boost levels. Since the bleed system is sized for the stock turbo at stock boost levels, it is

typically incapable of correctly metering air at higher
boost, allowing the wastegate to see pressure and
open before intended. Additionally, since the
wastegate is never completely cut off from seeing
compressor pressure, it can open at low boost levels
and inhibit boost buildup. Ideally, the wastegate
should remain entirely closed for fastest boost buildup
(as all exhaust is then forced through the turbine).

Figure 2: Pneumatic schematic for the GrimmSpeed
Boost Control Solenoid

D. 3-Port Operation and Installation

A 3-port solenoid does away with the bleed-based
system, explicitly shunting air from the compressor to
the wastegate, or compressor to vent (or back into the

intake, OEM-style). Drawbacks of the bleed-based
system are thus eliminated, with the wastegate seeing literally no pressure when the solenoid
is energized, to seeing all of the compressor pressure when the solenoid is de-energized.

G

rimm

s

peed

2