GFB G-Force2 - Manual (Page 16)

All products manufactured or distributed by Go Fast Bits P/L are subject to the following Limited Express
Warranties, and no others:
For a period of one year from and after the date of purchase of a new Go Fast Bits product, Go Fast Bits warranties
and guarantees only to the original purchaser/user that such a product will be free from defects of material and/or
workmanship in the manufacturing process. Go Fast Bits, at its sole discretion, shall replace or repair a defective
product. This express warranty shall be inapplicable to any product not properly installed or properly used by the
purchaser/user or to any product damaged or impaired by external forces. This is the extent of warranties available
on this product. Go Fast Bits shall have no liability whatsoever for consequential damages following from the use of
any defective product or by reason of failure of any product. Go Fast Bits specifically disclaims and disavows all
other warranties express or implied including, without limitation, all warranties of fitness for a particular purpose,
warranties of description, warranties of merchantability, trade usage or warranties of trade usage.
16 - Additional info
Duty Cycle - what the heck is it?
Duty cycle refers to how the solenoid valve is actually controlled. The G-Force II boost controller outputs a signal to
the solenoid valve that rapidly pulses it on and off about 30 times a second (0.033 seconds per cycle) to bleed air
from the wastegate, and duty cycle alters how long it is on for each cycle, and how long it is off.
For example, a duty cycle of 25% means that the solenoid valve is pulsed ON for 25% of each cycle, and OFF for
75% of the cycle. A 25% duty cycle output from the G-Force to the solenoid valve is illustrated opposite:
The higher the duty cycle,
the longer the solenoid is
pulsed on each cycle, which
bleeds more air from the
wastegate actuator, resulting
in a higher boost pressure.
Duty Cycle limits
Pulsing the solenoid at 0% duty cycle means that all of the pressure gets to the wastegate, which is effectively the
same as having no boost controller, meaning the turbo will run the minimum pressure (aka “gate” pressure)
possible.
Running the solenoid at 100% duty cycle prevents ALL of the pressure from getting to the wastegate, which is
effectively the same as removing the hose from the wastegate altogether, which results in the highest boost
pressure the turbo is capable of supplying.
Why can’t I just dial-in how much boost I want instead of fiddling with duty cycle?
Fair question. Unfortunately, the G-Force II (or any boost controller for that matter) doesn’t know what boost
pressure your specific turbo/wastegate/engine/weather conditions/etc will return for a given duty cycle - there
simply is no formula that says “for this turbo on that car, “X”% duty cycle will give “Y”psi of boost”.
The controller NEEDS to know this relationship between duty cycle and resulting boost pressure, because when
boost is rising quickly, it must pulse the solenoid at the correct duty cycle BEFORE the boost reaches the target
boost pressure. If it doesn’t know the correct duty cycle, it cannot do this.
The reason it must pulse the solenoid before boost reaches the target is because there is always a small delay
between the controller making a change to the duty cycle, and the wastegate (and therefore boost pressure)
responding to the change. This delay means that if the controller simply waited until the boost pressure reached the
target and then responded accordingly, boost pressure would overshoot the target.
Therefore, the only way to determine the duty cycle/boost relationship is through trial-and-error, by starting at a low
duty cycle, reading the resulting boost pressure, and increasing it until you reach the desired boost.
Once the G-Force II knows the duty cycle that results in the target boost pressure, it can then make changes to the
duty cycle to compensate for small variations in boost (when a value for “Taper” has been entered).
Tech
warranty
“OFF” period
(0.025 seconds)
“ON” period
(0.008 seconds)
1 cycle
(0.033 seconds)