Perfect Power SMT8-T5 User manual

SMT8-T5
Technical Manual V5
LetRipp II

Table of Contents: Page No:
1.
INTRODUCTION.........................................................................................1
2. HOW DOES IT WORK?................................................................................1
3. CALIBRATION ...........................................................................................3
3.1 AMP CALIBRATION (Shift F4 ................................................................3
3.2 ENGINE TEMPERATURE CALIBRATION (shift F5 .....................................4
3.3 RPM CALIBRATION ..............................................................................6
3.4 TPS CALIBRATION ..............................................................................7
3.5 DISPLAY OPTION ................................................................................8
4. TERMINOLOGY ..........................................................................................8
5. KNOW YOUR ENGINE .................................................................................9
6. SMT8T_5 PIN-OUT ...................................................................................10
7. COMMUNICATION WIRING and SEt-up .......................................................11
8. POWER WIRING ......................................................................................11
9. STARTING THE PC ...................................................................................11
10. PROFILES: PC SCREEN SETUPS..............................................................12
11. DYNO DISPLAY ....................................................................................13
11.1 INSTALLATION .................................................................................13
11.2 CALIBRATION...................................................................................13
11.3 SETTING UP .....................................................................................13
11.4 PRACTICAL USE OF DYNO FEATURE ....................................................14
11.5 CALCULATING THE HORSEPOWER.......................................................14
11.6 PRACTICAL USE OF THE FUEL MONITOR ..............................................15
12. SMT8T_5 SIMULATION..........................................................................15
13. BASIC WIRING: FUEL MONITOR.............................................................18
14. BASIC WIRING: RPM ............................................................................19
15. BASIC WIRING: TPS .............................................................................21
16. IGNITION WIRING................................................................................21
17. DISPLAY WIRING .................................................................................22
18. SYSTEM SETUP ....................................................................................23
19. MINIMUM INSTALLATION AND WORK .....................................................23
20. ANALOG: AMP......................................................................................24
21. ANALOG: AFR ......................................................................................24
22. INJECTION ..........................................................................................25
23. BOOST CONTROL .................................................................................26
24. IGNITION CONTROL .............................................................................27
25. APPLICATIONS: LIMITING AN AMP SIGNAL..............................................28
26. APPLICATION: MODIFYING AN AMP SIGNAL ............................................28
27. APPLICATION: MODIFYING THE TPS SIGNAL ...........................................29
28. APPLICATION: PROVIDING FUEL AT BOOST VIA AN EXTRA INJECTOR ........ 29
29. APPLICATION: MODIFYING LAMBDA .......................................................30
30. APPLICATION: IGNITION MODIFICATION ................................................31
31. APPLICATION: BOOST CONTROL ............................................................32
32. AUXILARY OPERATIONS ........................................................................33
32.1 FREQUENCY MODIFICATION...............................................................35
32.2 PWM MODIFICATION .........................................................................35
32.3 BOOST CONTROL..............................................................................35
32.4 DISPLAY OUTPUT ..............................................................................35
32.5 DYNO DISPLAY .................................................................................36

32.6 FUEL MONITOR.................................................................................36
32.7 PULLUP............................................................................................36
32.8 SUMMARY AUXILARY OPERATIONS .....................................................36
Table of Figu es: Page no:
FIGURE 3. SMT8T5 pin out ..............................................................................10
FIGURE 4. SMT8T_5 DISPLAY ..........................................................................22
FIGURE 5. SMT8T_5 Switching.........................................................................34

LETRIPP II SMT8T V5 TECHNICAL MANUAL www.perfectpower.com 2011/09/22
1
1. INTRODUCTION
Congratulations on the purchase of the SMT8T_5. This piggyback unit is the result of
20 years experience in the automotive industry and is the latest design in the range
of SMT8 piggybacks.
The SMT8T_5 (SMT8T Version 5 is a further development from the very popular
SMT8T Version 3 and packs unsurpassed features in a very small size. The unit is
available through the dealer network as branded and public versions.
The SMT8T_5 is a tool for tuning and monitoring engine performance. This manual
will explain in a structured fashion each connection, the use and purpose of outputs,
and in general everything associated with the SMT8T_5. Once the unit is installed
you will need the LetRipp II Tuning software, and the LetRipp II Software User Guide
as well as a PC or laptop and a communication cable to get started.
If you are an experienced engine mechanic, then you will find some of the
terminology strange and can skip over familiar sections.
2. HOW DOES IT WORK?
The SMT8T_5 has two functions:
A Monitor signals for display purposes
This function is a great tool during tuning, but is also great for collecting and
displaying data.
B Modify signals for changing the engine performance
This is its traditional purpose!
The SMT8T_5 ‘modifies’ and measures engine signals. The signals are used by the
ECU to ‘drive’ your engine in a pre-determined fashion. By modifying the signals, we
can change the ECU’s response.
Example #1:
We all know that an engine runs richer when cold. So, if you want to run the engine
richer, you modify the temperature wire so that the ECU thinks that the engine is
cold. Then the ECU will enrich the fuel mixture.
Example #2:
Your engine has a Lambda loop. This means it controls the fuel mixture by a probe in
the exhaust. By modifying the probe output you can now ‘direct’ the ECU to change
the mixture to lean or rich.
Example #3:
The ignition point is derived from a crank sensor. By ‘delaying’ this signal you can
retard the ignition.
Note: The SMT8T_5 can also advance ignition, but we will not go into detail here.
In most cases the ‘modification’ involves the cutting of a wire (the signal wire and
routing the engine side (source to an SMT8T_5 input. Then the signal is modified

LETRIPP II SMT8T V5 TECHNICAL MANUAL www.perfectpower.com 2011/09/22
2
inside the SMT8T_5 and presented as an output, which is then connected to ECU side
of the cut wire.
SMT8 T
Pin 12 of 16
Pin 13 of 16
CB1 + out
CB1 + in
ECU
Engine
Magnetic Sensor
Cut
CB1 - out
Pin 4 of 16
Cut
FIGURE 1. SMT8T_5 SIGNALS
The process by which the SMT8T5 ‘modifies’ the signal is called MAPPING. The
mapping involves looking up a number from a table, adding it to the looked up
number from another table, adding it to the input value, and output the result.
SIDE MAP (S
MAIN MAP
TPS
RPM
-5
+1+
Signal input = A Signal output
= A ± (-5+1
= A - 4
-
FIGURE 2. MAPPING
The numbers, which are ‘picked’ from the tables, are selected by a TPS and RPM
scale, and in case of the ‘side table’ (the table on the side from AMP or Engine
temperature scales.

LETRIPP II SMT8T V5 TECHNICAL MANUAL www.perfectpower.com 2011/09/22
3
The above shows a typical ANALOG MODIFICATION map, which does NOTHING.
Of course the user can set the scales applied to the tables. The process is called
CALIBRATION.
3. CALIBRATION
It is a necessary evil requirement. For starters you can ignore it, but eventually you
will need to calibrate the SMT8T_5 for optimum results.
3.1 AMP CALIBRATION (SHIFT F4)
Calibration principle:
Let’s assume a linear sensor, such as the AMP. You need to know 4 values to
calibrate it.
A LOW voltage and the associated LOW pressure
A HIGH voltage and the associated HIGH pressure
A standard 1.15 bar AMP sensor has the following points:
LOW: 0.25V at 0.25bar
HIGH: 4.8V at 1.15bar
You can try and get the datasheet specification for the sensor, or you can do it as
follows:
Use the LOW setting: 0.25V at 0.25bar at position 1
Then use as the high setting the value obtained at ATMOSPHERIC pressure, which is
1.0 bar at sea level. Therefore:
HIGH: Input reading (V at sea level=1.00bar
Of course the LOW/HIGH points don’t have to be at the end of the scales.

LETRIPP II SMT8T V5 TECHNICAL MANUAL www.perfectpower.com 2011/09/22
4
3.2 ENGINE TEMPERATURE CALIBRATION (SHIFT F5)
The engine temperature is a little different, because the SMT8T_5 first LINEARIZES
the input voltage. Here is what you do:
Let the engine cool down over night, and measure its temperature. Let’s assume it is
18°C. Then use the displayed input reading (V at point #6.
LOW: Input reading (3.5V at 18°C, at point #6
Then warm up the engine until it has reached operating temperature. Let’s assume it
is 85°C.
HIGH: Input reading (1.25V at 85°C, at point #18
You can shift the points up or down to cover the expected operating range.

LETRIPP II SMT8T V5 TECHNICAL MANUAL www.perfectpower.com 2011/09/22
5

LETRIPP II SMT8T V5 TECHNICAL MANUAL www.perfectpower.com 2011/09/22
6
3.3 RPM CALIBRATION
The RPM calibration is different. You can only specify the LOW/HIGH end points.
Let’s assume we use 600 to 6000 RPM.
The UNLINEAR RPM scale looks crazy. BUT: Each RPM step is by the SAME
PERCENTAGE higher than the next one. Why? In this way the change in engine
parameters are constant.
Then there is the CUSTOMIZE option: You can type in the complete scale.

LETRIPP II SMT8T V5 TECHNICAL MANUAL www.perfectpower.com 2011/09/22
7
The result of some customization may look like the following:
3.4 TPS CALIBRATION
Each car has a different TPS sensor. The calibration is needed to adapt the SMT8T_5
range to the mechanical range of your sensor.

LETRIPP II SMT8T V5 TECHNICAL MANUAL www.perfectpower.com 2011/09/22
8
The UNLINEAR function is chosen. This is the preferred one, because the airflow
changes dramatically with very small butterfly openings. But, the other LINEAR and
CUSTOMIZE options are available.
3.5 DISPLAY OPTION
The SMT8T5 has an external display option installed. This option allows the use of
the AUXOUT pin 11 as a display output. For wiring check the BASIC DISPLAY wiring.
The AUXOUT output has 4 possible drives as indicated in the drawing below:
The AUXOUT pin can drive up to 8 displays, each display can display one engine
measurement from the DISPLAY list in the PC.
The choosing of an item (from the list for display does not switch the AUXOUT pin to
the required configuration. This must be performed with the SYSTEM DEF. Finally the
Display can be switched off, which frees the AUX pin to a 2k2 pull-up resistor for
other purposes.
Applicable items from the SYSTEM DEFINITION:
F eq. Mod Tick for Frequency modification, otherwise PWM mod.
Boost Output Tick for Boost output, otherwise Freq. or PWM operation.
Enables DYNO or FUEL MONITOR
AUXIN to DYNO Enables AUXIN for DYNO operation, otherwise Fuel Monitor
Display on AUX Tick for display output, otherwise any of the above is output.
Display off Tick to switch display off
4. TERMINOLOGY
ECU: Your stock standard electronic control unit.
MODIFICATION: A means of changing a signal.
ANALOG: A voltage. The information is contained in the voltage level.
DIGITAL: A frequency. The information is contained in the transitions.
DISPLAY: An optional external display to the SMT8T_5

LETRIPP II SMT8T V5 TECHNICAL MANUAL www.perfectpower.com 2011/09/22
9
MAPPING: The process, which results in the signal modification.
MAPS: A bunch of numbers. Only one number will be used for mapping at any given
time.
SIDE-MAPS: The same as maps, just smaller.
PARAMETERS: Single entry values, which influence a process as a whole.
SYSTEM DEFINITION: Click on/off points, which influence a process.
STATUS: A display, which shows the state of the SMT8T5.
DYNO: A convenient way to measure performance.
FUEL MONITOR: Monitors the ECU fuel injection in percent utilization
5. KNOW YOUR ENGINE
Obtain a wiring diagram from your ECU. This will show you the various engine
components. Apart from this you need to make some decisions as to the suitability of
your engine for the intended modification.
Does the engine use an AMP (Absolute manifold pressure sensor, or a Mass Air Flow
sensor (MAF ?
In general an AMP sensor is preferred, because an MAF sensor has other
items attached: it may measure air temperature, it may have damping, or it
may have overshoot. There are some MAF sensors with a digital output, which
is un-suited for the SMT8T5. The AMP sensor is clean!
Does the engine use an ETC (Electronic Throttle control ?
The ETC is used during traction control. A little motor drives the butterfly. If
the engine uses an ETC, then the TPS input must be connected to the ETC
wires.
Does the engine use active ignition knock control?
This is difficult to determine. Use the ECU wiring diagram, or consult a brand
mechanic. If it has active knock control, then it is impossible to modify the
ignition point, because the ECU will ‘undo’ your modifications. Find out if your
engine uses knock control at wide-open throttle (WOT , or only during idle
and cruising. Whenever the active knock control is off, you can modify the
ignition point.
Does the engine use Lambda feedback?
Most engines do. There are TWO different exhaust probes: NARROW and
WIDE band probes. The SMT8T_5 has the ability to modify ONE Narrow BAND
PROBE.
If the answer to these questions is not obvious, then you need to consult a
knowledgeable mechanic or consult a friend. Of course, it all depends on the type of
modification you intend doing.

LETRIPP II SMT8T V5 TECHNICAL MANUAL www.perfectpower.com 2011/09/22
10
6. SMT8T_5 PIN-OUT
512 3
4
6
101112 9
78
13141516
FIGURE 3. SMT8T5 PIN OUT
PIN DESCRIPTION SIGNAL I/O
1 GROUND GND I
2 GROUND GBD I
3 BIPOLAR IGNITION OUTPUT BIPOUT O
4 NEG. CRANK OUTPUT -IGOUT O
5 AUX INPUT AUXIN I
6 AFR INPUT OXYIN I
7 ENGINE TEMPERATURE ENGTIN I
8 ANALOG INPUT ANIN I
9 INJECTOR/BOOST DRIVE INJECT O
10 PLUG BATTERY +13 I
11 AUX OUTPUT AUXOUT O
12 POS. CRANK OUTPUT +IGOUT O
13 POS. CRANK INPUT +IGIN I
14 ANALOG OUTPUT AOUT O
15 TPS (DEFLECTION INPUT TPSIN I
16 AMP INPUT AMPIN I

LETRIPP II SMT8T V5 TECHNICAL MANUAL www.perfectpower.com 2011/09/22
11
7. COMMUNICATION WIRING AND SET-UP
The SMT8T_5 has a standard USB
interface. Once the PC is connected
to the USB port the unit will
function. Use the ‘SLOW 1.0’ USB
option on LETRIPP.
8. POWER WIRING
This wiring must be done for every application.
SMT8T_5
PIN 1 NEGATIVE, CHASSIS, of power source
PIN 13 POSITIVE, 6-12V, of power source
Once you apply power, the green LED will flash!
9. STARTING THE PC
Loading and configuring the PC is explained in the LETRIPP II Software User Guide.
This manual is located on your installation disk.
1. Start your LETRIPP II software. A screen must appear.
2. Click on TOOLS, Communication, and set: USB-1.0.
3. You should have communication within 3 seconds.
Once you have communication, you can ACCESS the SMT8T_5. The following is just
an exercise to familiarize your self with the LETRIPP II operation.
1. Click on COLUMN
2. F1 brings up the INJECTION map
3. Select a column, and type any number
4. Reset the unit via TOOLS
5. Click on UPLOAD, and observe that the entered number column is there
6. Load the DEFAULT values via TOOLS, Default
7. Click on UPLOAD and observe that all numbers are zero, except in the setup
screens.
Advanced task:
BLEND “G” numbers from one selected spot to the other extreme corner!
Blend numbers in a side table

LETRIPP II SMT8T V5 TECHNICAL MANUAL www.perfectpower.com 2011/09/22
12
The following is a blend of the four corner values:
10 -10
-20 5
10. PROFILES: PC SCREEN SETUPS
The LetRipp II software can save your favorite screen ‘layout’. This is called a
PROFILE. That is to say which tables are open, and their position, and the display
points used. This is handy when you are coming back to an already performed task,
and are used to a certain layout.
The profiles are accessible through the Profile button. The Profiles do not change the
way the SMT8T_5 operates, but the way you monitor its behavior. You have to click
items on/off, and load a map from the hard drive to change the behavior of the
SMT8T_5. In Short: Profiles are a convenient way to put the things you want to see
on the screen.

LETRIPP II SMT8T V5 TECHNICAL MANUAL www.perfectpower.com 2011/09/22
13
11. DYNO DISPLAY
The DYNO (Dynamometer display itself can be seen on the PC screen or on the
EXTERNAL displays.
11.1 INSTALLATION
The DYNO feature utilizes the AUXIN input to measure road speed. The signal can
come from the:
Prop-shaft
Wheel
Speedometer
In the absence of any electrical road speed signal a magnetic transducer must be
installed and connected to the SMT8T_5 AUXIN, pin 5.
11.2 CALIBRATION
Open the DYNO SETUP screen (Config . The first field
Millimeter per AUXIN pulse
Must be set to an exact distance, if you work in the IMPERIAL system (See: Display
units then you must still enter the distance in MILLIMETER. There are 25.4Millimeter
to an INCH! This completes the calibration!
11.3 SETTING UP
The SMT8T_5 Measures:
Time in seconds
Distance in Meters or Yards
Speed in Km/H or Miles/H
The unit of measure is chosen in the TOOLS, Display units!
A performance run (a DYNO measurement is performed between two points:
A The Trigger point, the starting condition
B The end point
The following trigger points are available:
RPM trigger
TPS trigger
Speed Trigger
Enter a value in any of the above fields and the trigger point becomes active. Of
course, you can use more then one field, but then a LOGICAL ‘AND’ is performed.
The following END points are available:
Speed
Time
Distance
RPM
Set one END point ONLY! If more then one end point is set, then the first point is
serviced.
Finally, you need to assign the AUXIN pin to the dyno function by:
System Definition: Auxin to DYNO.
Click on it, and the ‘Dyno Ready’ status must show.

LETRIPP II SMT8T V5 TECHNICAL MANUAL www.perfectpower.com 2011/09/22
14
11.4 PRACTICAL USE OF DYNO FEATURE
The SMT8T_5 displays three DYNO variables on the PC or external display. They are:
Dyno time in sec
Dyno Distance
Dyno Speed (Speed at end
These items are updated at the end of a dyno run, and remain there until replaced
by the next run. If a run is aborted, then the values are not affected.
Depending on your preferences, you may display the applicable item or all.
Example #1: Measure time from 50 to 80 Miles
Set Tools: Display unit: Imperial
Enter 50 in Trigger Speed
Enter 80 in End Speed
Make sure other end and trigger points are zero!
Check that the status indicates: Dyno Ready
Find a level road without any speed restrictions
Hit the Gas!
At 50 miles the Status,’ DYNO Active’ comes on
At 80 miles the Status goes off, and the result is displayed!
Example #2: Measure time and distance for 100 meter standing start
Set Tools: Display unit: Metric
Chose RPM or TPS as a trigger, or a very low speed.
Enter 100 in to End Distance
Make sure other end and trigger points are zero
Check that the Status indicates: Dyno Ready
Find a level road without any restrictions
Hit the gas!
After 100 meters the results (Time and distance is displayed.
Here are some practical hints:
If you repeat a run on the same road in opposite direction then you eliminate the
slope.
Do not underestimate the effect of wind or a slight breeze.
Check out the effect of fuel quality.
The Air temperature has an influence on the results.
Check out the effects of the side mirrors on high-speed runs.
Obvious reason to do a dyno run is performance tuning. The SMT8T_5 gives you a
very accurate tool to measure the effects of any changes you do to the engine.
11.5 CALCULATING THE HORSEPOWER
The unit has the ability to calculate the horsepower of the engine in Kilo Watt (KW if
you perform a ¼ mile (=402 meters run. You need to set the ‘End distance=402’
meters and perform a calibration as outlined above. This entitles:
Setting the ‘Millimeter per AUXIN’
Choosing a trigger point
Set the vehicle (including driver weight in Kg
Setting the END DISTANCE=402

LETRIPP II SMT8T V5 TECHNICAL MANUAL www.perfectpower.com 2011/09/22
15
Then perform a ¼ mile run from a standing start, and the unit will calculate two
different KW readings. Sorry, the real horsepower is not available, but here is the
conversion factor:
1 Kilo Watt (KW = 1.36 HP Horse Power
KW calculated from the end speed (Trap speed method
The speed at the end of the ¼ mile run is used to calculate the engine power.
KW calculated from the Time method
The Time it takes from start to the end (Dyno Time is used to calculate the engine
power.
The formula is available from:
www.ajdesigner.com/phpho sepowe /ho sepowe _equation_trap_speed
Both calculation methods yield surprisingly good results. If both differ too much,
then you can form a mental average, or ignore the higher reading. Practical tests
have shown that the numbers are fairly accurate, considering that the timing is only
performed with a 0.01 second resolution.
As outlined before, perform a run twice in the opposite direction to eliminate slope
and wind conditions. This is a great tool for tuning!
Of course you can shorten the distance. The KW readings are wrong because they
are based on ¼ mile, but you can get good comparative numbers out and see the
effect of your tuning efforts.
11.6 PRACTICAL USE OF THE FUEL MONITOR
The SMT8T_5 has a fuel monitor build in. All that is required is to connect the power
and the AUXIN, pin 5 to any injector.
NOTE: If one wi e does not show any indication, take the othe wi e!
There are two display options available:
Fuel Utilization
Fuel Average
The Utilization is a ‘spot’ measuring and will show instantaneous reading. It displays
the duty cycle in percent. Typical readings are 0.5-1.5% at idle, and 50-85% at full
throttle.
The average reading has the same scale, but is averaged over 32 readings. This
gives a more stable display, but does not show any short-term fluctuations.
Both reading allows the driver to choose a speed (power , which is economical. With
experience this number can be matched to the actual fuel consumption.
12. SMT8T_5 SIMULATION
The purpose of the simulation is to experience the features and operation of the unit
on the desk before installation. Of course, if you have experience with piggybacks
then you can skip this section.
The following items can be simulated:

LETRIPP II SMT8T V5 TECHNICAL MANUAL www.perfectpower.com 2011/09/22
16
RPM Simulation: Entry in RPM
It produces no ignition output signal, but the map deflection is affected.
TPS Simulation: Entry in Volt
It affects the map deflection, and if selected as an analog mapping input, the AOUT
signal is active.
AMP Simulation: Entry in Volt
It affects all AMP readings and maps. If it is selected for analog mapping then the
AOUT signal is active.
AFR Simulation: Entry in Volt
The AFR/Lambda readings are affected. If it is used for analog mapping then the
AOUT signal is active.
ANA Simulation: Entry in Volt
The Analog input and output readings are affected. If it is used for mapping then the
AOUT is active.
Engine Temperature Simulation: Entry in Degree
The display reading is affected.
Frequency Simulation: Entry in Hz
The display and the AUXOUT is affected
Simulation Exercise
Use the Simulation profile
Make the simulation field visible by clicking: CONFIG, SIMULATION.
Then Set RPM simulation: 2500
Then Set TPS simulation: 2.5V
Then Set AMP simulation: 2.5V
Then Set AFR simulation: 0.45V
Make the Status field visible: CONFIG, STATUS
Confirm that the Simulation is active.
Load any map: e.g. F3, Analog
After the above simulation settings your screen looks like:

LETRIPP II SMT8T V5 TECHNICAL MANUAL www.perfectpower.com 2011/09/22
17
Observe that the field indication somewhere in the middle of the tables is set. The
exact points depend on your scale calibration. The number in this field is used in the
mapping process.
Change the Set Simulation RPM to 3500RPM and observe that the point changes.
The following demonstrates an analog signal modification:
• Use the ANALOG SIMULATION profile
• Select in System definition: Analog Output.
• Display Analog input, Analog modification and Analog outputs
• Enter in Set Analog Simulation: 2.22V
• Observe that it shows as an input
• Enter a value in the Analog map at the field indication
• Observe that the modification display shows the field number
• Observe that the Analog output display shows the input PLUS the
modification.
Simulation