DIY EGT display approx $16

#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
int OLED_RESET = 4;
Adafruit_SSD1306 display(OLED_RESET);
float Vcc_Per_ADC = 0;
void setup() {
Serial.begin(9600); //To comunicate with the PC
display.begin(SSD1306_SWITCHCAPVCC); //To supply the 3.3V power supply
pinMode(0, INPUT); //Set analog pin 0 as an input from the sensor
pinMode(1, INPUT); //Set analog pin 1 as an input from the sensor
display.clearDisplay(); //Clear the display and ram
Vcc_Per_ADC = readVcc()/1024.0; //initialise the calbration of ADC voltage
delay(500);
}
void loop() { // Start loop 
static int raw_bst = 0; // Setup raw boost sensor value
static int raw_emp = 0; // Setup raw emp sensor value
static int peak_raw_bst = 0; // Setup peak boost value
static int peak_raw_emp = 0; // Setup peak emp value
static int peak_raw_bst_st = 0; // Setup peak boost value last two minutes
static int peak_raw_emp_st = 0; // Setup peak emp value last two minutes
static int grphboost = 0; // Setup value for boost bar
static int grphemp = 0; // Setup value for boost bar
static int bst_bar = 0; // Setup boost value
static int emp_bar = 0; // Setup boost value
static int bst_barpeak = 0;
static int emp_barpeak = 0;
static int bst_barpeak_st = 0;
static int emp_barpeak_st = 0;
static int x = 0; //counter
static int samples = 20;
static int sample_interval = 8;
static unsigned long lasttime = 0;  //time value to reset peak every two minutes
Vcc_Per_ADC = (9*Vcc_Per_ADC + readVcc()/1024.0)/10.0 ; //calibrate the ADC voltage with a running average to smooth noise
raw_bst = analogRead(0); // Read MAP sensor raw value on analog port 0
raw_emp = analogRead(1); //Read MAP sensor raw value on analog port 0
delay(sample_interval);  //wait as per following routine between raedings
for(x = 0; x <= (samples-2); x++) { //loop to average a few readings
raw_bst += analogRead(0);
raw_emp += analogRead(1);
delay(sample_interval);
}
raw_bst =  int ((raw_bst/samples)+0.5); //get avergage and convert to integer
raw_emp = int ((raw_emp/samples)+0.5); //get average and convert to integer
//vw 4 bar sensor p bar = V volts x 0.85261 + 0.1581 bar
//vw 4 bar formula = raw x 0.003911 + 0.1581
bst_bar = int (((raw_bst*Vcc_Per_ADC*0.85261/1000) + 0.1581)*10-10+0.5); // Calculate manifold bar from raw value
//Mcnally 75psi p bar = V volts x 1.293 - 0.647bar //think 500mV=0mBar absolute, 4500mV=75psi
//Mcnally raw x 6.743 - 1.439bar
emp_bar = int (((raw_emp*Vcc_Per_ADC*1.293/1000) -  0.647)*10-10+0.5); // Calculate emp from raw value
grphboost = int ((bst_bar) * 3.2); // Calculate boost value for the bargraph 4 secions 125 pixels wide total 
grphemp = int ((emp_bar) * 3.2); // Calculate boost value for the bargraph 5 secions 125 pixels wide total
if ( millis() - lasttime > 120000) {
lasttime = millis();
peak_raw_bst_st = 0;
peak_raw_emp_st = 0;
}
if (raw_bst > peak_raw_bst){ // If current boost is higher than peak, store new value
peak_raw_bst = raw_bst ; // Store new peak value in peak memory
bst_barpeak =  (((peak_raw_bst*Vcc_Per_ADC*0.85261/1000) + 0.1581)*10-10); // 
}
if (raw_bst > peak_raw_bst_st){ // If current boost is higher than peak, store new value
peak_raw_bst_st = raw_bst ;  
bst_barpeak_st =  (((peak_raw_bst_st*Vcc_Per_ADC*0.85261/1000) + 0.1581)*10-10); //      (((peak_raw_bst_st * 0.003911) + 0.1581)*10-10);
}
if (raw_emp > peak_raw_emp){ // If current boost is higher than peak, store new value
peak_raw_emp = raw_emp ; // Store new peak value in peak memory
emp_barpeak = (((peak_raw_emp*Vcc_Per_ADC*1.293/1000) -  0.647)*10-10);     //
}
if (raw_emp > peak_raw_emp_st){ // If current boost is higher than peak, store new value
peak_raw_emp_st = raw_emp ; // Store new peak value in peak memory
emp_barpeak_st = (((peak_raw_emp_st*Vcc_Per_ADC*1.293/1000) -  0.647)*10-10);     //(((peak_raw_emp_st *0.006743) - 1.439)*10-10);
}
display.display();
display.clearDisplay();
display.setTextColor(WHITE);
send_pres_to_oled(10,7,4,emp_bar); //send emp
send_pres_to_oled(72,7,4,bst_bar); //send boost
send_pres_to_oled(68,45,2,emp_barpeak_st);
send_pres_to_oled(100,45,2,bst_barpeak_st);
send_pres_to_oled(4,45,2,emp_barpeak);
send_pres_to_oled(36,45,2,bst_barpeak);
display.drawRect(1, 40, 131, 24, WHITE); //Border of the bar chart
display.drawLine(32,40,32,63, WHITE); //draw bar boost markers
display.drawLine(64,40,64,63, WHITE); //draw bar boost markers
display.drawLine(96,40,96,63, WHITE); //draw bar boost markers
//display.drawLine(125,40,125,63, WHITE);
display.fillRect(1, 40, grphboost, 9, WHITE); //Draws the bar depending on the sensor value
display.fillRect(1, 55, grphemp, 9, WHITE); //Draws the bar depending on the sensor value
display.drawRect(1, 1, 127, 63, WHITE); //Border of the entire screen
//delay(100);
}
long readVcc() {
long result;
// Read 1.1V reference against AVcc
ADMUX = _BV(REFS0) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1);
delay(2); // Wait for Vref to settle
ADCSRA |= _BV(ADSC); // Convert
while (bit_is_set(ADCSRA,ADSC));
result = ADCL;
result |= ADCH<<8;
result = 1076490L / result; // Back-calculate AVcc in mV
//Serial.println(result);  //use this to adjust line above to calibrate readVcc should be the same as measure on 5v pin or Vref pin, mine read 4.71 volts on usb supply
return result;
}
void send_pres_to_oled(int first_pos,int height_pos, int text_size,int press_val){
//first_pos = 10, second_pos = 35, height_pos = 7 , text_size = 4
display.setTextSize(text_size);  
display.fillRect(first_pos + 6* text_size, height_pos + 6 * text_size , text_size, text_size, WHITE); //decimal point  
if (press_val < 9.5)  {    //anything from 9.5 upwards would be rounded to 10 so using two chars
if (press_val < 0) {   //deal with negative as normal negative requires entire char width
press_val = press_val*-1;
display.fillRect(first_pos-1, height_pos-text_size, 2*text_size, text_size/2, WHITE);
}
display.setCursor(first_pos, height_pos);
display.println(0);
display.setCursor(first_pos + 7*text_size, height_pos);
display.println(press_val);
}
else   {
display.setCursor(first_pos, height_pos);
display.println(press_val);
}
}

//Arduino nano , 1.3" I2C OLED 

#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SH1106.h>
#define sensorPin 0

int OLED_RESET = 4;
Adafruit_SH1106 display(OLED_RESET);

// bar graph

float rawval = 0; // Setup raw sensor value
float barboost = 0; // Setup value for boost bar

// peak

int boostPeakReset = 4000; // time in milis to reset peak value
float boostPeak = 0.00;
float boostMax = 0.00;
unsigned long boostPeakTimer = 0;

// log

byte count;
byte sensorArray[128];
byte drawHeight;
boolean filled = 0; //decide either filled, or dot-display. 0==dot display.


void setup()
{
  display.begin(SH1106_SWITCHCAPVCC); // 3.3V power supply
  display.clearDisplay(); // Clear the display and ram
  for (count = 0; count <= 128; count++) //zero all elements
  {
    sensorArray[count] = 0;
  }
}


void loop() // Start loop
{
  int boostmbar = map(analogRead(sensorPin), 21, 961, 100, 2600);
  rawval = analogRead(0); // Read MAP sensor raw value on analog port 0
  barboost = (((rawval * 0.19) - 69.45) + 10); // Calculate boost value for the bargraph  


  if (boostPeak < boostmbar && boostmbar > 0.50) {
    boostPeak = boostmbar;
    boostPeakTimer = millis();
    if (boostMax < boostPeak) {
      boostMax = boostPeak;
    }
  }
  else if (boostPeak > boostmbar && (millis() - boostPeakTimer) > boostPeakReset) {
    boostPeak = 0.00;
  }


  // log 

  drawHeight = map(analogRead(A0), 0, 1023, 0, 25 );  

  sensorArray[0] = drawHeight;

  for (count = 55; count <= 128; count++ )
  {
    if (filled == false)
    {
      display.drawPixel(count, 71 - sensorArray[count - 55], WHITE);
    }
    else
      display.drawLine(count, 1, count, 71 - sensorArray[count - 55], WHITE); 
  }

  for (count = 80; count >= 2; count--) // count down from 160 to 2
  {
    sensorArray[count - 1] = sensorArray[count - 2];
  }

  display.drawLine(55, 43, 55, 64, WHITE);
  display.setTextColor(WHITE);
  display.setTextSize(4);
  display.setCursor(0, 0);
  display.println((boostmbar * 0.001) - 0.97);    // 0.97 = 970mbar atmospheric pressure correction

  display.drawRect(0, 31, 128, 12, WHITE); // Border of the bar chart
  display.fillRect(0, 31, barboost, 12, WHITE); // Draws the bar depending on the sensor value

  display.setTextColor(WHITE);
  display.setTextSize(1);
  display.setCursor(97, 20);
  display.println("BOOST");

  display.setTextSize(2);
  display.setCursor(3, 48);
  display.println((boostPeak * 0.001) - 0.97); // 0.97 = 970mbar atmospheric pressure correction


  if (2700 < boostmbar ) {
    display.setTextSize(1);
    display.setCursor(105, 5);
    display.println("MAX");
  }
  else if (2700 > boostmbar ) {
    display.setTextSize(1);
    display.setCursor(105, 5);
    display.println("");
  }

  delay(1);
  display.display();
  display.clearDisplay();
}