Auto Racing: EXHAUST PIPING DIAMETER, exhaust gasses, exhaust piping

Question
HI, I HAVE MR2 TURBO WITH STOCK TURBO UPGRADED INTERCOOLER AND BOOST CONTROLLER, AND I WAS WONDERING WHAT DIAMETER OF PIPING I SHOULD USE FOR THE EXHAUST FOR MAXIMUM HORSEPOWER. AND WHAT IS BACK PRESSURE? AND HOW DOES THE EXHAUST SYSTEM WORK WITH THE TURBO AND EFFECT HORSEPOWER? THANKS

Answer
Use 2 1/2" pipe for the exhaust.  

Back pressure is the pressure that builds within the exhaust system from the movement of the exhaust gasses. As the pistons rise to expel exhaust gas, it meets resistance and retards the piston's movement. In that way it steals horsepower.  Reducing backpressure usually increases power a small amount which is why race cars run without mufflers.

For more info on turbochargers, Google H-P books and look for the title "Turbocharging "   you can order it from Amazon for about $18.00 plus $3.99 shipping.  In the kind of racing I do, we don't use forced-air induction so I'm not real familiar with it.

Good luck

Dan Liddy
Sarasota, Florida