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Auto Racing/EXHAUST PIPING DIAMETER

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Expert: - 5/12/2007


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  

Auto Racing

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Dan Liddy

Expertise

Anything concerning race cars, 20 years competition experience, Senior Competition Driver Instructor , car builder, mechanic, welding, fabrication, tuning , engine modifications, set up, suspension design. Specializing in Datsun/Nissan products. Please submit questions about RACE CARS ONLY. No street cars, no video game scenarios Thank you.

Experience

I have been racing for 20 years, I have been the Central Florida SCCA Regional Championship points for 5 years running, and won the championship in my class 2 times. During my first start in the 60's I won many solo awards and the State Championship Drags. I serve as a senior instructor for SCCA, and have taught in Mercedes AMG events at Daytona, and Dodge Viper Days at Sebring International. I have been in the thick of the competition for all of my career. At one time or another I have driven race cars at speeds nearing 195 MPH. It's quite a ride !

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