ok, my family has been building Perfromance Cars for donkeys years, (my dad owns his own company building engines) and im learning more and more from him every day!
Anyway, this subject about Exhaust Back pressure confuses me?!? Ive always been under impression and always built exhausts with this in mind: -
1.) A Forced -induction engine (Turbo'd or Supercharged) runs better performance with a bigger diameter exhaust and less back pressure to get rid of gases quickly and evenly because Turbo or S/C-er forces air in engine quicker.!
2.) A Normally Aspirated Engine (not turbo'd or Supercharged) needs some back pressure to keep gases in Combustion Chamber to burn the Fuel better, otherwise unburnt fuel exits exhaust and fuel is ignited at wrong times.
3.) The Bigger diameter pipe will increase BHP but will loose Torque at Low RPM?
4.) The Smaller diameter pipe creates more Torque at Low RPM and loses it at high RPM.
This is why cars are produced in the factory with a specific diameter Exhaust for various reasons, and when moddifing cars, Turbo cars generally have bigger Exhausts...i.e. Escort RS Turbos usually have 4" Pipes and no silencers which give that Barble sound. (get rid of gases quicker) and thats why they flame, - unburnt fuel!
Anyone else got any other views?
