Exhaust, Header, and Performance Calculators and Guides

These pages are here to help you make smarter decisions when you’re building headers, sizing an exhaust, picking a carb, or trying to get rid of exhaust drone. The goal is not to bury you in engineering language, but to give you useful formulas in a way that makes sense for real-world shop work and street or race builds

• Header Primary Sizing
  Use this when you’re trying to choose the right primary tube diameter for an engine build. Smaller tubes usually help keep velocity up and improve low- and mid-range response, while larger tubes tend to work better for bigger engines and higher-RPM power.
  
  
• Header Primary Length
  Use this when you want to tune where the header works best in the RPM range. Tube length changes when the returning pressure wave reaches the cylinder, which is why primary length affects torque and scavenging.
  
  
• Collector Sizing
  Use this to estimate collector diameter and length once the primary tubes are figured out. The collector ties the whole header package together and has a real effect on how the system carries the power curve
  
  
• Carburetor CFM Calculator
  Use this to estimate how much airflow your engine actually needs before choosing a carb. The main inputs are displacement, RPM, and volumetric efficiency, and the result helps you avoid going too small or too big.
  
  
• Quarter-Wave Resonator
  Use this when you have a very specific drone frequency and want to tune a side branch or J-pipe to knock it down. It’s one of the simplest ways to target a narrow band of exhaust noise.
  
  
• Helmholtz Resonator
  Use this when you want a more compact drone-control chamber than a long J-pipe. It works by matching chamber and neck dimensions to the frequency you want to reduce.
  
  
• Turbo Pressure Ratio
  Use this when you’re sizing a turbo or comparing compressor maps. Pressure ratio is one of the first numbers you need when boost pressure becomes part of the conversation.
  
  
• Boost Horsepower Estimate
  Use this when you want a rough idea of what kind of power increase a given boost level might support. It’s a planning tool, not a promise, but it’s useful early in a build.
  
  
• Exhaust Pipe Sizing
  Use this for main exhaust diameter planning based on airflow, power, and RPM goals. This helps keep you out of the trap of picking a pipe just because it “sounds right” or “everyone uses 3-inch.”
  
  
• TIG Argon Flow
  Use this to set a starting point for shielding gas flow based on cup size and weld setup. It’s especially helpful for stainless work where gas coverage matters and too much flow can be almost as bad as too little.
  
  
• Argon Bottle Usage
  Use this to estimate how long a bottle will last based on flow rate and welding time. It’s simple, but it helps with quoting work and planning jobs.