TunerBench learning center
Understand the math behind the build
Worked examples, primary sources, and practical limitations—connected directly to calculators you can rerun with your own numbers.
Worked examples
Latest guides
Worked tire comparison
225/45R17 vs 245/40R18: Diameter, Speedometer Error, and Fitment
A worked comparison of 225/45R17 and 245/40R18 tire sizes, including diameter, sidewall, circumference, speedometer error, and the checks the numbers cannot answer.
Worked ethanol blend
How Much E85 Do You Need to Make E30?
Calculate an E30 fuel blend from the fuel already in the tank, the actual ethanol content of pump E85, and the target tank volume.
Wheel fitment geometry
Wheel Offset Explained: Calculate Poke and Inner Clearance
Understand positive wheel offset and calculate how a width and offset change moves a wheel toward the fender and suspension.
Datalog workflow
How to Read a Turbo Datalog Without Chasing One Channel
A practical workflow for comparing boost, timing, lambda, fuel pressure, trims, throttle, RPM, and temperature in a turbocharged-engine datalog.
Fuel-system planning
Injector Sizing for E85: A Worked Horsepower Example
Size port injectors from horsepower, BSFC, injector count, and duty cycle, then understand why pressure and ethanol content still matter.
Dyno comparison
SAE vs STD Dyno Correction: Why the Numbers Differ
Understand SAE, STD, and uncorrected dyno numbers, how weather normalization works, and how to make a defensible before-and-after comparison.
Power math
Why Horsepower and Torque Cross at 5,252 RPM
Derive the familiar horsepower equation from torque, rotational speed, and the horsepower unit instead of treating 5,252 as engine magic.
AWD tire planning
AWD Tire Circumference Mismatch: Why One Universal Limit Is Wrong
Calculate front-to-rear tire circumference mismatch and understand why the vehicle manufacturer—not a universal internet percentage—sets the final limit.
Compressor-map math
Turbo Pressure Ratio at Altitude: Why 20 PSI Is Not Always the Same Work
Calculate compressor pressure ratio from gauge boost and atmospheric pressure, then see why the same boost target is harder at altitude.
Vehicle identification
VIN Decoder vs Build Sheet: What Each Can Actually Tell You
Understand what NHTSA VIN data can identify, what requires a manufacturer build sheet, and why recalls and enthusiast codes are separate layers.
Garage references
Chassis and engine indexes
BMW reference
BMW chassis codes
Look up E, F, G, and U-series chassis families by generation and body style.
BMW reference
BMW engine codes
Match common BMW engine families with their layouts, induction, and applications.
Porsche reference
Porsche chassis codes
Decode familiar internal model numbers across modern Porsche generations.
Useful before searchable
Every guide begins with a real decision, shows the equation or evaluation process, and states what the result cannot prove. Articles cite primary or manufacturer sources where a formal definition or platform behavior matters.
Use these pages to understand the assumptions, then open the connected calculator to work with your own vehicle.