Mechanics Calc

Blog

Guides on fuel systems, engine building, forced induction, and more.

General

Power-to-Weight Ratio: Why It Matters More Than Peak Horsepower

Why power-to-weight ratio is the best single predictor of acceleration, how to calculate it, where your car sits relative to common benchmarks, and whether to add power or subtract weight.

·8 min read
General

Weight Transfer in Drag Racing: How to Get More Traction at Launch

How weight transfer works during acceleration, what determines how much weight shifts to the rear, and how to use it to improve traction off the line.

·9 min read
General

Dyno Correction Factors: SAE, DIN, and STD Methods Explained

What dyno correction factors are, how SAE J1349, DIN 70020, and STD corrections work, why they exist, and how to compare dyno numbers across different conditions.

·8 min read
General

How Air Density Affects Engine Performance

Why hot, humid, high-altitude air costs you horsepower — how temperature, pressure, and humidity change air density, and what that means for naturally aspirated and turbocharged engines.

·9 min read
Forced Induction

How Boost Pressure Translates to Horsepower

The relationship between turbo boost PSI and horsepower gain — why it's not linear, what efficiency has to do with it, and how to estimate boosted power from NA baseline numbers.

·8 min read
Drivetrain

Speedometer Error After Changing Tire Sizes: How to Calculate and Fix It

How tire size changes affect speedometer accuracy, how to calculate the exact error, and the different ways to recalibrate your speedometer.

·7 min read
General

Quarter-Mile ET: How to Estimate, Measure, and Improve Your Drag Strip Time

How quarter-mile elapsed time and trap speed work, what determines your ET, and the most effective ways to go faster — from weight reduction to traction to power adders.

·10 min read
Engine Building

Exhaust Sizing Guide: How to Pick the Right Pipe and Header Size

How to size exhaust pipes and header primaries based on horsepower, why bigger isn't always better, and how exhaust flow affects torque and power curves.

·8 min read
Forced Induction

Turbo Sizing 101: How to Choose the Right Turbo for Your Build

Learn how to pick the right turbocharger — compressor maps, A/R ratios, frame sizes, and how to match a turbo to your horsepower and displacement targets.

·12 min read
General

Spring Rate and Ride Frequency: Choosing the Right Springs

How to calculate the right spring rate from corner weight and motion ratio, what ride frequency means, and how to set up springs for street, autocross, or track use.

·9 min read
Drivetrain

Gear Ratios Explained: How to Choose the Right Gears for Your Build

How gear ratios work, how to pick the right final drive and transmission gears, and how tire size affects your effective gearing. Covers street, drag, and road course setups.

·10 min read
General

Wheel Offset and Backspace: A Complete Fitment Guide

How wheel offset and backspace work, how to convert between them, what happens when you change width or offset, and how to avoid rubbing and clearance issues.

·8 min read
Engine Building

Cam Specs Explained: Duration, Lift, LSA, and Overlap Demystified

How to read camshaft specs — what duration, lift, lobe separation angle, and overlap mean, how they affect power, idle, and drivability, and how to choose the right cam for your build.

·11 min read
Engine Building

Piston Speed and Rod Ratio: What They Mean for Your Engine

How mean piston speed limits RPM, what rod ratio affects, and how to use these numbers when planning a stroker build or choosing an RPM range.

·9 min read
Engine Building

Compression Ratio Explained: How to Calculate, Measure, and Optimize

Everything you need to know about compression ratio — how to calculate it, how to measure it, and how to choose the right CR for your fuel, cam, and boost level.

·10 min read
Engine Building

Volumetric Efficiency Explained: What VE Means and Why It Matters

What volumetric efficiency is, how it's measured, what affects it, and why VE is the single best indicator of how well your engine breathes.

·9 min read
Fuel Systems

How to Size a Fuel System: Pump, Injectors, and Lines

A complete walkthrough of fuel system sizing — from calculating pump flow to choosing injectors and line diameter. Covers NA, turbo, and E85 builds.

·10 min read
Engine Building

Coolant Mixture Guide: Ratios, Freeze Points, and Common Mistakes

How to choose the right antifreeze-to-water ratio for your climate, what happens when the mix is wrong, and why coolant does more than just prevent freezing.

·7 min read
Fuel Systems

Understanding Air/Fuel Ratio: How to Read and Use a Wideband Gauge

What AFR and lambda mean, how to read a wideband gauge, target AFR ranges for idle, cruise, and WOT, and common mistakes that cause lean or rich conditions.

·9 min read
General

Bolt Patterns Explained: How to Measure and Match Wheels

How to identify your wheel bolt pattern (PCD), how to measure it with different lug counts, common bolt patterns by make, and what to know about adapters and hub-centric rings.

·8 min read
Engine Building

Choosing the Right Carburetor: CFM Sizing, Types, and Common Mistakes

How to pick the right carburetor for your engine — CFM calculation, vacuum vs mechanical secondaries, and the mistakes that kill performance.

·8 min read
Engine Building

Engine Displacement Explained: Bore, Stroke, and Why Size Matters

How engine displacement is calculated from bore and stroke, the difference between oversquare and undersquare designs, and how displacement affects power and torque character.

·9 min read
General

Tire Sizing Explained: How to Read Tire Sizes and What Changes Affect

How to decode tire size numbers, what happens when you change tire sizes, and how it affects speedometer accuracy, gearing, clearance, and ride quality.

·8 min read
General

Fuel Economy: What Actually Affects Your MPG

What determines your real-world fuel economy — driving habits, vehicle weight, aerodynamics, tire pressure, and maintenance. How to measure and improve MPG.

·8 min read