Engine-build.com — Free Engine Builder Calculators

Free engine building calculators and reference tools for machinists and DIY engine builders. No accounts, no paywalls.

Calculators

• Compression Ratio Calculator — Static and dynamic compression ratio with octane recommendations. Includes Pat Kelley dynamic CR algorithm with rod length.
• Engine Displacement Calculator — Calculate engine displacement in cubic inches, CCs, and liters from bore, stroke, and cylinder count.
• Piston Ring End Gap Calculator — Application-specific ring gap recommendations for NA street, NA performance, forced induction, and race builds.
• Cam Duration & Timing Calculator — Full Vizard cam analysis: valve events, overlap, LSA recommendations, dynamic compression ratio, and rocker lift table.
• Connecting Rod Ratio Calculator — Calculate rod ratio (L/S) and compare against common engines like SBC 350, LS1, Ford 302, 2JZ.
• Horsepower & Torque Converter — Bidirectional HP to torque conversion with Nm and kg-m unit conversions.
• Piston Speed Calculator — Mean and peak piston speed in feet per minute with color-coded safety zones.

Camshaft Selection Guide

Cam Guide — The systematic approach to selecting the right camshaft for your combo. Includes cam comparison tool, valve spring calculator, and Vizard LSA recommendations.

Torque Specs Lookup

Torque Specifications — OEM torque specs for 2,400+ engines across 36 manufacturers. VIN decoder included. Validated against minimum two independent sources.

Common Engine Reference

Small Block Chevy 350: 4.000" bore, 3.480" stroke, 349.8ci, 5.7L. Stock compression 10.8:1 with 64cc heads. Rod length 5.700", rod ratio 1.638.

GM LS1 5.7L: 3.898" bore, 3.622" stroke, 346ci. Rod length 6.098", rod ratio 1.684.

Ford 302 Windsor: 4.000" bore, 3.000" stroke, 302ci. Rod length 5.090", rod ratio 1.697.