Javascript is disabled on your browser.
To view this site, you must enable JavaScript or upgrade to a JavaScript-capable browser.
Skip to main content
US Store
Cart
Your cart is empty
Search
Clear
Go
Quick Links
Intake Manifold
Downdraft Manifold
Complete Cylinder Heads
El Rayo Ignition
DNA Roller Rockers
Instructions
Explore
Discover
Outlet Store
Refurbished & clearance deals
Calculators & Tools
Engine specs, compression ratios & more
Instructions
Install guides & tech sheets
Resources
Newsroom
Product launches, builds & updates
Company Overview
Our story & engineering philosophy
SFI Approvals
Safety certifications & compliance
Community
Authorized Resellers
Find a dealer near you
Influencer Program
Partner with Speedmaster
Sponsorship Program
Racing & event sponsorships
SPEEDMASTER
Login
Welcome
Sign in to access your account, track orders, and earn rewards.
Sign In
Create Account
Contact & Support
Store
Shop by Engine
Complete Systems
Popular Categories
DNA® Collection
Visit the Store
›
More Ways to Shop
What's New
Special Pricing
Outlet
Merchandise
Resources
Military Discount
Emergency Services Discount
Catalogs
Installation Instructions
Merchandise
Apparel
›
Explore All Apparel ›
Clothing
Headwear
Eyewear
Lifestyle Accessories
›
Explore All Lifestyle Accessories ›
Backpacks & Bags
Lanyards & Wristwear
Pins, Patches & Keychains
Umbrellas
Beverage & Drinkware
›
Explore All Beverage & Drinkware ›
Beverages
Drinkware
Coasters
Collectibles & Gifts
›
Explore All Collectibles & Gifts ›
Diecast & Collectible Cars
Swag Packs
Signage & Displays
›
Explore All Signage & Displays ›
Banners & Flags
Display Stands
Printed Materials
›
Explore All Printed Materials ›
Catalogs & Books
Stickers
Cars
Air&Fuel
Air Cleaners, Flame Arrestors & Scoops
›
Explore All Air Cleaners, Flame Arrestors & Scoops ›
Air Cleaner Bottoms
Air Cleaner Studs
Air Cleaner Tops
Air Cleaners
Air Filter Assembly Adapters
Air Filter Assembly Vents
Air Filter Assembly Wingnuts & Fasteners
Air Flow Enhancers
Carburetor Scoops
Air Filter Elements & Accessories
›
Explore All Air Filter Elements & Accessories ›
Air Filter Elements
Air Intakes & Boxes
›
Explore All Air Intakes & Boxes ›
Idle Air Controls
Carburetors & Accessories
›
Explore All Carburetors & Accessories ›
Carburetor Accelerator Pump Covers
Carburetor Adapters
Carburetor Base Plates
Carburetor Dust Covers
Carburetor Fasteners
Carburetor Linkage Kits
Carburetor Main Bodies
Carburetor Metering Block Gaskets
Carburetor Metering Blocks, Replacement
Carburetor Needle and Seats
Carburetor Spacer Burst Panels
Carburetor Spacers
Carburetors
Choke Cables
Choke Kits
Throttle Cable Brackets
Throttle Cables
Throttle Return Spring and Bracket Kits
Throttle Return Spring Brackets
Fuel Cells & Tanks
›
Explore All Fuel Cells & Tanks ›
Fuel Cell Caps
Fuel Cell Filler Valves
Fuel Cell Tip Over Valves
Fuel Cells
Fuel Filters
›
Explore All Fuel Filters ›
Fuel Filter Elements, Replacement
Fuel Filter Replacement Parts
Fuel Filters
Fuel Injection
›
Explore All Fuel Injection ›
Fuel Injection Sensor Kits
Fuel Injection Systems
Fuel Injector Spacers
Fuel Injectors
Fuel Rail Components
Fuel Rails
Throttle Bodies
Throttle Body Adapters, EFI Manifold
Fuel Pumps & Regulators
›
Explore All Fuel Pumps & Regulators ›
Fuel Pressure Regulators
Fuel Pump Block-Off Plates
Fuel Pump Mounting Plates
Fuel Pump Mounts
Fuel Pump Pushrods
Fuel Pumps, Electric External
Fuel Pumps, Electric In-Tank
Fuel Pumps, Mechanical
Intake Manifolds
›
Explore All Intake Manifolds ›
EGR Adapters
Intake Manifold Adapters
Intake Manifold Spacers
Intake Manifolds, Carbureted
Intake Manifolds, Fuel Injected
Intake Manifolds, Fuel Injected Components
Intake Manifolds, Supercharger
Throttle Body Intake Elbows
Nitrous Oxide
›
Explore All Nitrous Oxide ›
Nitrous Oxide Bottle Brackets
Nitrous Oxide Plates
Nitrous Oxide Safety Blow-Off Discs
Superchargers & Turbochargers
›
Explore All Superchargers & Turbochargers ›
Pressure Relief Valves
Supercharger Drive Belts
Supercharger Fasteners
Supercharger Idler Brackets
Supercharger Mounting Brackets
Supercharger Nose Drive Assemblies
Supercharger Pulley Spacers
Supercharger Pulleys
Supercharger Top Plates
Superchargers, Centrifugal Style Head Units
Superchargers, Roots Style Components
Superchargers, Roots Style Kits
Supercharger Restraints
Engine
Accessory Brackets & Eliminators
›
Explore All Accessory Brackets & Eliminators ›
Air Conditioner Brackets
Alternator Bracket Components
Alternator Brackets
Power Steering Brackets
Bearings & Bearing Spacers
›
Explore All Bearings & Bearing Spacers ›
Cam Bearings
Main Bearings
Rod Bearings
Belts & Pulleys
›
Explore All Belts & Pulleys ›
Accessory Belts
Accessory Drive Systems
Alternator Pulleys
Crankshaft Pulleys
Idler Pulleys
Power Steering Pulleys
Pulley Adapters
Pulley Fasteners
Pulley Kits
Pulley Nose Cones
Pulley Spacers
Water Pump Pulleys
Camshafts & Valvetrain
›
Explore All Camshafts & Valvetrain ›
Camshaft Bolts
Camshaft Locking Plates
Camshaft Thrust Buttons
Camshaft Thrust Plates
Camshafts
Cylinder Head Valvetrain Kits
Guideplates
Lash Caps
Pushrods, Assembled
Rocker Arm Nuts
Rocker Arm Screws
Rocker Arm Shaft Shim Kits
Rocker Arm Stud Girdles
Rocker Arm Studs
Rocker Arms
Timing Belt Drive Replacement Parts
Timing Belt Drive Systems
Timing Chain and Gear Replacement Parts
Timing Chain and Gear Sets
Timing Cover Fasteners
Timing Covers
Timing Gear Drive Replacement Parts
Timing Gear Drive Sets
Timing Gears
Timing Pointers
Valve Locks
Valve Spring Locators
Valve Spring Retainers
Valve Spring Shims
Valve Springs
Valves
Crankshafts & Connecting Rods
›
Explore All Crankshafts & Connecting Rods ›
Connecting Rod Bolts
Connecting Rods
Crankshafts
Cylinder Heads
›
Explore All Cylinder Heads ›
Cylinder Head Bushing Kits
Top End Kits
Cylinder Head Dowel Pins
Cylinder Head Fasteners
Cylinder Heads
Valve Guides
Valve Seats
Engine Blocks & Accessories
›
Explore All Engine Blocks & Accessories ›
Engine Block Expansion Plugs
Engines, Bare Blocks
Main Cap Fasteners
Main Cap Girdles
Main Caps
Rear Main Seal Adapters
Engine Kits & Rotating Assemblies
›
Explore All Engine Kits & Rotating Assemblies ›
Engine Rotating Kits
Crate Engines
Harmonic Balancers
›
Explore All Harmonic Balancers ›
Harmonic Balancer Bolts
Harmonic Balancers
Timing Tape
Oiling Systems
›
Explore All Oiling Systems ›
Crankcase Evacuation Systems
Dipstick Handles
Engine Oil Dipsticks
Oil Filter Adapters
Oil Filter Covers
Oil Filter Mounts
Oil Filters
Oil Pan Fasteners
Oil Pans, Individual
Oil Pump Driveshafts
Oil Pump Pickups
Oil Pumps
Oil Restrictors
Pistons & Piston Rings
›
Explore All Pistons & Piston Rings ›
Piston Oil Ring Spacers
Piston Rings
Piston Wrist Pin Retainers
Pistons
Valve Covers & Dress-Up Kits
›
Explore All Valve Covers & Dress-Up Kits ›
Valve Cover Baffles
Valve Cover Breathers
Valve Cover Fasteners
Valve Cover Grommets
Valve Cover Hold-Down Tabs
Valve Cover Oil Fill Caps
Valve Covers
Driveline
Driveshafts & Yokes
›
Explore All Driveshafts & Yokes ›
U-Joint Fasteners
U-Joints
Yoke Adapters
Yokes
Driveshaft Safety Loops
Shifters & Control
›
Explore All Shifters & Control ›
Automatic Transmission Brackets and Levers
Automatic Transmission Gate Plates
Shifter Cables, Automatic Transmission
Shifter Solenoids, Air
Shifter Sticks, Manual Transmission
Shifters, Automatic Transmission
Shifters, Manual Transmission
Wheel & Axle Hardware
›
Explore All Wheel & Axle Hardware ›
Axle Bearings
Axle Seals
Ring and Pinion Gear Installation Kits
Automatic Transmission Components
›
Explore All Automatic Transmission Components ›
Automatic Transmission Bands
Automatic Transmission Cases
Automatic Transmission Center Supports
Automatic Transmission Clutch Hubs
Automatic Transmission Clutch Steels
Automatic Transmission Drums
Automatic Transmission Filter Extensions
Automatic Transmission Filters, Direct Fit
Automatic Transmission Front Pump Drives
Automatic Transmission Gears
Automatic Transmission Input Shafts
Automatic Transmission Kickdown Cables
Automatic Transmission Output Shafts
Automatic Transmission Pans
Automatic Transmission Gaskets
Automatic Transmission Rebuild Components
Automatic Transmission Servo Kits
Automatic Transmission Shift Kits
Automatic Transmission Sprags
Automatic Transmission Tailhousings
Automatic Transmission Trans-Brake Solenoids
Automatic Transmission Valve Bodies
Automatic Transmissions
Transmission Fluid Dipsticks
Valve Body Replacement Components
Manual Transmission Components
›
Explore All Manual Transmission Components ›
Manual Transmission Shifter Forks
Manual Transmissions
Manual Transmission Throwout Bearing Retainers
Manual Transmission Synchros
Manual Transmission Replacement Components
Manual Transmission Bearings
Torque Converters
›
Explore All Torque Converters ›
Torque Converter Shims
Torque Converter Upgrade Combos
Torque Converters
Bellhousings & Adapters
›
Explore All Bellhousings & Adapters ›
Engine To Bellhousing Separator Plates
Bellhousings
Bellhousing Adapters
Flywheels & Flexplates
›
Explore All Flywheels & Flexplates ›
Flexplate Fasteners
Flexplates
Flywheel And Flexplate Dust Covers
Flywheel Counterweights
Flywheel Fasteners
Flywheel Locating Dowels
Flywheels
Counter Balance Plates
Clutch Components
›
Explore All Clutch Components ›
Clutch Fork Pivot Balls
Clutch Forks
Pilot Bearings and Bushings
Throwout Bearings
Transmission Accessories
›
Explore All Transmission Accessories ›
Oil Pan Drain Plugs
Others
Axle Assemblies & Housings
›
Explore All Axle Assemblies & Housings ›
Axle Assemblies
Axle Shafts, Custom Built
Axle Shafts, Direct Fit
Axle Upgrade Combos
Floating Axle Kits
Axle Housing Braces
Axle Housing End Fasteners
Axle Housing Ends
Axle Housing Tubes
Rear Axle Housings
Axle Retainer Plates
Differential Gears & Carriers
›
Explore All Differential Gears & Carriers ›
Ring and Pinion Gears
Differential Carriers
Spools and Mini Spools
Third Member Complete Assembly
Third Member Case Only
Axle Drive Flanges
Differential Hardware
›
Explore All Differential Hardware ›
Differential Carrier Bearing Adjusting Nuts
Differential Carrier Bearings
Differential Covers
Differential Cross Shafts and Fasteners
Differential Main Cap Fasteners
Differential Pinion Bearing Spacers and Sleeves
Differential Pinion Nuts
Differential Shims
Differential Spanners and Side Adjuster Tools
Differential Third Member Fasteners
Pinion Bearings and Races
Pinion Support Fasteners
Pinion Supports
Electrical
Charging Systems
›
Explore All Charging Systems ›
Alternator Fans
Alternator One Wire Conversion Kits
Alternators and Generators
Battery Boxes
Battery Trays
Voltage Regulator and Rectifiers
Computers, Sensors & Programmers
›
Explore All Computers, Sensors & Programmers ›
Coolant Temperature Sensors
MAP Sensors
Oxygen Sensor Mounting Clamps
Oxygen Sensors
Throttle Position Sensors
Electrical Wiring
›
Explore All Electrical Wiring ›
Ballast Resistors
Distributor Wiring Harnesses
Wiring Connectors and Pigtails
Wiring Harnesses
Ignition Components
›
Explore All Ignition Components ›
Crank Trigger Replacement Pickups
Distributor Advance Kits
Distributor Cap and Rotor Kits
Distributor Caps
Distributor Gears
Distributor Hold-Down Clamps
Distributor Replacement Parts
Distributor Rotors
Distributors
HEI Distributor Upgrade Kits
Ignition Box Mounts
Ignition Boxes
Ignition Coil Brackets
Ignition Coil Covers
Ignition Coils
Ignition Modules
Ignition RPM Module Kits
Ignition System Combo Kits
Multi Step Module Selectors
Rev Limiters
Tachometer Adapters
Voltage Boosters
Spark Plug Wires and Accessories
›
Explore All Spark Plug Wires and Accessories ›
Ignition Wire Looms and Separators
Spark Plug Wire Components
Spark Plug Wire Sets
Spark Plugs & Glow Plugs
›
Explore All Spark Plugs & Glow Plugs ›
Spark Plugs
Starters
›
Explore All Starters ›
Starter Bolts
Starter Drive End Blocks
Starters
Accessories
Brake Systems
›
Explore All Brake Systems ›
Disc Brakes
Drum Brakes
Master Cylinders & Boosters
Chassis, Steering & Suspension
›
Explore All Chassis, Steering & Suspension ›
Bushings & Mounts
Chassis Components
Steering Components
Suspension Components
Cooling & Heating
›
Explore All Cooling & Heating ›
Air Conditioning
Fans
Oil and Fluid Coolers
Overflow Tanks & Catch Cans
Radiators and Accessories
Thermostats, Housings & Fillers
Water Pumps
Exterior & Accessories
›
Explore All Exterior & Accessories ›
Grilles & Grille Shells
Hoods, Tops, Body Panels, Parts & Sections
License Plates
Lights & Lenses
Mirrors, Side View & Towing
Roof Racks, Carriers, & Storage Racks
Scoops & Louvers
Gaskets & Seals
›
Explore All Gaskets & Seals ›
Differential Gaskets & Seals
Engine Gaskets & Seals
Exhaust Gaskets & Seals
Transmission Gaskets & Seals
Miscellaneous Kits
Gauges & Accessories
›
Explore All Gauges & Accessories ›
Gauges, Individual
Sending Units
Tools & Shop Equipment
›
Explore All Tools & Shop Equipment ›
Electrical & Electrical Testing Tools
Emergency Roadside Repair Tools
Engine-Related
Hand & Other Tools
Shop Equipment
Storage, Organizers
Tire Pressure
Trailer, Towing & Winches
›
Explore All Trailer, Towing & Winches ›
Tie-Down Straps & Tow Straps, Ropes
Trailer Accessories
Winches
Wiring & Lights
Wheels & Tires
›
Explore All Wheels & Tires ›
Lug Nuts, Studs & Washers
Tire & Wheel Accessories
Fittings & Hoses
›
Explore All Fittings & Hoses ›
Fittings & Plugs
Hose & Line & Tubing
Valves, Check & Shutoff
Fasteners & Hardware
›
Explore All Fasteners & Hardware ›
Bolts
Nuts
Washers
Other Parts
Exhaust
›
Explore All Exhaust ›
Exhaust Flame Thrower Kits
Headers
Interior & Accessories
›
Explore All Interior & Accessories ›
Door Accessories
Pedals & Pedal Pads
Steering Columns and Components
Steering Wheels
Assembly
Ignition System Combo Kits
›
Explore All Ignition System Combo Kits ›
Speedmaster El Rayo ignition system are designed for the enthusiast that is serious about performance but needs the small cap size due to space considerations when installed.
Engine Rotating Kits
›
Explore All Engine Rotating Kits ›
Churn out all the asphalt-chewing, road-grating horsepower you want with our massive selection of rotating assemblies! SpeedmasterTM kits bring together everything you need.
Top End Kits
›
Explore All Top End Kits ›
Speedmaster has taken the guesswork out of top-end component selection by actually placing the top end components together in complete kits. They include almost everything you need to make serious horsepower.
Cylinder Heads
›
Explore All Cylinder Heads ›
Performance cylinder heads enhance the airflow into your engine, giving you improved power and torque. Bolt on a set of Speedmaster's fully assembled cylinder heads for instant power gains.
Fuel Injection Systems
›
Explore All Fuel Injection Systems ›
Speedmaster™ line of EFI systems is all you need when deciding to upgrade your engine to modern electronic fuel injection. Our EFI systems provide excellent throttle response throughout the RPM range along with smooth engine operation.
Superchargers, Roots Style Kits
›
Explore All Superchargers, Roots Style Kits ›
Speedmaster’s 6-71 Street Supercharger kits can give you 45-55 percent more streetable power. They feature double-pinned rotors (timed and clearanced after assembly), heavy duty front and rear bearing plates, and an intake manifold.
Crate Engines
›
Explore All Crate Engines ›
Speedmaster crate engines have become a huge success all over the world. We deliver reliable horsepower, torque and drivability. We use only quality name brand parts that we trust giving our customers a superior product for their money.
Third Member Complete Assembly
›
Explore All Third Member Complete Assembly ›
Assembly has been carried out at the Speedmaster’s TDS Department by the Head differential technician. Quality is assured with 40 years experience in the Differential Industry and full involvement in all forms of motorsport from V8 SUPERCAR To Group 1 Drag Racing.
Continue shopping
Home
›
Rod to Stroke Ratio Calculator | Speedmaster Tools
Rod/Stroke Ratio Calculator
Calculate the rod-to-stroke ratio from connecting rod length and stroke size.
Stroke
in.
mm
Rod Length
in.
mm
Calculate
Rod/Stroke Ratio
—
Speedmaster Tools
Engine / Performance
Bore Size & Bore/Stroke Ratio
Carburetor Size Needed
Engine Size
Engine Compression Ratio
Fuel Injector Flow from Fuel Pressure
Fuel Injector Sizing from HP
Horsepower from Intake Airflow
Horsepower Gain from Blower Pressure
Intake Airflow from Horsepower
Rod Stroke Ratio
Stroke Size
Turbo / Supercharger Sizing
Air/Fuel Ratio
Drivetrain / Tires
Rear End Gear Ratio Needed
Speed from RPM & Gear Ratios
RPM from Speed & Gear Ratios
Tire Size Comparison
Speedometer Correction
Drag Strip
⅛ Mile HP from MPH
⅛ Mile HP from ET
⅛ Mile ET from MPH
¼ Mile MPH from Horsepower
¼ Mile HP from MPH
¼ Mile HP from ET
¼ Mile ET from Horsepower
¼ Mile ET from MPH
MPH from 60ft Time
General
Weight-to-Power Ratio
Also available on
