Sunday, April 11, 2021

Retro Review: Hot Rod Calculator

 Retro Review:   Hot Rod Calculator

Quick Facts:

Model:  8703, Hot Rod Calc

Company:  Mr. Gasket Co/Calculated Industries

Years of Production: 2009 - 2020*

Memory Registers:  1

Batteries:  2 LR-44

Operating System:  Chain

Display:  8 digits, unit indicators 

New Price: $80 retail; can be found on sale or clearance

* I can no longer find the Hot Rod calculator as a new calculator on the Calculated Industries website.  However, the Hot Rod app for both iOS and Android.  

Ladies and Gentlemen, Start Your Engines!

The Hot Rod Calc is a specialty calculator that emphasizes on automotive mathematics, with solvers and applications including:  

*  Air Temperature, Relative Humidity (Moisture), Elevation

*  Vehicle Weight, Elapsed Time (1/4 mile traveled in seconds), MPH

*  Bore, Stroke, RPM, Torque, Engine Displacement

*  Tire Ratio, Gear Ratio

*  Engine Volumetric Efficiency

*  Carburetor Size

*  Vehicle Weight, Horsepower, Elapsed Time

*  Conversions including length, area, volume, temperature, mass, velocity (speed)

You can download a PDF version of the manual here:

The manual has several reference tables:

*  Drag Coefficients depending on the automobile type

*  Holley Jet Chart

*  Jet Orifice Area Conversation Chart


The calculator comes in a bright red Armadillo Gear case.   The keys are bright and colorful, with most of them sporting a warm color palette (red, orange).  The keys are responsive, but have a rubber feel to them.  I believe the keys are made to handle dirt and oils given the target audience of the Hot Rod Calc.

The case has a quick reference guide.

Example Calculations

The calculator is set to U.S. units (default)

Example 1:

Calculate Air Temperature given:

Elevation:  1,284 ft

Air Pressure:  30.12 inHg

Humidity:  33%

1284 [ Elev/ADI ]

33 [ Moisture ]

30.12 [ Conv ] [Air Temp] (Pressure)

[Air Temp],  Result:  55.4211 °F

Example 2:

Find the weight of a vehicle given:

It's horsepower:  426 HP

It's elapsed time:  9.73 sec to run 1/4 mi

426 [ HP ]

9.73 [ ET ]

[ Vehicle Wt ],  Result:  1999.7337 lb

Example 3:

Find the speed, in miles per hour, for an automobile traveling with the following specifications:

1st Gear:  3.26

Final Drive Gear: 3.03

RPM: 5800 (revolutions per minute)

Diameter of the tires: 26 inches

3.26 [ × ] 3.03 [ Gear Ratio ]

5800 [ RPM ]

26 [ Conv ] [ Gear Ratio ] (New Tire Dia)

[ MPH ],  Result:  45.417902  mph


If you are into racing, hot rods, and automobiles, and you need a quick mathematics tool, the Hot Rod calculator is worth the investment.  Its user manual is a well written.  Now may be the best time to purchase one before the calculator becomes a rare item.  


All original content copyright, © 2011-2021.  Edward Shore.   Unauthorized use and/or unauthorized distribution for commercial purposes without express and written permission from the author is strictly prohibited.  This blog entry may be distributed for noncommercial purposes, provided that full credit is given to the author. 

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