background image

40 — H

OT

 R

OD

 C

ALC



 

       

 RPM  S 3000.



 

SPEED  S  65.  M PH



 

       

GEAR  S  3.08 RATIO

10. Calculate the New Tire Size:



 (New tire diameter) 

TIREn  22.431 SIZE IN

 

Repeated presses of 

 will toggle through the inputs and 

outputs, starting with the final-drive ratio input.

From the above calculation, it is estimated that in order to reach 
3,000 RPM in 4th gear, at 65 MPH, the LX could utilize 22.4 inch 
diameter tires to achieve roughly the same performance as the 
previous example where you solved for a new final-drive ratio. It 
may not give you the look you like, but it would be a cost effective 
way to reach your goal. Just remember, by changing the tire size, 
your speedometer will be effected (see Calculating Effects of 
Changing Tire Sizes for more information).

Calculating Carburetor Size

The Hot Rod Calc can calculate carburetor sizes in four 
configurations based on different volumetric efficiency (VE) values: 
User, Theoretical, Street, and Race. See 

Calculating Volumetric 

Ef

fi

ciency

 for more about VE.

The User carburetor size configuration utilizes a user-entered VE 
value, whereas Theoretical uses a predefined VE value of 100%, 
Street uses a VE value of 85%, and Race uses a VE value 110%.

When calculating the carburetor size for your application, be 
careful about what RPM you enter. Selecting an overstated/
unrealistic RPM for your engine at wide open throttle (WOT) will 
result in a mathematically valid carburetor size, but will likely not 
work well with your application. It is best to consult your vehicle’s 
manual or an expert regarding the WOT maximum engine RPM for 
your vehicle.  

Summary of Contents for Hot Rod Calc 8703

Page 1: ...HOT ROD CALC 1...

Page 2: ...cts of motorsports racing especially those with deep understanding of the relationship between weather conditions and engine performance Calculated Industries gratefully acknowledges Patrick Hale Drag...

Page 3: ...for predicting elapsed time and trap speed at 1 8 and 1 4 mile intervals The Hot Rod Calc is a powerful cost effective tool for every performance car and truck owner s toolbox Helps you at the track...

Page 4: ...eed Conversions 13 Engine Displacement Conversions 14 Torque Conversions 14 Weight Conversions 15 Volume Conversions 15 USING THE HOT ROD CALC 16 Important Terms and Definitions 16 Motorsports Standar...

Page 5: ...metric Efficiency 42 Estimating Flywheel Horsepower at a Known RPM 43 Estimating Flywheel Torque at a Known RPM 44 Calculating Compression Ratio 44 Calculating Mill Amount 48 Calculating Piston Speed...

Page 6: ...g twice clears all non permanent values Off Turns all power off Clears all non permanent values Arithmetic operation keys and Keys used for entering numbers Convert Used with the dimensional keys to c...

Page 7: ...gling between linear area and volume units Converts dimensional value to units of inches with repeated presses toggling between inches and feet Feet Identifies entry as feet with repeated presses togg...

Page 8: ...mber e g 8 0 125 Clear All Returns all stored values to the default settings Does not affect Preference settings Displays value of 3 1415927 Toggle displayed value between minus and plus value Prefere...

Page 9: ...can enter a value from 0 to 360 Vehicle Weight Enters or calculates the vehicle s weight Vehicle weight typically includes the driver s weight Calculates vehicle weight given ET and HP or MPH and HP...

Page 10: ...ear ratios adjusted for manual and automatic transmissions New Tire Diameter Enters the new tire size for solving tire and gear ratio problems Engine Displacement Enter or calculate Engine Displacemen...

Page 11: ...lumetric Efficiency Enter or calculate the volumetric efficiency of an engine Calculate given values for Engine Displacement RPM and Carburetor Size Bore Enter or calculate Bore diameter Use to calcul...

Page 12: ...Used in calculating Compression Ratio Horsepower Enter or calculate the engine horsepower calculates Horsepower Correction Factor HPc and Motorsport Standard Atmosphere MSA adjusted horsepower when th...

Page 13: ...Press to exit Preferences Your calculator will keep Preference settings until a Full Reset alters your settings to the default values KEYSTROKES DISPLAY Functional Rounding F RND 0 000 F RND 0 00 F RN...

Page 14: ...re entered press after each entry DIMENSIONS KEYSTROKE 4 5 inches 95 millimeters 1320 feet 201 meters Square and Cubic Dimensions Examples of how square and cubic dimensions are entered press after ea...

Page 15: ...Repeated presses of will toggle between meters and millimeters Enter and convert 4 5 inches to millimeters KEYSTROKES DISPLAY 0 4 5 IN 114 3 MM Repeated presses of will toggle between meters and milli...

Page 16: ...ES DISPLAY 0 450 CU IN LITER 7 3741788 Enter and convert 5 0 liters to CID KEYSTROKES DISPLAY 0 LITER 5 305 11872 CU IN Torque Conversions Enter and convert 42 lb ft to Newton meters KEYSTROKES DISPLA...

Page 17: ...pounds to kilograms KEYSTROKES DISPLAY 0 LBS 2700 KG 1224 6994 Volume Conversions Enter and convert 5 5 gallons to liters KEYSTROKES DISPLAY 0 GAL 5 5 LITER 20 819765 Enter and convert 15 25 liters t...

Page 18: ...s performance enabling better ET and MPH predictions To further understand the Hot Rod Calc s outputs and how to use the calculator please get familiar with the following technical and weather related...

Page 19: ...ly the higher the HPc the slower it will run less horsepower is produced Patrick Hale Motorsports Standard Atmosphere and Weather Correction Methods Arizona DRPro 2008 Density Altitude Density Altitud...

Page 20: ...uire that much less fuel to maintain the same level of performance Be careful It s safer to be 3 rich than to be 1 lean ADI can tell you a lot about what you need to know for carburetor jetting change...

Page 21: ...asurement you might get from the local radio station TV station from the Internet or from a corrected barometer It is corrected for sea level and is not suitable for motorsports Do not use Corrected P...

Page 22: ...r current local measured weather conditions TEMP S 63 2 F Absolute Pressure P ABS S 28 83 INHG Moisture Relative Humidity RH S 58 2 Calculate ADI and density altitude ELEV S 0 ADI 94 641 D ALT 1873 41...

Page 23: ...Firebird International Raceway are unlikely this example demonstrates an ADI value of over 100 which is certainly a possible situation As stated previously air density is typically over 100 when temp...

Page 24: ...Using a Fuel Correction Index Note In this example it is assumed that your current air fuel settings and jet numbers are correct for your engine s requirements at wide open throttle This example uses...

Page 25: ...ADI ELEV S 0 ADI 92 038 D ALT 2813 209 F Notice that the elevation output is 0 feet This is because the example did not include entering an elevation Elevation is only a required input if absolute pre...

Page 26: ...The fuel correction index is about 89 indicating air density is about 89 of the air density from which you baselined your jet numbers In other words the new air density has gone down about 11 from yo...

Page 27: ...example density altitude has gone up so it stands to reason that a leaner jet number may be required A conservative change however would be to go from the 78 to the 76 which has a flow of 587 cubic c...

Page 28: ...ing with the relative humidity input Basic ET Prediction Note Your calculator s ET predictions may vary from other ET prediction sources primarily due to traction The Hot Rod Calc assumes ideal condit...

Page 29: ...after the previous Basic ET Prediction example Your calculator s ET predictions may vary from other ET prediction sources primarily due to traction The Hot Rod Calc assumes ideal conditions with no t...

Page 30: ...d weather conditions are 73 F absolute pressure of 25 88 in Hg and 14 relative humidity KEYSTROKES DISPLAY 1 We have already entered the vehicle s weight and HP so we can skip to the next input local...

Page 31: ...Repeated presses of HP will toggle back through the inputs and outputs starting with absolute pressure Note Recall from the key definitions for Mechanical Efficiency ME that ME is a numeric value repr...

Page 32: ...and direction were when the ET was recorded Additionally you need to know the race car s frontal area and drag coefficient To determine your race car s frontal area measure the vehicle from head on me...

Page 33: ...dan style body we will select a value of 45 Enter the Drag Coefficient of our 1970 Ford Mustang Notchback KEYSTROKES DISPLAY Drag Coefficient DRAG S 0 45 Your disappointing ET was 13 85 at 102 304 MPH...

Page 34: ...rrected Speed SPDc 105 85 MPH Repeated presses of will toggle back through the inputs and outputs starting with the Wind Speed input So if you were to re do your run everything being the same except t...

Page 35: ...has a 2005 Ford Mustang GT with an estimated horsepower of 520 HP and ran a 1 4 mile at 121 6 MPH Calculate the estimated Vehicle Weight KEYSTROKES DISPLAY 4 Clear the memory first 0 5 Enter the esti...

Page 36: ...d 14 relative humidity then calculate the estimated Horsepower again KEYSTROKES DISPLAY 4 Enter current local measured weather conditions TEMP S 73 F Absolute Pressure P ABS S 25 88 INHG RH S 14 5 The...

Page 37: ...diameter of 28 9 inches whereas the mud tires you are looking to upgrade to have a tire diameter of 33 inches Your four wheeler currently has a final drive ratio of 3 08 Calculate the equivalent drive...

Page 38: ...ed will be with an indicated gauge speed of 65 MPH Don t clear the memory on your calculator we can use your inputs from the previous example which are currently in memory 4 Enter a target indicated g...

Page 39: ...99 for 2nd 1 32 for 3rd direct drive 1 00 in 4th and an overdrive 0 68 in 5th The final drive ratio is 3 08 Lastly the tires have a diameter of 26 inches In this example calculate your top speed in 2...

Page 40: ...RATIO 5 Enter your cruising speed of 65 MPH SPEED S 65 MPH 6 Calculate the RPM RPM 1760 004 Repeated presses of will toggle through the inputs and outputs starting with the gear ratio input From the...

Page 41: ...00 RPM in 4th gear at 65 MPH the LX will need a final drive ratio of 3 57 And for the users who have experience with the Larry Shepard correction method your calculator also shows a manual transmissio...

Page 42: ...ng Effects of Changing Tire Sizes for more information Calculating Carburetor Size The Hot Rod Calc can calculate carburetor sizes in four configurations based on different volumetric efficiency VE va...

Page 43: ...RPM S 5400 ENG S SIZE 400 CU IN 2 Calculate the carburetor sizes THEOR CARB SIZE 625 CFM STREET CARB SIZE 531 25 CFM RACE CARB SIZE 687 5 CFM The theoretical carburetor size of about 625 cfm was calc...

Page 44: ...B SIZE 625 CFM STREET CARB SIZE 531 25 CFM RACE CARB SIZE 687 5 CFM Notice within the outputs the User carburetor size appears first in the output This carburetor size is calculated using the entered...

Page 45: ...actual measured airflow capacity at 7000 RPM RPM S 7000 ENG S SIZE 400 CU IN USER S CARB SIZE 625 CFM 2 Calculate your engine s VE EFF 77 143 VOL The calculated VE of your GTO at 7000 RPM is about 77...

Page 46: ...is example your 400 CID engine produces 366 HP at 5400 RPM Calculate the torque for the same RPM KEYSTROKES DISPLAY 0 1 Enter your HP and RPM HP S MSA 366 RPM S 5400 2 Calculate the Torque at 5400 RPM...

Page 47: ...r amount of air fuel mix that is compressed the greater the combustion power will be The greater the combustion power is the hotter the combustion is which can lead to detonation Detonation pinging an...

Page 48: ...uld be entered as a positive number they add to the chamber volume and have a lowering effect on compression Cylinder Head Combustion Chamber Volume You will need to measure this manually Note Your Ho...

Page 49: ...ore The calculated compression ratio is about 8 81 1 At this point if you were not satisfied with this ratio you can use your Hot Rod Calc to play out some other scenarios For this example to raise yo...

Page 50: ...nt to determine how much material to remove from your engine s heads Note Your Hot Rod Calc user s guide does not go into details on the milling process Your local engine building shop will likely hav...

Page 51: ...g racing Piston speed is the speed typically in feet per minute at which the piston moves up and down within a cylinder As your engine s crankshaft rotates once your cylinder s piston travels two stro...

Page 52: ...at about at 5000 RPM 3 Enter the RPM for which you want to determine piston speed RPM S 5000 4 Calculate the Piston Speed at 5000 RPM FPM 2900 M MIN 883 92 At 5000 RPM your piston speed is 2 900 feet...

Page 53: ...ication or modifying one and want to know the effects on displacement by changing bore and or stroke the Hot Rod Calc can do it In this example your 1968 Pontiac GTO s Ram Air II engine has a publishe...

Page 54: ...layed in cubic inches In this example your 1962 Ford Falcon straight 6 engine has a published engine displacement of 169 95 CID The spec Bore and Stroke are 3 5 inches and 2 94 inches respectively Cal...

Page 55: ...respectively Keeping the stock Stroke length calculate a new Bore size First clear the memory on your calculator including temporary and semi permanent entries KEYSTROKES DISPLAY ALL CLEArEd 1 Enter...

Page 56: ...roke length STROK 3 797 IN Notice you can also meet your goals by keeping the stock bore and going to a longer stroke of 3 797 In terms of cost it will be more cost effective to go over bore to reach...

Page 57: ...Convertible 0 5 0 7 Station Wagon and Van Body 0 5 0 6 Notchback or Sedan 0 4 0 55 Fastback 0 3 0 4 Fairings all around streamlined shape 0 2 0 25 K shape 0 23 Optimum streamliner 0 15 0 2 Motorcycle...

Page 58: ...er Drill Size and Flow JET NO DRILL SIZE FLOW 40 040 117 41 041 122 42 042 129 43 043 135 44 044 142 45 045 149 46 046 156 47 047 163 48 048 170 49 049 178 50 049 185 51 050 194 52 052 203 53 052 212...

Page 59: ...92 68 069 411 69 070 429 70 073 448 71 076 470 72 079 492 73 079 517 74 081 542 75 082 566 76 084 587 77 086 615 78 089 645 79 091 677 80 093 703 81 093 731 82 093 765 83 094 795 84 099 824 85 100 858...

Page 60: ...58 HOT ROD CALC 92 105 1150 93 105 1200 94 108 1260 95 118 1320 96 118 1375 97 125 1440 98 125 1500 99 125 1570 100 128 1640...

Page 61: ...01697 0 175 0 02405 0 032 0 0008 0 061 0 00292 0 09 0 00636 0 119 0 01112 0 148 0 0172 0 176 0 02433 0 033 0 00086 0 062 0 00302 0 091 0 0065 0 12 0 01131 0 149 0 01744 0 177 0 02461 0 034 0 00091 0 0...

Page 62: ...EET Drag Coefficient 0 35 Mechanical Efficiency 85 Cylinders 8 Volumetric Efficiency 100 If you replace your batteries or perform a Full Reset press hold down and press your calculator will return to...

Page 63: ...t following the instructions listed below may result in damage not covered by your warranty Refer to the Repair and Return section on page 44 for more details Do not expose calculator to temperatures...

Page 64: ...re key the problem ERROR CODES DISPLAY ERROR TYPE OFLO Overflow too large MATH Error Divide by 0 DIM Error Dimension error ENT Error Invalid entry error Auto Range If an overflow is created because o...

Page 65: ...me very dim or erratic replace the batteries Note Please use caution when disposing of your old battery as it contains hazardous chemicals Replacement batteries are available at most discount or elect...

Page 66: ...Toll Free 1 800 854 8075 Outside USA 1 775 885 4900 www calculated com warranty WARRANTY Warranty Repair Service U S A Calculated Industries CI warrants this product against defects in materials and w...

Page 67: ...ht and duties Disclaimer CI MAKES NO WARRANTY OR REPRESENTATION EITHER EXPRESS OR IMPLIED WITH RESPECT TO THE PRODUCT S QUALITY PERFORMANCE MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE AS A RES...

Page 68: ...66 HOT ROD CALC...

Page 69: ...registered trademark of Calculated Industries Inc ALL RIGHTS RESERVED Designed in the U S A Looking For New Ideas Calculated Industries a leading manufacturer of special function calculators and digi...

Page 70: ...registered trademark of Calculated Industries Inc ALL RIGHTS RESERVED Designed in the U S A Looking For New Ideas Calculated Industries a leading manufacturer of special function calculators and digit...

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