Mr. Gasket 8703 Hot Rod Calculator - Manual (Page 46)

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* Repeated presses of  will toggle through the inputs and outputs,
starting with the entered final-drive ratio.
** 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 section on page 39
for more information).
CARbuRetoR sIze
The Hot Rod Calc
can calculate Carburetor Sizes in four config-
urations based on different volumetric Efficiency (vE) values:
User, Theoretical, Street and Race. See Volumetric efficiency
section on page 46 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 of 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.
Lastly, while carburetors come in many sizes, they are not avail-
able in just any size. It is quite possible you won’t find one that is
of the exact size you calculated on your Hot Rod Calc.
Carburetor Sizes are designated by airflow capacity in cubic feet
per minute (CFM).
(cont'd)
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