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
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