Name: __________________________________________________________ Hr. _____
The .07 Vertigo RC 1/16 Nitro engine:
Disassembly, Measurements and Calculations, and Reassembly
Data Sheet
Step 6: Stroke (s) =
_______________ millimeters (mm)
Step 7: Bore (B) =
_______________ millimeters (mm)
Step 9: Radius (r) =
Bore/2 =
_______________ millimeters (mm)
Step 9 (continued): Cylinder Cubic Displacement (d). d = pi*(radius2)*stroke = pi*(r2)*s
Step 9 (a) = Cylinder Cubic Displacement in mm3 (cubic mm) = ________________________ mm3
Use the following conversions to covert cubic mm to cubic cm (cc or cm3), to liters (L), and to cubic inches (in3).
There are 10 mm per 1 cm, 1000 cm3 per liter, and 1.54 cm per inch.
Step 9 (b) = Cylinder Cubic Displacement in cm3 (cubic cm or cc) = ________________________ cm3
Step 9 (c) = Cylinder Cubic Displacement in liters (L) = ________________________ L
Step 9 (d) = Cylinder Cubic Displacement in in3 (cubic inches) = _________________________ in3
Side note: Engine size (cubic displacement, http://en.wikipedia.org/wiki/Engine_displacement)
is given as a volume. Different car manufactures use different units. Most today use Liters but in the past,
cubic inches were often used. To obtain the cubic displacement of an engine, you would do the above
calculations for one of its cylinders and then multiply by the number of cylinders.
For example, the 426 Hemi means that the engine is 426 cubic inches in volume. A current Mustang GT comes
with a 5 L engine. My Honda Fit, on the other hand, comes with a 1.5 Liter engine.
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Step 11: Combustion Chamber Volume (c). Each drop of water = 0.5 mL. Take your number of drops* 0.05 mL to
obtain the combustion chamber volume (c).
11a. Your number of drops of water = ___________________ drops
11b. Your combustion chamber volume = ____________________ mL or cc or cm3
11 c. Compression ratio = cubic displacement of engine in cubic centimeters (see step 9b) / your combustion
chamber volume (in mL or cc or cm3) found directly above:
Compression ratio = step 9b / 11b = ____________________________________________________
The compression ratio is a unitless number (volume in cc / volume in cc.)
Side Note: Compression ratio (http://en.wikipedia.org/wiki/Compression_ratio) is one of the fundamental
measures of an internal combustion engine. It is a ratio of the volume of the cylinder and combustion chamber
at BDC (Bottom Dead Center) to the volume of the cylinder and combustion chamber at TDC (Top Dead Center).
Larger values of the compression ratio mean that the engine is compressing the fuel-air mixture a greater
amount and consequently, the engine can get more energy from the fuel. There is a downside, though. If a
lower octane fuel is used in an engine with a high compression ratio, then this fuel may be ignited by the
compression at an earlier moment, instead of by the spark plug at the correct time. This is known as engine
knocking. Engine knocking can damage an engine. Premium gasoline has a higher octane number and can
reduce knocking. Also, there exists knock sensors that act to slightly adjust the spark plug timing.
Four stroke gasoline engines have a compression ratio of around 10:1. With the proper anti-knock technology
employed, gasoline engines with compression ratios as high as 13:1 can be produced. As diesel engines use
compression to ignite the fuel-air mixture and not a spark plug, compression ratios will be larger. They common
exceed 14:1 and may be as high as 22:1. The TDI Jetta diesel engine from Volkswagon has a compression ratio
of 16.5:1. My Honda Fit (four stroke gasoline) has a compression ratio of 10.4:1. Methanol engines (RC cars
running on nitromethane) may have compression ratios of around 16:1.
----------------------------------------------------------------------------------------------------Manufacturer’s Spec for the .07 Vertigo RC 1/16 Nitro engine:
Bore = 11.5 mm or 1.15 cm
Stroke = 11 mm or 1.1 cm
Cubic Displacement = 1.14 cc
RPM = 31,000
Power = 0.65 HP
Mass = 125 g
--------------------------------------------------------------------------------------My measurements and calculations:
I obtained a stroke of 11.5 mm and a bore of 10.5 mm using a ruler and straw. I then calculated a cubic
displacement of 995.2 mm3 = 0.9952 cm3 or Liters = 0.2725 in3. Using a pipette, I counted 2.5 drops to fill the
combustion chamber = 0.125 mL or cc or cm3. Finally, I calculated a compression ratio = 0.9952 cm3/0.125 cm3 =
8:1.
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