Star Performance Products, Discount Car Parts - Formulas
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Star Performance Products, Discount Car Parts - FormulasWed, 04 Oct 2017 16:25:34 GMTWed, 04 Oct 2017 16:25:34 GMT60FormulasFormulas2017-10-04T16:25:34ZCarburetor CFM Formula
http://www.starperformanceproducts.com/Carburetor-CFM-Formula-Carburetor-CFM-Formula.htm?categoryId=329
CI X RPM X VE / 3456<br/><br/><br/><br/><a href= "http://www.starperformanceproducts.com/Carburetor-CFM-Formula-Carburetor-CFM-Formula.htm?categoryId=329"><img src="https://www.starperformanceproducts.com/images/no_product_image_lg.gif"/></a> <br/><br/><b>Price:</b><b> $0.01</b><br/><br/><a href="http://www.starperformanceproducts.com/Carburetor-CFM-Formula-Carburetor-CFM-Formula.htm?categoryId=329">Purchase Now</a>http://www.starperformanceproducts.com/Carburetor-CFM-Formula-Carburetor-CFM-Formula.htm?categoryId=3290.01$0.01446https://www.starperformanceproducts.com/images/no_product_image_lg.gif100100CFM, Cubic Feet per Minute of air flow. This is the number that determines how much air your engine flows or requires at maximum operating RPM. CFM is used to determine the size of the carburetor you need. It is calculated using the following formula. It's important to get your carburetor the correct size for several reasons. By over carbureting you reduce or lose low-end performance, economy, vacuum signal and throttle response. Under carbureting will limit your upper end horsepower and usable RPM range.
The variable in the calculation is Volumetric Efficiency (VE). This number takes into account the type of cam, heads, intake manifold, etc. that you are running. VE is a fancy way of saying how much air actually gets into the engine while the engine is running versus how much air can fit into the engine when it's sitting still. When the piston is a BDC or Bottom Dead Center and the engine isn't running the amount of air that gets into the cylinder is determined by the outside air pressure, around 15 psi. When the engine is running, the air meets lots of restrictions to getting into the cylinder. These restrictions start at your air cleaner, then your carburetor, your intake manifold runners, cylinder head ports and finally valves. All of these things create a restriction for air to enter into your cylinder. VE is the percentage of air that could get into your engine versus the air that actually gets into your engine. On a typical stock motor that number is around 80-85%, on a street performance motor that number can increase from 85-90%. On a very hot street motor that number can go as high as 95%. On all out race motors that number can exceed 100%, but only for a very small RPM band. For the sake of building a street motor, we'll use 90% VE when sizing a carburetor, just to be on the safe side. We'd rather be a little over carbureted than under carbureted.
<ul>
<li>CFM = Displacement X RPM X VE / 3456</li>
<li>Example: CFM = 350 CI X 6000 RPM X 90% Volumetric Efficiency / 3456</li>
<li>CFM = 350 X 6000 X .90 / 3456 = 546.87</li>
<li>CFM = 546.87</li></ul>Compression Ratio Formula
http://www.starperformanceproducts.com/Compression-Ratio-Formula-Compression-Ratio.htm?categoryId=329
Compression Ratio<br/><br/><br/><br/><br/><br/><b>Price:</b><b> $0.01</b><br/><br/><a href="http://www.starperformanceproducts.com/Compression-Ratio-Formula-Compression-Ratio.htm?categoryId=329">Purchase Now</a>http://www.starperformanceproducts.com/Compression-Ratio-Formula-Compression-Ratio.htm?categoryId=3290.01$0.01490<ul><li>Compression Ratio:</li>
<li>This formula comes in handy when you're designing your engine and you need to know what Compression Ratio you're going to end up with when choosing the stroke of the crank, the final bore size and the cylinder head chamber size. Compression Ratio or CR is described as the amount of space a cylinder has when the piston is at BDC (Bottom Dead Center) versus the amount of space there is when the piston is at TDC (Top Dead Center) and is indicated in ratio form. It is one of the more difficult numbers to get absolutely accurate. That can only be done if the engine is disassembled and you can measure the volume of several critical areas, i.e., the compressed gasket volume, the deck height clearance volume, etc. You need five different measurements. They are described below. For the sake of keeping it simple we'll give you some averages to work with, with respect to some of these numbers. But first we'll give you the actual formula. We'll use a typical 350 Chevy engine.</li>
<li>Compression Ratio = Cylinder Volume + Deck Clearance Volume + Head Gasket Volume + Piston Dish or Dome Volume + Cylinder Head Chamber Volume / Deck Clearance Volume + Head Gasket Volume + Piston Dish or Dome Volume + Cylinder Head Chamber Volume</li>
<li><strong>1. Cylinder Volume:</strong></li>
<li>The cylinder volume is the actual volume of just the cylinder with the piston at BDC which is calculated by the bore and the stroke times 0.7853982 (the number to calculate the area of a circle.)</li>
<li>Example:</li>
<li>Cylinder Volume = 0.7853982 X Bore X Bore X Stroke</li>
<li>Cylinder Volume = 0.7853982 X 4.0" X 4.0" X 3.48"</li>
<li>Cylinder Volume = 43.73 CI</li>
<li><strong>2. Deck Clearance Volume:</strong></li>
<li>Deck Clearance Volume is the space left by the piston from the top of the piston to the top of the block deck surface. Although this number can range from 0.003" to 0.020", we're using 0.015" as an average.</li>
<li>Example:</li>
<li>Deck Clearance Volume = 0.7853982 X 0.015" X Bore X Bore</li>
<li>Deck Clearance Volume = 0.7853982 X 0.015" X 4.0" X 4.0" = 0.188 CI</li>
<li><strong>3. Head Gasket Volume:</strong></li>
<li>The Head Gasket Volume is the space that is left by the diameter and compressed thickness of the gasket, that can range from 0.015" to 0.051". We're using 0.030" thick gasket for our calculation.</li>
<li>Example:</li>
<li>Head Gasket Volume (HGV) = 0.7853982 X 0.030" X 4.0"X 4.0" = 0.376 CI</li>
<li><strong>4. Piston Dish or Dome Volume:</strong></li>
<li>The Piston Dish or Dome Volume is the amount of material which either cuts into the top of the piston like valve reliefs or protrudes upward like a higher compression dome. This will actually need to be measured but we'll use a flat top piston with 0.275 CI valve reliefs for our calculation.</li>
<li>Example:</li>
<li>Piston Dish or Dome Volume = 0.275 CI</li>
<li><strong>5. Cylinder Head Chamber Volume:</strong></li>
<li>The Cylinder Head Chamber Volume is the combustion chamber of the cylinder head. Although this number can vary depending on the condition of the head, we're using 64CC heads for our calculation. This number will need to be converted to CI by multiplying the 64 CC by 0.0610237.</li>
<li>Cylinder Head Chamber Volume = 64 CC X 0.0610237 = 3.905 CI</li>
<li><strong>Final Calculation of Compression Ratio:</strong></li>
<li>Example:</li>
<li>Compression Ratio = Cylinder Volume + Deck Clearance Volume + Head Gasket Volume + Piston Dish or Dome Volume + Cylinder Head Chamber Volume / Deck Clearance Volume + Head Gasket Volume + Piston Dish or Dome Volume + Cylinder Head Chamber Volume</li>
<li>Compression Ratio = 43.73 + .188 + .376 + .275 + 3.905 / .188 + .376 + .275 + 3.905</li>
<li>Compression Ratio = 48.474 / 4.744</li>
<li>Compression Ratio = 10.21:1</li></ul>Cubic Inch Displacement (CID) Formula
http://www.starperformanceproducts.com/Cubic-Inch-Displacement-CID-Formula-Cubic-Inch-Displacement.htm?categoryId=329
Cubic Inch Displacement<br/><br/><br/><br/><br/><br/><b>Price:</b><b> $0.01</b><br/><br/><a href="http://www.starperformanceproducts.com/Cubic-Inch-Displacement-CID-Formula-Cubic-Inch-Displacement.htm?categoryId=329">Purchase Now</a>http://www.starperformanceproducts.com/Cubic-Inch-Displacement-CID-Formula-Cubic-Inch-Displacement.htm?categoryId=3290.01$0.01491<ul><li>Engine Cubic Inch Displacement (CID) or (CI):</li>
<li>This is handy when determining what your final CID will be by using different combinations of crank stroke and overall bore diameter. We used a typical 350 Chevy small block in this example.</li>
<li>Cylinder Volume: The cylinder volume is the actual volume of just one cylinder with the piston at BDC which is calculated by the bore and the stroke times 0.7853982 (the number to calculate the area of a circle).</li>
<li>Cylinder Volume = 0.7853982 X Bore X Bore X Stroke</li>
<li>Cylinder Volume = 0.7853982 X 4.0" X 4.0" X 3.48"</li>
<li>Cylinder Volume = 43.73 CI Per Cylinder</li>
<li>Total CID = 43.73 X 8 (if you have an eight cylinder engine) = 349.84 CID, rounded off to 350 CID</li></ul>