Porting cylinder heads
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==Preamble== | ==Preamble== | ||
| − | The purpose of this article is to acquaint engine builders to the possible benefits of cylinder head porting and making more power through the porting process. | + | The purpose of this article is to acquaint engine builders to the possible benefits of cylinder head porting and making more power through the porting process. |
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| + | ==Port volumes vs. HP== | ||
| + | Port volume (or actually cross sectional area) is an important consideration when it comes to how big to make ports. Below is a table by David Vizard showing the relationship between port volumes and HP on a SBC 23 degree head. | ||
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| + | [[File:Vizard port volume vs hp sbc.jpg]] | ||
==Areas to work on== | ==Areas to work on== | ||
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When a port is machined for a seat, often a lip is left below the seat. This lip is sometimes semi-removed using a type of tapered reamer that helps smooth the transition from the seat into the pocket portion of the port. But because this is done quickly and by machine and not carefully and by hand, there is still almost always places where improvements can be made. | When a port is machined for a seat, often a lip is left below the seat. This lip is sometimes semi-removed using a type of tapered reamer that helps smooth the transition from the seat into the pocket portion of the port. But because this is done quickly and by machine and not carefully and by hand, there is still almost always places where improvements can be made. | ||
| − | [[File:EXH PORT.jpg|thumb|400px|left| Arrows indicate lip left after the machining process. This needs to | + | [[File:EXH PORT.jpg|thumb|400px|left| Arrows indicate lip left after the machining process. This needs to be carefully removed so the transition from the seat to the pocket is smooth.]] <br style="clear:both"/> |
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===Gasket matching=== | ===Gasket matching=== | ||
| − | This is a simple process whereby we will match thermostat housing to an intake manifold for better flow of coolant from the engine to the radiator. Begin by cleaning off the surface of both housing and intake mating surfaces. Remove all gasket material and glue with acetone and a gasket scraper. True the surface of slight imperfections by using a mill/bastard file place flat on the gasket surface working the file back and forth. The shiny | + | This is a simple process whereby we will match thermostat housing to an intake manifold for better flow of coolant from the engine to the radiator. Begin by cleaning off the surface of both housing and intake mating surfaces. Remove all gasket material and glue with acetone and a gasket scraper. True the surface of slight imperfections by using a mill/bastard file place flat on the gasket surface working the file back and forth. The shiny spots are the highs and the dull ones are the lows, true these surfaces. When a flat surface is obtained,paint the surface with Dykem dye, lay a new gasket on the surface and insert the bolts in the holes of the intake to center the gasket over the openings. With a scribe, scratch along the gasket edge around the opening. When complete, remove bolts and gasket. This will reveal a scribed line in the purple dye that you will be enlarging up the opening to. |
*If this is an aluminum intake, chuck up a open cut burr that is used for aluminum, and spray it with WD40 or similar lubricant. This will make cleaning the tool easier, reduce friction and heat. | *If this is an aluminum intake, chuck up a open cut burr that is used for aluminum, and spray it with WD40 or similar lubricant. This will make cleaning the tool easier, reduce friction and heat. | ||
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*[http://www.empirenet.com/pkelley2/DynamicCR.html Dynamic compression calculator] by Kelly | *[http://www.empirenet.com/pkelley2/DynamicCR.html Dynamic compression calculator] by Kelly | ||
*[http://www.kb-silvolite.com/calc.php?action=comp2 Dynamic compression calculator] by KB | *[http://www.kb-silvolite.com/calc.php?action=comp2 Dynamic compression calculator] by KB | ||
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| + | ===Other calculators=== | ||
| + | *[http://users.erols.com/srweiss/calcplv.htm Port Limiting Velocity | ||
| + | or Minimum Port Cross Sectional Velocity] | ||
| + | *[http://users.erols.com/srweiss/calccsa.htm Port CSA] | ||
| + | *[http://users.erols.com/srweiss/calcacsa.htm Average Port CSA] | ||
| + | *[http://users.erols.com/srweiss/calcfps.htm Port FPS / CFM / CSA] | ||
| + | *[http://users.erols.com/srweiss/calcdchg.htm Convert Airflow to a Different Depression] | ||
| + | *[http://users.erols.com/srweiss/calcafhp.htm Estimate Horsepower from Intake Airflow] | ||
| + | *[http://users.erols.com/srweiss/calchpaf.htm Estimate Intake Airflow needed from HP wanted] | ||
| + | *[http://users.erols.com/srweiss/calcve.htm Estimate Volumetric Efficiency] | ||
| + | *[http://www.rbracing-rsr.com/runnertorquecalc.html Inlet Runner and Peak Torque Calculators] | ||
==Related links== | ==Related links== | ||
| − | * | + | *[http://www.centroidcnc.com/cnc_porting_machine.html CNC cylinder head porting and block machines] |
| − | * | + | *[http://www.ruffstuff.com/ Cylinder head porting abrasives] |
| − | * | + | *[http://hubpages.com/hub/Cylinder-Head-Porting-101 Cylinder Head Porting 101] |
| − | * | + | *[http://www.diyporting.com/Shrouding.html Valve shrouding] from diyPorting.com |
| − | * | + | *[http://www.superchevy.com/technical/engines_drivetrain/cams_heads_valvetrain/sucp_0902_chevy_engine_port_variations_measuring/viewall.html How to calculate the optimum intake port volume] |
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