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The components responsible for manipulating airflow are:
Manifolds (plenum size and transition smoothness)Gaskets and how they match up to the ports
Runners (texture and shape)
Ports (long turn and short turn radius) texture and shape.
Valve's:
- Valve guide length
- Valve stem diameter
- Valve seats
- Valve face
- Valve sealing area
Piston top shape and Clearance with valves
Equipment used for modifying a cylinder head:
Air-flow test bench (uses actual forced air and calibrated devices to measure air flow pressure).
Porting tool and sanding bits
Milling machine
Valve cutting/grinding machine
Valve seat cutter/grinder
Welder or epoxy to add material
Machinist blue dye to lay out your work
Plenty of measuring devices
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Check out a NJ cylinder head porter called "Head Games". They seem to work on everything! Click the link and browse their website. They have many different makes and models of cars in their menu which show the work they have done.
Link to Head Games website
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Harley forum posting explaining a Valve Job and it's complexities.
Link to Harley forum on Valve Jobs
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Crankshaft Coalition's WIKI page on introduction to cylinder head porting.
Link to Crankshaft Coalition
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In this website, Chevy Thunder, the author describes all of the components that must also be modified and how, when performing cylinder head porting. I really enjoy his graphics and his attention to the numbers.
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Here is a forum thread from the H.A.M.B/Jalopy Journal on basic cylinder head porting. If you browse through this forum there will be many people building really cool hot rods and documenting them extensively.
Link to HAMB and Jalopy Journal Basic Head porting.
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This article was produced by a company called Standard Abrasives explaining how their products are used for cylinder head porting. They went ahead and explained the basic porting process in great detail! It is a very informative document.
Link to Standard Abrasives porting document.
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The website article here describes the use of thread to view air flow and turbulence. The thread can also find "dead spots" where the air isn't even present during its flow path towards the cylinder. You can see the tumble and the swirl produced by the port. This air is directed purposely towards areas in the combustion chamber such as squish pads and the spark plug (forces the air fuel mixture to go right to the source of pressure and ignition).
Link to DIY Porting Using Thread to check flow
There is also a bunch of information on engine performance and set up in this website DIYPorting. Check this link to the Piston to Valve Clearance. It is important to get a tight PtoVC, but not enough clearance and you will run the valve into the piston when it expands!
Link to DIY Porting PVC
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This MotorGeek forum thread shows extensive modifications performed on a 5-cylinder 20-valve Audi engine. There are also pictures of it on the flow bench.
Link to MotorGeek forum thread
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Here is an Audi inline-5 20-valve that has set a world land speed record. In the following links you will see the amount of work that goes into building a high-HP high-speed engine. There are MANY Pictures and detailed explanations.
Project Pad link to FRP (Four Rings Performance) LSR Audi.
Link to Quattro World article on the car and a VIDEO!
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Link to Engine Builder Mag article on pistons and cylinder finishes.
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Last but not least.... A link from Speed Academy that explains how rotary engine porting works. This defies much of what you already understand from piston engine porting.
