Custom Headwork by Dave Mackie Engineering

For decades Dave Mackie Engineering (DME) headwork has been ranked with the best available anywhere.  The Keith Ruxton engines in the Easyrider Harley Streamliner were running DME ported heads when it became the Worlds Fastest Motorcycle at over 322 miles per hour.  Bob Taft of Rat’s Whole Place was running DME ported heads when his drag bike became the World's First 8-Second Evolution Powered Drag Bike.  The list goes on to include Scores of National Records, many National Championships and Sturgis and Daytona Dyno Shootout Winners.

DME headwork has several features that make it unique in the industry.  After glass beading and cleaning ports and combustion chambers we take measurements to determine the effects of foundry core shift.  We then select the best program and CNC shape each port.  The use of CNC equipment assures that we get we our best shape every time.  When the CNC work is complete we apply the polishes and atomization finishes.

A few words about polishing.  There are several conceptions about polishing ranging from “it’s magic” to “it doesn’t do a thing.”  The truth lies somewhere in between.  Polishing actually melts and seals the skin of the surface being polished thus forming a bit of a barrier to help retain heat in that area.  At DME we polish the combustion chambers and the exhaust ports.  It is desirable to keep heat in the combustion chamber because heat is power which is what we are after.  We also want to keep heat in the exhaust ports because the hotter the exhaust gases are the greater the velocity they will have.  Increased velocity will get the gases out faster.  These benefits exist even after these areas carbon up because the underlying surfaces are still sealed.

Areas that should not, in our opinion, be polished are the intake ports and manifold.  Polishing has little or no effect on flow characteristics but it can have a detrimental effect on atomization.  The reason for this is that the fuel in the intake charge is heavier than the air.  When the charge bends its way through the manifold and port the fuel tends to centrifuge out of the air stream and onto the port wall.  When the wall has a high polish the fuel tends to cling to the wall and slides on into the combustion chamber as raw fuel.  Raw fuel does not burn as well or as completely as when atomized and this can result in less power, less economy, and a “dirtier” motor.  For these reasons DME creates very coarse textured, high atomization intake ports and manifolds.  This coarse finish inhibits the sliding of the fuel and kicks it back into the air stream where it is then re-atomized.  This can result in more power, better economy and a cleaner running engine.
 
When the ports are finished we do our competition valve job and blend and contour the seat areas with the ports and combustion chambers.  DME competition valve jobs are done on state of the art Sunnen and Kwik-Way equipment to assure that we get the most concentric and accurate results possible.  Our valve jobs may have as many as six angles, can fully radiused, or have a combination of angles, radiusing, and blending by hand depending on the effect we are trying to create. 
 
At DME there is no such thing as “one size fits all.”  There are no heads in boxes on shelves ready to ship.  We make every effort to customize each set of heads to the individual needs of the customer.  Although we, and most of our customers prefer that we work on their own heads, we do have an exchange program available.  Even so, we want to discuss the needs of the customer before we finalize the job.  We can usually ship very shortly after the discussion.