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The Magic, Art and Science of Cylinder Head Porting

An internal combustion engine is a breathing machine, a self powering pump that creates power in proportion to the mass of air/fuel mixture following through it. The greater the flow the more power it will create, any modification that increases the flow, increases the power. Modifications to the short block (other than increasing the displacement) are for adding durability and strength; they don’t significantly contribute to enhanced power. The cylinder heads are a totally different story.  Bolting on a set of professionally ported heads can often really ‘wake up’ a motor which has all the traditional upgrades, sometimes seeming to add more power than all the other components combined. It is because of this many believe there’s some secret magic art to cylinder head porting. It appears mind boggling that the strategic removal of metal and the reshaping of the ports can do so much; it’s just got to be magic, right? In reality the unported head is often the last bottleneck restricting the engine’s power.  Simply put without good flowing heads big power is impossible. However, bigger isn’t always better, it has to be optimal for the given application. If we made the flow of every component huge the maximum peak power would also be huge, but the engine may become weak or even incapable of running at low and moderate throttle positions and the more frequently used street rpm ranges. If the ports are too large the fine mist of air and fuel that is required for powerful fast combustion will be severely compromised, because the mixture flow velocity will be too slow under such conditions. It is important that the flow of all the individual components is well matched to produce a great running motor. This is where the knowledge and skill of an experienced engine builder and head porter becomes indispensable. Flow through a curved irregularly shaped port is not easily guessed at. This is somewhat analogous to aerodynamic drag, where an exotic super car looking as slick as a fighter jet can often have a much poorer drag coefficient than an econo-box car. A novice with a grinder on the kitchen table can make some improvements but unless they have the luck of a Lotto winner they aren’t going to produce a top performing head. Professionals develop and refine their port designs through years of experience, and feed back from experiments utilizing flow benches, engine dynamometers, and of course the race track to produce powerful and efficient products to match their intended use.
At Nitemare Performance we can optimize ports to match your other engine components and intended RPM range and power. Currently, all our work involves hand porting.  We feel that those detailed touches only a skilled hand porter can do make for better heads. CNC (Computer Numerically Controlled) cut heads are only as good as the port they are duplicating; if you copy a poor port design or a ‘hack job’ all the CNC cut heads you produce will be poor/hack jobs too. Remember, CNC cut ports aren’t good just because they are CNC, but they can be good if they duplicate great port designs that fits your application.  Many places use the same digitized port design for nearly all the heads they sell, even for applications where it may not be appropriate, if your goals are performance don’t buy a head just because it says CNC. There are two places where CNC cut ports really shine; consistency of flow from port to port, and labor saving (cost) and these benefits are not lost on us, which is why we will soon be offering some of our best port designs as CNC offerings that are then individually inspected and hand detailed as required.
All machine work is performed to exacting standards and tested on our state of the art flow bench.  We can modify your personal cylinder heads or supply you with heads from the wide range of casting numbers we have in stock.
Stage 1 Ported Heads. These heads include the following:- All cast iron heads are boiled, liquid magnaflux tested to ensure they are free from cracks and defects, glass beaded and resurfaced on the deck (for the desired compression ratio) and the intake faces (for fit). The intake and exhaust ports are ported per application (326, 350, 389 and 400 cubic inch engines). All heads are sonically tested during and after all porting procedures in our shop and detailed reports including material thicknesses in crucial areas are provided to our customers for their records. Fully detailed flow sheets for the intake and exhaust ports are supplied for .100” to .700” lift ranges. Additionally the following procedures and parts are included:
*Street/Strip valve job*New 2.11 Intake and 1.77 Exhaust valves*Bronze wall guides *
*Spring seats trued*New valve springs for your cam application*New retainers*New super locks*
*New 7/16 rocker studs*New guide plates*Machined for valve seals *Porting to application appropriate CFM*
Stage 2 Ported Heads. These heads include everything from stage 1, plus additional port work per application for 421, 428 and 455 cubic inch engines. 
Stage 3 Ported Heads. The stage 3 heads include everything from stage 2, plus the maximum amount of port work possible, while still maintaining a ‘SAFE’ port. These are full competition heads for larger cubic inch engines (462 to 500 cubic inch).
At Nitemare Performance we always endeavor to keep our customers fully informed. Call ( 203 239 6868 )  or E-mail: for pricing and your casting number requests or for recommendations for your application. We sell our heads outright fully assembled but, if you desire, we can use your castings and perform the same services.