Compacted graphite iron (CGI) is a form of cast iron which has elongated graphite particles mixed with spherical graphite particles present within the alloy, as opposed to the graphite “flakes” present in typical cast iron.
6061 is an aluminum alloy containing elements of silicon and magnesium, and is typically supplied in billet rather than cast form. The alloy has excellent mechanical properties that make it highly suitable for a wide range of high strength manufacturing applications, from automotive parts to aircraft components.
Computer Numerical Control machining, commonly called CNC, means that all of the actions of the machining center are controlled by a computer program rather than directly by the human operator.
The Platinum version of the Dart’s popular Iron Eagle and PRO 1 heads are the direct descendants of Dart’s Pro Stock engine program. wet-flow technology and improved combustion efficiency propelled the project.
Wet flow testing allows a cylinder head designer to look at how the air/fuel mixture behaves when routed through a head and into the combustion chamber. The air/fuel mixture is much heavier and behaves very differently than dry air, so managing the mixture efficiently gives much better results than just increasing air flow will.
The term “billet” generally refers to components which are machined from a drawn or forged blank of aluminum, usually 6061 alloy, rather than a cast shape. Billet aluminum differs from cast aluminum both in alloy and grain structure.
Dart’s Iron Eagle Platinum small block cylinder heads with 49cc combustion chambers are very popular among oval track racers competing in classes that require flat top pistons, but what pistons to use?
With Dart’s vastly improved oiling system, the need to “band-aid” the oiling system with a high volume oil pump is a thing of the past. Using a standard oil pump and today’s lifters, without restrictors, makes engine assembly easier and eliminates the guess work of determining restrictor size.
Dart’s Molybdenum Disulfide based coatings, such as the DC-4 lubricating coating often used on camshafts, are an excellent way to increase load capacity and improve durability… but you need to be selective about the type of break-in oil used on an engine that employs these coatings.
One of the great features of the Dart Special High Performance (SHP) small-block is its provisions to use OEM hydraulic roller lifters.