McAfee clued us in on what to look for on Dart's big wet-flow bench, and it didn't take long to see some significant differences in flow patterns between the older Iron Eagle heads and the new Platinum Speed Flow technology. The goal with any intake-port development, especially in regard to wet flow, is to design the port so the fuel is vaporized or mixed with the inlet air stream as uniformly as possible. This is difficult to accomplish because even the tiniest fuel droplet has significantly more mass than air, which means it is much easier for air to turn a corner or move around a valve seat than fuel.
The idea behind wet-flow development is to make it as easy as possible for the fuel to remain in suspension with the air. In a poorly designed head, the fuel will tend to collect as a series of small rivers of liquid that stream into the cylinder. Large droplets of fuel take longer to burn and burn incompletely as compared with very tiny spheres of fuel that burn very quickly and more completely. This means the smaller the droplets within the air stream, the less fuel is required to make the same power. It also means a leaner air/fuel ratio for the same (or more) power. This is why the Pro Stockers can make best power with an air/fuel ratio of roughly 13.5:1 instead of 12.5:1.
Since these smaller fuel particles will burn more quickly, a well-designed intake port and chamber will result in an engine that requires less timing to make the same power. Roughly 25 or 30 years ago, it was common for a small-block to require 38 to 40 degrees of total timing to make best power. The latest Gen III GM small-blocks now routinely make best power with less than 30 degrees of total timing. When it comes to ignition timing, less is better than more.
Looking at the photos of the Platinum compared with the Iron Eagle head, you should be able to see how the Platinum head introduces a much less defined and more evenly distributed air/fuel stream into the cylinder. The goal is to create an air inlet stream where the fuel is completely vaporized and integrated into the inlet air stream. When, or if that happens, you can expect power to take a significant leap forward.
Flow Test
In this dry-flow test performed on a SuperFlow 600 flow bench, you can see there is very little difference between the Iron Eagle and Platinum intake ports, each with 2.05-inch intake valves. Both heads were flowed at a 28-inch test depression on a 4.060-inch bore diameter.
| Valve Lift | Iron | Platinum | Iron | Platinum |
| Eagle | Intake | Eagle | Exhaust |
| | Intake | Exhaust
w/pipe | w/pipe |
| 0.100 | 65 | 64 | 59 | 57 |
| 0.200 | 129 | 128 | 112 | 111 |
| 0.300 | 182 | 180 | 139 | 140 |
| 0.400 | 226 | 221 | 166 | 172 |
| 0.500 | 258 | 253 | 178 | 189 |
| 0.600 | 255 | 273 | 186 | 198 |
Wet-Flow Test Comparison
215 Iron Eagle 112.6 lbs/hr fuel flow rate215 Platinum 115.7 lbs/hr fuel flow rate
Difference: approximately 3 percent
This photo shows how the intake port vanes direct air and fuel toward the center of the bore as they flow past the intake valve. This angles the air and fuel away from the cylinder wall where fuel tends to separate from the inlet stream.
Since the chamber is very much an extension of the intake port, note how the heart shape is actually dictated by laying the combustion chamber wall back to improve dry and wet flow as the air and fuel enter the chamber.
This is a shot of the wet-flow characteristics of the Iron Eagle port. Note how there is a distinct curved line of fuel exiting the intake port (arrow).
This is a photo of the Dart Platinum head at the same valve opening and test depression. Despite the fact that the Platinum head flows more fuel than the Iron Eagle, the distribution of the fuel is more uniform and less distinct. This is visual evidence suggesting the wet-flow modifications are successful in creating a more homogeneous mixture entering the cylinder.