“Wet-flow testing has dramatically changed my thinking,” McAfee reported. “There are ways to ‘trick’ the air on a dry-flow bench that simply don’t work in the real world. In our Pro Stock engine program, I’ve built heads that had incredible flow on the dry bench, but were down on power on the dyno. When we tested these heads on the wet bench, we understood why. After we introduced fuel to the mixture, the airflow was down 100 cfm. We learned there were significant differences between dry and wet flow that we needed to understand.

“If you can keep the port the same size or smaller, and move more air and fuel at the correct mixture through it, the engine will respond with more power,” he revealed. “Making a port bigger usually allows it to flow more air and fuel – but if you can keep the port small and still put more air and fuel through it, the engine always makes more power.

“The wet-flow bench is teaching us what the fuel likes,” McAfee continued. “For example, fuel loves sharp edges around the intake seats. Shearing the fuel on an edge usually increases the mixture cfm. If the flow starts to become unstable, the fuel enters the chamber in a solid stream. That’s often a sign that port has become saturated, so the fuel collects and runs down the corners of the ports into the chamber.”

Although Dart’s ambitious Pro Stock engine program initially sparked Maskin’s interest in wet-flow testing, the obvious benefits of this technology have inspired Dart’s R&D staff to apply wet-flow testing to other Dart products. During our visit, the company’s complete line of cast-iron small-block heads was being wet-flow tested. It didn’t take a trained eye to see the advantages of the new Platinum series small-block heads. The evenly dispersed fuel mixture flowing into the cylinder was a clear improvement over previous designs. The wet-flow bench’s computer monitor confirmed the gain: Flow at .600-inch valve lift showed a 40 cfm improvement along with an increase of 15 pounds of fuel per hour.

“Wet-flow testing is a new game and we’re still learning,” McAfee noted. “At this point, we know that an increase in air/fuel volume and a more even distribution of fuel around the valve and chamber makes an engine perform better. We’re becoming more adept at transferring what we’ve learned in the Pro Stock development program to our production cylinder heads to give racers more of what they want. For example, you’d be hard pressed to find a ported head that performs as well as the as-cast ports and chambers in the new Platinum small-block head.”

Like dry-flow benches and dynos, the wet-flow bench is another weapon in Dart’s arsenal. The wet-flow bench makes the invisible movement of fuel and air apparent, and it provides data on a cylinder head’s ability to move fuel and air efficiently.

“With every test on the wet-flow bench, we learn more about how fuel and air behave,” Maskin said.

And the science of acceleration marches on.