Direct port water methanol injection setups have gained popularity in recent years, and it’s easy to see why as the array of feed lines and injection nozzles turn an intake manifold into a work of art that screams power! This system of providing a water methanol nozzle for each intake runner is gaining traction in a serious way so we decided to discuss the science behind it and look at the results compared to single point injection.
Aesthetics aside, the direct port system has been touted as a superior way to inject water methanol because it will ensure that each cylinder receives the exact same amount of spray and therefore no cylinder can be starved. This is felt to provide more precision and has been somewhat driven by the evolution of gasoline engines as they have moved from throttle body injection , to sequential multi-port fuel injection and now to direct injection. It has been made a bit of a universal truth that if car manufacturers have found injecting closer to the cylinder is better there is no reason not to follow their lead.
The popularity of direct port injection for water methanol systems has also been driven by carbureted engines when a poor manifold design could lead to cylinders being starved and consequently damaged by running lean. These stories have stuck around even after sequential fuel injection has ensured every cylinder receives the same amount of fuel. It’s easy to see why the direct port injection systems have become the perceived pinnacle of water methanol injection when we take these accounts at face value.
We want to take a more in depth look at the science behind these widely held beliefs and look at the real-world comparison of a single point injection system and a direct port injection system. For the purposes of this article a single point injection system will be defined as one or two nozzles mounted in either a throttle body spacer plate or the intake tube/charge pipe.