While we were plugging in one of Hondata's reflashed ECUs, they suggested we try one of their heatshield intake manifold gaskets. Never one to turn away a product for testing, we obliged. Honda intake manifolds soak up a lot of heat. They're made of aluminum and are spaced away from the cylinder head with nothing more than a paper-thin gasket. The Honda-issued gasket seals well, even under high boost, but does little to prevent the intake manifold from taking on the heat of the combustion process and isn't reusable. Hondata's heavy-duty plastic gasket serves as an insulator and doesn't allow as much heat transfer. We measured the intake temperature at 135 degrees F at the end of the runners, right next to the cylinder head, prior to installing Hondata's gasket. This might not sound like a lot, but intake temps are directly proportional with horsepower-at least that's what we used to think. Hondata's gasket quickly dropped our temperature to a cooler 118 degrees. We thought this 17-degree drop surely would have translated into one or two additional horsepower, but this wasn't the case.
Hondata's heatshield intake...
Hondata's heatshield intake manifold gasket lowered our intake temps by 17 degrees F in comparison to the factory-issued metal gasket.
To be fair, we even revisited XS Engineering's dyno a second day to keep our outside temperature consistent. This didn't work either. The results: Hondata's gasket does its job, it dropped intake temperatures almost 20 degrees near the head and roughly 8 degrees inside the runners and near the plenum. This just didn't translate into a horsepower increase on our Si. But, to be fair, we have to give it up for the Hondata heatshield gasket. We have in fact seen it produce power on other vehicles and, at the very least, $50 is a small price to pay for a reusable gasket. That's reason enough for us to want one.