A few times I have had the question, does the new larger intake and throttle body produce more power? Without a before and after dyno it is hard to tell.
We can base it on a sensor in the intake manifold. It measures the intake manifold air pressur (MAP), its done in kPa.
When the engine isn't running its 100kPa. This is just the airpressure we live in, 14.5psi
When the engine is running the cylinders are pulling a vacuum. The ideal pressure on the intake is the same pressure as when its not running at all. This means the cylinders are being fed all the air they need and dosn't pull a vacuum as enough air is present for that not to happen.
The 3 inch intake running 70mpg, foot to the floor. We get 96kPa (around 13.9psi), so pretty good, but its not quite 100kPa.
This is the new intake, 4 inch throttle body, 3D printed ram air air box, and large k&n filters. Not getting 99.0kPa, this meands we are supply more air to the cylinders, more air = more power, how much I do not know. 99kPa is around 14.4psi. So effectivly a 0.5psi increase. Not quite turbo pressures, but a good bolt on gain.
Is the ram air air box making a difference? Well going full throttle at a lower speed would prove that. 2nd gear, still seeing 99.0kPa.
From calculations it was only around 0.1psi at very high speeds. Possibly 120+ MPH we would see the pressure increase in the box to bereadable on the MAP sensor. Would need to find an air strip for that one.