I think it’s safe to say most of us, even those of us uncomfortably car-obsessed, don’t spend a lot of time thinking about intake manifolds. I feel like we tend to treat them as just those tubes that hold up the fun stuff, like carburetors and turbochargers and that sort of thing. Really, though, there’s a ton of engineering in these things, which is why this video showing Porsche’s radical approach is so interesting.
Engineering Explained does an excellent job here explaining how conventional intake manifolds work, specifically how they’re designed to increase pressure a bit right before the intake valve, to cram in just a bit more fuel-air mixture, even without a turbocharger.
Porsche is essentially doing the opposite: they have an expansion area to lower the intake manifold pressure before the fuel-air gets into the cylinder, which seems counterintuitive, until you really look at the whole system. Porsche introduced this setup back in 2008, on the 911 GT2.
Here, let the man with the whiteboard explain:
The result of Porsche’s seemingly counter-intuitive approach is that, on engines like their flat-four and flat-six turbos, they get the intake air much cooler, which reduces knock, and allows for 12 percent less fuel use for the same amount of power as a more conventional setup would allow.
It’s really clever. It’s pretty remarkable how much engine tuning can be done just by varying the size and shape of tubes.