Thread: Inlet manifold coolant?

It is to warm the inlet manifold.
As liquid fuel enters the manifold from the carburetor, the vacuum vaporizes the fuel and causes a chilling effect on the walls of the manifold much like the chilling effect of spraying an aerosol on your skin. Now you have a cold manifold. If you do not supply a continuous supply of heat the manifold will remain cold and even build frost in some conditions. At this point, if acceleration is attempted, the vacuum will drop, fuel will no longer vaporize, and will condense on the cold manifold walls until they are fully saturated with wet fuel. This takes about three seconds, during which time no fuel is going into the engine and thus no power. After the walls are fully saturated with fuel the air flow finally picks up and floods some of the cylinders but not all of them because liquid fuel is notoriously bad for equal distribution.
Heat supply to keep the walls of the inlet manifold warm and fuel in vapor form fixes this problem. Water heat is very clean and not corrosive to aluminum manifolds. This method utilizes the water pump to continuously supply warm water to a passage underneath the manifold.
Used to get this problem when I put extractors on the Minis.

You wouldn't get that problem if you had a diesel.

Thanks Mick, I've always wondered what the practicalities are.
That's an injected d2 though, so i wonder how the cooler air would effect the manifold injection.

In an article where they took some then new l322 v8 diesels into the arctic circle, the diesels air inlet iced up. Lamdrover said this wouldn't have happened if they had snorkels fitted as the drop in pressure caused the icing. I wonder in cold environments wether the same thing would happen in the inlet manifold.

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