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In this question on the movies StackExchange @Gear54rus asks what is the liquid seen in the clip below in the 2013 movie Rush:

Rush clip

The scene takes place at a 1970 Formula Three race in London and there is some discussion about which tires to use because of recent rain.

I answered, with the help of some discussion in the comments, that it's likely to be water from the rain that got in when the engine was exposed prior to the race.

Given that I am not that knowledgeable about engines, I was wondering about a couple things that I hope someone here can clarify:

  1. Is this actually (rain) water, and is it normal to see water there or is this just Hollywood nonsense?
  2. Would it be a problem for these high performance engines to have some water there or would it just evaporate?
shim
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1 Answers1

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From strictly a motorsports sense, this is fuel being squirted against the throttle blades. In 1970, the fueling systems used in cars were either carburation or mechanical fuel injection. During the "tip in" (when the throttle blades first open) there is a moment where the rush of air comes into the intake and makes the engine run lean. This can actually make an engine stumble. To compensate, there is fuel squirted directly into the incoming air path to make it richer. This applies to both mechanical fuel injection as well as carburation. Electronic fuel injection had come into being at that time, but was not widely used. In the clip provided by @shim, it appears the engine is being shown "revving", which would inject fuel to compensate.

EDIT:

Those "cones" are open from above. An engine is, for all intents and purposes, an air pump. Air goes in, gets mixed with fuel, gets burned, then goes out the exhaust. Since it's an air pump, air only goes in those cones (velocity stacks) and doesn't come out. Fuel is injected into the air stream as it enters the stacks, which puts it against the throttle plates.

As I stated, the stacks are open from above, but they are still covered by a cowling. The cowling (marked by a red circle) covers this area during racing or even when getting ready to race.

racecar with cowling circled

This is why the liquid you see would not be water from rain. They only leave this area uncovered when there's an issue, if they are prepping it to run before a race, or if they are doing a post-race autopsy. In the movie, they are showing this area through "movie magic", as if the cowling wasn't there.

Here are two short videos pulled from YouTube which hopefully proves my point of why the liquid is fuel on the throttle blades. Neither of the videos is exactly what is being shown in the movie, but the principles are the same. The first video is of a 4-barrel carburetor which is on a dyno. What's good about it is, there are lights being shown down the barrels so you can see the fuel. The second video is of an old BMW engine. This engine has mechanical fuel injection. You can see the injectors at the 6 o'clock position of each "stack".

https://www.youtube.com/watch?v=exVHXLTzlfY

https://www.youtube.com/watch?v=XdU0T7r5zcQ

Pᴀᴜʟsᴛᴇʀ2
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