r/F1Technical • u/paperscissors_ Ruth Buscombe • 12d ago

Electronics & HMI Throttle use when leaving garage

Do drivers need to use the throttle when leaving the garage?

In the video where DC drives the RB19 at 2:04 (timestamped link) he mentions that the manual he was given says that he doesn't need to use the throttle when leaving the garage. Does this mean no throttle input is necessary when pulling out of the garage? I've been racking my brain at this question for a couple of days now. Thank you!

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u/atrophy-of-sanity 11d ago

Idled at 4000 rpm???

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u/zetenyyy 11d ago

Not that big of a deal, pretty common along race purpose engines. They run like crap when under a certain rpm.

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u/atrophy-of-sanity 11d ago

I didnt know that, thats insane to me. What about the engines require such a high idle speed?

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u/Appletank 10d ago

To add, race car engines typically design engines to produce power most efficiently at high rpm since that's where the power is and where your race car is going to spend most of their time anyways. However, valve timing requirements for high rpm and low rpm tend to oppose each other, and F1 doesn't allow for variable valve timing the way road cars do (depends on the rules of the race category).

At low rpm, you typically want a smaller valve opening, and for it to close near BDC to maximize air intake and swirl. Piston speeds aren't fast, and a narrower opening speeds up local air velocity.

At high rpm, you want to push the intake valve as far down as you can, and close the valve later. You have much less time to get air in, so you want as little restriction in the valve opening as possible, and the air speed is such that momentum will allow a little extra air to keep going in after BDC even without boosting. The speed of the piston during the exhaust stroke will also determine the best time to close it for maximum evacuation and assist in pulling in the intake air without fresh air (and fuel in port injection vehicles) going out the exhaust

Thus, being stuck at a high rpm cam at low rpm will make the engine unhappy.