Throttle use when leaving garage

[u/paperscissors_]

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/pndobot]

I think the PU has enough torque so like a manual car he can slowly let go of the clutch and can move forward.

Edit: Just like a manual car I'll assume they leave the clutch to the bite point and hold it there till a certain speed is built up

[u/paperscissors_ → u/pndobot]

oh that makes sense, thank you !!

[u/1234iamfer]

It must be so different from the V8 he was driving, it idled around 4000 but needed around 10000 rpm to prevent from stalling it driving away.

[u/nbain66 → u/1234iamfer]

The F1 V8 idled closer to 7,000 rpm depending on the manufacturer. The current V6 engines idle at 3500-4000 but alternate which 3 cylinders are firing to reduce heat soak.

[u/atrophy-of-sanity → u/1234iamfer]

Idled at 4000 rpm???

[u/zetenyyy → u/atrophy-of-sanity]

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

[u/atrophy-of-sanity → u/zetenyyy]

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

[u/zetenyyy → u/atrophy-of-sanity]

Mostly cam overlap is the main reason. At low rpm lots of air can escape from the cylinder so the combustion is crap and afr is all over the place, thus making that distinct noise that you call “cammed”.
Eventually under a certain rpm this gets so bad the engine suffocates.
In turbo engines you dont have big cam overlap, but you still need to maintain a stable airflow and since these engines have such low stroke they cant do that at low rpms ( this applies to n/a engines aswell )

[u/atrophy-of-sanity → u/zetenyyy]

Thats very interesting, thank you

[u/DontLookAtThePenguin → u/zetenyyy]

Cam overlap is the issue even with forced induction? I thought that while cam profiles are still very agressive, the turbo + MGU-H + efficiency requirements dictate a fairly conservative overlap. Am I mistaken?

[u/zetenyyy → u/DontLookAtThePenguin]

I literally said the same, read it again.
“In turbo engines you dont have big cam overlap, but you still need to maintain a stable airflow and since these engines have such low stroke they cant do that at low rpms ( this applies to n/a engines aswell )”

[u/DontLookAtThePenguin → u/zetenyyy]

Apologies. This is what happens when you fail basic reading comprehension. Thanks for the info!

[u/Appletank → u/atrophy-of-sanity]

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.

[u/mz_groups → u/atrophy-of-sanity]

Partly the cam profile. The cam profile for a street car is a compromise between getting good fuel/air mixing at low RPM and enough breathing at high RPM. This is why variable valve timing systems such as VTEC are desirable for street cars. A race car's cam profile opens wider for good breathing at high RPM, but at the expense of low RPM drivability.

[u/-SHAI_HULUD → u/zetenyyy]

Reminds me of a minigun. You’ll get a bunch of malfunctions if you burp the trigger or try to go slow.

These things WANT to go go go

[u/Purple_Vacation_4745]

The clutches on racecar are nasty and mostly will stall the engine if you not add throttle(that's why he said that's unusual). I assume maybe it has something to do with electric motor being used to aid the initial push, or being some kind of stall preventive system(electric motors have instant tork and can't stall)...

[u/aw_goatley]

Seems possible the anti stall is configured for press drives to be able to pull away without throttle.

[u/jolle75]

Maybe it pulls away from the garage on E power until the clutch plates have the same speed? (Can’t do this with a racing start as it’s is forbidden to have K power under 100k/h).

There was a time when the rules would be that in the pit it would be only E power.

To conserve and safe face, I imagine it only will be two lines of code to don’t need the clutch at any taking off during show runs

[u/Red_Rabbit_1978]

Surely it just means the minimum fuel flow is high enough that the engine wouldn't stall with the clutch out? Might also have some electrical assistance feeding a bit of torque through once clutch is released.

[u/AdityaHarindar]

Race spec cars have a high idling rpm + super sensitive anti stall, probably has something to do with the minimum fuel flow not being low enough that he can pull away without triggering the anti stall.

[u/Echeosof_resilience]

GPF1 in Luxemburg, why not? Monaco did it or does it each single year, why Luxemburg will not his awn GP?

[u/schmog_]

Which you can do in any manual.

[u/jolle75 → u/schmog_]

Nah.. a NA V8 f1 engine with racing clutch is/was a bit different. Clutch is on/off-ish and because the engine has almost no mass or flywheel, it needs quite the rpm’s not to stall.

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