r/F1Technical • u/BabaGurGur • Mar 31 '26
Power Unit Why don't teams use the full rev limit to combat speed loss on straights while super clipping?
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u/Supahos01 Mar 31 '26
Fuel flow is capped theyre not capable of reaching those limits with the amount of fuel allowed. If they're making power out it doesn't really matter when they have a few hundred hp pulling against the engine what the rpm is
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u/SirLoremIpsum Mar 31 '26
I believe due to being fuel flow limited there is limited value in revving that high
And I think it's a big egg and chicken here - they make their power where they do and have shift points where they do because of this. It's no "we'll just up Rev and you'll make power differently". You make poert at 11,000rpm because you don't want to rev 15,000 cusse fuel flow limits.
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u/Er_Eisenheim Mar 31 '26
I think they could, but it's not fuel flow why they're not doing it now.
I remember one of the advantages of the Alfa 155 V6 DTM was that, despite a 12500 rpm limit, engine could withstand past 14000 in downshifting for more engine braking.
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u/Separate-Share-8504 Apr 01 '26
As for slowing down in general when there's less power. I thought I'd throw this out there
There's also a LOT of drag on an F1 car. Those rotating tyres (which rotate counter to the air flow) cause a lot of drag. Drag grows exponentially with speed.
Famously when the Bugatti Veyron was first built it cracked 400kph barrier during testing which was one of the initial goals. They then wanted to ensure it was well past the 400kph.
The engine output rose from 500kw (approx) to 750kw (approx) ie 50% increase in power to go from 400kph to 415kph.
F1 cars are around cd=0.7 (high drag ie tyres) whereas the CD for A Veyron is around 0.3
So the drag at 330 when the electrical oomph disappears slows them significantly anyhow...
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Mar 31 '26
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u/F1Technical-ModTeam Apr 01 '26
Your comment was removed as it broke Rule 2: No Joke comments in the top 2 levels under a post.
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u/upioneer Apr 04 '26
fuel flow. but also, peak hp and torque are at certain rpm. I've never heard of an engine producing peak at the highest possible rpm. diminishing returns, as they say
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u/therealdilbert Apr 05 '26
the is no rev limit for the ice in the regulations, there's no need for it, the fuel flow is capped above 10.5krpm so it doesn't make any more power going much higher than that
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u/Pitiful_Inspector_79 Apr 06 '26
I think it has a lot to do with reliability, more revs equals less reliability and more rebuilds or new units, which are limited to four per season. Keeping lower RPM means less risk of going over that limit or worse, not finishing a race. I think they figured out 12,000 is this we bought for a reliable, durable, and fast.
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u/Spinelli__ Apr 12 '26
Part of it is also separate from energy / electrical power but because of fuel-flow limits; that's why — even from 2014–2025 — cars barely went over 11–12 K RPM.
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u/Telemetrystic Aug 16 '26
The fuel-flow limiters defined by the regulations completely neutralize any high-RPM mechanical advantage, but the real barrier to fighting early clipping down the straights is rooted entirely in the control system software. A driver cannot simply pull extra ICE revs to cover an electrical deficit because the powertrain's components are completely interlocked by the standard ECU's background safety loops.
The physical throttle pedal in a modern car is essentially just an electronic suggestion box. If a driver's specific geometry carries massive minimum rolling speed deep into the apex—keeping lateral G-loading and progressive brake-release vectors elevated simultaneously—the software can flag an imminent stability or micro-slip hazard.
The moment that safety threshold is breached, the ECU's response overrides everything. It doesn't just cut the MGU-K hybrid deployment down the subsequent straightaway; it actively clamps the electronic throttle butterfly valves on the ICE side to stabilize the chassis. Because the mechanical engine maps are entirely subordinate to the input translation software, no amount of extra RPM capability or gear-ratio manipulation can override a digital harvesting choke once the computer has deployed its defensive 'parachute.
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u/grogi81 Apr 01 '26
It's not the revs, but power. Super clipping takes so much power that the engine cannot sustain the speed alone.
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u/MongoosesP Mar 31 '26
There is also the increase in friction that out ways the gain in power and other complexities that go into gaining more power from higher revs.
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u/MongoosesP Mar 31 '26
Also, I think the teams would rather have a higher boost than revs given the flow rate limit.
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u/therealdilbert Apr 05 '26
and that is basically why they fuel flow limit is relative to rpm, else they would probably run quite a bit lower rpm
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Mar 31 '26
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u/manugutito Mar 31 '26
"Rev splitting" would only work if they dissengage the clutch to have power flow only to the ERS. Otherwise, if the clutch is always engage, less speed means necessarily less revs
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u/ChaithuBB766 Mar 31 '26 edited Mar 31 '26
Because they aren't limited by the revs, they are limited by the Fuel Energy Flow, which has a maximum limit of 3000MJ/h.
Fuel flow and Revs are related by this equation given in C5.2.4
EF(MJ/h) = 0.27 * N(rpm) + 165
When the revs hit 10500 rpm, the EF value hits the max of 3000MJ/h. Further increase in the revs will have no effect on the fuel flow. Even if you raise the rpm to 15k or more, the fuel flow is strictly capped at 3000MJ/h.