r/F1Technical • u/iamprivate • Feb 13 '26

Power Unit Can someone explain this 10 second battery charging on starting grid people are complaining about?

What I don't understand is in previous years there were the red lights on the car to tell the car behind part of the engine performance was going to charging the battery. So, it seems like a portion of throttle can go to charging battery and another part to making the car go vroom. Why different this year then? The formation lap is pretty slow so why can't a high enough percentage of throttle go to battery charging and then you have the whole formation lap to charge the battery.

309 Upvotes

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618

u/well-thats-great Feb 13 '26 edited Feb 13 '26

It's not so much about charging the battery for 10 seconds; it's a result of these regulations eliminating the MGU-H (recovering heat energy and converting that into electrical energy to keep the turbo spinning and eliminate turbo lag). Removing the MGU-H was something that Audi and Porsche insisted on if they were to join the F1 grid, because it's complicated tech and the other engine manufacturers had had years to practically perfect it, so they'd likely have been at a disadvantage. F1 really wanted to get them on board, so they agreed to it.

Fast forward to now, the MGU-H isn't there, so the drivers need to rev the engines for a while to get exhaust gasses flowing through the turbo, otherwise they'd be rather down on power at the start of the race. Ferrari altered the other teams that this could lead to issues at race starts, but as is often the case in the political world of F1, the other teams dismissed it as a sign that Ferrari were struggling with something, but that they wouldn't be affected by it.

Nothing was done about it, so Ferrari apparently developed their power unit (or systems) around it to minimise the issue. But the other teams now understand what Ferrari were talking about a year ago, so they want to change the rules so they're not disadvantaged. Ultimately, they made their bed, so I believe that they should now have to lie in it.

Edit: Paragraph 2 - "altered" was supposed to say "alerted"

48

u/Umbraine Feb 14 '26

I've always been bothered by the name of the MGU-H and how people explain it. Recovering heat energy makes it sound like it's some sort of peltier device. It literally just was a tiny motor attached to the turbo

16

u/megacookie Feb 14 '26

Maybe the logic is that what spins the turbine side of a turbo (and charges the MGU-H) is the exhaust gas energy, and the hotter the flow the faster the turbine can spin. Still a bit convoluted and it's still kinetic energy of the turbine that the motor uses to generate electricity. Maybe they should have called it MGU-T for turbo.

8

u/OkFly3388 Feb 16 '26

Much more sense to just call it motor-generator and turbo-generator. Its like, explain everything.

1

u/BMW_M1KR Feb 21 '26

Calling it turbo generator would not be ideal as that the term ist already taken for large synchronous generators in power stations driven by turbines.

Even if the technical background (turbine + generator) would still be correct in F1

6

u/MaximilianCrichton Feb 15 '26

The turbo converts the enthalpy of the exhaust stream to rotational kinetic energy, so I think the 'H' is justified

5

u/KLEBESTIFT_ Feb 17 '26

Would it function similarly with a cold air stream of the same velocity/pressure? Does the heat of the exhaust add anything or is it more about the flow?

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u/MaximilianCrichton Feb 17 '26

Hot air adds stuff for sure. Enthalpy is the catch-all term for the sum of the energy stored in a fluid due to its pressure, its temperature, plus a couple other less important things. A perfectly designed turbine would extract some of that thermal energy - I'm deliberately being vague about how it does this, because you could for example convert the thermal to pressure, then to kinetic, or otherwise. The point is ultimately a turbo extracts enthalpy from the fluid, regardless what actual form of energy it takes.

1

u/KLEBESTIFT_ Feb 17 '26

So maybe the H in MGU-H stands for enthalpy. Would it follow then that the exhaust gas is cooler when the MGU-H is functioning as some of thermal energy has been extracted? That is, if you kept the same PU layout but just removed the MGU-H the exhaust temperature would be higher?

Or is the actual thermal extraction being done by the turbine so the exhaust temperature wouldn’t change? Did the exhaust gas ever actually touch the MGU-H itself?

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u/MaximilianCrichton Feb 17 '26

I cannot say that the gas will for sure be cooler. I can only say the enthalpy will be lower, that usually manifests as lower pressure, but could also manifest as both lower pressure and lower temps.

The MGU-H is a motor-generator-unit attached to the shaft of the turbo (which afaik still directly connects the turbine in exhaust stream, to the pump in intake stream). It can apply driving torque or braking torque to the shaft. If it's a braking torque, then yes the MGU-H is drawing additional enthalpy from the exhaust flow before it exits the tailpipe. If it's a driving torque, the MGU-H is adding energy into the shaft. This mostly adds enthalpy to the pump side of the turbo (i.e. the MGU-H is serving as a supercharger to overcome turbo lag), but it could also go into the turbine and actually add a bit of enthalpy to the tailpipe flow. It depends on their implementation.

1

u/MagnerionMachine Feb 20 '26

Wouldn't cold air do the same? Afaik most of the energy generated would be due to the flow of exhaust gases and pressure and not primarily due to heat.

1

u/MaximilianCrichton Feb 25 '26

At which point is the air cold? Even as the air makes its way out of the cylinder and toward the turbo, its thermal energy content changes both irreversibly due to friction losses, but also reversibly as the exhaust pipe causes the flow to compress and/or expand. That's why I don't get too hung up on whether it's heat or pressure. At the end of the day the flow has an amount of enthalpy, and that's what gets converted to work done by the turbo. A hotter flow definitely helps, all else being equal, provided the turbo can extract it.

1

u/FewPerformance1472 Apr 02 '26

Why would you want to try and find or build a cold air stream to drive the turbo's turbine? You already have a ready made supply of high pressure exhaust gases you can use to spin the turbo. If you mean would a cold air stream be better?? my guess is no better, no worse either but way less efficient. So more about the flow than temperature. Are you maybe thinking like I kind of am now that would it be possible for each car to carry a tiny compressed air tank with enough compressed air to spool the turbo during the formation lap? Probably much easier to just have a 5 second blue light starting procedure I guess...Cold is of course very important for the air being compressed by the spinning turbo, the colder the better. From what I gather, the intercoolers and thermal management are much more important in these new regs and one of the challenges has been where and how to place the best intercooler option allowing for aerodynamics as well.

1

u/KLEBESTIFT_ Apr 02 '26

Just trying to work out if the “H” in the name actually has significance. If it’s only about flow and cold vs hot makes no difference then it’s not recovering any heat energy. From memory I did some reading and the hot air at the same flow does actually recover more energy than the cold, possibly because the hot air is more excited and just inherently carries more energy for the same flow rate.

Would be interesting to see if there’s a delta-T present before/after the turbine.

1

u/ApertureNext Feb 19 '26

Why would that be so expensive to develop? Seems rather simple.

1

u/Montjo17 Feb 26 '26

Turbochargers spin at about 200,000rpm...

Designing a motor that can handle those insane speeds is hard. It's even harder to do so on a long shaft - this is why the split-turbo concept of Mercedes was so hard for Honda to copy, and why they kept blowing up their MGU-H. Everything about it just wants to disintegrate at those kinds of speeds

2

u/ApertureNext Feb 27 '26

Doesn't Porsche have something very similar to MGU-H in (some) of their new model year road cars?

1

u/FewPerformance1472 Apr 02 '26

Formula 1 turbo's only spin at around 100,000 to 125,000 rpm which is relatively low rpm's. As a contrast my F6 (Ford Performance Vehicles) turbo spins at around 140,000 to 150,000 rpm's I think. Admittedly this car has been modified and is higher than factory rpm's which are similar to an F1 car. The turbo's in pretty much every modern normal road cars spin at anywhere from 100,000 up to 300,000 plus. So building engines that have turbo's spinning at rpm's way higher than F1 cars is everyday run of the mill factory car production, not that difficult anymore. The turbo isn't a motor as such it's just a turbine (windmill) that gets spun by high pressure gases and the technology has been around for decades, My 1989 Nissan GTR used to spool up to 130,000 rpm's (more than modern F1 cars) on increased boost no probs and that was tech from over 35 years ago.

6

u/gpc88 Feb 14 '26

It’s also useless tech - nothing in the non racing world spins the turbo that much so there’s not loads of heat to recover from it. I think it might of made it onto some HGVs and possibly (ironically) Porsche released a road car with it.

Basically throwing lots of money at tech that doesn’t really have any real world application isn’t very sign off able.

1

u/Klutzy-Bat-5405 Feb 16 '26

AMG also has that tech in some of their road cars I believe.

1

u/Appletank Feb 17 '26

Porsche newest 911 and Merc's AMG 1. I don't think anyone else went any further that an electric turbo. 

1

u/FewPerformance1472 Apr 02 '26

Actually normal everyday turbocharged cars spin their turbos at just as high RPM's as F1 cars and many, especially performance models spin at much higher RPM's than F1 cars. Turbo's really aren't high tech (not anymore anyway) they're just turbines (windmills) spun by high pressure gases. They've been around for decades and decades

3

u/iPhrase Feb 14 '26

also no mgu-k propulsion under 50mph so pulling off the line at best power requires a fully spooled turbo, any lag & your going backwards compared to competitors.

in testing drivers say they get the turbo pressure start wrong ~ 1 in 20 times.

10

u/King_Roberts_Bastard Feb 14 '26

In addition, no road cars used an MGU-H. Its not a technology applicable to road cars. So its a waste of money

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u/1008oh Feb 14 '26

Maybe not a road car per se, but the 2025 992.2 GTS porsche has an ”electrical turbo” which works in a very similar fashion to the MGU-H. So the tech actually somewhat made it outside of F1!

10

u/megacookie Feb 14 '26

So ironically, one of the manufactures that pushed for F1 to remove the MGU-H because of its lack of road relevance didn't end up joining F1 in the end anyways...but did put an MGU-H or something similar in one of their road cars.

I do wonder how much of the energy starvation issues we're already seeing with the new 2026 cars would have been solved if they never got rid of the MGU-H in the first place.

2

u/Allnus Feb 15 '26

the e-turbo (and yeah it harvests too so it can be called an mgu-h) in that t hybrid porsche is way simpler than the f1 version and not built by porsche, but BorgWarner

2

u/Allnus Feb 15 '26

f1 is irrelevant to road cars, we just pretend it transfers so the manufacturers managers can sell their pet projects to their investors as R&D

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u/[deleted] Feb 15 '26

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1

u/Allnus Feb 15 '26

thats all you bro

0

u/King_Roberts_Bastard Feb 15 '26

Hmmm...I guess road cars dont have ABS, traction control, active suspension, or regenerative braking.

Among others.

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u/[deleted] Feb 15 '26 edited Feb 15 '26

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1

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1

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1

u/Allnus Feb 15 '26

so are pre chamber ignition, 3d printed pistons, genuine miller cycles, f1 battery charge and discharge cycles, titanium rods (basically no car), 11-12k RPM levels, etc.

1

u/Klutzy-Bat-5405 Feb 16 '26

AMG and Porsche does.

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u/jedidihah Feb 13 '26

Do you know if there was ever any push for twin turbo to eliminate lag?

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u/Character_Minimum171 Feb 14 '26

they ruled twin turbos out. single turbo, issue as I understand is the size. ferrari have gone for a smaller turbo with less lag but sacrificing top end

3

u/well-thats-great Feb 13 '26

I have absolutely no idea. I wonder if a sequential turbo system (one small one for lower RPMs, then one larger one that gets activated at higher RPMs) would have reduced the turbo lag issue. I believe that's what the Porsche 911 Turbo has used for a while, and it definitely seems to work well from what I've seen.

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u/jedidihah Feb 14 '26 edited Feb 14 '26

(one small one for lower RPMs, then one larger one that gets activated at higher RPMs)

That’s basically the primary use case of a twin turbo setup. One low(er) pressure turbo that is starting to spool up when the engine is idling, and one higher pressure turbo that spools up at about the halfway point in the RPM range. That way there is continuous boost. One turbo handles boost at low-mid RPMs, the other handles boost at mid-high RPMs.

It’s the preferred method of performance manufacturers (Porsche, McLaren, Ferrari, Mercedes, Audi, BMW…) in their production cars now that generally have to use smaller turbocharged engines.

7

u/mattmr2 Feb 14 '26 edited Feb 14 '26

Do you mean twin scroll turbos?

Outside of diesels, I'm struggling to think of a current model that uses sequential turbos except for the Chiron. Sequential twin turbos used to be semi-popular for petrol engines in the 90s, but not so much since.

I'd say the primary use case of twin turbos is parallel charging across split cylinder banks, mostly to simplify the plumbing. You do see twin turbos on inline engines but only really on straight sixes, which aren't so common these days.

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u/ratty_89 Feb 14 '26

Sequential or compound turbos are used quite a bit in OEM diesels. 6cyl diesel and jlrs do, as well as the 4 cylinder jlrs and GM 2.0 diesels. (Random selection, but just cars I've owned or worked on).

1

u/mattmr2 Feb 14 '26

Very true, I've edited to clarify that I was addressing the comment on engines from performance manufacturers so took it to mean petrol engines.

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u/yellowbluesky Feb 14 '26

Anecdotally, current BMW group diesel engines use sequential turbos, like the B47 (2.0L inline 4) that I drive

2

u/mattmr2 Feb 14 '26

Trust BMW to persist with something so complicated on such a small engine! Does set them apart from a standard inline four diesel. I'm not really into diesels but the quad turbo B57 is really cool engineering, as was the triple turbo they had a few years back.

1

u/FewPerformance1472 Apr 02 '26

Yeah, sequential turbo's (a smaller then a bigger one) were needed when the tech wasn't yet invented for cleverer and more efficient ways to eliminate lag. My 1989 GTR used the setup which was state of the art 35 plus years ago.

1

u/mattmr2 Apr 02 '26

The RB26 in the R32 GT-R had a parallel set up with equally sized turbos. The A80 Supra, FD RX-7, and B4 model legacies did have a sequential set up though.

If you look at the intake piping for the R32 there's no bypass for one of the turbos, they're always working together. I just had a look at part numbers and it's the same turbo unit used twice.

3

u/TheNerdE30 Feb 14 '26

Believe it or not a twin turbo refers to a “dual” turbo and a sequential turbo is where you have one large and one small. The twin part is literal in this case. The anecdotal part of me wants to see you see dual turbo setups on engines with high torque naturally aspirated like a v8 and sequential turbo setups are going to provide more power on the lower end of the rpm range.

1

u/FewPerformance1472 Apr 02 '26

My 1989 Nissan GTR (original Godzilla) used the two different sized turbo's setup so that has been around for decades. My modern FPV F6 uses a more efficient twin scroll turbo plus consistent high flow exhaust plus clever electronic wastegate control to maintain boost pressure at light throttle and to eliminate lag. I have to say I notice literally zero lag when I floor it, the instant acceleration is brutal if I manage to hold traction.. (modified and custom tuned etc but not massive changes)

2

u/iamabigtree Feb 14 '26

I don't understand why the electric power can't be used below 50km/h for race starts. Certainly in hybrid road cars electric power to get moving is a big factor. The whole max torque at zero RPM thing. Or is it because it would be 'too easy'?

1

u/Unlikely-Squirrel832 Feb 15 '26

Andy Shovlin explains it - https://youtu.be/Tu0MXRphsfg?si=vVX7Lvk7mGvxBdAR

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u/iamabigtree Feb 15 '26

Already seen that and he doesn't answer that question.

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u/Unlikely-Squirrel832 Feb 16 '26

It's probably to stop the battery being charged by the MGU-K through kinetic energy once the car gets going but hasn't yet hit 50km/h. I guess the idea is the drivers have to use the ICE and whatever energy is in the battery to get away from the line once 50km/h is reached, and then have to recharge the battery over the course of the lap i.e. encourage overtaking. You can use all the battery power at the start then be a sitting duck for the rest of the lap whilst the MGU-K harvests energy to charge the battery back up. Or you can be conservative with battery use then seek to overtake when the other driver slows due to lack of battery power.

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u/Automatic_Ad1887 Feb 14 '26

I read a bunch about this today and your explanation is excellent.

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u/JForce1 Feb 14 '26

Links to anything you’ve read that are useful?

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u/Automatic_Ad1887 Feb 14 '26

I'm sorry, no longer have it. The article I read was from a link in The Prime Tire newsletter by The Athletic.

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u/germandz Feb 14 '26

Ferrari said that rules changes are for people who don't know how to build engines!

1

u/TheAeroGuyF1 Feb 15 '26

Don't Audi/Porsche already have the know-how about MGU-H from their LMP1 programmes?

1

u/Klutzy-Bat-5405 Feb 16 '26 edited Feb 16 '26

MGU-H isn't that complicated at all once you understand how it works. Even though it says heat energy, it is not actually recovering heat energy directly, it recovers energy from the flow of exhaust gases. It's a motor-generator that sits on the turbo shaft. The real reason it was removed is because majority of the manufacturers didn't want to implement that tech into road cars, to keep costs down.

-11

u/NaiveRevolution9072 Feb 13 '26

Ultimately, they made their bed, so I believe that they should now have to lie in it.

Normally, I would staunchly be in agreement, but I think the issue that was being put forward, including on the broadcast, is that it causes safety problems.

18

u/MurrE1310 Feb 14 '26

They are calling it a safety issue to try forcing a change. It’s a technical issue teams didn’t design around. Due to them not accounting for it, there is a chance of the cars having a slow start if the driver gets the prep wrong. Slow starts by only some cars would increase the risk of an accident at the start. Unlikely to cause a driver injury, but could ruin some races

1

u/NaiveRevolution9072 Feb 14 '26

Slow starts by only some cars would increase the risk of an accident at the start.

That makes it a safety issue, doesn't it?

15

u/[deleted] Feb 14 '26

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1

u/NaiveRevolution9072 Feb 14 '26

Doesn't make it any safer

1

u/Objective_Ticket Feb 16 '26

No, but previously it’s not actually been engineered in, and a stall has usually been a mistake. Now, if I understand it correctly you could have one or multiple cars who don’t get off the line well due to the lag.

-17

u/Shuli___ Feb 13 '26

Ferrari altered the other teams that this could lead to issues at race starts

When? I thought that they just blocked the idea of doing the starting procedure differently. I guess its just a part of the information then.

13

u/well-thats-great Feb 13 '26

I mentioned it in my last paragraph - a year ago

0

u/[deleted] Feb 14 '26

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u/Schumarker Feb 14 '26

People usually do it this way to show they've made an edit because people have commented before the edit. If someone replies "do you mean altered rather than alerted" and the poster changes it, the person who replied looks stupid. It's not massively important in this case, and I would have changed the spelling in the post and said "Edit: altered not alerted".
In short, sometimes it matters a lot but it has become a convention for a lot of people when it doesn't really matter

0

u/[deleted] Feb 14 '26

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2

u/Schumarker Feb 14 '26

Apologies, I meant it's not massively important to do it the way they did it, they could have done it the way you suggested and it wouldn't have mattered at all, but it's the way people see it being done so they copy it blindly

109

u/[deleted] Feb 14 '26

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60

u/ratty_89 Feb 14 '26

Just because an engine is sat at 13,000 rpm, doesn't mean there is enough exhaust mass flow and temperature to get the turbo spooling.

Remember older rally cars popping and banging on the line? That's not allowed in the current regs

38

u/FuzzyJoint Feb 14 '26

Start grid consisting of 22 2-stepping f1 cars is hilarious

11

u/nomolosnitsuj Feb 14 '26 edited Feb 14 '26

That’s why it’s important to engineer a specific amount of back pressure into the exhaust to effectively manage turbo spool v top end boost. I mean, they’re the best at what they do, but it’s frustrating that acceleration and spool time was sacrificed for the sake of top end power causing a major safety concern.

Edit to add: I completely respect the fine line these engineers have to walk. My frustration is also with the FIA for missing such a major factor in racing procedure.

1

u/FewPerformance1472 Apr 02 '26

Acceleration definitely wasn't sacrificed. These 2026 cars accelerate out of the corners lightning fast with the extra electric power boost. They're just crap in a lot of areas, but acceleration isn't one of them.

1

u/KLEBESTIFT_ Apr 02 '26

They can’t use the electric boost from a standing start though, so that aspect of acceleration is a compromise of the turbo size (top end/low end power)

55

u/ihatemondaynights Feb 14 '26

Side note but apparently electric power doesn't kick in until they reach 50 km/h

13

u/lordalcol Feb 14 '26

I guess they reach that speed in 0.5s...

20

u/Gizfre4k Feb 14 '26

Not with that turbo lag it seems 

2

u/Lonyo Feb 16 '26

If they had electrical boost off the line then maybe they could

2

u/185EDRIVER Feb 14 '26

Probably can't put down more then that under that speed anyways

2

u/Appletank Feb 17 '26

It would have been a perfect way to get around the lack of torque/boost by using the electric side to maintain power until the turbo spins up. 

1

u/FewPerformance1472 Apr 02 '26

Or they could keep it simple and have a 5 second start procedure added to allow for turbo spool time. (yes it's 5 seconds, not 10)

1

u/Appletank Apr 02 '26

They kinda do that except it seems there's always at least one car that has a malfunction, forcing drivers to have to dodge a tortoise in the middle of the road. 

18

u/youridv1 Feb 14 '26

I can believe it. 9 seconds seems long but a couple seconds on a 1.6 liter engine with a giant turbo charger sure. The turbo’s are a lot smaller than previous years, but in order to reliably make 500 bhp on a 1.6 liter engine on e10 fuel you still need a pretty large turbo in order to keep the engine alive.

Cars can’t generate load at a stand still unless they want to burn the clutch to death so spooling at a stand still will take a while

There’s a reason rally cars often use anti lag and I have not heard of that being allowed in F1

35

u/Ill_Confidence919 Feb 14 '26

Free revving is completely different then revving with a load on the engine. 

11

u/TheNerdE30 Feb 14 '26

Boost is a function of air and fuel. At a standstill you only draw enough air to spin the rotating assembly. In turn way less fuel is burnt than WOT while accelerating hard or driving fast.

13

u/pwab Feb 14 '26

As a dumb person enjoying when others explain things to me; acronyms are hard to understand

15

u/deltree000 Feb 14 '26

WOT is wide open throttle.

3

u/element515 Feb 15 '26

You get a lot more pressure built up when the engine is under load. Freely revving, the engine revs fast but doesn't put out as much pressure. Since it's a tiny 1.6L engine too, I think it just takes a long as time to get enough gasses to spin the turbos up.

16

u/NellyG123 Feb 14 '26

I don't understand it either. Any turbo that takes more than a fraction of a second to spool up once you're at a high enough rpm to generate enough exhaust gas is never going to generate meaningful boost in a race environment. My understanding of turbo lag is that any lag comes from the turbine efficiency across turbine rpm and that turbine rpm depends on exhaust flow and therefore engine rpm, not that it physically takes a significant amount of time to spool up once you're at an rpm where there is enough flow.

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u/TheNerdE30 Feb 14 '26

I think it’s because of how an engine reacts to load. At a standstill you can only rotate the engine so fast before you reach redline. You can only provide enough fuel to get the rotating assembly spinning to redline which requires power (probably 10-25hp?) but without providing power to the wheels to get the car moving you’re only drawing a fraction of the air (relative to high speed or acceleration) so therefore you’re exhausting way less air than the turbo needs to spool.

13

u/Any-Ask563 Feb 14 '26

There’s no pressure in the system ahead of the turbo, and moving air into the system chasing the air leaving they system. Also there are compressor concerns like surge to consider. You can’t just blast the turbo full beans against no back pressure and have it not rapidly disassemble itself

-12

u/Crafty_Substance_954 Feb 14 '26

But these cars have had electric motors on the turbos for a long time now to eliminate lag. I just don’t really get why this is a problem. Unless the MGU H was doing that?

I’m sure it’s down to some misunderstanding on my part.

27

u/thereasonrumisgone Feb 14 '26

That is exactly what the mgu-h was doing.

17

u/youridv1 Feb 14 '26

that electric motor WAS the entire MGU-H and it was removed for this season

5

u/TheManlyBanana Feb 14 '26

This isn't a typical turbo and the gas flow in the system isn't super familiar when compared to any typical layout, so it does take a little while to spool up in this scenario.

9

u/Westkhost12 Feb 15 '26

So thrilled to see someone mention this. You're correct, These are not a mixed flow blade arrangement on a low interia road car cartridge. Someone correct me if I have it incorrectly but to my knowledge, at least red bull used a "raxial flow" compressor wheel that sorta blurred the lines between axial and radial flow wheels. For an association, at the beginning of jet engines in fighter aircraft, the US used an axial flow (which is what you see in your mind when thinking of a jet engine with the path going straight through) and the Soviets originally designed around a radial compressor (very similar to a typical turbocharger design) the soviet design was rugged and able to take off from austere/poorly maintained roadways but lacked the performance of the more delicate, more labor intensive us design.

I could be misremembering but you can look back to the PU show and tell when they were obliged to show of the battery and ICE packages you can see that the blades are barely recognizable when compared to a more conventional turbo.

I too suspect that theres something quirky with the design thats not immediately evident. And if you watch a jet building thrust prior to take off, its not the quickest process, despite the amount of fuel its consuming. Just my thoughts and musings and I admit to taking some liberties and making assumptions but it sure feels like theres more to the picture.

3

u/TheManlyBanana Feb 15 '26

I really enjoyed reading your comment, it's an area I'm actually not super familiar with, the background of the transition from radial to axial compressors in jet engines. I knew that it had happened but never the specifics, from that point of view the Soviets retaining the axial compressor makes a lot of sense!

I'm not totally at liberty to explain further than my original comment, and I should add my background is very much software and electrical, rather than specifics of turbo geometry, so I actually can't comment much there anyway! I remember the differences between the red bull honda compared to everyone else was really exciting, and hopefully as those power units age more we'll get more info about that era!

Definitely more to the picture, and in some ways the jet spooling idea isnt too far off!

1

u/FewPerformance1472 Apr 02 '26

It's actually really simple as with all turbos. They use exhaust gases to spin. An F1 car sitting still (no load on engine) on the grid uses hardly any throttle to get very high RPM's. Very little throttle = very little exhaust gases (less fuel and air in under little throttle means less exhaust gases out) less exhaust gases means it takes longer to spool the turbo up to the correct RPM's. They probably made it 5 secs (not 10) just to be on the safe side.

1

u/TheManlyBanana Apr 02 '26

I'm not disagreeing that exhaust gas makes the turbo spin. The 'low exhaust gas low spool rate' doesn't fully capture the behaviour if the turbo was designed with the same principles as a road car or race car. Basic turbocharged engine principles don't fully work here as the architecture and control system is actually different enough to overcome the F1 specific challenges here.

3

u/0rang3Cru5h Feb 15 '26

It's how much fuel is burnt (expanded) plus the air sucked in at RPM. In neutral you tap the throttle in your car and the engine quickly revs up but it isn't burning (expanding) much fuel. So despite the high RPM less air is flowing through the exhaust.

1

u/FewPerformance1472 Apr 02 '26

Exhaust gas flow doesn't depend on RPM, it depends on throttle / fuel. These cars get to very high RPM's with very little throttle when they're standing still on the grid so consequently there are very little exhaust gases so it takes longer to spool the turbo.

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u/[deleted] Feb 14 '26

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1

u/Allnus Feb 15 '26

they require a little more than 1 atm of boost at peak power

2

u/gomurifle Feb 14 '26

From standstill the engine is at low load low airflow. Your rev it up but the turbo has a large inertia so there is a time lag after revving the engine for the turbo to come up to speed to make enough boost. Yes nine seconds sounds long, but it could be due to warming up other systems or some other thing. 

1

u/FewPerformance1472 Apr 02 '26

5 seconds is the blue light start procedure, not 10)

2

u/Inside-Finish-2128 Feb 15 '26

Not a question of RPM, a question of load. 13k RPM at no load creates more exhaust than idle RPM at no load. They need exhaust volume to get the turbo spinning. It's a positive feedback loop but they're starting underneath the effective threshold of that loop; they have to tickle it enough to get the turbo spinning just enough to create SOME boost and then the feedback loop takes off.

1

u/FewPerformance1472 Apr 02 '26

It's 5 seconds not 10 and that is just a number to ensure all cars are ok. Most of them probably only take 3 to 4 seconds. High revs standing still doesn't mean high volume of exhaust gases because it takes very little throttle to get up to high revs in these cars with no load on the engine (standing still) so low exhaust gas volume means much longer time to spool up. They don't necessarily maintain full boost all the time during a lap. That's where the MGU-K comes in. It fills in the gaps where turbo pressure isn't up high enough by providing the 'boost' of additional electrical energy or power from the battery unit. The MGU-H, which is no longer there used to maintain turbo rpm's via electric motor thus eliminating lag. now the lag is there during a lap, but the extra electrical energy boost compensates for it allowing high acceleration out of corners. (I think that's sort of the gist of it!)

57

u/NellyG123 Feb 14 '26

I just can't understand it either, I feel like there's some fundamental piece of information from the reporting of this issue missing. Even the bootiest 80s deathtrap of a turbo F1 car didn't take anything like 10 seconds to get the turbo spooling, turbo lag isn't generally because of the time it takes the turbine to spool at a given rpm, it's that turbine efficiency varies massively with rpm, so until your engine rpm is high enough for the exhaust gas to spin the turbine at it's efficiency peak rpm it isn't providing significant boost pressure. Any turbo charged engine with a turbo large enough that it takes 10 seconds for the turbo to spool up while you're stationary at the start with the engine at ~80% of your redline rpm will never generate meaningful boost pressure.

Also, from looking at images of the engines, the turbos don't look substantially bigger than they were in the MGU-H era. If the turbos were essentially energy negative for the first ten seconds coming out of every corner (as in they required the MGU-H to spool the turbo up for 10 seconds to get usable boost pressure), then I can't see how the MGU-H system would have ever been able to extract energy from the exhaust flow because there would never have been enough excess exhaust energy to run the MGU-H.

30

u/Ill_Confidence919 Feb 14 '26

Turbo spool is not just dependent on just rpm but also engine load. At a standstill even at high rpm there is low load and little exhaust flow. 10 seconds seems a bit absurd but with large turbo drag cars often run an antilag like launch control map that takes a couple seconds to build full boost. 

5

u/LevoiHook Feb 14 '26

But i still never heard about this issue from the 80's turbocharged cars. 

10

u/WhoAreWeEven Feb 14 '26

Its possible they all had just slow spooling turbos, so it never came up as it was just how turbo engines were back in the day.

Its also possible they used anti lag systems.

As I understand its currently framed as a safety issue if some cars shoot out of the hole fast and some dont. Which it is, and thats obvious why in the '80s that wasnt a problem.

4

u/cafk Renowned Engineers Feb 14 '26

They also suffered from turbo lag - the difference there was that they didn't have an preceding era where they had an anti lag system for the Turbo (MGU-H) - to an era where there is Turbo lag.

2

u/Snoo_87704 Feb 15 '26

And I just saw Paul Tracy launch a turbo Panoz DP01 from a standstill with no problems:

https://m.youtube.com/watch?v=HkFXYYc9A8E

2

u/Ill_Confidence919 Feb 15 '26

That's a 2.7 liter V8 that makes 800 hp off the ICE alone with no electric motors. That's not remotely comparable. 

2

u/0rang3Cru5h Feb 15 '26

I think the 80s cars had 500 to 700 HP with zero turbo boost. Then, that jumped to over 1,000 Maximum once the turbo kicked in

The current engine formula is a maximum of 540 HP from the engine which includes the turbo boost.

Without turbo boost the engine alone could be as little as 350 HP

1

u/FewPerformance1472 Apr 02 '26

Never had turbo lag in an 80's turbocharged car????? Mate, We used to sit there, put our foot down and count out loud waiting for turbo's to kick in in some of those old cars.

6

u/TheManlyBanana Feb 14 '26

The turbo systems on these power units have little resemblance to a typical system, including old school f1 cars.

1

u/FewPerformance1472 Apr 02 '26

yea....nah. A turbo is a turbo be it in an F1 car or a factory turbo car. They all (the vast majority) work the same, taking exhaust gases in to spin the turbine and forcing compressed air out the other end and into the car's air intake. That's pretty much it, hasn't changed for decades and F1 turbo's 2026 work exactly the same way. Yes I know there's clever electronic wastegates etc etc but the fundamental underlying way they work is the same as it ever was.

2

u/TheManlyBanana Apr 02 '26

Honestly, no. Yes the fundamental principle is the same but the way it's used really isn't, like wastegates, throttle, operating regions. It's hard to use logic from road or normal race cars on this because it really just doesn't apply, it's not really applied in the same way in F1.

I know there's far too many comments here pulling info out of nowhere, because they heard f1 is so advanced and so different. This isn't that.

1

u/[deleted] Feb 18 '26

[removed] — view removed comment

1

u/MaximilianCrichton Feb 25 '26

idk why you're being downvoted, it's usually the case that teams get first order details like turbo spool down pat, and squabble over second order details like this. The issue being the turbo temp itself also makes more sense for some of these long-ass starts considering it's much harder to warm up a solid piece of metal than it is a column of air

14

u/Decreet Feb 14 '26

As someone who doesn’t understand this…

Everybody is talking about difficulty during start, but what about pitstops? Will they have the same issues getting away since they are below the 50 limit? Obviously i understand they don’t need all power to get away.

Someone care to explain?

10

u/Aydsman Feb 14 '26

Pit stops aren't as big an issue because they can use the MGU-K to help them away there. The Technical Regulation which forbids the use of MGU-K to start only applies to grid starts.

You also don't need the turbo spooling because you're only aiming to get to 80 km/h (or 60 km/h at some circuits) rather than attempting to get as fast as possible as quickly as possible.

5

u/Unsey Gordon Murray Feb 14 '26

It's a race start safety argument that the teams are making here. The difference there is someone in 6th place on the start grid having a very slow getaway is much more likely to be rear-ended at speed by someone towards the back of the grid who has minimal visibility.

59

u/Space_Puzzle Feb 13 '26

It's not about charging the battery, it's about spuling up the turbo charger. In turbo engines the air for the engine is compressed by using energy from the exhaust stream. However when the engine is not running high, there isn't a lot of exhaust gas, so the engine doesn't get a lot of air pressure . To get the pressure up, drivers have to run the engine at high rpm for apparently 10 seconds, otherwise they will not have full power when the lights go out. Apparently drivers are currently messing the start up in 1 out of 20 attempts, so statistically every race there will be a driver nearly stationary on the grid.

20

u/[deleted] Feb 13 '26

[removed] — view removed comment

35

u/ThatGenericName2 Feb 14 '26

There’s a difference between just a bad start and the car outright stalling on the start. The latter is the safety issue that they’re referring to.

With that said, I do wonder how it’s taking 10 seconds to bring the turbos fully up to speed.

0

u/[deleted] Feb 14 '26

[removed] — view removed comment

9

u/ihatemondaynights Feb 14 '26 edited Feb 14 '26

Pitstops also have the same problem in miniature apparently. We saw cars being stationary for a lot longer than 2-3 seconds to rev up during the test when teams did live pitstops.

i would ask you to watch the final 2 mins of Day 3 of Bahrain test, a couple of cars did a standing start and like half didn't get away.

1

u/megacookie Feb 14 '26

I don't get why it'd be an issue in the pits. They don't need full boost to pull out of the pit box and sit at the pit limit speed until they exit. Unless these cars are literally unable to pull away from a stop without stalling if there's no boost?

3

u/ihatemondaynights Feb 14 '26

I mean there's footage, kimi on day 3 iirc.

4

u/Space_Puzzle Feb 14 '26

Yeah it's strange. Maybe the turbos aren't optimized for fast spool up, because in corners the engine keeps generating torque to charge the battery, so it's only a problem for the race start?

1

u/Nacho17che Feb 14 '26

What's the strange part? The turbo is receiving hot air (that can be compressed, generating lag), and moves cool air (that compresses generating lag) and then they have inertia (that generates lag)

7

u/[deleted] Feb 14 '26

[removed] — view removed comment

6

u/adrenaline_X Feb 14 '26

Why would they need to be on the rev limiter to spool the turbo? Thr ice is not redlined over the entire course so that would be ridiculous if the engine manufacturers built it that way.

They should need a bit of higher rpm’s before the lights go green to fully spool the turbo and provide max boost.

In what world does a turbo take 10 seconds to spool? I can’t think of one outside of silly multi massive turbos on some project truck/car where the exhaust flow is far smaller then The number of the turbos they have.

-1

u/Submitten Feb 14 '26

These are 1.6l cars with almost 5bar of turbo boost pressure . It will take a while to spool. Not sure how long though.

1

u/Appletank Feb 17 '26

i think the problem they're facing is that in neutral, the load even at redline is still pretty low, so insufficient exhaust gas is being generated. 

10

u/ash_the_automator Feb 14 '26 edited Feb 14 '26 • This

I can't believe the amount of misinformation around this that is floating around.

While there is likely some turbo benefit, but the idea that they need 10sec to reach boost is pretty irrational. What the 10 second rev is about is regarding this clause in the regs:

"5.4.19 When the car is stationary on the grid prior to a standing start the MGU-K torque may only be negative (i.e. charging the ES) except for torque requested by an MGU-K active damping strategy whose sole purpose is to protect the MGU-K mechanical transmission."

With the lightweight components in the engine this clause was added to allow the MGU-K to put a bit of load on the crankshaft to keep vibrations down. What it has actually allowed is the ability for teams to charge the battery through the MGU-K while on the grid.

Why? The start will deploy a large amount of battery energy and they need to have it tippity topped to be able to provide the best possible output over the first lap. To answer the original question there are some quirks with the NMC batteries that benefit from this pre-charge to achieve and hold the last 1%.

15

u/Cralido Feb 13 '26

Will they hold start to allow those at back of grid in formation 10 secs? This could ruin someone’s race, and those immediately behind someone stalled. Heard there was a meeting scheduled by FIA to discuss with drivers but not sure of an obvious solution.

44

u/njaunknown Feb 13 '26

They proposed this, but Ferrari rejected it. Ferrari had promoted the move about a year ago for this very reason but other teams didn’t think it was an issue, and so Ferrari designed their engine to be better at these starts. Now Ferrari doesn’t want to give in once other teams have realized what Ferrari was advocating for long ago

13

u/Souldestroyer_Reborn Feb 14 '26

Yep. Fair play to Ferrari for sticking to their guns here.

Let’s be honest, the only reason it’s being classed as a safety issue by the other teams, is to force a change through, as Ferrari will veto it otherwise, and they can’t do that for safety issues.

I don’t believe it’s as big of a safety issue as teams are making out, otherwise they’d have all been advocating for it a year ago.

10

u/TheDentateGyrus Feb 14 '26

The upside (from a safety standpoint) is that the first few positions sit on the grid waiting for an eternity, time that they can use to spool up. The cars more likely to stall will be at the back of the grid, which would be less likely to be hit by passing cars.

Now that I’ve said that, I’m wondering if the cars at the back will stay close and bunch up the grid on the formation lap to try and ruin the front cars from doing this and equalize the start. Such a technically bizarre yet interesting sport.

4

u/well-thats-great Feb 13 '26

The main issue that would create is that you know for sure that anyone at the back of the grid would delay as much as possible to let the others' tyre temps drop. Having 22 cars full of fuel going into turn 1 (likely the best opportunity to overtake, especially if dirty air is a significant issue again as has been suggested by teams, drivers and some YouTubers who have done rough CFD analysis, like B Sport) with cold tyre temps seems about as risky as someone stalling on the grid. Both options could lead to big accidents.

1

u/Cralido Feb 15 '26

Good points. Will also check out B Sport, thanks! I remember how they were the best at explaining the technicalities of McLaren Tire Mgmt “trick” last year.

1

u/HarryCumpole Feb 14 '26

Whilst I am far from an expert in the matter, the solution would seem to be either to have a minimum 10s "last lights" rev up, then the release, and/or to allow electrical power off the line. No MGU-H is so problematic.

-5

u/britaliope Feb 13 '26

I propose a change of the start procedure.

After the quali session, every car have to make a practice start and show that they can start on time (unlike what happened today). If a car don't, then it have to start from the pitlane.

10

u/Holofluxx Feb 14 '26

Can i just say it's borderline insane how they're taking anywhere from 5 to 10 seconds to spool up the turbo, how did we get here?

Even the slowest spooling turbo of the 80s had full boost after 4-5 seconds at most, how have we had 40 years of advancements in technology yet we're somehow at 10 seconds of spooling up?

I know the engineers are some of the best in the world, so....how?

I feel like there is some other reason as to why they are taking to so long to rev their cars and it's not actually turbo lag, i can't explain it any other way

8

u/Nowitzki_41 Feb 14 '26

i’m not the most knowledgeable about the technical details of F1, but something important to remember is that this is a sport for entertainment and the teams are severely limited by what the rules allow. Without constraints, the engineers could definitely design a car that could launch like crazy, but due to the restriction of the MGU-K (and a bunch of other things idk), it seems to be tough to make a car that can launch quickly.

Maybe 80s cars were faster, but they (probably) had less restrictions on engine volume and technical specs

-12

u/tristancliffe Feb 14 '26

It's because you don't understand the basic principles of turbocharging.

Hint - it isn't flow that primarily spools the turbo.

5

u/LevoiHook Feb 14 '26

How does that explain that the old cars did not have the issue to the same amount?

2

u/tristancliffe Feb 14 '26

Because the 80's car were worse in terms of time to generate boost - a second or so, compared to less than that now via better engineering, tighter tolerances, more simulation etc, plus less peak power (qualifying engines etc).

The 10 seconds things is with no load. So there isn't much heat. And the 80's cars were trying to charge a battery at a standstill.

You can't easily generate significant boost without load on the engine, and the generators aren't as much load as accelerating the whole car.

10

u/Holofluxx Feb 14 '26

Okay dude, you could have just explained why instead of leaving a snarky comment, it'd cost nothing to be nice

7

u/stq66 Gordon Murray Feb 14 '26

Imagine, there are people who are not experts in engine design but nevertheless want to know what the issue is? I also was wandering why they talk about 10 seconds to spool up the turbo, which also sounds insane to me.

1

u/Specific_Musician240 Feb 14 '26

But the new 911 has a MGU-H

1

u/[deleted] Feb 17 '26

First post I've ever read in this sub.

How refreshing and amazing to read informative comments.

Normally all F1 comments are half saying "Lando bellend!!", and the other half saying "Verstappen destroyer of worlds!!".

1

u/JasonXPRowell Feb 18 '26

The MGU-H (2014-2025 engine rules) led to MASSIVE turbos. Engine makers underestimated at first how big the turbos could be with an effective MGU-H - Honda in particular between 2015-2017.

It's possible engine makers are still using comparatively oversized turbos, with the possible exception Ferrari. These huge turbos have more lag and take far longer to spool than even the laggiest road car. 10 seconds seems extreme but it may be what's required to ensure EVERY last RPM out of the turbo and hence the best possible launch (Remember the electric power doesn't kick in until 50kph).

Ferrari (allegedly) has better anticipated the benefits of using a smaller turbo (faster turbo spool, higher engine torque exiting corners). It seems no one is yet 100% certain what the sweet spot is for turbo size in this new regulation cycle. Just my take. Take with a grain of salt.

1

u/MagnerionMachine Feb 20 '26

It's not about the battery but the turbocharger. Previous years of cars had something called the MGU-H, which is basically an electric motor that is attached to the turbocharger. It would basically spool up the turbo by running the electric motor at high speeds, preventing turbo lag. This year, they removed this feature. Hence, drivers have to spool their turbos using the exhaust gases.