THE WORLD'S FASTEST GRENADES! The Story of F1's Turbo Era (1977-1988) 

I probably used injection when I meant induction.

Between this, Group B, and Group C, the 80s were insane for motorsport.

I'm a yellow teapot, Short and stout. Here is my... ** Bang **

I tweeted Nigel Mansell a few years ago asking about that period of F1, saying how I'm amazed anyone could keep those cars in a straight line with all that power. In his reply he commented that in '85 during during practice for a GP (he couldn't rember what circuit) he pulled 6th gear (H pattern box don't forget) on the straight and he got wheel spin. He estimated he was doing close to 150 MPH at the time. 😳

This and the ground effect era (well they coexisted for a few years) are my favorite bits of F1 history.

The 80s were mad, Group B, Peugeot's 405km/h P88 and F1 ground effects!

Turbos & Tantrums is a very good yt channel that deserves more attention. A video recapping each race from 1981 through the end of the turbo era. Very quality content that most of this audience might find interesting. I’m a big fan of what that guy is doing.

Ahhh, the days when Ferrari engines were heavy, thirsty, underpowered, went pop for fun and used eye watering fuel brews.

A man is only as good as his turbo. -Benjamin Franklin

Historical notes: Turbochargers had been used on cars since the 1962 Oldsmobile Jetfire and Chevy Corvair, a good decade and a half before the beginning of the F1 turbo era. Porsche had used twin turbos on its 1972 917/10 Can-Am car, so even its use on race cars wasn't completely new. Probably fair to say that it was still in its infancy, though. The Spitfire, Hurricane, et al, used gear-driven superchargers. The US was the only country in WWII to have production combat aircraft with exhaust-turbine-driven superchargers, AKA turbochargers. The first, according to Wikipedia, was the B-17 in 1938. The P-38 Lightning and P-47 Thunderbolt were probably the most famous turbocharged fighters. Most planes relied on the supercharger, as turbos were still new and controls for them were more complex than the gear-driven ones. A great book on these engines (which could still use a good copy-edit IMHO) is "The Secret Horsepower Race" by Callum Douglas. It goes into some detail regarding superchargers and turbochargers.

They had plenty of supercharged racing cars before the war and were beginning to get turbo’d cars when the war broke out and the govt banned forced induction engines on cars to reduce fuel use

Oddly enough the first entry in an F1 World Championship race with a Turbocharged engine was in fact a Diesel. In 1952 Cummins (of truck engine fame) partnered with Kurtis Kraft (of Racecar fame) to enter that years Indy 500. Thanks to 430hp and some clever engineering it actually achieved pole position despite its immense weight, before retiring from the race due to a clogged intake. In period footage you can just see the tires being torn to shreds through every single corner.

Nobody snuggles with Max Powers, you strap yourself in and feel the G's. Well placed reference Aidan!

The racers at Indy had been working on turbocharging for a lot of years by the time the F1 guys picked it up. Bobby Unser got the first turbocharged win at Indy in 1968 and by 1972 the Offy was making 1000 hp out of 167 cubic inches. Every Indy winner after 1968 was turbocharged until the IRL mandated 4.0L NA engines in 1998. I also have noticed that the output of the BMW 4-cylinder keeps going up and up the farther in the past it gets.

This channel is so bloody good. I've got one huge complaint though. The videos are too short!! 😂😂 seriously, the quality is unsurpassed. I love Formula One history, especially from the 1970's and 1980's.

I remember when the Renault turbo first came along, I was rooting for them because it was something new and interesting, where they were taking a chance on the engine rule. In the seventies there were a lot of different experiments, the most interesting was the 6 wheeled Tyrell. It just seemed a more visible variation of methods to try to gain an advantage. Today the cars have slightly different looking sidepods. Another weird effect was when they had a "ride height" check to try to get rid of the skirts, so they put pneumatics in the suspension so that when the cars were measured before or after races, they were jacked up so the skirts weren't too low to the ground. Another fun one was the freezing of fuel when there was a limit of how much volume of fuel you could use during the race.

I wish F1 did something like this today for like 1 race a season. Letting the teams innovate is F1 necessary

Some WW2 aircraft used exhaust driven turbochargers, for example the Allison V12’s in the Lockheed Lightning and the radial engine in the Republic Thunderbolt.

I read article long time ago about this 5,5bar BMW turbo engine - there was quite well described that it had usable powerband of about 1000rpm from 10k to 11k. Everything else was just turbo lag (to be 100% accurate then it should be called "turbo threshold" ), if engine rpm fell down then it took half a lap to spool the turbo up again.

I think one point to add that wasn't mentioned much was another reason why turbos were becoming more of a possibility, that being that electronics were becoming advanced enough that you could control fuel injection with them, which was required for the turbos as a traditional carb wasn't up to it.

Ahh the real turbo Era. The bwm's with 1500HP. The Era when anyone could go racing in F1. Not like now which is nearly impossible.

Thank you not only for a great subject and vid, but that picture of Gilles thank you so much for those memories :) It was a mad time in F1, in a good way.

IndyCar and sports cars had done quite a bit of the legwork on making turbochargers reliable and functional.

There is an excellent period documentary out there that follows Cosworth building their Turbo V6 for the '86 season I believe. It's called "Turbo F1 Engines: How they started", currently available to watch on RU-vid in two parts.

Who doesn't love these old turbo? Btw, turbo were used in ww2 as well. Planes like the P 38 and P 47 used turbo on top of driven supercharging. Complex but highly effective.

I'm a vendor, machine /fab shop for Garrett turbo in Torrance ca. Garrett aka, Honeywell, They started supplying Turbos to Ferrari in the electric assist era. I made a temporary exhaust, to the turbo supplied in Ferrari's F1 exhaust system. The Turbo has a housing around the Turbine that was not cast but was made from sheet, stamped and fabricated Probably Inconel, maybe .040" thick. This I assume was for weight and space reductions. Anyway the reason I had to make the special plumbing was so they could put in on a gas stand test bed and spool it up to grenade. the turbo. The heavy casting seen on all turbo's has a very important reason for being massive and that was to contain the bits in a failure. Ferrari gave the turbo back to Garrett with some parts but the main bit that they wanted to check was the containment assembly. It was a Kevlar shield/blanket going around the turbo in the shape of the roll over/ induction tunnel, it would fit inside this area. The Turbo was above the engine, centered, coupled to the electric motor. The blanket was massive thick. must had been .5" thick in ply thickness. It was to kept the fragments from getting out in a RUD (SpaceX term for Rapid Unscheduled Disassembly). They spooled it up on a natural gas burner stand and let it rip, in a explosion proof room. It contained the event. Fun fact: In what situation is a Turbo used in that causes failure, the hardest application? Big open pit mines, race cars, race boats....? Answer: City busses. According to Garrett the spooling up and down all day long is the killer.

The 70s are my favourite era of F1 from the engineering side. Tall airboxes, the DFV's best years, sidepod mounted radiators, all sorts of different front and rear wings, ground effect, and of course turbochargers!

Remembered dad had a blast watching F1 in this era, and always up early in the morning on Sundays, coverage of the European races started at this time in N.America. Turbo was one of them, I am sure.

I'm sure I've seen people claim the BMW engine was even 1600hp in qualifying trim, it was 1200 when I first read about it. I guess the phrase "the older I get the faster I was" applies to engines as well as drivers

I just discovered you today (19, Nov 2022). I'm really enjoying your content!! Greetings from the USA.

The rumors say that the BMW engine did on bench dyno about 1400hp...at least that was the limit for the dynometer... Also there is a story where BMW E21 316 owners having their engines replaced with new so that M Division could keep the old ones that have been run in and their blocks where stressed enough to handle the extra power...the same story says that the personel kept the blocks in a backyard and they went to piss them when they needed to relieve themselves instead of just going to the toilet...they said that this technique was helping the engine blocks to become stronger...

My abiding memories of the 80s turbo era was seeing the first puffs of smoke and then a few laps later the big plume of smoke from the exhausts as the turbos eventually failed and wrecked the engines and of course the resulting fire if the engine wasn't shut down in time.......Ah good memories! 😂😂

1300bhp and 540kg min weight = madness

Some other numbers from Berger's 218.6 mph trap speed at Monza in 1986: 1350 bhp, boost flashed at over 5.0 bar. All from a 1.5 liter four banger.

I started watching F1 at the Monaco GP in 1989, so just missed the end of the turbo era. Reading about it, and watching videos like this as well as all those classic F1 races from the 80s, makes me feel like I was born too late and missed something pretty special. (Speaking of which, I was actually born on the same day the photo in the thumbnail of this video was taken!) The turbo engines gave F1 one of its most distinctive eras, and although we’ve had turbo engines/power units back again since the start of 2014, they’ve been so much more homologated and have lacked the raw spontaneity of the 80s ones, so it doesn’t feel the same to watch as F1 in the 80s must’ve felt, IMO.

Great video tons of great info

awesome video

Didn't Keke Rosberg once say of the turbo cars and the lag "When you press the gas pedal, nothing happens. And then, everything happens".

The first Grand Prix I went to was in Adelaide and I still remember the commentator telling us, the reason for Sunday morning practice is so that if an engine blows it can be replaced by race time. Since every one had replaced their qualifying engines with race engines this was actually a good idea.

Regulating performance in F1 really is (or at least was) a game of Wack-a-Mole, especially from the late-70s until the current era. It didn't take many years for Renault to recover most of the engine performance lost when turbos were banned. Thanks to the air spring technology they developed for their turbo engines, and fully pneumatic valves. In commentary for a 1993 race (Spanish GP iirc) Murray Walker mentions a figure of 850Bhp - very close to the peak race power from the late turbo era, and probably a better performing engine overall. And power was increasing rapidly each year as the engine technology was still far short of its ultimate rpm limits. I remember engine guru Brian Hart writing in Autosport's 1996 F1 pre-season supplement that the FIA made a huge mistake by not banning pneumatic valve technology, as it was allowing both engine performance and costs to rapidly escalate out of control. (If you haven't covered it already, I think the Renault V10 engine (1989-1997+) could make an interesting topic for a video. It is arguably the only F1 engine which can come close to the Ford DFV for true greatness, and was instrumental in making modern F1 what it is. From what I've read, although successful the Honda engines in the McLarens were crude, heavy and thirsty by comparison.)

Quality Stuff, Mr. Millward - well Researched imo.

great presentation..... thanks

Hello Aidan: Thank you very much for this. The 1980's bring out my inner "Clarkson". Stay well and safe.

During World War II the US used turbosupercharging on the B-29 and P-47. Today we call it turbocharging. It allowed the planes to reach high altitudes to avoid some of the flak and some less powerful German and Japanese fighters. The P-47 was more about speed and it was very complex with twin wastegates and ducting with intercooling.

I remember Autosport in 85-86 giving the power output of each teams engines as part of their F1 coverage. I remember them stating that BMW having some 1220 for qualifying, and about 1000 for the race. The McLaren's TAG engine's put out 960 hp in both qualifying and race trim.

Ford and Cosworth also tried to build an inline 4-cylinder turbo for this era. 4 cylinders equalling much lightness. They couldn't get the engines to not rip themselves apart, though, and switched to an underperforming V6 configuration. I have no idea what wizardry BMW had to do to get theirs working reliably

A point to mention is that qualifying engines were essentially banned in 2004 when an engine was supposed to last an entire race weekend, not that hot qualifying engines were a thing anymore, but the whole idea of forcing the teams to get more mileage out of an engine had a huge impact on performance. 2004 cars held records for over 10 years, because in 2005 the engines had to last 2 race weekends....and now it's sometihng like 3 engines per 20+ race season....I guess what I'm hinting at is a story on the various successful and more often than not, unsuccessful attempts to slow down F1 cars.

Love you channel, great video today. Living in the U.S.A.

Those cars must have caused a heart attack to the drivers every time they press the accelerator pedal

I suspect skill sets are similar today, for different reasons, but the sheer nerve has to go to the old squad. Imo.

Supposedly, the BMW 4cyl engine blocks were hand-picked from crashed saloons and left outside for 24 hrs. To get some rust on the block surfaces to aid in the production of power from turbo.

A few manufacturers really failed at developing reliable turbo engines, which I think is why turbo engines got banned for 1989. McLaren were arguably the best performing team over the turbocharged period from 1983 to 1988, finishing 1st or 2nd in the Constructors Championship every year, using first TAG (Porsche) and then Honda engines. It even took Honda a good few years to get their turbo engine reliable (see 1983 Williams FW09 and all Laffite's DNFs). Renault and BMW didn't have great reliability (see Piquet's title defence in 1984 - 9 DNFs out of 15 races), while Alfa and Ferrari's turbos were appallingly unreliable - Alboreto famously lost the 1985 World Championship with 4 consecutive DNFs at the end of the season, handing Prost his first title.

The B-17 Flying Fortress and P-38 Lightning were some of the Turbo's first major production applications. The US Army Air Force decided in the late '30s that Turbos were the way to go after General Electric - yes, the lightbulb people - demonstrated one on an aircraft, and the Lightning and P-47 were designed with them as part of a requirement - the only reason the P-51 Mustang had a supercharger instead was because it was designed at Britian's request. GM would later introduce turbos on the Corvair and the Oldsmobile Jetfire road cars in the early '60s...before dropping them like they were hot, and turbo Offenhausers started appearing alongside Cosworth DFXs at Indianapolis in the mid to late '60s and became a staple of USAC and later CART competition. So they'd been around by the time Renault started developing them for F1...but when you've got F1 money...whooooboy.

This American thanks YOU!!

I’d love to see you cover or talk about some dragsters and their drivers, a group of drivers who strap themselves into a car with over half the f1 grids worth of power behind them. Or for another cool fact when the NHRA goes to vegas or Charlotte for the 4 wide events those starting lines have more total power than the f1,f2 and f3 grids combined.

9:00 lol I had a similar argument about group B, some guy claimed the Delta S4 ran 600hp on stage and occasionally 1014hp lol. The 1000+ was during a engine dyno test, and the 600 is closer to 480-520... Gotta love how the number just go up and up

can am series ...was ended when porsche rolled out with the 917/30 with 1000+ hp in race trim and won all in one season. or something like that....:D

Road and Track tested a Benetton B186 in 1987, their 1986 car with a BMW engine, and they rated it as 900 BHP in race trim and 1100 BHP in qualifying trim, but I remember an article from 1986 where they tried to estimate HP based on speed and they suggested up to 1300. These are ALL guesses by the way, but the point I'm making is this was the claims made in period, because yes, there is an exaggeration factor over time...

Let’s be honest, it’s a miracle any drivers at all made it out of F1’s turbo era alive. Imagine being strapped inside the equivalent of a jumbo go kart with body panels with 1300 hp.

I remember reading that while at the start of a race the turbo cars could give close to 1000hp the problem was heat efficiency (or lack there off). By lap 2 the heat build up was so bad that the output would drop to around 850hp.

Great book (no longer in print, I believe, but a great read if you can find it) on this topic is Ian Bamsey's The 1000 BHP Grand Prix Cars. Covers the entire turbo era of F1. Lots of great technical info and interviews with various players (including drivers) from that era.

From the days when a quali engine was binned, to the days where a team wiping the dead bugs off the nose of the car earns a 3 grid spot penalty.

I know you said the number of the bmw engine kept growing in power as decades passed, but I would like to refer to a comment Murray Walker made at the 1986 Adelaide GP where he said and I quote "the tremendously powerful 1350hp in qualifying trim, bmw powered benetton". So I have a feeling thats where the outrageous numbers came from. Where he heard these numbers I don't know but the video is on youtube named 1450bhp f1 bmw turbo 🤦🏻‍♂️ (100hp more than claimed). Still a bonkers era and I love it!

I just remember the Renaults ,I think it was , exploding in huge white plumes of smoke during qualifying over and over . The drivers LOVED those cars. Damn, were they fast when they worked. I miss the craziness. Fun times.

Just really enjoyed the horsepower extrapolation segment! I have *not* enjoyed watching JPM's records fall to cars using a battery (er um power store)

It was the best, era BY FAR in open wheel racing. In my opinion. Beastly powerful cars driven by incredible drivers on amazing tracks.

Re boost. For anyone interested, Richard Holdener on his channel does extensive testing of engines particularly turbo engines. He has indeed found that 1 Bar increase does very closely approximates double the horsepower. For example a 300 hp engine becomes 600hp with boost of 14.5psi. This is shown so many times as to be thoroughly predictable. Supercharged engines don't produce double since the blower is slaved to the crankshaft and each rotation of the blower yields a known amount of volume, and blower pumping losses are greater, and due to the slaved nature of them the boost they produce actually degrades with altitude increase - (which is why aircraft often had 2 speed superchargers for high and low altitude). Turbos free spool so they can keep producing boost and although it drops off with altitude too it has high excess capacity and is easily able to compensate for example if a turbo at 1 Bar might have a capacity of 1.5 Bar and as altitude increases then the capacity drops to 1.2 Bar still allowing the full 1 Bar. You can do this with blowers but because they don't free spool the drive ratio has to be increased adding to even greater pumping losses - all of which has to be paid for in fuel and therefore weight of course.

Any chance, if you haven't done a video about it already, of doing one about Nigel Mansell's time at Ferrari?? Some of the stuff the FIA have banned in the past levelled the playing field and made racing more competitive. Other stuff they banned, like active suspension and traction control at the end of the 1993 season, just made the cars harder to drive, with tragic results....

Point of order - the Rolls Royce Merlin engine used in the Spitfire & Hurricane was mechanically supercharged (driven off the crankshaft), NOT Turbocharged (driven by the exhaust gases). As to the peak power of the BMW M12/13/1T engine, the honest truth is that nobody REALLY knows how much power it was putting out when in qualifying trim, not even BMW. At the time, BMW's test dynamometer only read up to 1,100hp, which the engine was capable of producing at around 9,700rpm. As the engine redlined at 11,500rpm, there was no way for BMW to get a truly accurate figure for peak output, but people involved estimated it to be in the 1320-1370hp range. As to why nobody's ever tested one of these engines since? Simple. They don't exist anymore. The qualifying engines were so highly stressed that they would deform the block during a "full beans" run, and as such, every quali-spec M12/13/1T was scrapped immediately after being used in anger. There are regular race-spec M12/13/1T's around, but the quali-spec engines are all gone, and it is almost impossible to make a race-spec engine into a quali-spec engine, as there were many minor differences between the two specifications, both internally and externally. One of the most important changes was to the electronics, with a special chip needed to unleash maximum power. Without that chip (the "Hitler" PROM, as it was called), a quali-spec engine would put out around 1,050hp using the standard race PROM, and would be safe to run for roughly 150km before failure. With the "H" PROM, you got a roughly 30% increase in power, at the expense of a 90% reduction in engine life, with the engines only lasting for roughly 15km. And AFAIK there was only ever 1 "H" PROM made... Oh, and if you were wondering, the engineers named the "H" PROM that because when it was fitted to a quali-spec engine, that engine would very briefly blitzkreig the opposition, before having a meltdown & killing itself. German humour...🤷

Turbocharging/Supercharging was originally introduced in F1 for the 1966 season alongside the 3.0 litre Formula for the British teams who might have wanted to carry on with using the 1.5 litre V6 Coventry Climax engines

If this guy did the F1 Tech Talks, I would watch. Such a good voice

How has this guy got 85k followers? I’m 3:16 in and the inaccuracy is hilarious; let’s pretend Ferrari, Alfa Romeo and Matra didn’t build F1 engines and BMW were already supplying Brabham and didn’t test the Turbo unit alongside the DFV in practice sessions until it was ready. Cool stories bro.

As I remember it, the late ‘60’s regulation either specifically mentioned supercharging, or it was assumed to be superchargers because the idea of using turbo’s was not around. So, there was much protesting that the Renault turbo’s were not adhering to the regulations or were against the spirit of the regulations.

Now, now... Any depiction of Mike the Bike that does not mention the TT comeback with Ducati in the late-1970s is stunningly incomplete.

Supercharged cars go back to Roles Royce and a 1904 V8 powered car. Likely further back then that but I haven’t found one yet.

Could you create a video about Rene Arnoux? He is one of the sole drivers of the era (which aren't Prost, Senna or Lauda) that just stay in my head but I don't know why anymore... With Keke Rosberg I don't have any idea how he won his championship. Same for Jody Scheckter. And I just really like your rambling Mr.Millward! And I feel like there's a little bit too little videos about those other drivers of the Era.

I do wonder how powerful the Turbo hybrid era engines of today could get if we went back to pre 2022 fuels and party mode with no fuel flow limit the fact they get over 1000hp with said restrictions is pretty amazing Regarding the original turbo engines I think the FIA simply went on an acid trip in the 1980s regarding the crazy turbos group B and group C

These cars are really insane 1000+ hp even today is still a thing just in the hybrid era

Remember watching senna (turbo) and mansell (normal aspirated) battling it out, mansell would catch senna up in the corners, then on the straight senna would just sprint away as his turbo kicked in.

There's a fantastic old BBC documentary on youtube about the development of turbo engines & the ford one in particular - search for 'Turbo F1 engines - How they started, part 1'

Indy cars were using turbo Offenhausers years before turbos came into F1 - Bobby Unser won the 1968 Indy 500 with a 2,75 Offy turbo

Audi could supposedly tune up the 2.1L I5 in the later Quattro rally cars to 1000 hp, but the car was underivable, and probably wouldn't have lasted very long if it was. They may have used these settings at Pikes Peak, where the altitude robs the engine of 25% of its power from start to finish (power was already reduced due to 9000 ft elevation at the start line), and the run only lasted 10 minutes. Lancia said they could also tube their Delta S4 engine to hit 1000 hp, but it certainly wouldn't have lasted very long. Even putting out less than 500 hp, most of the engines in Group B were good for one rally before needing a complete teardown. Maybe two; the engine in the Ford RS200 needed a rebuild after 10 hours of competition.

A massive change since the original turbo days is the fuel allowed.

I saw the turbo cars when they raced in Adelaide back in 1986. At the time they were the F1 cars of the day, of course we had no idea what the future held. I wish I'd understood the significance of exactly what I was witnessing at the time. Those cars were just wild, and whilst I can appreciate the speed of the modern era the cars are somehow less unhinged. Those 1980s turbo cars were about as controllable as a feral tomcat with two dicks. A whole lot of hissing and snarling, very sharp claws and chock full of hate.

10:00 Senna was doing the throttle blip in NA go garts lonnngggg before he was driving anything with a turbo. He does it to test the traction limits of a car. C'mon Aiden I thought you knew better than common myths :((

Top fuel nitro motors are the fastest grenades. Gasoline and alcohol motors come apart violently nitro motors explode.

ah yeah good old times of qualifying spec fuel that if leaked a drop it would evaporate before hitting the ground. So they kept it cooled until they couldn't anymore (also for volumetric reasons)

I am old...i am so old..my father took me to F1 races at Mosport.That being said,i've watched many decades of F1.Good ole CBC here in Canada showed them all,usually with Jackie Stewart as guest presenter.AND..the turbo era was the most bland boring era of F1 ever,except the first year when they all blew up..that was actually fun :P

That’s the biggest difference between superchargers and turbochargers, turbochargers are exhaust driven and suffer turbo lag, a supercharger is mechanically driven usually off the engine and has no turbo lag, it’s full boost at idle. The issue however is slight power loss due to the engine having to turn the supercharger, I’d like to have seen these F1 teams try and turbocharge a supercharger how some older Diesel setups

Always thought the planes you mentioned were supercharged, not turbo charged.

I haven’t had time to fact check the following. 1. Qualifying and grid position was crucial to a winning strategy. So qualifying engines were designed to wear out by the end of qualifying. 2. I believe that Toluene was used in the fuel mix. A sure way to destroy the internals of an ICE. 3. Ayrton Senna was a god.

The Golden Era of F1.

1983 BMW used illegal fuel needed for the large 4 cvlinders. Damples taken at Monza disappeared 1080 hp on the dyno in 1986, said the test engineer, but the teams modified the ECU 1982 constructors' was the first title in F1 won with a turbo. By Ferrari. Drivers' went to Keke due to the tragedies of Gilles Villeneuve and Pironi.

Is it strange that when I see a 4 cylinder BMW block, I have the urge to piss? #IYKYK

My favourite era

What a decade to be an adult and interested in Motorsport! Now you can’t smell, hear or really immerse yourself…hard to see 200 hairdryers going in circles for 2 hours

Reminds me of why my tiny little turbo in my Volvo S20 was quicker than my Monte Carlo's big block Chevy V8.

As a rough guestimate, you can use the formula of 10hp/litre/1k rpm. For forced induction multiply capacity by boost in bars. Hi speed engines like the dfv produced about 14hp/litre/1k rpm. At higher speeds the inertia of the gas flow creates a forced induction like effect. I've heard figures of up to 107% claimed on volumetric efficiency which would allow the engine to perform as if its displacement was 107% greater. For the BMW engine at 5.5 bar it would theoretically produce about 82hp/1k revs. To make 1300 it would have to pull 15k rpm. If you allow 10% for toluene fuels, it would still need to pull to 13500 rpm.

and it's this era that i'm going full alternative universe in rfactor

5:00 porsche has been using turbos on Can-am cars since the early 70s and the twin turbo flat 12 in the 917/30 giving it between 1100 to 1580hp so no joke to them (source Wikipedia)