duesy
Quattro Commander
Wow.
McMurtry Automotive McMurtry Speirling
- Thread starter WBarnes
- Start date
Founded in 2016, McMurtry Automotive is a British company that designs and builds custom electric vehicles, including the Spéirling Pure Electric Fan Hypercar. Official website: McMurtry Automotive
Tourbillon
Cornering Kingpin
That little bugger if they manage to get some into production might just end up being to it's limiter the King of the Hill in a straight line and around racetracks too. It's definitely been lapped at that track. Times I can't say but hopefully they'll publish something soon it'll be very interesting to see!
Tourbillon
Cornering Kingpin
That looks very bloody quick!
Courtesy Mcmurtry feeds
Tourbillon
Cornering Kingpin
I mean that's a Holy Trinity member, some state the finest and it had a head start. This hypercar is comically quick. I believe the event was obviously to increase exposure and sales.
Looks like a sterling job to me.
Looks like a sterling job to me.
Tourbillon
Cornering Kingpin
Tourbillon
Cornering Kingpin
Tourbillon
Cornering Kingpin
tristatez28lt1
Tire Trailblazer
Editing 
Tourbillon
Cornering Kingpin
Editing
It's OK man you should've left it. I'd of deleted it, I just got caught up in the Aston Martin stuff!
Jonathan19
Premium+
The production version will be completely crazy!
Tourbillon
Cornering Kingpin
TopspeedPT
Track Technician
Tourbillon
Cornering Kingpin
"The FASTEST LAP EVER of our 'home circuit' Castle Combe with the McMurtry Spéirling PURE VP1 driven by Max Chilton.
Running at 80% power with a 155mph speed limit, a lap time of 54.559s was achieved at Castle Combe Circuit, Wiltshire, England during private testing
The car is the McMurtry Spéirling PURE (Validation Prototype 1) fan car driven by Max Chilton on 29th April 2024.
This is 4.037s faster than the outright fastest race lap record (set by an F3 car in 2021)
It is 9.796s faster than the GT3 lap record (set by a Lamborghini Huracán GT3 in 2022)
Castle Combe is often referred to as the prettiest village in England, and its race track, Castle Combe Circuit, has a 74 year racing history. It’s 1.85mile long featuring a mix of fast corners, a blind crest and two technical chicanes."
Running at 80% power with a 155mph speed limit, a lap time of 54.559s was achieved at Castle Combe Circuit, Wiltshire, England during private testing
The car is the McMurtry Spéirling PURE (Validation Prototype 1) fan car driven by Max Chilton on 29th April 2024.
This is 4.037s faster than the outright fastest race lap record (set by an F3 car in 2021)
It is 9.796s faster than the GT3 lap record (set by a Lamborghini Huracán GT3 in 2022)
Castle Combe is often referred to as the prettiest village in England, and its race track, Castle Combe Circuit, has a 74 year racing history. It’s 1.85mile long featuring a mix of fast corners, a blind crest and two technical chicanes."
StartYourEngines
Tarmac Traveler
Being 4 seconds faster at Castle Combe than a race lap record (so not even a qualifying lap - which would be faster - from the F3 car) of a 240 hp Dallara F317 is a good feat, but not super impressive.
They said they were running at 80% power (so around 810 ps peak power), but - AFAIK - they did not mention this time the % of employed downforce from the active fan.
I hope they were not running with 100% fan downforce, otherwise this result would be disappointing.
But, given that 4 seconds margin on this circuit over a 58.5 s lap time from a F317 would roughly be equal to a 1'41-1'42 lap time at Silverstone - compared to the current lap record from a F317 which is 1'49.7 - there is a good chance that the Speirling Pure was running here as well with 80% downforce level.
In fact, with 80% power and 80% downforce settings the car clocked a high 1'40 lap time in Silverstone earlier this year.
Back to the Castle Combe lap time, I said not super impressive because a Dallara F317 is not even a current official FIA F3 car, but rather a Formula 3 one.
The FIA F3 race car is in fact the current Dallara F3 2019 (which will be soon replaced by the upcoming F3 2025), which packs 380 hp and is significantly faster than the F317.
In fact, at Silverstone, while the race lap record of the F317 is the previously mentioned 1'49.7 time, a Dallara F3 2019 clocked a significantly faster 1'45.7 lap time.
Now, we know that the Speirling Pure is even faster than that (clocked a high 1'40 lap time at Silverstone, as already mentioned), but I would have expected a bigger gap over a F317 at Castle Combe.
In any case, regarding the Speirling, the required jump to match serious F1 lap times is quite huge.
It is true that, thanks to its active fan, the Speirling has big downforce edge over everything else at low-to-medium speeds, however from a certain speed value onward the advantage of a F1 is going to be massive.
For example, the downforce-to-weight curve (as function of speed) of the Speirling Pure is basically a flat line from 0 km/h to its top speed. There is in fact a minimal dependency from the square value of velocity due to the rear wing (but we are talking about a very low amount of downforce of 250 kg at around 241 km/h), while everything else is provided by the active fan (so, at full beans, claimed 2000 kg from 0 km/h onwards).
This means that, compared for example to a 2021 low-mid end F1 car, the Speirling Pure has a significant downforce-to-weight advantage until around 160 km/h. Then, from 160 km/h to around 200 km/h this advantage is considerably reduced and at around 205-210 km/h there is the turning point in favour of the F1 car.
But the downforce-to-weight profile of the F1 car increases with the square of velocity while that of the Speirling stays basically flat, so for example at 260 km/h the Speirling still has a downforce-to-weight ratio of around 2 while the F1 car is already hitting and then quickly surpassing a value of 3.
So, in high-speed tracks such as Silverstone or Spa the Speirling is going to have a clear disadvantage in high speed corners compared to F1s and, to ultimately match their lap times, it has to totally compensate in low-speed turns thanks to its fan-driven downforce at the immediate power delivery of its electric powertrain.
This can theoretically be done but it's not an easy feat to accomplish in practice, also because the LMP2 tyres of the Pure are way narrower and with far less mechanical grip compared to soft or qualy slick tyres of post-2017 F1 cars.
Moreover, nobody basically mentioned this fact, but on McMurtry website they are claiming that the battery pack capacity of the Speirling Pure has been increased to 100 kWh.
This, however, led to a claimed weight increase of 200 kg, going from the original 1000 kg value to 1200 kg.
And a 200 kg negative delta in weight is a massive penalty when you are trying to get close to modern F1 lap times around a track.
Then, they theoretically could increase downforce to compensate, however a combination of 1200 kg weight (with no driver) + 2000+ kg of downforce is already exceeding the 3.2 tons mark, which is probably already not far away at all from the load limit of the fitted LMP2 tyres.
So yeah, overall the Speirling Pure is obviously a very, very fast track car but is has not an easy task to accomplish in its pursuing of modern F1 cars lap times.
I am interested in the upcoming developments and next steps from McMurtry to see how they are going to face this challenge.
They said they were running at 80% power (so around 810 ps peak power), but - AFAIK - they did not mention this time the % of employed downforce from the active fan.
I hope they were not running with 100% fan downforce, otherwise this result would be disappointing.
But, given that 4 seconds margin on this circuit over a 58.5 s lap time from a F317 would roughly be equal to a 1'41-1'42 lap time at Silverstone - compared to the current lap record from a F317 which is 1'49.7 - there is a good chance that the Speirling Pure was running here as well with 80% downforce level.
In fact, with 80% power and 80% downforce settings the car clocked a high 1'40 lap time in Silverstone earlier this year.
Back to the Castle Combe lap time, I said not super impressive because a Dallara F317 is not even a current official FIA F3 car, but rather a Formula 3 one.
The FIA F3 race car is in fact the current Dallara F3 2019 (which will be soon replaced by the upcoming F3 2025), which packs 380 hp and is significantly faster than the F317.
In fact, at Silverstone, while the race lap record of the F317 is the previously mentioned 1'49.7 time, a Dallara F3 2019 clocked a significantly faster 1'45.7 lap time.
Now, we know that the Speirling Pure is even faster than that (clocked a high 1'40 lap time at Silverstone, as already mentioned), but I would have expected a bigger gap over a F317 at Castle Combe.
In any case, regarding the Speirling, the required jump to match serious F1 lap times is quite huge.
It is true that, thanks to its active fan, the Speirling has big downforce edge over everything else at low-to-medium speeds, however from a certain speed value onward the advantage of a F1 is going to be massive.
For example, the downforce-to-weight curve (as function of speed) of the Speirling Pure is basically a flat line from 0 km/h to its top speed. There is in fact a minimal dependency from the square value of velocity due to the rear wing (but we are talking about a very low amount of downforce of 250 kg at around 241 km/h), while everything else is provided by the active fan (so, at full beans, claimed 2000 kg from 0 km/h onwards).
This means that, compared for example to a 2021 low-mid end F1 car, the Speirling Pure has a significant downforce-to-weight advantage until around 160 km/h. Then, from 160 km/h to around 200 km/h this advantage is considerably reduced and at around 205-210 km/h there is the turning point in favour of the F1 car.
But the downforce-to-weight profile of the F1 car increases with the square of velocity while that of the Speirling stays basically flat, so for example at 260 km/h the Speirling still has a downforce-to-weight ratio of around 2 while the F1 car is already hitting and then quickly surpassing a value of 3.
So, in high-speed tracks such as Silverstone or Spa the Speirling is going to have a clear disadvantage in high speed corners compared to F1s and, to ultimately match their lap times, it has to totally compensate in low-speed turns thanks to its fan-driven downforce at the immediate power delivery of its electric powertrain.
This can theoretically be done but it's not an easy feat to accomplish in practice, also because the LMP2 tyres of the Pure are way narrower and with far less mechanical grip compared to soft or qualy slick tyres of post-2017 F1 cars.
Moreover, nobody basically mentioned this fact, but on McMurtry website they are claiming that the battery pack capacity of the Speirling Pure has been increased to 100 kWh.
This, however, led to a claimed weight increase of 200 kg, going from the original 1000 kg value to 1200 kg.
And a 200 kg negative delta in weight is a massive penalty when you are trying to get close to modern F1 lap times around a track.
Then, they theoretically could increase downforce to compensate, however a combination of 1200 kg weight (with no driver) + 2000+ kg of downforce is already exceeding the 3.2 tons mark, which is probably already not far away at all from the load limit of the fitted LMP2 tyres.
So yeah, overall the Speirling Pure is obviously a very, very fast track car but is has not an easy task to accomplish in its pursuing of modern F1 cars lap times.
I am interested in the upcoming developments and next steps from McMurtry to see how they are going to face this challenge.
Revvd
Meister Mechaniker
Ah, good info! I didn't notice the 200 kg weight increase. Seems like they went one step forward (slicks), two steps back.
Every time they put out a video, I'm left wondering why they're holding back power and downforce to ~75%.
BTW, do you know if commonly used slicks have a concrete load rating (just like there's index table for road tires)? I can't find any numbers online and it would help me get a better idea assessing some of these track toys.
Every time they put out a video, I'm left wondering why they're holding back power and downforce to ~75%.
BTW, do you know if commonly used slicks have a concrete load rating (just like there's index table for road tires)? I can't find any numbers online and it would help me get a better idea assessing some of these track toys.
StartYourEngines
Tarmac Traveler
Sadly I do not have exact data available for that as well.
The closest thing we can do is to identify theoretical max downforce numbers for race cars wearing a specific set of slicks and then also factoring in the weight to see if an average trend of total amount (weight + downforce) can be extrapolated.
Of course, as always at this level (i.e. forum chatting), this would be just a mere and rough simplification of many more actual data/parameters which influence the actual performance on track of a race car.
Tourbillon
Cornering Kingpin
"McMurtry Spéirling PURE BEATS Koenigsegg JESKO ATTACK on Laguna Seca... FULL REPORT!"
Revvd
Meister Mechaniker
According to Top Gear UK (October-2024), both of the SWB Spéirling prototypes are still under or around 1,000 kg. It's only the planned production version that will gain in weight and size:
They tested both of the prototypes on Dunsfold against a GT3 RS:
| 0-30 | 0-60 | 0-100 | 0-150 | 1/4mile | |
|---|---|---|---|---|---|
| Spéirling* | 0.70 | 1.38 | 2.61 | 5.48 | 8.18 @ 148** |
| 992 GT3 RS | 1.47 | 3.14 | 6.84 | 16.62 | 11.17 @ 128.7 |
*First gen Spéirling used for drag race is limited to148mph (the Pure raises that to 190mph), but rate of acceleration saw it push past that on momentum alone
**lt had been sitting on the limiter at 148mph for 2.7 seconds as it crossed the line
