Just thinking

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anonymous-user

Original Poster:

54 months

Monday 5th October 2020
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[redacted]

Verde

506 posts

188 months

Sunday 11th October 2020
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This is super interesting. I own a Tesla and the thought of the same power/curve with the weight of a GTR would be cool. I know it would lack the visceral sense of a thundering LS7 and rowing the gears but the Tesla experience is really fun. But realistically the placement and weight of the batteries would limit range and likely make for a different/heavy driving experience

ephemera

215 posts

159 months

Monday 12th October 2020
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Indeed interesting! For an Ultima, the standard (large) Tesla drivesystem/transaxle seems a more logical choice however. The V8 substitute in the link above is more suited for front engined RWD (muscle) cars. We have built quite a few electric sportscars by now (also with Tesla drive systems), and I think an Ultima can be done. As you correctly stated, the battery choice (type, size and packaging) will be paramount for a good end result, and it will all depend on how a specific owner would want to use the car (trackday car transported on a trailer, all round car, boulevard bruiser, weekend blaster etc). There are already GT40's and Cobra's out there with Tesla drive systems.

BogBeast

1,136 posts

263 months

Monday 12th October 2020
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I think you would be better off starting from scratch rather than trying to re-shape an electric powertrain into an Ultima. Everything about the shape, layout, and proportions of an Ultima would make it next to impossible to fit anything sensible EV wise in.

If I had there wherewithal, money, and inclination, I would look at building a PHEV component car (refuse to class an Ultima a 'kit'). I would retain the two-seat, rear-ICengine layout but would add a significant center 'spine' to hold batteries and a front-mounted electric motor for pure EV operation/energy recovery/supplemental power. That would make for a completely different chassis and perhaps a significantly different front end. And likely quite a bit bigger. weight wise who knows, but you would have to plan to add 500kg in weight for the EV related gubbins.

dandare

957 posts

254 months

Tuesday 13th October 2020
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BogBeast said:
I think you would be better off starting from scratch rather than trying to re-shape an electric powertrain into an Ultima. Everything about the shape, layout, and proportions of an Ultima would make it next to impossible to fit anything sensible EV wise in.

If I had there wherewithal, money, and inclination, I would look at building a PHEV component car (refuse to class an Ultima a 'kit'). I would retain the two-seat, rear-ICengine layout but would add a significant center 'spine' to hold batteries and a front-mounted electric motor for pure EV operation/energy recovery/supplemental power. That would make for a completely different chassis and perhaps a significantly different front end. And likely quite a bit bigger. weight wise who knows, but you would have to plan to add 500kg in weight for the EV related gubbins.
+1 for the summary. It makes sense.
I worked on a BEV program recently, and was surprised how complicated all of the extra battery cooling was. Plus there is the battery controller, and all ancillaries (air-con, water pumps) that need to be electrically driven. There was no more space than in an ICE car. In fact, less (it was more or less the conversion of an ICE car to EV). The Ultima has side pods that aren't really used, so compared to a regular car, the Ultima has potentially better packaging.

Also you could forget trans-European road trips, so not for me, but I'm sure it would fit some peoples' requirements.

TR3B

172 posts

52 months

Tuesday 13th October 2020
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dandare said:
The Ultima has side pods that aren't really used, so compared to a regular car, the Ultima has potentially better packaging.
But then there's the weight penalty, the complication, limited use (especially for the track), the potential electrocution and 3 day lithium fire after you crash it.

I think I'll stick with ICE.

dandare

957 posts

254 months

Tuesday 13th October 2020
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TR3B said:
dandare said:
The Ultima has side pods that aren't really used, so compared to a regular car, the Ultima has potentially better packaging.
But then there's the weight penalty, the complication, limited use (especially for the track), the potential electrocution and 3 day lithium fire after you crash it.

I think I'll stick with ICE.
Absolutely. I have no interest in electric cars, either. Batteries are great for milk floats.

ephemera

215 posts

159 months

Wednesday 14th October 2020
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Hi all!

First of all, I respect that a lot of people don't like EV's and EV conversions. On the other hand, a small portion of people might be interested in how this thought experiment would look like, therefore good to have this small discussion thread.

Regarding the mass calculation, two small but important remarks: the original Tesla drive is equipped with a reduction gear and diff, and an aftermarket LSD is available, so the original Ultima (e.g. Porsche) transaxle is not needed anymore, saving extra mass and costs. Also the Tesla transaxle can cope with the power and torque the motor produces. Various versions of the large Tesla drive exist, ranging from around 335 to 475 kW.

Regarding the battery systems, the Tesla drive units require around 365V nominal, and a battery that can deliver the power (current). This means that the Tesla modules as used in the Model S and X (22.8Vnom per module) are normally connected in series in a Tesla (16 modules) to get to the required pack voltage. So choosing a lower amount of modules, means not only lower energy (kWh), but also lower voltage. Also to be able to get the required current out of the packs, you have to check which modules you use (there are different versions available). And finally, to get a usable duty cycle out of the drive system and battery, the thermal aspect is paramount. Normally, the Tesla battery modules are liquid cooled/heated. So if you go for Tesla batteries, the packaging, mass and thermal system are challenges in an Ultima (needs to be investigated per project, and depends on the use case of the owner). There are alternative battery systems available with better high power behaviour in a smaller and lighter pack, but they are almost always more costly.

Supercapacitors can deliver very high power for a short time. To give you an idea, the specific power of a supercap can be in the range of 5-10kW/kg, but their specific energy is very low, 2-5 Wh/kg (compared to 150-300Wh/kg for Lithium batteries).

Interesting to know, the Tesla drive units have a very large ratio of peak versus continuous power, around 10.

Because I don't want to hijack this thread, you can also PM me if you have any specific questions, either regarding the technical side or regarding the previous cars we've built for other companies (e.g. couple of Porsche's, Elise-based cars, a pure supercap series hybrid car, etc).

As a personal hobby, I've e.g. built a Matra Murena with the standard mid engined petrol engine still in place driving the rear wheels, and an extra electric drive system mounted in the front driving the front wheels, making it a through-the-road hybrid. It uses a small high power Lithium Polymer battery pack.

I have also built another Matra Murena as a daily, three seater, fully battery electric, 150kW, 6 speed gearbox, 40 kWh battery.

And don't worry, I also love tinkering with my gasoline Fury's and TVR's ;-)

dandare

957 posts

254 months

Wednesday 14th October 2020
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Hello ephemera,

Just out of interest, how much do you think all of the EV components (battery, motors, differential, gearbox(?), cooling, air-conditioning, controller, etc) would weigh for an Ultima that would be used on a track day? (say 5 hard laps of the Nürburgring, max 180mph/290km/h, with no recharges, just maybe 10 minute rests between laps).

Bearing in mind that the Ultima probably weighs well under 600 kg without engine, gearbox, cooling system, and fuel tanks (I'm guessing).

Would it need extra battery cooling because it would be used flat out all of the time? I can imagine the batteries would get pretty hot when releasing the equivalent power to a mildly-tuned LS7?

Regards Dan.

Steve_D

13,747 posts

258 months

Wednesday 14th October 2020
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dandare said:
Hello ephemera,

Just out of interest, how much do you think all of the EV components (battery, motors, differential, gearbox(?), cooling, air-conditioning, controller, etc) would weigh for an Ultima that would be used on a track day? (say 5 hard laps of the Nürburgring, max 180mph/290km/h, with no recharges, just maybe 10 minute rests between laps).

Bearing in mind that the Ultima probably weighs well under 600 kg without engine, gearbox, cooling system, and fuel tanks (I'm guessing).

Would it need extra battery cooling because it would be used flat out all of the time? I can imagine the batteries would get pretty hot when releasing the equivalent power to a mildly-tuned LS7?

Regards Dan.
Hi Dan
Should I stop work on your LS while you have a think about this?

PS Sent you an email this AM.

Steve

dandare

957 posts

254 months

Wednesday 14th October 2020
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Steve_D said:
Hi Dan
Should I stop work on your LS while you have a think about this?

PS Sent you an email this AM.

Steve
biglaugh Hello Steve. No way! Don't stop!
I'll check my mail, thanks, and take care.
Dan

ephemera

215 posts

159 months

Thursday 15th October 2020
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Hi, I ran some numbers for you, it is an interesting case.

LDU (Tesla Large drive unit): Three versions available: 335-475kW. All 132 kg. Only the 475 kW version has a 18000 rpm limit, the rest around 15000 rpm. With the 18000 rpm limit, the top speed of a standard Tesla S (fastest) is around 155mph, so for 180 mph you need to change the fixed reduction gear set or wheel diameter (both resulting in a slightly slower acceleration, but due to RWD probably traction limited). Or of course choose a 2 or more speed gearbox. In that case, the Revolt system might possibly becomes an option. For this first thought experiment, I would say the standard LDU in 475 kW version with the Tesla transaxle, equipped with an aftermarket LSD (available). Then you can delete the original V8 engine and the gearbox/diff, and only have to add 132 kg for the LDU.

Then the demand for 5 hard laps N‘ring without recharging: From simulations in a published paper based on an Audi R8, 1564 kg, 300kW, two speed gearbox, it shows that the average discharge power is around 75 kW in that case. I will use 100kW for now for the Ultima EV case (but it could be slightly higher, just a first guess). Roughly 8 minutes per lap, so 40 minutes. That means 67 kWh nett energy is needed. When the battery is at low SOC, it often cannot deliver full power, so some extra energy content is needed. Purely on energy, it seems that a 100kWh pack is a good starting point. If you use the original Tesla 100kWh pack, this is around 500 kg.

Then the thermal aspect needs to be addressed. This would also need some calculations, but I think it is safe to say that you will need a thorough cooling system on the battery and another one for the LDU to avoid the system quickly overheating. Mass wise, this will not add that much weight, and also heater/airco etc will all be second order to the battery weight.
The LDU is rated at 45kW cont, 160 kW for 12 min, 475 kW peak.

Option to think about would be to reduce the demand for the 5 laps, then you could use a lighter high power battery with less energy, and then you can save some mass there.

For max performance and lowest lap times, it might be useful to use a stepped transmission. More complex and more difficult to package, but there a lot of variables at this stage.

If the car will be trailered, an on-vehicle charger could be left out.

If the 10 minutes cooling down time (with coolant chilled by the a/c running through the cooling system of battery and LDU), is enough, is not possible to say now. But worst case, the 10 minutes should be longer.

Then always good (and fun) to look at some similar cars, in the broadest sense, as a sanity check (some not road legal, some not yet available, some very expensive):
Drayson Lola EV, Tesla Model S Plaid, Lotus Evija, NIO EP9, VW ID R, Rimac Concept 2, Elmofo Radical SR8. Radical E-Wolf, Tesla Roadster, Porsche Taycan, Genovation GXE, Inmotion TUE, etc.





Edited by ephemera on Friday 16th October 10:59


Edited by ephemera on Friday 16th October 11:00


Edited by ephemera on Friday 16th October 11:02

UltimaCH

3,155 posts

189 months

Friday 16th October 2020
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Interesting read

T-Rev

109 posts

278 months

Tuesday 15th December 2020
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Hi All,
I've recently been looking/pondering at a potential EV conversion for my very analogue GTR currently running a Knight Race SBC 6.7ltr/G50-03 5speed!
So, I've found this very interesting and thank you for your very detailed input ephemera.

I've come to the conclusion that I would not want to add any weight but would want to retain the performance I currently have, though of course that would be the easy bit with a Tesla high performance motor perhaps with modified gearing/LSD capable of circa 450bhp and max torque from the off! The difficult bit that has been touched on, is the battery pack? Of course, your intended use is going to be a deciding factor, so for me that would be occasional track use and more frequent road use with a minimum range of say 100 miles (dependant on how the car is driven)? With that in mind, I suspect as 'ephemera' has suggested, a 100kWh battery pack would be required? In terms of weight, I believe once you have accounted for the 'wet' weight of the engine, transmission, cooling and fuel tanks, there would be very little difference?

The Tesla unit could be situated in place of the gearbox with the diff forward (normal fitment) inline with the existing diff but lower which would enable the driveshafts to be horizontal. The battery pack would be situated within the engine bay with all associated necessary components and cooling within the side pods! Whilst I've not yet physically measured anything, I'm sure it can be achieved.

The really difficult bit, is the justification for the conversion? Part of the joy of owning an Ultima is of course the drama and noise in driving it, not to mention the workout that beats going to a gym! Like many on here, I've been fortunate enough to have had the opportunity to drive a variety of high performance cars on the road and track and would suggest that performance wise, the Ultima is well up there with the very best of them!

So, driving an Ultima EV would be a very different experience. Yes, you should certainly still have the performance to keep that big grin on your face, but you would also lose pretty much all of the drama and of course the noise! It would be much easier to drive and of course get it wrong? But with more and more EV's coming in the next 10 years, I wonder how that will affect the market for supercars? There will no doubt still be a strong market for ICE based supercars for a few more decades to come, but how will that impact on values? Only time will tell. So I guess it'll all come down to personal preference.

And of course, what will the Ultima Sports factory be doing post 2030? I'm sure they'll already be thinking about that!

Finally, for me at least, I'm still on the fence. It's the current potential costs of the conversion that is putting me off or holding me back. I think you'd be looking at circa £30k+ at the moment? Yes, you could sell off your engine, gearbox etc. but then you have to find buyers which isn't going to be easy and may take some time to recover 'some' of the costs? In addition, battery technology is consistently changing, so performance and costs 'should' improve quite significantly in the coming years? This would also beg the question, is now the right time to convert your Ultima to EV?

I'm sure there'll be an Ultima EV out there sometime soon, though I doubt I'll be the first!
Merry Christmas to you all.
Trevor.

UltimaCH

3,155 posts

189 months

Monday 21st December 2020
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There is an interesting article in the December issue of 911 & Porsche World on a Tesla powered Boxster. If I recall the conversion is overall lighter than the petrol engine inside

T-Rev

109 posts

278 months

Friday 22nd January 2021
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Hi all,
Having made some more inquiries and conducted more of my own research, the current situation is as follows;

The average classic car EV conversion is costing around £55k (for a professional job that is - there are cheaper options and you could save by DIY)?

Land Rover Defenders (which seem very popular at the moment) are coming in between £75k and £90k?

Bearing in mind an Ultima is already a supercar, so in order to maintain the kind of performance you’d expect, you'll actually need to use a Tesla 600HP High Performance motor and suitable battery pack, so a drop in conversion would cost around £75k? The parts alone will cost £50k to £60k just to buy in at trade! That doesn't cover any additional development work that ‘may’ be required to make it all fit?

You could of course go for a more stock Tesla motor (@450HP), but that will still cost in excess of £50k with a suitable battery pack?

On the other hand, if you wanted to use your Ultima EV on the track, that’s completely different ball game! Additional development would be required in order to ensure the motor and batteries can cope with the demands from regular track use e.g. rapid acceleration, hard braking and fast charging/discharging which will require significantly more cooling? Not to mention the need for specific gearing and suitable battery pack etc. As such, it is estimated it may cost well over £100k in development in order to just achieve acceptable results?

Consequently, for me anyway, it is simply not at all a financially viable option!!! It would be cheaper to just go out and buy a good used Tesla P100D.

Good luck to anyone else that is considering going down the EV route for an Ultima and do let us know how you get on?

Steve Dean

55 posts

74 months

Sunday 24th January 2021
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This is an interesting thread ...... but here's a question. If you built an Ultima (or any other car) as described above, could you submit it for an IVA test? I've not seen anything that indicates that the IVA test has been updated to set out the procedure and details to test such a vehicle. To use the official jargon, it may be "outside of scope".
Given that here in the UK the Government is still stating that IC engines will not be allowed in new vehicles as from 2030 then one would presume (a risky assumption) that something will be put in place.
I've spoken to a few manufactures of kits and they have not heard anything from 'officialdom'.
A knowledgeable response would be appreciated.

Steve_D

13,747 posts

258 months

Monday 25th January 2021
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As you say nothing in the IVA manual.
Hydrogen is mentioned but not electric.

Steve

Steve Dean

55 posts

74 months

Wednesday 27th January 2021
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Hi Steve ..... I am also thinking about the bigger implications. We are now just 8 years & 11 months away from 2030 and many decent kit built cars (Ultima., Cobra's, GT40s) all become effectively NEW cars and if fitted with an IC engine will not be able to be registered. Given the typical time taken to build one and get it through IVA is probably 2-3 years (we all know someone who's done it quicker) then in about 5 years from now the manufacturers will struggle to sell kits. This has a huge knock-on effect to the industry that supports our passion.
If ever we get the other side of Covid and events start up again, then we should enjoy every moment as we may be the last to enjoy this pursuit.
Our friends in America will no doubt be pondering a similar situation under President Biden and his pledge to re-join the Paris agreement.