Just another daydream: electric 911

[WasserGKuehlt]

Would you not think that synthetic fuel is - like hydrogen for passenger cars - a desperate but futile attempt to redefine sustainable propulsion while keeping some of the old technology alive?

Sustainable and reliable. The energy density of CH-based fuels means the ICE will continue to exist for decades (at least). It may be desperate and futile on Porsche's part (to justify the continued existence of the 911), but battery technology has a _very_ long way to go. (Probably 10-20 years to reach 'cow dung' level.)

 

[f1eng]

What is the large Porsche investment into the synthetic fuel development for?

I assumed that was to keep certain ICE models (911) going.
But I may be completely wrong??

It is mainly to justify continuing racing.
Same with Mercedes in F1.

It is a publicity campaign really.

It makes me laugh. Both the critiscism of pollution from racing where in the whole F1 season the cars themselves consume about the same fuel as a single leg Jumbo flight London to New York.

The vast bulk of pollution "caused" by sport is fans driving to the venue and competitors travel.

Edit addition.
One of my old colleagues is running one of the synthetic fuel businesses. It uses a huge amount of energy so is based at a hydroelectric project and runs off peak but the reality is commercial quantities at competitive prices are as unlikely as bio fuels. Humans need agriculture to produce food not fuel and electricity generation to power homes and industry, not cars.

 

[or1]

...
One of my old colleagues is running one of the synthetic fuel businesses. It uses a huge amount of energy so is based at a hydroelectric project and runs off peak but the reality is commercial quantities at competitive prices are as unlikely as bio fuels. Humans need agriculture to produce food not fuel and electricity generation to power homes and industry, not cars.

Indeed. As long as there is a deficit of clean energy, efficiency is important. As far as I can see, e-fuels will be very inefficient and should be avoided whenever possible.

 

[daveo4EV]

Sustainable and reliable. The energy density of CH-based fuels means the ICE will continue to exist for decades (at least). It may be desperate and futile on Porsche's part (to justify the continued existence of the 911), but battery technology has a _very_ long way to go. (Probably 10-20 years to reach 'cow dung' level.)

given the efficiency of EV motors (90%+) you do not need cow-dung level's of energy capacity - a modest 20-30% increase in battery energy density per-unit/volume/mass will lead to two things (this level of improvement is already with in reach and will not take 10-20 years)

1. EV's weighing less than their ICE counterparts
2. 400+ mile range for that level of battery

but it is true HC's are a f'ing miracle and their energy density per-unit volume/mass is only topped by nuclear elements (truth look it up)

but you do not need HC level's of energy density for transportation if you have a 90% efficient conversation of power to motion (which we have with Taycan and other EV's)

84.3 kWh of power (usable on the Taycan) is the equivalent of about 2.5 gallons of gasoline worth of energy - and yet we all can go about 250 miles on that amount of energy - 2.5 gallons of "fuel" will go about 75 miles of range…

with the EU pushing for no ICE's by what now 2035 is what I read yesterday - the demise of the ICE seems to be on an accelerated glide path…as to if that continues we will see…

if batteries were to reach HC levels of energy density per unit volume/mass - then about 16 lbs of batteries would be 2.5 gallons of fuel worth of power (83.4 kWh) - so a 100 lbs battery would contain about 500 kWh's of power - at 2.7 mile/kWh would be over 1300 miles of driving range - but we'd get much more range because of the lower weight effciiency per/kWh in terms of range would be even higher…

focusing on battery energy density, while important, isn't the key criteria - it's efficiency with power provided - and we've proven now for about 10 years (since the Model s) that a about 2-3 gallons worth of battery leading to 200-300 miles of range is a workable solution - now if we can get modest increased in power-density per-unit volumn/mass that usable range goes up and the EV approaches ICE weight (Model 3 is already only one-passenger heavier than equivalent AWD BMW 4 series in terms of curb weight) - a 20% increase in energy density with battery will lead to Model 3 type vehicle be lighter than an ICE equivalent…

 

[daveo4EV]

think of it another way:

20 gallons of fuel at 6 lbs per gallon = 120 lbs
one gallon of fuel contains ~33 kWh
so 20 gallons = 660 kWh total battery capacity…

at current Taycan levels of consumption/efficient - 660 kwh * 2.7 mile/kWh = 1,800 miles of driving range - probably way more due to lower battery weight.

so "ideal" would be a 120 lbs battery that can store 660 kWh - that would "match" HC energy density of a normal fuel tank.

I suspect we honestly only need about 200 kWh of capacity - that would more than double Taycan's current drivable range.

and we have a 1500 lbs battery for current capacities…
if I can get to about a 1000 lbs battery we're are "matching" over all vehicle weight and increasing range due to lower overall weight…for the same amount of energy.

an 800 lbs battery with about 120 kWh of capacity would be no where near HC levels of energy density but a vehicle with that weight/capacity would drive further than a equivalent ICE, and be lighter over all curb weight…

there is this strange calculus as you reduce battery weight you increase range for same amount of power - but you don't have to target the same energy capacity - due to lower weight - you can play with 2 variables at once - weight vs. total energy capacity - you can play one off of the other - for same weight you can store more energy (longer range) - or I can lower overall capacity - also lowering weight but keep the range the same as previous model…

we are at two extreme - at current production levels batteries are:

• LiON batteries - 1500 lbs = 100 kWh of capacity - EV 250-300 miles range - (Model 3 4,500'is lbs)
• HC Fuels = 120 lbs = 660 kWh of capacity - ICE 300-400 miles range (BMW AWD 4,200 lbs)

now a 4,000 lbs EV with 150 kWh of capacity = 400+ miles of range, and does not require HC levels of energy density to match/exceed current ICE vehicles, and yet you retain the lower CG, instant EV torque/power and the lower emissions - and would be lighter than equivalent existing ICE vehicles with better driving characteristics.

HydroCarbon Fuel densities are not required if you have a 90%+ efficient propulsion system. 150 kwh of capacity @ 4.2 kwh/Mile consumption = 630 miles effective driving range (current 2023 Chevy Bolt and Lucid-Air levels of EV efficiency) and less than 30 min fast charging time at 350 kW chargers…

I do not think it will take 10-20 years to get a 150 kwh battery to weight less than 1,500 lbs or even less than 900 lbs…but as weight comes down and energy density goes up - we may choose to target only 80-100 kWh of capacity for 350 miles overall range…there are so many variables we can play with - the proper mix has yet to be determined. But again HC level's of density are not required in my opinion.

a current tank of gasoline is 600-800 kwh of total chemical energy - a Taycan at that level of capacity is a 1,800-2,200 mile range vehicle…

 

[daveo4EV]

note a 120 lbs (current ICE fuel tank full) battery providing Taycan with 660 kWh of power would be well over 2000 miles range and lower Taycan's curb weight from ~5,000 lbs to ~3,500 lbs…vehicle packaging opportunities would be interesting as I'm sure the battery would be much smaller in this case - so a vehicle of this nature would be potentially "awesome" sauce…4 AWD door sedan with 800-1000 HP @ 911 sports car curb weight…

@f1eng do you have any feelings/swags/guesses for increased in range efficiency per-kWh if Taycan @ 5,000 lbs is 2.7 miles/kWh - you have thoughts on what range increase we'd see for dropping 1,500 lbs?

 

[Sidicks]

I'm not a buyer for that. The instant torque and low service intervals have me sold on BEVs as just simpler and better.

It's like Motorola RAZR vs iPhone.

Instant torque and low service intervals are not priorities for most 911 enthusiasts!

 

[Kingske]

Instant torque and low service intervals are not priorities for most 911 enthusiasts!

Instant torque is pretty addictive, though...

 

[Sidicks]

Instant torque is pretty addictive, though...

For me it soon becomes boring. There’s nothing like revving a car out to 9,000rpm.

That’s why I need a GT3 alongside my Taycan!

 

[DerekS]

Instant torque and low service intervals are not priorities for most 911 enthusiasts!

They are for this one. I love the cars and hate handing them over for service.

Having been through 3 Boxsters and 3 911s I am tired of engines that run by constantly trying to destroy themselves.

I realize I’m in the minority on this, but to me electric cars are just better, simpler designs that are less failure prone.

 

[Sidicks]

They are for this one. I love the cars and hate handing them over for service.

Having been through 3 Boxsters and 3 911s I am tired of engines that run by constantly trying to destroy themselves.

I realize I’m in the minority on this, but to me electric cars are just better, simpler designs that are less failure prone.

Most Porsches have a 2-year service requirement (although I did used to have an oil change in between the servicing, for my GT3), which meant a visit to the dealer and the opportunity to try out other cars. Unless you live a very long way from the dealership, that doesn’t seem that onerous.

In any case, the servicing timetable for the Taycan is also 2 years!!!

And surely the (known) decreasing efficiency of batteries over time and the (unknown) long-term reliability of electric motors masks the comparison somewhat?

 

[daveo4EV]

Most Porsches have a 2-year service requirement (although I did used to have an oil change in between the servicing, for my GT3), which meant a visit to the dealer and the opportunity to try out other cars. Unless you live a very long way from the dealership, that doesn’t seem that onerous.

In any case, the servicing timetable for the Taycan is also 2 years!!!

And surely the (known) decreasing efficiency of batteries over time and the (unknown) long-term reliability of electric motors masks the comparison somewhat?

industrial grade EV motors have been used in elevators, locomotives, manufacturing for over 100 years…- most of them have MTBF's measured in millions of hours if not 10's of millions - EV motors are not new they are in fact a well understood component with reliability that exceeds the wildest dreams and fantasies for any ICE design. With only one moving part and world class engineering and effectively solid state physics based design it is nearly impossible for them to fail…the basics and characteristics of AC powered multi-mode magnetic field driven EV motors have been understood for almost 100 years - and designs are both ubiquitous, deployed, and have demonstrated longevity…I really do not think the EV motors reliability is a question - other aspects of EV are perhaps evolving, but I'm much less concerned about the longevity of my Taycan's twin EV motors than I am about my wife's 911 TurboS flat-6 or the bi-turbo V8 in our Cayenne…EV motors will not be the EV's weak point.

 

[DerekS]

In any case, the servicing timetable for the Taycan is also 2 years!!!

Yeah, and it cost me around $200 and around an hour of time drinking Porsche's coffee.

You're dreaming if you think a 911 only needs service every 2 years.
In addition to the oil changes, there are bigger service intervals every 10K or so. These get more costly over time and use - the 60K interval I recall as particularly expensive as it involved replacing the timing belt.

That's not to mention random ICEy failures - covered by warranty but still a hassle. Had a water pump die once, had multiple issues with changeover valves on the 991 Targa.

And don't even get me started on the engine failures that plagued the 986/996 era...

 

[Sidicks]

Yeah, and it cost me around $200 and around an hour of time drinking Porsche's coffee.

You're dreaming if you think a 911 only needs service every 2 years.
In addition to the oil changes, there are bigger service intervals every 10K or so. These get more costly over time and use - the 60K interval I recall as particularly expensive as it involved replacing the timing belt.

That's not to mention random ICEy failures - covered by warranty but still a hassle. Had a water pump die once, had multiple issues with changeover valves on the 991 Targa.

And don't even get me started on the engine failures that plagued the 986/996 era...

Yes, a 911 needs servicing every 2 years - see the Porsche website for more details.
Unless Porsche are ‘dreaming’ too?

”Porsche services need only be repeated every two years or 20,000 miles (12,000 miles for 911 GT models) for cars built after 2005 and your Porsche Centre will remind you when your service is due.”

The oil change is one part of the minor or major inspection services.

I guess the good thing is that no-one has ever had any issues with an EV….

 

[f1eng]

Instant torque and low service intervals are not priorities for most 911 enthusiasts!

Instant torque was a major priority for me.

In the ‘90s I had a TVR Griffith and my boss kept trying to persuade me to change it to something with better crash safety.
The 993 version of the 911 had just come out and I liked the look of it so had a test drive. Being 300+kg heavier than the TVR and a bit less power it felt disappointingly slow.

When I told Porsche GB that they were surprised and promised me a go in the Turbo when it arrived (I was technical director of a Formula 1 team at the time so they were very keen for me to buy a Porsche).
Anyway I got the demonstrator for a weekend, unfortunately the British GP weekend so I was working but I drove it to Silverstone for each day anyway, it was clear roads at 6am and midnight when I was mostly travelling and the car was super fast on open roads, but the lag meant that in traffic the throttle response meant it was inadequate for overtaking.
In traffic a car with instant throttle response will safely overtake in places a turbo IC engined car can’t IME.