Electric 914 Conversion - Fully Documented, Current state of 914EV Conversions Options

[mcbrems]

I’ve been away from the forum for a while. During this time I've done complete electric conversions on both of my 914s and have been driving them daily. I've also converted a bunch of VW Beetles, Buses, a Ghia, and several 356 replicas, but I'm only here to talk 914, and I owe it to this community to share back for all the help you've given me over the years.

When I started my first conversion in 2010, lithium batteries had just become accessible to the public. Telcom companies were using LiFePO₄ cells as UPS backup for cell towers, and that availability propelled EV conversions from hobbyist into practical daily driver territory.

My first build was a ground-up ’74 restoration using prismatic LiFePO₄ cells. Shortly after, salvaged Tesla Model S battery modules became widely available. They offer strong energy density for the cost and they simplify the design. Both of my 914 conversions use Tesla modules housed in custom battery boxes designed specifically for the chassis. There is now a healthy variety of new lithium batteries to choose from, so it's likely I will come up with new box design.

My first '74 conversion uses the HPEVS AC-50 motor and Curtis 1238-7601 controller, giving equivalent power and torque to the stock flat four engine, and using the stock 901 side shift transaxle. A lightweight flywheel and clutch is mounted on the motor shaft, and then married to the transaxle with an off-the-shelf adapter.

My second '75 conversion uses the NetGain HyPer9 HV permanent magnet AC motor with an AC-X144 controller. Output is about 40% more horsepower and 69% more torque than stock. The driving experience remains very 914 - smooth, quick and now sounding like a little UAP.

• The open fuel tank space is used to house the electric ceramic core heater, the DC/DC converter, the relay box, and the small 12V motorcycle battery.
• Three Tesla modules sit in a front trunk battery box ahead of the firewall.
• The engine bay uses a custom motor crossbeam that maintains factory drivetrain angle and mounting geometry, and provides support for dual battery box saddlebags.
• Seven Tesla modules provide the 175 VDC that the controller needs to operate at maximum peak performance.
• Dual chargers are mounted on the front firewall of the motor bay above the rear battery boxes.
• Charging port is located under a flip-down license plate holder on the front bumper.
• Cabling joining the front and rear battery boxes travel through the tunnel, while the signal harness bundle runs up the unused driver side rocker heater duct, and the 12V and high voltage bundle is separated into the passenger duct.
• All BMS data is transmitted via Bluetooth to a Samsung Galaxy tablet in the console.
• Total dry curb weight after conversion is 2413 lbs.

Range is typically 100–120 miles, which covers my daily use comfortably. Longer trips might require a stop for a sandwich and coffee.

The tech has evolved significantly since the early conversion threads here. Modern batteries and controllers simplify packaging significantly. The challenge now isn’t feasibility - it’s doing it cleanly.

I'm happy to answer technical questions for anyone considering it. I documented the process carefully because I wished that roadmap existed when I started.

Cheers,
Mark

(IMG:http://www.914world.com/bbs2/uploads_offsite/cdn.shopify.com-11660-1771975906.1.jpg)

(IMG:http://www.914world.com/bbs2/uploads_offsite/cdn.shopify.com-11660-1771975907.2.jpg)

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(IMG:http://www.914world.com/bbs2/uploads_offsite/cdn.shopify.com-11660-1771975907.4.jpg)

(IMG:http://www.914world.com/bbs2/uploads_offsite/cdn.shopify.com-11660-1771975908.5.jpg)

[fiacra]

Thank you! Nice looking car. I don't possess the skills to do a conversion myself, but I'm glad that there are people out there who have proven the concept is viable. I'm been hoping someday I'll be able to have my '75 1.8 converted. 100 mile range is plenty for me so maybe the time is now... Can you share with us the cost involved, how long the conversion took, and how reliable the vehicle is.

[Ninja]

That looks nicely done! (IMG:style_emoticons/default/first.gif)

The work is top notch; the car is gorgeous!

@TINKERGINEERING should take a look.

Just WOW! (IMG:style_emoticons/default/ninja.gif)

Has the top been "fixed"?

Sure looks that way!

I'm not really an electric guy but will be watching this post.

You seem to have your stuff together Sir! (IMG:style_emoticons/default/beerchug.gif)

[jim_hoyland]

Stunning ! (IMG:style_emoticons/default/smile.gif) You have a beautiful and functional conversion.

[emerygt350]

Is it still a 5 speed?

[914werke]

seeing the shifter I was going to ask the same.

[914werke]

Stunning ! (IMG:style_emoticons/default/smile.gif) You have a beautiful and functional conversion.

Well Im impressed its only a couple hundred lbs more than OG & indeed its a tidy install, ... but 100-125 mile range im not sure Id call functional. (IMG:style_emoticons/default/hide.gif)
Since you weighed it what is the bias post conversion, it appears to be front heavy now?

[Ninja]

I'd really appreciate some more pictures of the top if you can post.

Just love that!

extra 40% torque, details would be great!

Sounds everyday usable.

[Root_Werks]

That is a really clean conversion!

[Steve]

Is it still a 5 speed?

He has a similar post on Pelican. He says he still uses the higher gears 3-5.
http://forums.pelicanparts.com/porsche-914...documented.html
Very nice conversion. These have come along way. I know classic retrofit built one with a Tesla drivetrain. Very impressive, compared to early butchered cars with lead acid batteries.

[mcbrems]

... Can you share with us the cost involved, how long the conversion took, and how reliable the vehicle is.

Thanks! I appreciate the kind words.

The conversion was done using a NetGain HyPer9 HV motor and seven Tesla Model S battery modules. In real-world driving the car gets right around 120 miles of range, which has been more than enough for normal use and canyon drives.

Parts for the EV system currently run in the neighborhood of about $20k–$25k depending on battery pricing, suppliers, and shipping costs. The guide includes a full parts list with vendor links so builders can see exactly what is used and what the current pricing looks like.

As for the time involved, it really depends on how consistently someone can work on the project. Builders working evenings and weekends usually spread it out over several months.

Reliability has actually been excellent. Electric drivetrains are mechanically simple compared to gasoline engines — no oil changes, fuel system, carburetors, or ignition system to maintain. Both of my converted 914s are daily driven and have been very dependable.

One of the things I tried to do with the guide was remove the guesswork that normally slows down first-time EV conversions. The whole process is documented step-by-step so builders can follow along without having to reinvent the wheel.

A few people have asked similar questions about cost, range, and what’s involved, so I put together a pretty detailed FAQ page that explains the system and the build process:

https://www.914electric.com/pages/frequently-asked-questions

Happy to answer any questions people have.

[mcbrems]

That looks nicely done! (IMG:style_emoticons/default/first.gif)

The work is top notch; the car is gorgeous!

@TINKERGINEERING should take a look.

Has the top been "fixed"?

Thanks! I appreciate that. In fact, Frances @tinkergineering reached out to me to mentor her. The reason the guide was born was to give Frances everything she needs to succeed. There's nothing like an enthusiastic mentee who can put your knowledge into action.

The targa top came already skinned and painted when I bought the car, and had it repainted with everything else, but it is still removable.

And you don’t have to be an “electric guy” to enjoy driving one. It’s still a lightweight mid-engine Porsche with a manual gearbox — the driving experience is very familiar, just smoother but just as punchy.

Cheers.

[mcbrems]

Is it still a 5 speed?

Indeed it is! Most people believe EVs don't have gears, but they are usually thinking about modern factory electric vehicles. That doesn't really apply to most standard conversions, which simply use the existing drivetrain, whether a transmission or transaxle. Far be it from me to argue with 100 years of Porsche design and engineering.

Also, eliminating the clutch and gear shift would definitely detract from the fahrvergnügen. It just wouldn't be a Porsche without being able to run through the gears. The beauty of the electric motor is that the power band is so broad that there is a wide overlap between gears, so the car pulls strongly in almost any gear. First gear becomes optional instead of necessary. Frankly, I live mostly in 3rd, 4th, and 5th.

Not to mention — since the motor does not need to idle, the car can remain in gear while stopped, reducing overall clutch wear. And since there is no combustion hammering the crankshaft, the flywheel can be much lighter. The starter ring gear is eliminated as well, which reduces rotational mass and helps the car jump off the line more quickly.

Cheers. (IMG:style_emoticons/default/beerchug.gif)

[jim_hoyland]

Is a clutch still needed ?

[mcbrems]

I'd really appreciate some more pictures of the top if you can post.

extra 40% torque, details would be great!

Sounds everyday usable.

I actually inspected those numbers more closely, and had to revise my figures above. I discovered I was getting more HP and torque than originally calculated. The stock 1.8L delivers 84hp, and the HyPer9 motor outputs 120hp, which is about 42% more ponies. As far as torque, the stock 1.8L puts out 102 lb⋅ft, and the AC motor delivers 173 lb⋅ft, which is 70% more. So apologies, and pardon my faulty math.

I'm glad you like the targa top. It's really just the usual, but has just been sanded, skinned and painted with the car. Here's another shot:

(IMG:http://www.914world.com/bbs2/uploads_offsite/cdn.shopify.com-11660-1772837256.1.jpg)

Cheers.

[mcbrems]

Stunning ! (IMG:style_emoticons/default/smile.gif) You have a beautiful and functional conversion.

Well Im impressed its only a couple hundred lbs more than OG & indeed its a tidy install, ... but 100-125 mile range im not sure Id call functional. (IMG:style_emoticons/default/hide.gif)
Since you weighed it what is the bias post conversion, it appears to be front heavy now?

I appreciate the props. It's been a true labor of love (mostly fun).

Of course the range is determined mainly by the size of the battery pack. This conversion uses a 37 kWh pack made up of seven Tesla Model S battery modules, which is roughly half of a Tesla 75 kWh pack. So the range ends up being appropriately about half the range of a Model S 75.

I drive both of my 914EVs daily and rarely put more than about 50 miles on the odometer in a day. I have so much fun tooling around and turning heads that I rarely think about running out of electrons. The only time range really comes into play is when we head up to Sierra Madre to visit @tinkergineering , which involves a quick charge and a welcome brunch stop in Irvine. The car charges faster than I get hungry.

We four-pointed the car just after it started driving, and you can see the exact weight on each wheel in the attached photos. The chassis is now biased about 96 lbs to the rear, and the car gained roughly 300 lbs overall compared to the stock ~2100 lb curb weight of a 1.8L 914. I can't account for the variance between port and starboard, since all of the batteries and components are symmetrical to the center line. Maybe it was that turkey and Swiss in my driver side pocket.

Crazy how the total landed right at 2400 lbs on the button. I should have played the lottery that day.

(IMG:http://www.914world.com/bbs2/uploads_offsite/cdn.shopify.com-11660-1772839852.1.jpg)

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(IMG:http://www.914world.com/bbs2/uploads_offsite/cdn.shopify.com-11660-1772839853.3.jpg)

Cheers.

[Mike Fitton]

Waste of time with no resale value at all!

[mepstein]

If the OP is selling a manual for $500 that documents the conversion, shouldn’t this be in the classifieds.

[mcbrems]

If the OP is selling a manual for $500 that documents the conversion, shouldn’t this be in the classifieds.

Fair to ask. I'm not selling the car — this thread is mainly documenting the build and answering questions people have about the conversion.

There is a classified listing for the conversion guide in the DIY EV classifieds section for anyone interested, but this thread is really just about the project itself.

MB

[URY914]

What does the conversion cost in parts?

I've thought about doing an E conversion to my autocross car.

I think my car would be the perfect platform.