# Will I be disappointed with AC-50 in a Porsche 914?



## Scollier (Jan 17, 2015)

Recently picked up a 1970 Porsche 914 with the intent to convert. Still keeping it ICE-powered while I work on minor restorations and upgrades, which gives me plenty of time to research motors, batteries, etc.

Seems like the many 914 conversions went with the AC-50 (EV West's 914 kit is "baseline"). I'm not a hot-rodder and just want something that accelerates as good or better than the original 1.7 Liter ICE.

For those that used this AC-50 set-up - Once you were over the thrill of a working EV, were you eventually disappointed and wish you had gone with an AC-75 or dual AC-35s?

Are there other motor/controller up-grades for this light little car?


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## evmetro (Apr 9, 2012)

Scollier said:


> Recently picked up a 1970 Porsche 914 with the intent to convert. Still keeping it ICE-powered while I work on minor restorations and upgrades, which gives me plenty of time to research motors, batteries, etc.
> 
> Seems like the many 914 conversions went with the AC-50 (EV West's 914 kit is "baseline"). I'm not a hot-rodder and just want something that accelerates as good or better than the original 1.7 Liter ICE.
> 
> ...


I think an AC50 in a 914 would make a fun EV, but I don't think you will get the same performance as with the ICE. I upgraded from an AC35 to an AC74 in one of my conversions, but it is not really a huge difference since the controller is still the same. It is pretty fun, but I had to re gear to take advantage of the boost in torque. The twin AC35 kit would make a big difference, since you have twice as much controller, but I would imagine that it would take quite a bit of custom work to pull this off.


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## onegreenev (May 18, 2012)

Even if you're not a hotriodder you would be better off with the dual ac-35. You will want that extra power when needed and can still sip when you want to cruise. I do believe the dual ac-35 will fit in the confines of the little Porsche.


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## tomofreno (Mar 3, 2009)

This reference: http://www.carfolio.com/specificatio...car/?car=23067

says:
It's powered courtesy of a naturally aspirated engine of 1.7 litre capacity. This powerplant features overhead valve valve gear, 4 cylinder layout, and 2 valves per cylinder. It produces 79 bhp (80 PS/*59 kW*) of power at 4900 rpm, and maximum torque of 131 N·m (*97 lb·ft*/13.4 kgm) at 2800 rpm.
A 5 speed manual gearbox supplies the power to the driven wheels.
It weighs a stated 898 kg at the kerb.

An AC50 with the 1238-7601, 650A, controller has about 108 ft-lb peak torque from a bit above 0 rpm out to about 3900 rpm. It's peak power with a 115V nominal voltage pack (36 LiFePO4 cells in series) is about 60kW (see the power curves at hpevs.com). This should give slightly better performance than the original engine due to the higher peak torque over a wider rpm range. Zero to 60 mph time with the 1.7 l engine is listed as 13 seconds. Acceleration scales linearly with motor torque for a given vehicle. Peak power limits the max rpm up to which you can maintain peak torque. You could use an AC75 which has higher peak torque for faster off the line. The 0 to 60 time won't decrease all that much due to the about 60 kW peak power of it's motor controller limiting torque and acceleration at higher speeds.  The dual AC35 uses two controllers so roughly doubles both peak torque and peak power, so you might expect around 7 - 8 sec 0 to 60 with it if the tires don't spin too much. I don't know if a dual AC35 will fit.


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## onegreenev (May 18, 2012)

I just recently sold my 73 Porsche 914. It was a good runner but by no means quick. Spritely, yes but not quick. It was fun and handled well. It was not a good candidate for a daily commute of 45 miles round trip. You have to wear the vehicle. Its not exactly an easy one to just jump in and go but damn, it was a fun little car. Plenty of room for the tall guys. 

The pedal assembly should be rebuilt using the bronze oil impregnated bushings. I did mine and the brakes should be done too. 

Pete 

If the AC-35 dual fits, go with that. The little Porsche needs some good power to really enjoy the vehicle. The 1700 engine is underpowered for the Porsche.


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## dougingraham (Jul 26, 2011)

It depends on your expectations. You will have a little more torque with the AC-50 to the point that you probably won't use first gear often or maybe even ever. So your off the line will be fun. The driving experience is quite different because the EV power system produces all its torque down low while the ICE produces it starting at 1500-2000 rpm, peaks at around 3500 to 4000 rpm and then slowly tapers off up to redline. The EV power system tends to taper off more steeply. This causes you to shift at a lower RPM than you would have with the ICE. I've not had the chance to drive a converted 914 but the ones I have seen with an AC-50 all seem to be a lot of fun.

If your goal is to use the car as a Daily Driver then a single AC-50 will give you a good driving experience. You might even consider a single AC-35 and the higher voltage controller. The differences between the different HPEVS frame sizes pretty much just moves the shift point around when you are driving the car. An AC-35 with the high voltage controller might make 1st gear usable. The torque is less but that just means you can leave it in the lower gear longer than the high torque motors because the torque band is wider. The AC-35 saves weight as well. The AC-35 weighs about 85 lbs. The AC-50 weighs about 115 lbs. This is 30 lbs that could be used for batteries. In that car the 30 lbs of additional batteries instead of motor weight would give you about 4 to 5 additional miles of range.


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## Tesseract (Sep 27, 2008)

The *smallest* engine used in the 914 was 1.7l; also used were 1.8l and 2.0l. The latter developed a peak of 120hp, IIRC (I rebuilt one in high school, so it's been awhile).

EDIT - Wikipedia sez 74kW/100hp for the 2.0l....


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## Moltenmetal (Mar 20, 2014)

A single AC50 will be fun. In my little Spitfire, even with a comparatively low voltage pack (32 series, 105V nominal), it is an absolute blast! Your car is larger and heavier and the performance expectations come along with the brand to some degree. A dual AC35, if you can afford it, will be really fun in your car...


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