The stock alternator is fine, but any alternator running consistently at 90% output vs 50% output will fail more quickly. The modern 6-phase is more efficient, so even the same load on the engine results in more power to the electronics. In addition, 1hp is something like 750W...It's not an AC compressor we're talking about—you'll never feel a power drop even with your 2kW subwoofer booming.

Really, the big thing is that factory alternators (sometimes even rebuilds unless you "know a guy who rebuilds these") are already in the $500-1,000 range, so why bother...?

Time passes and technology improves. Nowadays it is quite normal for a small hatchback (e.g. VW Golf) to have a 180A alternator and SUVs are regularly seen with 220A+ units. Even tiny cars like the Toyota Aygo have 100A units.

An alternator only provides the juice to cover the electrical load at any one time. A larger alternator does not load the engine anymore than a standard unit for the equivalent power output. In fact, our units, being super efficient at turning rotary motion into power, most likely load the engine and the belt LESS.

In the USA, the 3.2 cars had the largest battery I have ever seen in a sports car - 100Ah. European cars generally had the shorter 75A battery. Maybe this was only on the AC equipped cars but it's a sure sign that the alternator was not large enough for the vehicle.

When you have a decent modern alternator, you can downsize your battery considerably. I have run the same Odyssey PC925 for 5 years now. It's only 28Ah and it always starts the car - I don't even use a battery tender.

I aprreciate that more efficient alternators have been produced since these cars were first in production, and if you can fit one without too much bother or alterations then I am all for that. My original point was aimed at folk who would fit a larger output alternator to supply add-ons that take a lot more current than the standard fitments; ie some were talking about fitting electric heater systems so they could do away with the heat exchangers, my point on that one is why ? you have free heat with your exchangers, why would you do away with them and fit an electric heater system that would put a lot more load on the alternator, thus more load on the belt and hence use more power from the engine!

^ Well the reason Singer asked us to design electric heat for the DLS was to save the weight of the heat exchangers and the associated pipe work. The heat uses 1600W, the AC uses 1000W, so combined this is around 3.5 HP.

Of course, we load balance the power if both are on so the reality is about 3 HP max. That’s about half the HP that the old York AC compressors used.

1600W = approx 133 amps from a 12v supply just for the heater :eek: with the heater and AC combined; your looking at over 200 amp, plus everything else the car needs to just run, is the weight saving really justified ?

Correct. IIRC, it saved about 20kg but it also solved a bunch of packaging, operational and optics problems. DLS has a 340A alternator. Ruf SCR/CTR alternator is even larger!

Is there really much (or any) need to run both AC and heat simultaneously?

I for one would think a small electric heat option for the Electrocooler would be well received but I guess you'd need to limit it to 1000W - in your experience would that be enough for the occasional de-mist or to take the chill off on those 5 degree mornings in the fall?

Very few of us driving these cars when the temps are below freezing and there's any possibility of snow (and road salt!)

Developing more efficient ways of producing electricity is good, especially when we are dealing with transport, ie; more efficient alternators take less energy to turn them for the same energy output as an older design, hence lower fuel use and less emisions etc and the more useable HP you keep under your right foot.
I get that and am fully suportive, however; what I struggle with is the fact that these savings are being made only to provide the extra energy needed for other power hungry devices which I struggle to justify, but I say again, what ever floats your boat, horses for courses etc :)

There are many compelling reasons to install electric AC in a 911. Cleaner engine compartment, no hoses running back and forth under the car, lighter weight, better packaging, better weight distribution.

Adding a small, light heating element to the blower assembly (I assume this is how this is being accomplished) would allow you to run headers (again with packaging and weight advantages) without heat which for many is a big deal.

:)

Really? Most all Porsche shops consider this modification as laughable and a way to ruin & devalue your Porsche.

I fail to understand how adding a luxury, that is totally reversible and made no additional holes or modifications to the stock car, can ruin/devalue the Porsche, especially if it never came from the factory with A/C. I'm not onboard with the electric heating aspect, as heat is free, but fully support the A/C. Survivor cars/all original cars would only benefit from an AC system. Also, if these cars are sooooo valuable that adding a luxury devalues them...why drive them at all...adding miles devalues them.

Sorry to derail the OP's thread subject.

Your minority opinion! There're exceptions though, i.e. when you convert your Porsche to electric and have a 400V battery supply, a 400V compressor is perfect and efficient
& requiring about 1/30 of a 12V system current. Since the typical AC engine power consumption is about 3 HP (2250 watts), the typical 12V AC system requires more than
150 amps from the alternator alone!

Clearly we are not talking to the same shops! 😂.

Below is a poll of the 30 best Porsche shops IN THE WORLD, we supply 22 of them with our electric AC kits. Several OPCs have fitted our kits as well. Sorry, I know we should try harder…

https://www.supercars.net/blog/best-restomod-porsche-restoration-shops/

Ruin, devalue? Not sure I follow. Our AC kit requires no modifications to the 911 body at all, not a single hole drilled or wire cut.

Makes for a good "labor sell" when shop business is slow, right?

Johny..do not even try dude, to reason with him ignore is the best..
Ivan

Many high end Porsche shops are installing electric a/c. I believe PMS is a big purchaser of the systems. If you don't like electric ac, fine but don't make **** up.

Really? I'm involved with many Porsche shops here in SoCal , and most/all indicate that they have NO interest in an after-market installation,
and ALL the on-going headaches once the install is completed. You're obviously not knowledgeable about operating a business,
and much less about what's required to be a successful Porsche independent long term (10-25 yrs).

In what capacity are you involved and what is your business name?

[QUOTE=mysocal911;11816938]Really? I'm involved with many Porsche shops here in SoCal ]

most of the people i know in Socal think you are a numbnut dude;-)

Ivan