Electric heating

[spjuvern]

What ideas do you guys have on any electric heating add on in a 964 turbo
If removed heating from headers.

[spuggy]

Probably should look into PTC; self-regulating/don't overheat, relatively safe/cheap/efficient.

PTC heater cores are pretty common on newer vehicles (VW/Audi etc) as either standard heat, or a supplementary "cold weather" kit. Then it's a packaging issue - they tend to be rectangular and fairly large (eg to match the water/air heater core). Not exactly a no-brainer to integrate them into the factory air system, you'd have to fabricate something pretty cunning.

There's dozens of 12V PTC heater blocks of varying shapes/sizes on Flea Bay for not very much. Most of the smaller ones with fans tend to be 100W or so. So you'd need to stack a fair number of those. And at $15 each, not sure I'd want them embedded deep in the car where I couldn't readily get a fire extinguisher on them...

Most factory EV systems (which also use lean heavily towards PTC for heat) don't run 12V. For example, if you can provide 400V, you could use these https://www.classicretrofit.com/en-us/collections/electric-vehicle-parts/products/400v-ptc-brick-heater-fan-and-ducting-1100w-for-vw-porsche-ev-conversions

As relatively pitiful as the heating is from performance header heater boxes when driving a mountain pass with 14F ambients, I'd leave them on. Just get out every 40 miles and walk around until you can feel your toes again... Maybe pack them with steel wool or something to increase the surface area/heat transfer.

"It's so frcikin' cold in here! Heat isn't doing anything!" (opens window).
"Uh. Darn. OK. It's much colder outside" (closes window).

I remember my factory heat exchangers would be beginning to melt 1/2" of ice off the windscreen within 2-3 minutes of starting - I'd have to crack the window driving around as otherwise it'd get too hot on "defrost" (necessary to keep the screen from fogging). Ho hum...

Another approach is to dress appropriately - eg dress for extreme cold sports, like ski/motorcycle clothing, but without the need for the abrasion/waterproof/windproof layer. Thermal layering works - silk works incredibly well, some "technical" fabrics are almost as good for 2x, 3x the bulk (and usually much cheaper). Or heated clothing.

Heh. Other strategies include "move somewhere ambient doesn't drop below 65F" - bonus is avoiding the need for a set of snow tires,..

Or I hear some folks don't drive 911s in the winter.

[908/930]

I think you will need to add another alternator, need lots of current at 12v to get any significant heat.

How about placing oil coolers inside the car, lots of hot oil around.

[spuggy]

Originally Posted by 908/930

I think you will need to add another alternator, need lots of current at 12v to get any significant heat.

One of those 100W PTC heaters @ 12V is 100/12 = 8.3 amps. Almost as much as both high beams.

You'd need 10 of them for 1000W, and that'll run you 90+ amps @12V. Which is fairly *cough* significant.

The 1100W PTC heater @ 400V, by comparison, is 1100/400 - 2.75 amps.

The Classic Retrofit alternator kit (includes massively uprated ground/starter cables you'll be wanting), BTW, is rated 175A. Because it includes a WOSP alternator, built on a modern Denso comb-style core, delivers much of that rating at idle.

The actual alternator is rated "higher" (so likely a 200A unit, as a SWAG) - but Jonny doesn't think you can drive quite that much with a v-belt pulley. Wonder what my Clewett/Gates belt drive will do...

Some Clif Notes/thoughts:

• Transformers are exclusively AC/AC; there's no such thing as a DC/DC transformer (because no change in EMF means nothing happens between the two windings). There are, however, converters that use DC to generate a sine wave, put it through a transformer and convert back to DC once its at your desired voltage.
  
• However, 12V -> 400V DC doesn't really seem to be a standard thing (yet). (Although 400V -> 12V totally is)
  
• The "400V" PTC heater will apparently run on as little as 220V (according to the spec sheet, which describes it as "220-400V").
  
• 12V DC -> 220-240V AC is an off-the-shelf inverter for "aynwhere but the American continent" supply voltage. Converting single-phase AC to DC is pretty trivial (rectifier bridge), so that could work.

1100 watts @ 220V is 5 Amps. Just sayin'...

[spuggy]

Yeh, I know you said "electric heating". And you have a 964 - they lost the smugglers box, right? But for the benefit of anyone with an earlier car who wishes they had better heat exchangers - or some heat exchangers at all - and ends up on this thread, I'd just offer that the factory fitted Webasto heaters for a long time, which are generally considered very safe. They hardly ever explode, catch fire or anything... LOL.

Yeh, I've thought about this... Usually when ambient temps approach the teens (F)...

Vintage Wesbestos are kind of scarce. However, Webasto/Espar (Eberspacher) are still in business, both still making parking heaters, in either gasoline or diesel versions..

I believe either the Webasto 2000W Air Top or the Espar Airtronic S2 D2 2.2KW models (almost exactly the same size/shape) will fit in the smugglers box. Both are vented types, which means zero carbon monoxide from the combustion process getting into the heated air (as long as you run the exhaust away from the air intake). Seems like an important detail/design feature...

https://www.amazon.com/Webasto-Gasoline-Heater-install-9032227A/dp/B01M2ZCWTF/ref=sr_1_5?crid=25S9L1UKCYXJX&keywords=petrol+gas+parking+heater&qid=1663443245&sprefix=petrol+gas+parking+heater%2Caps%2C138&sr=8-5
https://www.amazon.com/Eberspacher-Airtronic-EasyStart-Diagnostic-Adjustment/dp/B07Z82FPD3/ref=sr_1_15?crid=25S9L1UKCYXJX&keywords=petrol+gas+parking+heater&qid=1663443245&sprefix=petrol+gas+parking+heater%2Caps%2C138&sr=8-15

I doubt anyone's going to live in a 911 in the winter(!), so not all of the "vanlife" parking heater info is applicable, but there's a wealth of installation and running detail there anyway:

https://faroutride.com/air-heater-installation/

There's even Chinese clones, although it can be harder to find the petrol ones:

https://weekendervanlife.com/chinese-parking-heater-webasto-copy/

https://www.alibaba.com/product-detail/Gasoline-heaters-2KW-12V-Parking-Air_1600496159724.html?spm=a2700.7724857.0.0.4abd2 8dcIiy0qw

Seems the diesel ones really don't run very well on petrol (burns too fast, flames out and doesn't get the combustion chamber temperature stable or hot enough). There's YouTube videos getting them (sort of) working for the curious.

[krasuskyp]

Cheap Amazon 3" tube unit stuck to windshield and plugged into lighter - works a treat!

8-)

[zakthor]

Doesnt it seem stupid though to use electric resistance for heat when a mass of burning gasoline is shedding heat a few feet behind you?

Assuming you still have the heater blower it Might make the most sense to fab up some boxes to wrap the new headers and connect to existing heater passages. Seems like even a small airtight box would provide great heat transfer compared to what even a new alternator could provide.

[TurboKraft]

Originally Posted by krasuskyp

Cheap Amazon 3" tube unit stuck to windshield and plugged into lighter - works a treat!
8-)

Elaborate, please

Originally Posted by zakthor

Doesnt it seem stupid though to use electric resistance for heat when a mass of burning gasoline is shedding heat a few feet behind you?

Assuming you still have the heater blower it Might make the most sense to fab up some boxes to wrap the new headers and connect to existing heater passages. Seems like even a small airtight box would provide great heat transfer compared to what even a new alternator could provide.

Not stupid at all.
Sure, that's a lot of BTUs available a few feet behind the driver, but finding leaks in stock heat exchangers isn't uncommon, and that's CO going into the heater duct system.
Aftermarket stainless exhaust is much less prone to leaking, but the heat exchangers usually leave a bit to be desired.

We are seeing more and more cars with the large WOSP alternators fitted, and electric heat seems like a great idea -- especially for those engines fitted with performance header systems.

[gsxrken]

This thread reminds me that I suck at electric math.

Originally Posted by spuggy

Some Clif Notes/thoughts:

• Transformers are exclusively AC/AC; there's no such thing as a DC/DC transformer (because no change in EMF means nothing happens between the two windings). There are, however, converters that use DC to generate a sine wave, put it through a transformer and convert back to DC once its at your desired voltage.
  
• However, 12V -> 400V DC doesn't really seem to be a standard thing (yet). (Although 400V -> 12V totally is)
  
• The "400V" PTC heater will apparently run on as little as 220V (according to the spec sheet, which describes it as "220-400V").
  
• 12V DC -> 220-240V AC is an off-the-shelf inverter for "aynwhere but the American continent" supply voltage. Converting single-phase AC to DC is pretty trivial (rectifier bridge), so that could work.

1100 watts @ 220V is 5 Amps. Just sayin'...

[krasuskyp]

Originally Posted by TurboKraft

Elaborate, please.

https://www.amazon.com/Portable-defroster-Cigarette-Lighter-Windshield/dp/B08YNMC17K/ref=sr_1_19?crid=OFIV2N8TFAVF&keywords=electric+car+heater+12v&qid=1663941337&sprefix=electric+car+h%2Caps%2C113&sr=8-19

OK, so I'd replied before using this as I'd gotten it last xmas & my car just arrived

Used it last night finally - works a treat may be too strong a sentiment

It works enough to take the sting out of the air or quickly warm your hand... I'd like it to warm a bit more, but am also cognizant of the draw on the cig lighter.

It's better than nothing certainly Mounts quick easy & secure, and stows nicely in glovebox...

[spuggy]

LOL. I liked this one:



I don't think/really hope that isn't an accurate depiction of the unit in use...

200W pulls 16.7 A @ 12V. The 150W one pulls 12.5A @ 12V.

On a (IIRC) unfused supply. Enough folks saying in reviews that they pop 20A fuses to be concerned. Uh, Hard nope...

6000W 12V->220V AC inverter runs $50 or so. Full-wave bridge rectifier should put out ~325V DC from 220V RMS (assuming a decent sine wave), and a 10A one runs around $30.

2200W (eg 2x1100W CR PTC heaters) @ 325V is 6.75A.

I'm not doing this - but if I were, those numbers look pretty compelling to me...

[fastricky]

I'm in a situation where I have Tangerine Racing headers and their heat exchanger on my 912E. This setup does not provide adequate heat and I'm looking to supplement in some way.

How about setting up a gas heater in the smugglers box, just like the original 911?

[spuggy]

Originally Posted by fastricky

How about setting up a gas heater in the smugglers box, just like the original 911?

LOL. There's some links above you might be interested in reading. Or not.

[908/930]

You really need a lot of heat to warm a car, uninsulated everything. if you get a 400A alternator and wire it direct to a 4800W heater that could do it, depending on the outside temp. LOL. If you get the valving changed on the AC can possibly convert to heat pump.

[fastricky]

Originally Posted by 908/930

You really need a lot of heat to warm a car, uninsulated everything. if you get a 400A alternator and wire it direct to a 4800W heater that could do it, depending on the outside temp. LOL. If you get the valving changed on the AC can possibly convert to heat pump.

Yes this is the right approach I think, I did more research on the gas powered heater and definitely not a safe route.

Anyone have a link to a recommended elec heater?

Found this, while it works via coolant, could it also work with the oil? I have an external oil cooler on my E so kinda the same concept maybe?:

https://www.americancoolingsolutions.com/24751-13-000-btu-12-volt-low-profile-universal-auxiliary-cab-heater-car-utv-truck-van/

[Jonny H]

My company designed the electric heating and AC for the Singer DLS. The heating is 1600W, essentially 800W per side of the vehicle. That's 130A but we have a power management strategy that can put the heating (and the AC) into low power should the voltage fall. The heating in that car is 'adequate' given the power budget available but lots of other work had to be done to the vehicle to make it work.. sealing the cabin being the main thing.

The main issue in a 911 with heating (or cooling) the cabin is that air gets into the trunk when you are travelling at speed. The air then gets forced into the cabin through all the holes in the metal behind the dash so you are constantly having cold air blown on you in winter which negates the warmth generated by the heat.

If you want to test this, try taking out the clock, drive at 70 mph and see for yourself!

TBH, the leaky cabin issue is the main reason we put our electric heating project on hold. I'm not sure customers would bear to take their dashboards out, seal all the holes and re-install it!

As a benchmark, a tea candle produces approx 50W of heat. Most of the ebay type heaters are 300W. Now if you think you can heat your car with 6 candles good luck to you!

[spjuvern]

Originally Posted by Jonny H

My company designed the electric heating and AC for the Singer DLS. The heating is 1600W, essentially 800W per side of the vehicle. That's 130A but we have a power management strategy that can put the heating (and the AC) into low power should the voltage fall. The heating in that car is 'adequate' given the power budget available but lots of other work had to be done to the vehicle to make it work.. sealing the cabin being the main thing.

The main issue in a 911 with heating (or cooling) the cabin is that air gets into the trunk when you are travelling at speed. The air then gets forced into the cabin through all the holes in the metal behind the dash so you are constantly having cold air blown on you in winter which negates the warmth generated by the heat.

If you want to test this, try taking out the clock, drive at 70 mph and see for yourself!

TBH, the leaky cabin issue is the main reason we put our electric heating project on hold. I'm not sure customers would bear to take their dashboards out, seal all the holes and re-install it!




As a benchmark, a tea candle produces approx 50W of heat. Most of the ebay type heaters are 300W. Now if you think you can heat your car with 6 candles good luck to you!

any inspire photos of how they done it?

[spuggy]

Originally Posted by Jonny H

As a benchmark, a tea candle produces approx 50W of heat. Most of the ebay type heaters are 300W. Now if you think you can heat your car with 6 candles good luck to you!

Average human male at rest generates 105W, or 356 BTU/hour, apparently.

I did not check the math...

[Jonny H]

Originally Posted by spjuvern

any inspire photos of how they done it?

The blower system is essentially the same as our classic 911 AC system blower, except it has PTC heater elements in the end caps.

Regarding how the cabin is better sealed, they replace the whole firewall/frunk section with a redesigned bonded in carbon fibre - it stops the air getting through to the cabin.

[spuggy]

Originally Posted by Jonny H

air gets into the trunk when you are travelling at speed.

...

If you want to test this, try taking out the clock, drive at 70 mph and see for yourself!

Many swear by the "air vent in the clock hole" mod for ventilation, so this seems to track/no reason to doubt your statement at all.

However, I am kind of puzzled why it's that bad - surely the trunk doesn't have any major holes in it, and there's a compressible seal around the lid? So where's it getting in?

Logically, if the trunk were (hypothetically) air-tight, then the lack of seal around the dash/rest of the cabin wouldn't matter very much, because there'd be no flow, correct?