‘76 911 Electric demister options?

[Alexandphoto]

Hi all!

I’m revisiting the interior in my car and exploring options for my heating.

currently running RSR headers which will have cats put in, and so SSIs aren’t an option.

Is anybody running an electric demister of some sort? Are there any 12V options that can either plumb in to the factory vents or run subtly on top of the dash?

Thank you

[Nditiz1]

It my be easiest to create a thin box around the headers on one side and them use the fan to push it into the cabin.

[chrisbalich]

I installed an electric forced air defroster over the winter.
It works excellently, but it draws a lot of amps.

my low budget dream car build

my low budget dream car build

[spuggy]

Originally Posted by Alexandphoto

Hi all!

I’m revisiting the interior in my car and exploring options for my heating.

currently running RSR headers which will have cats put in, and so SSIs aren’t an option.

Is anybody running an electric demister of some sort? Are there any 12V options that can either plumb in to the factory vents or run subtly on top of the dash?

Thank you

12V powered-heating is about the worst way you could go.

Don't believe these ads - not an accurate depiction of the unit in use...:



TL;DR:

• fit a heated windshield (factory option, still available, not cheap - but period-correct for 70's car)
• use heat exchangers on the headers
• fit a Webasto or Eberspächer heater in the smugglers box (Note)

(Note) Cheap Chinese clones of these very simple devices are available for about 1/10 the cost of the name brand German units in wide-spread use since the 1950's (still an option on VW/Audi, for example), and have become fairly popular - dozens of videos on YouTube from the "van life" crowd. But almost all of the cheap Chinese units are intended for use with diesel fuel and don't run properly on gas (not jetted correctly). That said, a small (2-3 pint) diesel fuel tank would last 10's of hours of use - and I like the idea of not futzing with the gas lines...

If you *must* use electric heat, realize that a candle puts out 80W, an adult human being - at rest - 100W. So you'd probably be better off just adding a passenger than using one of those 120-150W fan units, LOL.

To quote myself from another thread, comparing the power draw of the Classic Retrofit PTC heater bricks (that run at 220V-400V) to 12V heating units:

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...

Some links you might find interesting:

https://forums.pelicanparts.com/911-930-turbo-super-charging-forum/1126470-electric-heating.html
https://forums.pelicanparts.com/911-930-turbo-super-charging-forum/1136788-webasto-air-heater-installation.html