Greetings from Munich!

I’ve had my white car in storage over here for over 5 years and now it’s FINALLY going to become registered, but alas! It must pass the notorious TÜV inspection first!

While in California, being worked on by the guy who sold me the car, we unwisely decided to remove all the ducting and defrost vents in the front of the car. We also added those OBX headers which some will recall, which were subsequently removed and sent back to the US and sold here in 2019 or so and the car now has heat exchangers and heat in the cockpit. But there is no defrost functionality and TÜV likely will not allow the car to pass without SOME sort of defrost.

I am very skeptical about using a cheap 12v / 150 watt thing that plugs into the cigarette lighter port which won’t bring the desired result, although that may be enough for the inspector to give it a nod.

So my question is regarding powering a heater-blower with 1000w or even more, which would require a draw of some 125(!) amps at 12v.

I don’t know much about electrical systems, so thanks to those who do who may be so kind as to share their knowledge here with me / us how they would solve this little challenge. Should I upgrade the alternator? How would such a heater be wired? Etc.

Thanks very much in advance for your time and feedback!

With best regards,

Mike in Munich Click to view attachment

125A is a bit outside of the range of the 914 OEM alternator. I think it puts out 50A or so. Your current calculation is a bit off on the high side. P = V x I. So I = P/V = 1000/12 = 83A. Still outside of an OEM alternator.

Any heavy duty electrical load like this would really require a home run wire from the battery to the unit. What unit were you looking at that burns 1000W?

Spoke is right. You are not going to get 1000W of defrost out of an electric setup on a 914. The stock alternator is no where near big enough for it. The stock alternator for a 914/4 only puts out 55 amps.

Years ago, I had a "back seat heat" unit in my 914. It was mounted under the front edge of the driver's seat, and it kept me reasonably warm during a Texas winter. But it also required that I plug the car into a battery charger every night to keep the battery from going dead.

Winters in Germany are a lot longer and a lot colder than in Texas. So, if you want electric defrost, you will need a bigger alternator. There are members on here that make kits to upgrade the alternator to something with more output.

Good luck.

Clay

https://www.amazon.de/Brandson-Innenraumhei...DSYPMEY46CDBRP0

Yeah, I realize I would need an aftermarket Hi Amp Alternator...

I would source the parts you need to make defrost work as normal. It just would not have a fresh air function. The parts you need don't rust, should be thousands of them.
Matt

Thanks Matt, I already have them, but the vents are closed off entirely. It would mean a lot of work and taking apart my dash...etc. Don't really wanna have to go that route.

A china espar gas heater, the smaler 2K model.
It will take some work and you,ll have to weld a 2-3 inch tube through your gas tank but you can mount the heater in the bottom of the trunk and plumb it like Porsche did on the one 914/8.
You do have to run this on diesel or kerosene, the ebay kits come with a small tank.

This would blast the heat, tee it off to the factory risers and you're cooking with fire.

Now that is even MORE work! I was going to go that route and even bought a Webasto gas heater for that project but backed off it and sold it again.

Thanks anyway!

Would a fan to circulate the heated air pass? A small one on the dash, battery operated?

Go to a gas heater or go back to the stock set up. You will be happier with something that works right

Bob B

I don't know if this would be allowed, but you could look at putting a defroster grid on the windshield. I put one from FrostFighter on the front windshield of my race car, and it works surprisingly well. It's basically the same defroster grid as on your rear car window. It's a bit of a pain to install with the windshield in place, and a bit annoying to have to look through, but it's effective and only draws about 10 amps.

Take a look at a simple 12v fan made for boat bilge ventilaiton, duct it from the dash heat supply to the defrost openings....voila!
Here's a link...
https://www.amazon.com/Attwood-1731-4-Blowe...25570&psc=1

Thanks, but the vents were removed and covered. That’s the problem.

Interesting option! Thanks!

It wiĺl never come close to the heat produced by a heat exchanger or a gas heater. I doubt if any of the cheap electric devices can even produce 5% of the heat of a gas heater.

If you're just trying to pass inspection with something you'll remove later, here's an idea....I used this blower to bring warm air from the headers & cylinder cooling air flow to the cabin heat tube...actually knocked the chill off...Click to view attachment

How about this?

https://www.amazon.com/Windshield-Defogger-...9072&sr=8-6

That is going to take 65 Amps which is above the alternator output.

That's a lot like "An Ugly" we used to do in the bugs, except we used flex exhaust pipe, ran it from the back, between the front seats and bent it to aim at the windshield.

Creative solutions above but I'm betting that isn't going to cut it with TUV!

I agree.
I think you should discuss any non stock option with the TUV before you waste time and money on some system that doesn't pass anyways.


I'd go stock
better in the long run
not concerning to other future owners
passes inspection
a bit of work... but a better outcome.

with the post before me. If not going back to original, clarify it before with the TÜV to avoid surprises.
On another side, the TÜV never checked it on any of my vehicles... If you don't drive it in winter, wait for higher temperatures and chances are high they don't notice !

Antoine

Interesting. Hope you’re right. But as for „not checking“...with my car they won’t have to check, per es, as controls are missing from the dash. That’s a bit more „auffällig“, if you know what I mean.

Either bring a very attractive wife/girlfriend with you or rent an escort. Need to keep inspector highly distracted.

https://youtu.be/GIdjt_Asf7E

The funniest for our German friends

I also bought one to try out. I connected it directly to a battery on my bench. The wires inside and the connecting wires are too small. The wires immediately got hot and started smoking. Other people in the comments noticed the same thing.

Too bad it’s not 12v. It runs on 220v