Possible Heat Delete - Pros and Cons?

[carwash]

First off, I have read a ton of threads and pelican tech articles on how the heating system in my car works, and I must say that I am still a little bit confused.

My car only has one lever next to the parking brake, and it has the lever on the dash. The way I understand it is that the lever at my parking brake opens the flaps that lets heat into the channels. When i open the side rocker channels on my car, heat comes in them when i have the lever pulled up. When i lower it down, heat stops. Very cool. I like it. But the lever on the dash that controls the defrost one is an enigma. It doesn't seem to do much, especially control the amount of hot/cold air or the level and amount of air that blows. The control is sporadic and completely independent of what I do with the parking brake lever.

I would love to understand the system and its workings before I contemplate deleting the system altogether. Let's discuss the pros and cons of deleting the heating system... Keep in mind I am building a very minimal RSR IRO style stripped interior, racer clone...

PROS: Less plumbing, Less weight, Opens exhaust options, Less stuff to go wrong, Less stuff to put back in the car when rebuilding (lol), what else?

CONS: No defrost or heat. The heat i don't car about, as I'm not a pansy and the car will only be an 8 months a year car. The defrost I'm concerned about regarding condensation etc.... nothing worse than getting a fogged windshield and not being able to get it cleared.

What think ye pelicans?

[juanbenae]

it appears per your signature you car is a 2.2 six in a 912 original body? I can't say for sure, but I would suspect that the 4cyl of the 912 heating system may not be exactly like a 911 chassis. the two levers on the 911 tunnel each control a flapper box collecting heated air from each cylinder bank where as a single lever may indicate a different system. the 2.2 used the original heating system generating pressure from the fan, now refer to as "back dated heat". so, the 2.2 could if plumbed right move plenty of air through the heat exchanges into the cabin. if the 912 on body system is different with it's smaller 4 cyl fan even your six may not be conducting enough heat your way due to more restrictive ducting to the cabin to maintain velocity generated by the smaller 4. any knowing 912's better than I might very well debunk my statements, so there's that.

if the heating was by lantern & oil like I understand early 911s were could the 68 of yours be suited for that? one last thing, when I backdated the heat on my SC early in my ownership of the car it was far and away better than the fan driven junk it came with in 78. and when I say junk I mean the electric fan & plumbing in the motor compartment.

t

[75 911s]

Here here to a backdate system. Or just headers to muffler. It's prettier and cleans up the engine bay. we don't need no stinkin' heat. :-)

[Tidybuoy]

I have a '74 911 and it has the single lever near the parking brake. The only difference in this from the latter cars is that the later cars you can control left vs. right or both.

If your car is a 912 and if it is not producing enough heat, this can be solved with engine compartment fan. This is a very simple setup on the type IV engine and the electric blower motor is switched on when the central heat lever is pulled up.

My '74 is the "backdate" system that people talk about. This simply mean that my car does not have the engine compartment blower or any footwell blowers or any auto-climate control box between the seats. It's a very simple system but I will tell you it works very well. The '74 backdate system has far less hoses in the engine compartment and so the engine looks a little less cluttered. The only time it does not work well is when the engine is still cold and you are relying on the engine cooling fan to pump a little air to defrost the windshield. Once the car is warmed up, this system will cook your toes and defrost fine. I do have SSI exhaust - I'm not sure if that adds to the heat output of not.

Regarding the dash controls: two of these direct airflow to the floor or to the windshield. One is for cold and one is for hot; it basically gives you the ability to blend temps and direct the airflow (which is not much in an older, tiny-vent 911). The third lever is just a blower which produces "some" air but not a whole lot.

[Tidybuoy]

Backdated Heat - 2 hoses and that is it.

[gliding_serpent]

Backdate for the win.

[Canada Kev]

With a complete heat delete, you should still be able to have a rudimentary defrost system with just FRESH air and no heat. It's better than a poke in the eye, but not as good as if the air was heated. However, if it's a bit chilly and raining, you will likely experience a fogged windshield.

[Craig_D]

"I'm not a pansy and the car will only be an 8 months a year car."

How do you know you're not a pansy...you're not driving it in the cold months like the non-pansies do.

[RSBob]

Sounds like your mind is 90% made up already. Go ahead and do it because everything is reversible. If you can't live with no heat, then add it later.

Unless you never plan on selling the car or will keep it as a dedicated track car, then no worry about dimishing the value a bit.

[Bulldog9]

You basically have two systems.

The rear system has a blower in the engine compartment that is switched on by the lever by the E brake. Older models have just one. I think it changed to two in 77. Mine is a 76, and has one. When you pull up, it switched on the blower and also opens the flaps, which pushes air through the heat exchangers through the tubes in the rocker panels and up to the front heater box and controls. All it does is push hot air to the front of the car. The engine cooling fan also pushes air. WHen off the flaps close and the hot air gets vented under the car.

The second system is in the front, and works more or less like a normal heat system. If it has 3 levers like on my 76,, the top is the fresh air vent, left is off and as you move it right it opens and the far right will power the front fan. The next lever controls airflow to defrost or heat, and the bottom is for heat. But you wont have any heat unless you pull the lever on the center tunnel kapish?

Unless you are looking to change out the exhaust and ditch heat exchangers, lighten things for the track, I'd say leave it alone. If you do take parts off, and they are in good condition. keep them.

[Jonny H]

In some countries (UK for example) a defrost system is mandatory for the yearly inspection.

[JSV798]

There's no testing of the heating system in the UK. Here's the checklist:

Mirrors
Doors
Seats
Seatbelts
Horn
Lights
Registration Plate
Vehicle identification number
Exhaust emissions
Exhaust system
Fuel System
Wipers and washers
Steering and suspension
Vehicle structure
Wheels and tyres
Brakes
Windscreen

[tdw28210]

Heated windscreen. I expect to ordering mine shortly.

Porsche | 911 | Heated Windscreen

[carwash]

This is all excellent info. Much appreciated guys.

[carwash]

Originally Posted by Canada Kev

With a complete heat delete, you should still be able to have a rudimentary defrost system with just FRESH air and no heat. It's better than a poke in the eye, but not as good as if the air was heated. However, if it's a bit chilly and raining, you will likely experience a fogged windshield.

Please explain what I retain in the system to make this work.

[javadog]

Guys, he has an early car, which has a different system. Most of the comments above need to be thrown out.

Bottom line, if you are worried about fogging on the windshield, and you should be if you ever intend to drive with your windows rolled up, you need heat. A heated screen only heats the bottom few inches of glass and cold, humid air won't keep your windshield clear.

JR

[carwash]

ah the confusion deepens....

[javadog]

It's real simple. Get your owner's manual, and a copy of the parts diagrams for your car from PET, and spend 10 minutes looking at what you have and how you are supposed to operate it. It's different from the systems used from 1969-on, which is what most of the above comments related to, but it's not complicated at all.

The simplest heating system, regardless of what year 911 or 912 you have, just deletes the electric blowers and uses the air put into the heat exchangers by the engine cooling fan to push heated air through the system, to wherever you want it to go. It's simple ductwork. You don't even need the fresh air intake or controls, if all you want is heat.

JR

[carwash]

Actually all I want is defrost.... It's all i care about. I wish i could do that easily without heat exchangers, duct work, etc.... i just want warm air on the windshield, controlled with an on/off lever... impossible i guess.

[manbridge 74]

Another con for some would be having to constantly fiddle with lever between seats as the engine rpm/load can cause uneven heating. Example would be idling at a light, lever coming up. Once underway heat is increased so lever goes back down.

Later systems were an attempt at more consistent output.