What is backdated heat?

[Pstallo]

What is meant by backdated heat? And what is removed/added/altered? Does it mean you can remove the big, black plastic housing on the left side of the engine bay?

I only ask because I see the term used a lot in posts, but couldn't find an explanation in any of them.

[bgyglfr]

Yes. Removing the fan and all of the associated piping. Then you need to source early plates that go on both sides of the engine fan and pipe the tubes directly to the heat exchangers. Basically you eliminate the fan in the upper left and use the engine fan to push air forward to the cabin.

This is also often done in conjunction with adding early heat exchangers or SSIs for better exhaust flow. Photo below stolen from google image search.

http://www.google.com/imgres?imgurl=http://forums.pelicanparts.com/uploads5/enginebay31115691174.jpg&imgrefurl=http://forums.pelicanparts.com/porsche-911-technical-forum/220695-why-you-should-backdate-your-heat-3-2-a.html&h=480&w=640&tbnid=duKT73r0ZmH4mM:&q=backdate+heat+911&docid=ZHZAUffCtNZmMM&ei=c4crVs-aLsr2mAHEiqWYBw&tbm=isch&ved=0CB8QMygDMANqFQoTCI-g2Jyb28gCFUo7JgodREUJcw

[RSBob]

Did mine a couple of years ago and get plenty of heat in the cabin. I never have both levers full up or it would be intolerable. The blower motor in the engine bay, if yours still works, will never be missed with this set up. Engine bay is also much cleaner with all tubing and crap out and a tiny weight savings. A cheap mod relatively speaking with big aesthetic appeal and no downside for me. Bought the parts here. Do it.

[Farrell]

^^ Yes, its easy and well worth it. Get rid of the AC if you still have that in there too!

[Jack Stands]

I'd have to agree that the old system seemed to work just fine without all those fans, etc. cluttering up the engine compartment. I think it was Porsche's attempt at keeping up with other manufacturer's systems instead of staying with a tried and true system (as Morgan has been doing successfully). Also, once Catalytic converters became necessary, they needed to change the exhaust routing away from the most efficient routing.

My old 75 Targa with SSI heat exchangers could keep us toasty on the coldest days here in the Midwest. I don't think my complex '84 911 Targa does any better.

However, if you're in an area where it gets hot and humid in the summer, you might want to keep the AC system. I find myself taking my Targa more often than my 914-6 on those hot, humid summer days simply because I need to stay cooler now that I'm getting older.

[RDM]

I'm not sure the electric fan is to increase heated air into the cabin, but to make it less variable. More warm air at idle, less at speed. Less fiddling with the red levers.

[Pstallo]

I got kind of obsessed with this today and have been reading every post I can find on it.

So, for a Carrera, all you need is a duct from a turbo for the left side, correct? (like this one: Pelican Parts - European Automotive Parts and Accessories - Porsche • BMW • Mercedes • Volkswagen • Audi • Saab • Volvo • MINI)

Or, do you need to replace the right side as well? Tried to find a step-by-step for a Carrera, but didn't see anything with more specifics.

[SpyderMike]

http://forums.pelicanparts.com/porsche-911-technical-forum/819396-so-how-backdate-project-starts-2.html

Post 30 lists the parts I used. Real simple. Works great. I only used the left hand side duct.

[RSBob]

Got off my lazy ass to take a night time pic of the backdate and AC delete. Just learned that the latest iPad doesn't have a flash for the camera. What kind of BS is that when you spend big coin? Anywho, this the best for now.

[pmax]

When we got the SC, the engine compartment blower was burnt out. As a result, heating was marginal at lower engine speeds until I replaced it.

[James Brown]

here is a before picture (of a SC) exhaust system

and this is the updated (backdated) system that will work for your 3.2. You can see why the backdate system is so desirable, but no catalytic converter so it can't pass smog

[RDM]

Originally Posted by James Brown

here is a before picture (of a SC) exhaust system

and this is the updated (backdated) system that will work for your 3.2. You can see why the backdate system is so desirable, but no catalytic converter so it can't pass smog

This illustrates backdated exhaust, which is often (but not necessarily) done with backdated heat.

If you only use the left-hand turbo duct, you only have heat on the driver's side of the car.
Correction- on a 3.2, it has a heat crossover pipe on the underside. The Turbo pipe should do both sides.

[McLaren-TAG]

this *IS* backdated heat.

[theiceman]

The reason for the fan is to provide heat to the windshield at idle. For those who don't live in cold winter climates probably do not understand the reasons for it and consider it a mistake on Porsches part.
Those who live in cold winter climates and drive their care all year understand the fan is required to defrost / defog the windshield while engine rpms are not high enough to push air and is an obvious safety requirement Porsche had to address.
But if you don't need it knock yourself out.

This also has NOTHING to do with SSIs or back dated exhaust, As you can see the SSIs route the cabin heat ducting exactly the same way.

carry on

[McLaren-TAG]

Originally Posted by theiceman

The reason for the fan is to provide heat to the windshield at idle. For those who don't live in cold winter climates probably do not understand the reasons for it and consider it a mistake on Porsches part.
Those who live in cold winter climates and drive their care all year understand the fan is required to defrost / defog the windshield while engine rpms are not high enough to push air and is an obvious safety requirement Porsche had to address.
But if you don't need it knock yourself out.

This also has NOTHING to do with SSIs or back dated exhaust, As you can see the SSIs route the cabin heat ducting exactly the same way.

carry on

The windshield defrost is only an issue when cold. Once warm the interior of the car is a billion degrees because the heat you get from the straight flow over the the SSIs feels like a fireplace. Literally. Real men also take out the seized or non functional footwell blowers too.

[theiceman]

Originally Posted by McLaren-TAG

The windshield defrost is only an issue when cold. Once warm the interior of the car is a billion degrees because the heat you get from the straight flow over the the SSIs feels like a fireplace. Literally. Real men also take out the seized or non functional footwell blowers too.

footwell blowers ? what be those ? Sounds like some floofy comfort thing they would put in a Carrera.

[OsoMoore]

Originally Posted by theiceman

The reason for the fan is to provide heat to the windshield at idle. For those who don't live in cold winter climates probably do not understand the reasons for it and consider it a mistake on Porsches part.
Those who live in cold winter climates and drive their care all year understand the fan is required to defrost / defog the windshield while engine rpms are not high enough to push air and is an obvious safety requirement Porsche had to address.
But if you don't need it knock yourself out.

This also has NOTHING to do with SSIs or back dated exhaust, As you can see the SSIs route the cabin heat ducting exactly the same way.

carry on

I have backdated heat because the electricals to the blower became confused and I didn't want to dig into the wiring loom. It wasn't too hard to modify the right side fan cover, instead of buying expensive alternates.
http://forums.pelicanparts.com/porsche-911-technical-forum/767908-cheap-sc-heater-backdate.html

If you are idling in traffic, you won't get a lot of heat. But whilst driving at speed you get plenty.

[Pstallo]

I live in Alabama and won't be driving the car much in cold weather, so I went ahead and ordered tubing from Aircraft Spruce and the left-side duct. Hopefully, it will arrive in the next few days and I can get started!

[James Brown]

the only reason for backdating heat is to get full flow from the SSI exhaust headers and, to a small extent HEAT. if your just looking for cosmetics and happy with your exhaust/muffler combination well just keep the engine lid closed and no one will know. Performance upgrades are always welcome.

[RDM]

Originally Posted by James Brown

the only reason for backdating heat is to get full flow from the SSI exhaust headers and, to a small extent HEAT. if your just looking for cosmetics and happy with your exhaust/muffler combination well just keep the engine lid closed and no one will know. Performance upgrades are always welcome.

Disagree. I did it to simplify the underhood adventure as much as possible, to simplify maintenance and to lose weight where weight loss is best. Cosmetics is a nice bonus, but not a prime motivator.