Fan housing blockoff, no heat Options

[Mueller]

QUOTE (RandyLok @ May 9 2005, 01:45 PM)

Trying to learn here... Are these flaps the ones controlled by the thermostat for cooling, or by the driver to feed the heat ducts?

niether, the flaps in question are on the bottom of the housing, they blow air thru the heat exhangers

[Rand]

Dammit I hate sounding like a noob, but I gotta get my head around this. Ok, so what controls these flaps, if not driver or thermostat? What else moves flaps?

[tat2dphreak]

QUOTE (RandyLok @ May 9 2005, 03:56 PM)

Dammit I hate sounding like a noob, but I gotta get my head around this. Ok, so what controls these flaps (if not driver or thermostat)?

the ones we are talking about are at the bottom, they have no flaps... leter in the piping of heat there are the driver-controlled flaps, to let heat into the cockpit...

[MattR]

Not as much flaps, but outlets. These outlets go to the flapper boxes connected to the heat exchanger, which are controlled by the driver (on the tunnel). Opening the flapper boxes lets moving air into the hot heat exchangers and into the longs to toast your feet and to the blower assembly next to the gas tank to defrost the window.

[lapuwali]

I've heard this "ya gotta block them off" bit from the VW crowd, too, but it makes no sense. If the full HE and heat system is in place on the 914, then air gets blown out of those ports, through the HEs, and to the flapper boxes, which then decide if that air get's blown into the cabin or out onto the ground, depending on the position of the lever next to the shifter. So, at all times, air is getting blown through those ports, removing it from cooling the engine. If you remove the heater system, you remove some restriction from the system, so MORE air can come out of the ports, but it doesn't seem like it would reduce the restriction all that much, so the additional air coming out of those ports would be fairly small.

Closing off those ports with something flat at the end of the port would very probably give you some additional turbulence inside the fan housing, which could very well mess up the airflow. If you instead went with sculpted bits that closed the ports by leaving a smooth wall inside the fan housing (curved inner surface), this would reduce this turbulence, and should push more air smoothly into the tin.

[Mueller]

QUOTE (tat2dphreak @ May 9 2005, 01:59 PM)

QUOTE (RandyLok @ May 9 2005, 03:56 PM) Dammit I hate sounding like a noob, but I gotta get my head around this. Ok, so what controls these flaps (if not driver or thermostat)? the ones we are talking about are at the bottom, they have no flaps... leter in the piping of heat there are the driver-controlled flaps, to let heat into the cockpit...

actually, they do have "flaps" on the bottom, but those are more like one way doors....only way for them to open is when the engine is on and the fan blows them open

[Rand]

Ok, got on the wrong track by seeing what I thought were movable (by thermo or driver) flaps in the original photo. Guess I'll go dig in to some manuals and diagrams. In the mean time, any more pointers are appreciated.

[tat2dphreak]

QUOTE (RandyLok @ May 9 2005, 04:07 PM)

Ok, got on the wrong track by seeing what I thought were movable (by thermo or driver) flaps in the original photo. Guess I'll go dig in to some manuals and diagrams. In the mean time, any more pointers are appreciated.

this will help explain the flappers operated by the thermostat to help control engine warm-up and guide air...

Classic thread

this stuff at the bottom is just for the heat...

[McMark]

But here's the thing nobody's mentioned. There are flapper doors on those ports from the factory. Those port are blown open by the cooling fan most of the time. The flappers are there so that when you turn on the supplementary heater blower (electric one in the engine bay) those flappers are forced closed by the increased pressure on the HE side. So are we saying that turning on the heater fan in a stock car will overheat the motor because the flaps are closed? I find that hard to believe.

[nebreitling]

i'm with mark. makes no sense to me, IIRC the way they work.

[SirAndy]

QUOTE (McMark @ May 9 2005, 02:51 PM)

But here's the thing nobody's mentioned. There are flapper doors on those ports from the factory. Those port are blown open by the cooling fan most of the time. The flappers are there so that when you turn on the supplementary heater blower (electric one in the engine bay) those flappers are forced closed by the increased pressure on the HE side. So are we saying that turning on the heater fan in a stock car will overheat the motor because the flaps are closed? I find that hard to believe.

(IMG:http://www.914world.com/bbs2/html/emoticons/agree.gif) those outlets don't drive the *real* heat in a 914 anyways.
that is done by the external blower in the engine comp.
the one you start up when you move that red lever on the center tunnel.

as soon as you do that, the pressurized air from that fan will close the little flappers on the housing outlets. this is done to avoid the big cooling fan sucking in hot air from the heat exchangers.

i'd say, expoxy it close and be done with it ...
(IMG:http://www.914world.com/bbs2/html/emoticons/wink.gif) Andy

[Rand]

Now were hitting on my first thoughts. I can't imagine that running the heater would affect the engine temp adversely. Also wondered about just closing the flaps (or at least what I thought were flaps from the photo), securing them, and sealing the perimeter with heat-proof sealer of some kind.

[Al Meredith]

See if you can find a late 2.0L VW bus fan housing, it will have a VW and OOOO (audi) on the casting. They have no lower ducts and a larger (deeper) housing. Jake told me that this housing blows about 20%, if I remember correctly, more air over the oil cooler. Since it has a smooth path inside I don't see why you couldn't afix a piece of aluminum inside. BTW we used this set-up on my son's E production 914 for years and it cooled fine. OH! I forgot the alternator will not line up as the bus used a squirl cage blower on the end of the alternator as a heater fan. The race car did not use an atlernator!

[SirAndy]

QUOTE (RandyLok @ May 9 2005, 03:15 PM)

(or at least what I thought were flaps from the photo)

see the green arrows. they're pointing to the outlets in question. on a stock housing, they will have little "flaps" attached that open only one way (towards the outside) ...

for a motor with headers, simply epoxy those flaps close.
(IMG:http://www.914world.com/bbs2/html/emoticons/smash.gif) Andy

[SLITS]

QUOTE (RandyLok @ May 9 2005, 01:45 PM)

Trying to learn here... Are these flaps the ones controlled by the thermostat for cooling, or by the driver to feed the heat ducts?

There are metal flaps on a hinge over them to prevent reverse airflow when using the heater fan at low rpms.

Other than that, there is no control over the airflow. If the heater control boxes are closed to the cabin (driver control), the air heated air is exhaused thru the control box bell or whatever you want to call it.

I have not personally done airflow studies, so I ain't gonna say shit about it!

screw it...Andy's faster.....

[Allan]

Just a little input. The pictures you are looking at are from my motor. I drove the car from Bakersfield to Santa Maria then to Camarillo for the WCC with those ports open on the flattest roads I could find. On the way back I drove it directly from Camarillo to I-5 and up the grapevine. Ask SLITS on which run I called him. I don't believe it matters. Just my humble opinion. (IMG:http://www.914world.com/bbs2/html/emoticons/rolleyes.gif)

[Rand]

Thanks for the replies to my stupid questions on this. Learned a lot about part of the beast I didn't have experience with. Again, the community comes through!
(IMG:http://www.914world.com/bbs2/html/emoticons/smilie_pokal.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/beerchug.gif)

[Jake Raby]

Blocking these off is the fastst way to create huge imbalances in engine temps!

The shroud was designed for them to always have air passing through them, even when the heat is off (to cool the heater boxes)

I have tested this one on the dyno and plan to data log it as soon as I get the chance to show the differences. Leave them open!

The late model vanagon blower housing is an excellent addition to a race 914 or a car that runs a non stock alternator, as Al goes over in his post.

[MattR]

Cool, thanks jake!