From what I understand of the 914 heating system, the fan housing outlets have to be blocked off if I'm not running heat. Can anyone give suggestions on how to block these off? I could weld them up, but Im not sure about the material, and I'd like to be able to seperate the fan housing without grinding and rewelding.


(those outlets at the bottom)

don't laugh at my "solution"

I cut a few pieces of wood, shoved those into the openings, used RTV for a seal and drilled a hole into the bottom of the housing and used a wood screw to secure the wood block into place

don't block them, everything I've heard said that causes an "air disturbance" jus leave 'em be...

or figure out a way to use them for something else... tubing to help cool the back cylinders more?

Sorry mike, Im not putting wood in my car

I like the idea of tubing. I can chop up a stock piece and divert it with some rubber hose or something over the back cylinders? It probably wont do anything, but help with "peace of mind"

QUOTE (MattR @ May 9 2005, 11:08 AM)

I could weld them up

flat piece of aluminum and epoxy works just fine ...

Andy

QUOTE (MattR @ May 9 2005, 12:17 PM)

Sorry mike, Im not putting wood in my car I like the idea of tubing. I can chop up a stock piece and divert it with some rubber hose or something over the back cylinders? It probably wont do anything, but help with "peace of mind"

nobody has to know

QUOTE (MattR @ May 9 2005, 11:17 AM)

Sorry mike, Im not putting wood in my car

At least it won't rust!

NOT blocking them means a SUBSTANTIAL percentage of the available cooling air goes away, something you don't want to happen. Whatever method you use, they need to be blocked. The Cap'n

QUOTE (mike_the_man @ May 9 2005, 11:26 AM)

QUOTE (MattR @ May 9 2005, 11:17 AM) Sorry mike, Im not putting wood in my car At least it won't rust!

I dont want termites though


I was just thinking about maybe drilling some holes and mounting a thin piece of flexable sheet metal to the inside to maintain the contour of the housing. If it works the way I want, i'll post pics next weekend.

Duct Tape will work in a pinch!

QUOTE (MattR @ May 9 2005, 12:31 PM)

QUOTE (mike_the_man @ May 9 2005, 11:26 AM) QUOTE (MattR @ May 9 2005, 11:17 AM) Sorry mike, Im not putting wood in my car At least it won't rust! I dont want termites though I was just thinking about maybe drilling some holes and mounting a thin piece of flexable sheet metal to the inside to maintain the contour of the housing. If it works the way I want, i'll post pics next weekend.

actually, mine won't be food for termites or be subject to water damage or anything like that...I sprayed them with a silicon rubber protection coating..........

How about filling them flush on the inside so the fan will see a smooth scroll case where the vents used to be? You could use wood or rigid foam with epoxy, or maybe urethane spray foam to form the plug in each case half then bolt it together.

Mine have been open 100% of the time and I haven't seen high oil temps. Even will all the spirited driving at the WCC.

Duct tape will not work. That's what I tried originally and it came off almost instantly with all the heat.

If I were going to plug them off, I'd use aluminum and epoxy.

I had mine clean and painted, duct tape held on for a phoenix summer of driving

Mine are blocked off with duct tape. Works great.

But didn't we just have a thread discussing the fact that blocking these vents is detrimental to the air flow? It was stated that the flow needs to continue to and thru the heat exchangers?

Or am I just trippin'?

QUOTE

Duct tape will not work. sad.gif That's what I tried originally and it came off almost instantly with all the heat.

You didn't reinforce it with bailing wire!

Help a noob... I'm missing something. Opening these flaps is how the heater is fed, right? (Ducting hot air to the cabin?) Or are these the thermostatically-controlled cooling flaps, different from the driver-controlled heater flaps?

Can the flaps themselves be closed, fastened, and sealed with a heat-proof sealer around the perimeter?

QUOTE (joseph222 @ May 9 2005, 01:17 PM)

Mine are blocked off with duct tape. Works great. But didn't we just have a thread discussing the fact that blocking these vents is detrimental to the air flow? It was stated that the flow needs to continue to and thru the heat exchangers? Or am I just trippin'?

headers, no need for the ducting

if running heat exchangers, I'd think you'd want some air to blow thru them for cooling of the heat exhangers...........

QUOTE (Mueller @ May 9 2005, 03:22 PM)

QUOTE (joseph222 @ May 9 2005, 01:17 PM) Mine are blocked off with duct tape. Works great. But didn't we just have a thread discussing the fact that blocking these vents is detrimental to the air flow? It was stated that the flow needs to continue to and thru the heat exchangers? Or am I just trippin'? headers, no need for the ducting if running heat exchangers, I'd think you'd want some air to blow thru them for cooling of the heat exhangers...........

why do you want to cool off your H/Es... hotter the better(to an extent), hot air moves faster... which is good for exhaust...


Jake was the one saying that blocking these off is detrimental to airflow, it causes an extra turbulence which will increase head temps... the heads don't get as much air, because of the turbulence created when blocking these off... better to leave them open, with air going no where... I think something can be done to rout this air from these holes to help the head temps... I just don't know how yet...

the way mcMark has it now is right, which is why he isn't seeing temps climb, (though I think it would affect the head temps, not oil if the holes are plugged)

QUOTE

why do you want to cool off your H/Es... hotter the better(to an extent), hot air moves faster... which is good for exhaust...

tell that to the poor souls that own 2.7 powered 911's in the early days, hot air goes up, straight to heads

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

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

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?

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...

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.

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.

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

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.

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...

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.

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

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.

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 ...
Andy

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.

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!

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.
Andy

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.....

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.

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!

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.

Cool, thanks jake!