Printable Version of Topic

Click here to view this topic in its original format

914World.com _ 914World Garage _ WHAT DOES THIS DO? - closing flap for air return part#33

Posted by: dflesburg Jun 12 2009, 07:29 AM

closing flap for air return part#33

What does this do besides fall off when you don't have the return guides (S tubes) on?

What happens if you dont have them installed?

Does anyone have a diagram of how the air flows in a type 4?

There is a great thread on Pelican by DD that covers how air from blower fan pushes air into the system but what does the cooling shroud have to do with it?

http://forums.pelicanparts.com/showthread.php?threadid=80853

Posted by: dflesburg Jun 12 2009, 12:26 PM

So since nobody can tell me whats going on on the motor I had to gleem an answer from this pic.

The air coming past the little flapper door joins the air coming in from the jtube, this is heated in the heat exchanger and vented through the flapper box to either the passenger compartment or out the vent.

So the little flappers keep mice out while the motor isnt running.

Posted by: jhadler Jun 12 2009, 12:34 PM

You're referring to the flapper at the base of the fan shroud where it feed the heat exchangers right? I believe the intent of the flapper was to prevent forcing heated air into the fan shroud at low engine speeds.

When the auxiliary fan is on, it -might- generate more pressure then the impeller on the motor (at low engine speeds). As such, the air flow could (theoretically) reverse, and you'd be pulling heated air into the impeller, and hindering the cooling of the motor.

This is just an educated guess...

I've removed the flaps from my shroud and sealed them as I'm running headers.

-Josh2

Posted by: SLITS Jun 12 2009, 12:36 PM

Since I didn't have a diagram of #33, I had no idea of what you were talking about.

The flapper is designed to close when the heater blower is on to avoid over-riding the air flow from the impeller (motor cooling fan) at idle RPMs. The engineers figured the input from the heater blower would cause a disturbance in the cooling of the engine at lo RPMs.

Once you come up in RPMs, the impeller puts out far more air than the heater blower and forces the flaps open.

Heater blower is only for lo RPM situations.

Posted by: dflesburg Jun 12 2009, 12:48 PM

If anyone has a couple of these I need two.

Thanks

Posted by: dflesburg Jun 13 2009, 09:48 AM

This is what I need...

Part # 33 on this diagram
(two little doors and the pins that hold them on)

http://www.pelicanparts.com/914/parts/engi...oling_large.htm

Thanks!