Ed, great pictures and info!!  Thanks a lot.

The larger tube on my cores is exactly 3/4" OD.  The end seems to have a
1/2" long insert in it - insert has OD of 0.678, which is the ID of the

main tube.  If I cut off that 1/2" "tip" of the larger 3/4" OD tube to
eliminate the "insert" (which has a smaller ID of 0.565), then I'll have a
tube with 3/4" OD and .678 ID.

On the other end cap the tubing is exactly 1/2" OD and about .460 ID - and
has the little filter inside.

I plan to run my 2 evap cores in parallel - to get greater flow than would
be possible running them in series.
    -  I will use two home-made splitter blocks, each to have a standard
radiator hose on one side (attached to engine "hot" outlet or water pump,
respectively) and two smaller 3/4" ID hoses on the other side (to attach

evap cores, inlet or outlet, respectively).

After I modify each core to replace the 1/2" OD tubing with 3/4" OD, so

core has a 3/4" ID inlet and a 3/4" ID outlet, these inlets and outlets

have an inner area of 0.361 sq inches.
    -   With two cores, I'll have a combined inlet area (and outlet area)

2 times that, or .722 sq inches, to be "fed" by a single automotive

hose via the 2 splitters.
    -  Given "required area" of .722 (minimum), the "main single hoses"

any associated fittings must have at least .722 sq inch area which equates
to an ID of 0.9588 inches (or more - use of "stock" hose and fittings

may result in "next size bigger" than 1" ID).
    -  Looking at just one website for hoses & fittings, a fitting for 1"

hose had an inner bore ID of 0.84 inches.  To get a fitting bore ID of
approximately 1" requires going to a 1 1/4" ID hose.

    -  What is the standard sized water hose used on an RX-7?  1 1/4"? 1
1/2"?
. . . . . -- I'll  use whatever fits the stock pump and a stock radiator,
and run it to my home-made "splitter" blocks.

    -  Coming out of the splitter block to my 3/4" OD "inlet" tube on each
core, I'll use smaller "heater hose" of 3/4" ID to slip over 3/4"OD tubes

cores.  I'll select the tubing coming out of/going into my 2 splitter

to be identical to that 3/4" OD tubing on the cores.

    -  Using water hose instead of AN fittings, where do I look/go to find
"bungs" on  3/4" OD tubes and 1 1/4" ID hose bungs?  I'd want to use 2

hose clamps to hold hoses securely.  I haven't found a good website or
source for the "bungs" to weld onto the evap cores. (I'll be putting

"fire sleeve" on all hoses - and wiring? - in the engine compartment.)

In case I wanted to get even more flow than the 3/4 inch OD tubing on the
evap cores would allow, is there room in those little flat spots on the

caps to weld on a fitting or tubing with 1" OD (with approx ID of 0.964
inches or so if wall thickness is 0.036 + or -)?
    -  I held my core in my lap with an "end cap" on each side, the 13
coolant tubes running horizontally left & right; I laid my ruler on the

and measured 1" or maybe 1 1/8" from "inside" side of "end cap" to the
narrow (wasp waist) of the segments of the end cap.
. . . . - - Ed, I just reviewed your web 1998 web document on how many

you went thru before you found a good welder and how the low temp alloy of
the cores would melt when using the higher temps required to weld on the

fittings.
. . . .  ---- Looks like going to a "max size fitting" of 1" or so might

the welding heat too close to the seams and not be worth the risk of

the core.  I'm thinking I'll stick with 3/4" OD tubing on the cores.  Just
wondered if you could measure one of those "sample cores" to get the
dimension "perpendicular" to the nominal 3" thickness of the end caps that
is available for welding.

David

----- Original Message -----
From: "Ed Anderson" <eanderson@carolina.rr.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Tuesday, September 07, 2004 11:38 AM
Subject: [FlyRotary] Photos of Core tanks internals


> Well, David,  I just went down to the shop through the pouring remnants

> Frances and cut open each side tank of a core I had taken from the
junkyard
> years ago.
>
> The photos are attached and speak for themselves - no dividers or other
> impediments to coolant flow in the tanks - pretty clean channel from top
to
> bottom.  Each "row" has 5 approx 1/8" (perhaps slightly larger) dia

> that conduct the water through the core to the opposite side tank.  So

> rows * 5 * area of 1/8-3/16" dia hole would give a cross flow channel

> of around 0.86 sq inches to 1.93 sq inches - probably toward the larger
> figure.
>
> So as Bill suggested they may have redesigned the heat exchangers to

a
> different approach to recondensing the refrigerant calling for the

> plate.  Given the relatively small cross channels, it is my opinion that

> serpentine cooler is probably offering considerably more resistance to
flow.
> Some of the radiator shop webpages give an estimate of the increase in
flow
> resistance of a Serpentine core over the straight through - as best I
recall
> it was something like 4 times as best I recall.
>
> So, its clear that not all GM evaporator cores are created the same way.
> This one was from the an late 80s early 90s Cadillac.  I looked all over
for
> some identifying model number but could not find anything.  I do recall

> had a yellow sticker with a black C on it when I yanked it.
>
> In any case, it looks like we can not simply order just any GM cooler
core.
> I suspect that when they switched over to the more environmental

> refrigerant then  there could have been some redesign of the core, but
just
> speculation on my part.
>
> Here's the photos
>
> Ed.
>
>
> Ed Anderson
> RV-6A N494BW Rotary Powered
> Matthews, NC
> ----- Original Message -----
> From: "David Carter" <dcarter@datarecall.net>
> To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
> Sent: Tuesday, September 07, 2004 11:55 AM
> Subject: [FlyRotary] Re: Water pump problem
>
>
> > Thanks, Ed.
> >
> > I wonder Steve Brooks's core with a "plate" is different from the
> > GM/Harrison cores that I have (Chev'y Caprice).
> >     - When I probed my core last night and found no plates in the end
cap
> > with the larger of the two welded tubes, I DIDN'T check the other

> > those smaller 1/2" OD tubes turn 90 degrees and run about a foot, so I
> never
> > probed that side.  That is the side that has the little "filter"

> > "expansion jet" thing sitting about an inch down inside.  Perhaps
there's
> a
> > plate on that side that matches what has been discussed recently.
> >
> > If Steve's core is a typical GM/Harrison core, then I'd like to
understand
> > more about which end "the plate" is in and tell us more about "the

> that
> > was removed".  I've not yet cut into any of my cores to mod the
fittings,
> so
> > am ignorant of the insides.
> >
> > David
> >
> > ----- Original Message -----
> > From: "Ed Anderson" <eanderson@carolina.rr.com>
> > To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
> > Sent: Tuesday, September 07, 2004 6:54 AM
> > Subject: [FlyRotary] Re: Water pump problem
> >
> >
> > > Hey, David, not to worry.  We have all hit the "Send" button on an e
> mail
> > or
> > > two and later wondered why we did. {:>)
> > >
> > > Ed
> > >
> > > Ed Anderson
> > > RV-6A N494BW Rotary Powered
> > > Matthews, NC
> >
> >
> >
> > >>  Homepage:  http://www.flyrotary.com/
> > >>  Archive:   http://lancaironline.net/lists/flyrotary/List.html
> >
>


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