The Murphy Builders Site

OK guys. I've been belly aching over this decision and not getting any work
done. I know there are knowledgeable people out there that can venture an
opinion. I've been reading dozens of papers on the subject, researching,
talking to radiator builders (hard to do since you have to avoid the dirty
"airplane" word). I have a need for a radiator that will be about 16x23
total length and width. On the Howe radiator site I discovered that 67-69
Cameros use a radiator that is 21x17. That is about the same size and
implies that a Chevy V8 can be cooled with my 16x23 radiator. I am also
leading towards a philosophy that I have run across that the best path for
air through my radiator is to enter at the bottom of the cowl and exit at
the top of the cowl (or upper sides) since the heated air wants to rise. So
I'm leaning towards mounting my radiator under the engine angled about 30
degrees up at the front. I would then duct air to the bottom of the
radiator and make an exit point at the top of the cowl, probably with the
capability to vary the size of the outlet. I have also read that you want
the inlet to be at least three prop blade chord widths away from the prop to
minimize the turbulence and pulses created by the prop. I can just make the
three chord lengths. I'm hoping that the airflow from the prop on the
ground will be enough to keep the engine cool so that I won't need an
electric fan (I don't have enough room). I've made adjustments to the carbs
on various airplanes I have owned with the engine running and the prop blast
at idle is impressive! Also a little scary being that close to the prop!
Although the most common opinion I have found about flow is that slow flow
through the radiator is best, I have also encountered exactly the opposite
opinion. Radiators called "crossflow" flow faster than "double pass".

OK. Now for the questions. Opinions: Is a 16x23 radiator, two 1-inch
cores, total 3-inch thickness, big enough for a 400HP Chevy? Crossflow
versus double-pass? Will the cowl be "pressurized" enough from incoming air
in flight to prevent flow from the outlet side of the radiator to the cowl
outlet at the top of the cowl without ducting the radiator outlet? (Ducting
the outlet would be very, very difficult.) There are elements of the engine
mount, engine, and engine accessories that will be in the radiator outlet
flow path. Think that will be a problem? Thanks in advance for any ideas
everyone.

Mike Kimball (not looking forward to fabricating the cowl)
044SR




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Mike Kimball wrote:

I've been reading dozens of papers on the subject, researching,

talking to radiator builders (hard to do since you have to avoid the dirty
"airplane" word). I have a need for a radiator that will be about 16x23
total length and width. On the Howe radiator site I discovered that 67-69
Cameros use a radiator that is 21x17. That is about the same size and
implies that a Chevy V8 can be cooled with my 16x23 radiator. I am also
leading towards a philosophy that I have run across that the best path for
air through my radiator is to enter at the bottom of the cowl and exit at
the top of the cowl (or upper sides) since the heated air wants to rise.

Be careful with this. Air will not exit at the top of the cowl in front
of the windshield as that is a high pressure ares which is why
automobile cabin intakes are there. The truth is that the advantage of
heated air rising is not very significant at all at cruise speed so
don't expend a lot of extra effort to do that.

So
I'm leaning towards mounting my radiator under the engine angled about 30
degrees up at the front. I would then duct air to the bottom of the
radiator and make an exit point at the top of the cowl, probably with the
capability to vary the size of the outlet.

I believe that even one extra 90 degree turn of the cooling air will be
worse than any "hot air rises" advantage. Again air out the side of the
cowl will work. Air out the bottom rear of the cowl is almost for sure
preferable if you have to turn the airflow more than 90 degrees though
to do anything else. Crossflow does it this way with the rad positioned
as you mention and claim it always works if you have 1" of water head
pressure drop in the airflow across the rad. Not theoretically optimum
but simple.

I have also read that you want
the inlet to be at least three prop blade chord widths away from the prop to
minimize the turbulence and pulses created by the prop. I can just make the
three chord lengths.

Yes but as for all of this stuff there may be very little difference
between 2 or 3 chord widths. If 2 or 2 1/2 is a lot easier to do then go
with that.

I'm hoping that the airflow from the prop on the
ground will be enough to keep the engine cool so that I won't need an
electric fan (I don't have enough room). I've made adjustments to the carbs
on various airplanes I have owned with the engine running and the prop blast
at idle is impressive! Also a little scary being that close to the prop!
Although the most common opinion I have found about flow is that slow flow
through the radiator is best, I have also encountered exactly the opposite
opinion.

Well define what someone means by slow and fast. There is absolutely no
way that you will be able to force cruise speed air through a 1" thick
rad let alone a 3" rad. It would take more pressure loss than you have
available. Attempting it would create huge amounts of drag and most of
the air would go around it anyway. I personally concluded that very few
installations will have ducting good enough that ground prop blast with
move much air through a 3" thick rad. Of course loose fin spacing and
low louvre angles will help though. I decided on a 2" thick rad with
extra surface area to get the ground cooling and accept the extra cruise
drag. But then I put a extra effort into ducting to hopefully reduce
cruise drag. 3" rads are definately the way to go for 200mph + cruise
speeds but they will need fans to get good ground cooling. I also figure
it is pretty cheap to have another rad made 3" thick later if I want to
further experiment further. Your labour and effort is going to be way
more than the actual cost of a custom rad! You already know that so
don't hesitate to have a custom rad made by CRracing or Griffon or
someone that does them in aluminum. CR and Griffon will certainly
discuss the "airplane" thing from what I've heard and so did the local
guy that I used.

Radiators called "crossflow" flow faster than "double pass".

An industrial cooling engineer will define double pass as water goes
left to right across the rear of the rad and then comes right to left
across the front of the rad. If engine radiators are ever made this way,
I've not seen it but I would expect at least 10% more cooling from such
a rad for very sound and well documented reasons that I won't get into
unless you ask. My rad is more conventional with water going right to
left across the top half and right to left across the bottom half. Rad
builders are used to this and often suggest it will give a 4 or 5%
improvement but that is somewhat hit and miss. It generally does help as
it tends to reduce the effect of dead spots that have low coolant or air
flow. If easy to plumb I would do that on a 16x23 rad.

OK. Now for the questions. Opinions: Is a 16x23 radiator, two 1-inch
cores, total 3-inch thickness, big enough for a 400HP Chevy?

I think so. In fact if you get the airflow excellant with good ducting
even a 2 inch of that dimension might work and also perhaps give better
ground cooling. Well maybe a little larger if only 2" thick.

Crossflow
versus double-pass? Will the cowl be "pressurized" enough from incoming air
in flight to prevent flow from the outlet side of the radiator to the cowl
outlet at the top of the cowl without ducting the radiator outlet?

Again No. If you've seen anything like that work it is because they have
other radiators in the system that are in fact doing the cooling.

(Ducting
the outlet would be very, very difficult.) There are elements of the engine
mount, engine, and engine accessories that will be in the radiator outlet
flow path. Think that will be a problem? Thanks in advance for any ideas
everyone.

Ducting the outlet is just as important as the inlet but ducting can
take many forms and it is not a problem to let the air slowly pass
through the engine compartment as long as the exit is done reasonably
with at least a small area for the air to speed up and reenter the
external high speed airflow. Remember how on a cessna or a Rebel even
just rounding the bottom of the firewall makes a large difference.
Extending the exit ramp several inches aft of the firewall helps a lot more.

FWIW you might want to also consider a wider less high rad in the bottom
of the cowl with airflow straight out under the fuselage. I put a 23 x 6
rad that is 2" thick under the cage on my rebel with the ducting
entirely below the cowl. That is for a 135 hp engine. I believe it is
overkill and will provide unlimited ground and lake (floats) cooling.
But I didn't have any room inside the cowl.
Ken

Mike Kimball (not looking forward to fabricating the cowl)
044SR

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Ken:


Interesting discussion do you have any pictures of your installation?



Thank you,

Del Schmucker
Information Systems Manager
Keewatin-Patricia District School Board
807-223-1254
807-221-8769 Cell
807-223-4703 Fax
del.schmucker@kpdsb.on.ca
www.kpdsb.on.ca

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of
Ken
Sent: Tuesday, May 24, 2005 8:10 AM
To: rebel-builders@dcsol.com
Subject: Re: Radiator Opinions

Mike Kimball wrote:

I've been reading dozens of papers on the subject, researching,

talking to radiator builders (hard to do since you have to avoid the

dirty

"airplane" word). I have a need for a radiator that will be about

16x23

total length and width. On the Howe radiator site I discovered that

67-69

Cameros use a radiator that is 21x17. That is about the same size and
implies that a Chevy V8 can be cooled with my 16x23 radiator. I am

also

leading towards a philosophy that I have run across that the best path

for

air through my radiator is to enter at the bottom of the cowl and exit

at

the top of the cowl (or upper sides) since the heated air wants to

rise.
Be careful with this. Air will not exit at the top of the cowl in front
of the windshield as that is a high pressure ares which is why
automobile cabin intakes are there. The truth is that the advantage of
heated air rising is not very significant at all at cruise speed so
don't expend a lot of extra effort to do that.

So
I'm leaning towards mounting my radiator under the engine angled about

30

degrees up at the front. I would then duct air to the bottom of the
radiator and make an exit point at the top of the cowl, probably with

the

capability to vary the size of the outlet.

I believe that even one extra 90 degree turn of the cooling air will be
worse than any "hot air rises" advantage. Again air out the side of the
cowl will work. Air out the bottom rear of the cowl is almost for sure
preferable if you have to turn the airflow more than 90 degrees though
to do anything else. Crossflow does it this way with the rad positioned
as you mention and claim it always works if you have 1" of water head
pressure drop in the airflow across the rad. Not theoretically optimum
but simple.

I have also read that you want
the inlet to be at least three prop blade chord widths away from the

prop to

minimize the turbulence and pulses created by the prop. I can just

make the

three chord lengths.

Yes but as for all of this stuff there may be very little difference
between 2 or 3 chord widths. If 2 or 2 1/2 is a lot easier to do then go

with that.

I'm hoping that the airflow from the prop on the
ground will be enough to keep the engine cool so that I won't need an
electric fan (I don't have enough room). I've made adjustments to the

carbs

on various airplanes I have owned with the engine running and the prop

blast

at idle is impressive! Also a little scary being that close to the

prop!

Although the most common opinion I have found about flow is that slow

flow

through the radiator is best, I have also encountered exactly the

opposite

opinion.

Well define what someone means by slow and fast. There is absolutely no
way that you will be able to force cruise speed air through a 1" thick
rad let alone a 3" rad. It would take more pressure loss than you have
available. Attempting it would create huge amounts of drag and most of
the air would go around it anyway. I personally concluded that very few
installations will have ducting good enough that ground prop blast with
move much air through a 3" thick rad. Of course loose fin spacing and
low louvre angles will help though. I decided on a 2" thick rad with
extra surface area to get the ground cooling and accept the extra cruise

drag. But then I put a extra effort into ducting to hopefully reduce
cruise drag. 3" rads are definately the way to go for 200mph + cruise
speeds but they will need fans to get good ground cooling. I also figure

it is pretty cheap to have another rad made 3" thick later if I want to
further experiment further. Your labour and effort is going to be way
more than the actual cost of a custom rad! You already know that so
don't hesitate to have a custom rad made by CRracing or Griffon or
someone that does them in aluminum. CR and Griffon will certainly
discuss the "airplane" thing from what I've heard and so did the local
guy that I used.

Radiators called "crossflow" flow faster than "double pass".

An industrial cooling engineer will define double pass as water goes
left to right across the rear of the rad and then comes right to left
across the front of the rad. If engine radiators are ever made this way,

I've not seen it but I would expect at least 10% more cooling from such
a rad for very sound and well documented reasons that I won't get into
unless you ask. My rad is more conventional with water going right to
left across the top half and right to left across the bottom half. Rad
builders are used to this and often suggest it will give a 4 or 5%
improvement but that is somewhat hit and miss. It generally does help as

it tends to reduce the effect of dead spots that have low coolant or air

flow. If easy to plumb I would do that on a 16x23 rad.

OK. Now for the questions. Opinions: Is a 16x23 radiator, two 1-inch
cores, total 3-inch thickness, big enough for a 400HP Chevy?

I think so. In fact if you get the airflow excellant with good ducting
even a 2 inch of that dimension might work and also perhaps give better

ground cooling. Well maybe a little larger if only 2" thick.

Crossflow
versus double-pass? Will the cowl be "pressurized" enough from

incoming air

in flight to prevent flow from the outlet side of the radiator to the

cowl

outlet at the top of the cowl without ducting the radiator outlet?

Again No. If you've seen anything like that work it is because they have

other radiators in the system that are in fact doing the cooling.

(Ducting
the outlet would be very, very difficult.) There are elements of the

engine

mount, engine, and engine accessories that will be in the radiator

outlet

flow path. Think that will be a problem? Thanks in advance for any

ideas

everyone.

Ducting the outlet is just as important as the inlet but ducting can
take many forms and it is not a problem to let the air slowly pass
through the engine compartment as long as the exit is done reasonably
with at least a small area for the air to speed up and reenter the
external high speed airflow. Remember how on a cessna or a Rebel even
just rounding the bottom of the firewall makes a large difference.
Extending the exit ramp several inches aft of the firewall helps a lot
more.

FWIW you might want to also consider a wider less high rad in the bottom

of the cowl with airflow straight out under the fuselage. I put a 23 x 6

rad that is 2" thick under the cage on my rebel with the ducting
entirely below the cowl. That is for a 135 hp engine. I believe it is
overkill and will provide unlimited ground and lake (floats) cooling.
But I didn't have any room inside the cowl.
Ken

Mike Kimball (not looking forward to fabricating the cowl)
044SR

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Hi Mike !

I haven't gone through all the things that you and Ken have, but I
do know that the radiator setup on the Rotax 912 Rebel loks good,
and works great ! This is what Ken is suggesting - the air enters on top
of the horizontal (actually, slight upslope to front) radiator, flows through,
and exits the bottom of the cowl. Any surplus air exits the front and
flows down the sides of the cowl. This setup works very well, both
on the ground and in flight. I've flown a few Rebels with this same
setup for Subaru engines, up to 185 HP., with no problems.

Brian, of V-8 SeaBee fame, uses a STOCK Corvette rad., and
this works very well for him, so you shouldn't have any problems
with a similar sized custom rad....

Hope it really isn't as big a problem as you fear !

.......bobp

-------------------------------orig.-------------------------
On Tuesday 24 May 2005 12:06 am, Mike Kimball wrote:

OK guys. I've been belly aching over this decision and not getting any work
done. I know there are knowledgeable people out there that can venture an
opinion. I've been reading dozens of papers on the subject, researching,
talking to radiator builders (hard to do since you have to avoid the dirty
"airplane" word). I have a need for a radiator that will be about 16x23
total length and width. On the Howe radiator site I discovered that 67-69
Cameros use a radiator that is 21x17. That is about the same size and
implies that a Chevy V8 can be cooled with my 16x23 radiator. I am also
leading towards a philosophy that I have run across that the best path for
air through my radiator is to enter at the bottom of the cowl and exit at
the top of the cowl (or upper sides) since the heated air wants to rise. So
I'm leaning towards mounting my radiator under the engine angled about 30
degrees up at the front. I would then duct air to the bottom of the
radiator and make an exit point at the top of the cowl, probably with the
capability to vary the size of the outlet. I have also read that you want
the inlet to be at least three prop blade chord widths away from the prop to
minimize the turbulence and pulses created by the prop. I can just make the
three chord lengths. I'm hoping that the airflow from the prop on the
ground will be enough to keep the engine cool so that I won't need an
electric fan (I don't have enough room). I've made adjustments to the carbs
on various airplanes I have owned with the engine running and the prop blast
at idle is impressive! Also a little scary being that close to the prop!
Although the most common opinion I have found about flow is that slow flow
through the radiator is best, I have also encountered exactly the opposite
opinion. Radiators called "crossflow" flow faster than "double pass".

OK. Now for the questions. Opinions: Is a 16x23 radiator, two 1-inch
cores, total 3-inch thickness, big enough for a 400HP Chevy? Crossflow
versus double-pass? Will the cowl be "pressurized" enough from incoming air
in flight to prevent flow from the outlet side of the radiator to the cowl
outlet at the top of the cowl without ducting the radiator outlet? (Ducting
the outlet would be very, very difficult.) There are elements of the engine
mount, engine, and engine accessories that will be in the radiator outlet
flow path. Think that will be a problem? Thanks in advance for any ideas
everyone.

Mike Kimball (not looking forward to fabricating the cowl)
044SR




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Mike,

You may or may not be aware of "Contact" magazine. They have published a
number of articles regarding cooling of auto engine conversions over the
past 15 years. I have included a link to their back issue index. A friend
recently loaned me his complete collection and I've found many of the
articles include cooling information which isn't listed in the index.

http://www.contactmagazine.com/backissu.html

John... 369R



At 11:06 PM 05/23/05, you wrote:

OK guys. I've been belly aching over this decision and not getting any work
done. I know there are knowledgeable people out there that can venture an
opinion. I've been reading dozens of papers on the subject, researching,
talking to radiator builders (hard to do since you have to avoid the dirty
"airplane" word). I have a need for a radiator that will be about 16x23
total length and width. On the Howe radiator site I discovered that 67-69
Cameros use a radiator that is 21x17. That is about the same size and
implies that a Chevy V8 can be cooled with my 16x23 radiator. I am also
leading towards a philosophy that I have run across that the best path for
air through my radiator is to enter at the bottom of the cowl and exit at
the top of the cowl (or upper sides) since the heated air wants to rise. So
I'm leaning towards mounting my radiator under the engine angled about 30
degrees up at the front. I would then duct air to the bottom of the
radiator and make an exit point at the top of the cowl, probably with the
capability to vary the size of the outlet. I have also read that you want
the inlet to be at least three prop blade chord widths away from the prop to
minimize the turbulence and pulses created by the prop. I can just make the
three chord lengths. I'm hoping that the airflow from the prop on the
ground will be enough to keep the engine cool so that I won't need an
electric fan (I don't have enough room). I've made adjustments to the carbs
on various airplanes I have owned with the engine running and the prop blast
at idle is impressive! Also a little scary being that close to the prop!
Although the most common opinion I have found about flow is that slow flow
through the radiator is best, I have also encountered exactly the opposite
opinion. Radiators called "crossflow" flow faster than "double pass".

OK. Now for the questions. Opinions: Is a 16x23 radiator, two 1-inch
cores, total 3-inch thickness, big enough for a 400HP Chevy? Crossflow
versus double-pass? Will the cowl be "pressurized" enough from incoming air
in flight to prevent flow from the outlet side of the radiator to the cowl
outlet at the top of the cowl without ducting the radiator outlet? (Ducting
the outlet would be very, very difficult.) There are elements of the engine
mount, engine, and engine accessories that will be in the radiator outlet
flow path. Think that will be a problem? Thanks in advance for any ideas
everyone.

Mike Kimball (not looking forward to fabricating the cowl)
044SR




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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Fly too low or too slow and the ground will rise up and smite thee.






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Yep. I have a book called Alternative Engines that is nothing but Contact
magazine articles about converting and installing engines such as the Chevy
V8, Blanton Ford, Subaru, Mazda, etc. That's where I got most of the info
that led to my email to this list. Thanks for the tip though.

Mike

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com]On Behalf Of
John Kramer
Sent: Tuesday, May 24, 2005 9:57 AM
To: rebel-builders@dcsol.com
Subject: Re: Radiator Opinions


Mike,

You may or may not be aware of "Contact" magazine. They have published a
number of articles regarding cooling of auto engine conversions over the
past 15 years. I have included a link to their back issue index. A friend
recently loaned me his complete collection and I've found many of the
articles include cooling information which isn't listed in the index.

http://www.contactmagazine.com/backissu.html

John... 369R



At 11:06 PM 05/23/05, you wrote:

OK guys. I've been belly aching over this decision and not getting any

work

done. I know there are knowledgeable people out there that can venture an
opinion. I've been reading dozens of papers on the subject, researching,
talking to radiator builders (hard to do since you have to avoid the dirty
"airplane" word). I have a need for a radiator that will be about 16x23
total length and width. On the Howe radiator site I discovered that 67-69
Cameros use a radiator that is 21x17. That is about the same size and
implies that a Chevy V8 can be cooled with my 16x23 radiator. I am also
leading towards a philosophy that I have run across that the best path for
air through my radiator is to enter at the bottom of the cowl and exit at
the top of the cowl (or upper sides) since the heated air wants to rise.

So

I'm leaning towards mounting my radiator under the engine angled about 30
degrees up at the front. I would then duct air to the bottom of the
radiator and make an exit point at the top of the cowl, probably with the
capability to vary the size of the outlet. I have also read that you want
the inlet to be at least three prop blade chord widths away from the prop

to

minimize the turbulence and pulses created by the prop. I can just make

the

three chord lengths. I'm hoping that the airflow from the prop on the
ground will be enough to keep the engine cool so that I won't need an
electric fan (I don't have enough room). I've made adjustments to the

carbs

on various airplanes I have owned with the engine running and the prop

blast

at idle is impressive! Also a little scary being that close to the prop!
Although the most common opinion I have found about flow is that slow flow
through the radiator is best, I have also encountered exactly the opposite
opinion. Radiators called "crossflow" flow faster than "double pass".

OK. Now for the questions. Opinions: Is a 16x23 radiator, two 1-inch
cores, total 3-inch thickness, big enough for a 400HP Chevy? Crossflow
versus double-pass? Will the cowl be "pressurized" enough from incoming

air

in flight to prevent flow from the outlet side of the radiator to the cowl
outlet at the top of the cowl without ducting the radiator outlet?

(Ducting

the outlet would be very, very difficult.) There are elements of the

engine

mount, engine, and engine accessories that will be in the radiator outlet
flow path. Think that will be a problem? Thanks in advance for any ideas
everyone.

Mike Kimball (not looking forward to fabricating the cowl)
044SR




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-----------------------------------------------------------------

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Fly too low or too slow and the ground will rise up and smite thee.






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I'll get some pictures loaded to the archives soon. In the mean time there
are a couple of pictures on my homepage at http://home.gci.net/~kimball.

Mike

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com]On Behalf Of
Schmucker, Del
Sent: Tuesday, May 24, 2005 6:11 AM
To: rebel-builders@dcsol.com
Subject: RE: Radiator Opinions


Ken:


Interesting discussion do you have any pictures of your installation?



Thank you,

Del Schmucker
Information Systems Manager
Keewatin-Patricia District School Board
807-223-1254
807-221-8769 Cell
807-223-4703 Fax
del.schmucker@kpdsb.on.ca
www.kpdsb.on.ca

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of
Ken
Sent: Tuesday, May 24, 2005 8:10 AM
To: rebel-builders@dcsol.com
Subject: Re: Radiator Opinions

Mike Kimball wrote:

I've been reading dozens of papers on the subject, researching,

talking to radiator builders (hard to do since you have to avoid the

dirty

"airplane" word). I have a need for a radiator that will be about

16x23

total length and width. On the Howe radiator site I discovered that

67-69

Cameros use a radiator that is 21x17. That is about the same size and
implies that a Chevy V8 can be cooled with my 16x23 radiator. I am

also

leading towards a philosophy that I have run across that the best path

for

air through my radiator is to enter at the bottom of the cowl and exit

at

the top of the cowl (or upper sides) since the heated air wants to

rise.
Be careful with this. Air will not exit at the top of the cowl in front
of the windshield as that is a high pressure ares which is why
automobile cabin intakes are there. The truth is that the advantage of
heated air rising is not very significant at all at cruise speed so
don't expend a lot of extra effort to do that.

So
I'm leaning towards mounting my radiator under the engine angled about

30

degrees up at the front. I would then duct air to the bottom of the
radiator and make an exit point at the top of the cowl, probably with

the

capability to vary the size of the outlet.

I believe that even one extra 90 degree turn of the cooling air will be
worse than any "hot air rises" advantage. Again air out the side of the
cowl will work. Air out the bottom rear of the cowl is almost for sure
preferable if you have to turn the airflow more than 90 degrees though
to do anything else. Crossflow does it this way with the rad positioned
as you mention and claim it always works if you have 1" of water head
pressure drop in the airflow across the rad. Not theoretically optimum
but simple.

I have also read that you want
the inlet to be at least three prop blade chord widths away from the

prop to

minimize the turbulence and pulses created by the prop. I can just

make the

three chord lengths.

Yes but as for all of this stuff there may be very little difference
between 2 or 3 chord widths. If 2 or 2 1/2 is a lot easier to do then go

with that.

I'm hoping that the airflow from the prop on the
ground will be enough to keep the engine cool so that I won't need an
electric fan (I don't have enough room). I've made adjustments to the

carbs

on various airplanes I have owned with the engine running and the prop

blast

at idle is impressive! Also a little scary being that close to the

prop!

Although the most common opinion I have found about flow is that slow

flow

through the radiator is best, I have also encountered exactly the

opposite

opinion.

Well define what someone means by slow and fast. There is absolutely no
way that you will be able to force cruise speed air through a 1" thick
rad let alone a 3" rad. It would take more pressure loss than you have
available. Attempting it would create huge amounts of drag and most of
the air would go around it anyway. I personally concluded that very few
installations will have ducting good enough that ground prop blast with
move much air through a 3" thick rad. Of course loose fin spacing and
low louvre angles will help though. I decided on a 2" thick rad with
extra surface area to get the ground cooling and accept the extra cruise

drag. But then I put a extra effort into ducting to hopefully reduce
cruise drag. 3" rads are definately the way to go for 200mph + cruise
speeds but they will need fans to get good ground cooling. I also figure

it is pretty cheap to have another rad made 3" thick later if I want to
further experiment further. Your labour and effort is going to be way
more than the actual cost of a custom rad! You already know that so
don't hesitate to have a custom rad made by CRracing or Griffon or
someone that does them in aluminum. CR and Griffon will certainly
discuss the "airplane" thing from what I've heard and so did the local
guy that I used.

Radiators called "crossflow" flow faster than "double pass".

An industrial cooling engineer will define double pass as water goes
left to right across the rear of the rad and then comes right to left
across the front of the rad. If engine radiators are ever made this way,

I've not seen it but I would expect at least 10% more cooling from such
a rad for very sound and well documented reasons that I won't get into
unless you ask. My rad is more conventional with water going right to
left across the top half and right to left across the bottom half. Rad
builders are used to this and often suggest it will give a 4 or 5%
improvement but that is somewhat hit and miss. It generally does help as

it tends to reduce the effect of dead spots that have low coolant or air

flow. If easy to plumb I would do that on a 16x23 rad.

OK. Now for the questions. Opinions: Is a 16x23 radiator, two 1-inch
cores, total 3-inch thickness, big enough for a 400HP Chevy?

I think so. In fact if you get the airflow excellant with good ducting
even a 2 inch of that dimension might work and also perhaps give better

ground cooling. Well maybe a little larger if only 2" thick.

Crossflow
versus double-pass? Will the cowl be "pressurized" enough from

incoming air

in flight to prevent flow from the outlet side of the radiator to the

cowl

outlet at the top of the cowl without ducting the radiator outlet?

Again No. If you've seen anything like that work it is because they have

other radiators in the system that are in fact doing the cooling.

(Ducting
the outlet would be very, very difficult.) There are elements of the

engine

mount, engine, and engine accessories that will be in the radiator

outlet

flow path. Think that will be a problem? Thanks in advance for any

ideas

everyone.

Ducting the outlet is just as important as the inlet but ducting can
take many forms and it is not a problem to let the air slowly pass
through the engine compartment as long as the exit is done reasonably
with at least a small area for the air to speed up and reenter the
external high speed airflow. Remember how on a cessna or a Rebel even
just rounding the bottom of the firewall makes a large difference.
Extending the exit ramp several inches aft of the firewall helps a lot
more.

FWIW you might want to also consider a wider less high rad in the bottom

of the cowl with airflow straight out under the fuselage. I put a 23 x 6

rad that is 2" thick under the cage on my rebel with the ducting
entirely below the cowl. That is for a 135 hp engine. I believe it is
overkill and will provide unlimited ground and lake (floats) cooling.
But I didn't have any room inside the cowl.
Ken

Mike Kimball (not looking forward to fabricating the cowl)
044SR

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I suspected that the top/rear of the cowl would be high pressure. Thanks
for confirming that.

One thing I have read over and over again is to try to avoid a 90 degree
turn, or any large angle for that matter, in the airflow to the radiator,
yet I keep reading about numerous applications with the radiator horizontal
underneath the engine. One of the reasons I wanted to angle the radiator up
about 30 degrees is to reduce the bend in the incoming air from the front
scoop to the face of the radiator. Thanks to Ken's comprehensive response
to my query I am back to my original idea of mounting the radiator
horizontal under the engine, ducting air from the front of the cowl to the
top of the radiator and then out the bottom of the cowl. But to do that
means a 90 degree turn for the air. Rock and a hard place!

I'm confused about the contradicting comments that "There is absolutely no
way that you will be able to force cruise speed air through a 1" thick
rad..." followed later by "I decided on a 2" thick rad..." and then "it is
pretty cheap to have another rad made 3" thick later...".

Ken's comment regarding a double-pass radiator, "I would expect at least 10%
more cooling from such a rad..." I think tells me that double-pass is
preferable to cross-flow. Ron Davis, and Howe racing radiators offer both
types. I get another advantage from the double-pass. It would put the
inlet and outlet on the same side of the radiator which would make hose
routing easier.

Speaking of hose routing. I finished my beautiful heater box assembly,
mounted to the panel brace and installed the instrument panel only to
discover that the inlet to the heater core points right at the witches hat
attached to the firewall. Dang! I can't cut a hole in the witches hat.
Actually, can I? Think it would be a bad idea to cut a hole in the witches
hat and maybe add more witches hat next to it? That would be the easiest
soloution.

Mike



-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com]On Behalf Of Ken
Sent: Tuesday, May 24, 2005 5:10 AM
To: rebel-builders@dcsol.com
Subject: Re: Radiator Opinions


Mike Kimball wrote:

I've been reading dozens of papers on the subject, researching,

talking to radiator builders (hard to do since you have to avoid the dirty
"airplane" word). I have a need for a radiator that will be about 16x23
total length and width. On the Howe radiator site I discovered that 67-69
Cameros use a radiator that is 21x17. That is about the same size and
implies that a Chevy V8 can be cooled with my 16x23 radiator. I am also
leading towards a philosophy that I have run across that the best path for
air through my radiator is to enter at the bottom of the cowl and exit at
the top of the cowl (or upper sides) since the heated air wants to rise.

Be careful with this. Air will not exit at the top of the cowl in front
of the windshield as that is a high pressure ares which is why
automobile cabin intakes are there. The truth is that the advantage of
heated air rising is not very significant at all at cruise speed so
don't expend a lot of extra effort to do that.

So
I'm leaning towards mounting my radiator under the engine angled about 30
degrees up at the front. I would then duct air to the bottom of the
radiator and make an exit point at the top of the cowl, probably with the
capability to vary the size of the outlet.

I believe that even one extra 90 degree turn of the cooling air will be
worse than any "hot air rises" advantage. Again air out the side of the
cowl will work. Air out the bottom rear of the cowl is almost for sure
preferable if you have to turn the airflow more than 90 degrees though
to do anything else. Crossflow does it this way with the rad positioned
as you mention and claim it always works if you have 1" of water head
pressure drop in the airflow across the rad. Not theoretically optimum
but simple.

I have also read that you want
the inlet to be at least three prop blade chord widths away from the prop

to

minimize the turbulence and pulses created by the prop. I can just make

the

three chord lengths.

Yes but as for all of this stuff there may be very little difference
between 2 or 3 chord widths. If 2 or 2 1/2 is a lot easier to do then go
with that.

I'm hoping that the airflow from the prop on the
ground will be enough to keep the engine cool so that I won't need an
electric fan (I don't have enough room). I've made adjustments to the

carbs

on various airplanes I have owned with the engine running and the prop

blast

at idle is impressive! Also a little scary being that close to the prop!
Although the most common opinion I have found about flow is that slow flow
through the radiator is best, I have also encountered exactly the opposite
opinion.

Well define what someone means by slow and fast. There is absolutely no
way that you will be able to force cruise speed air through a 1" thick
rad let alone a 3" rad. It would take more pressure loss than you have
available. Attempting it would create huge amounts of drag and most of
the air would go around it anyway. I personally concluded that very few
installations will have ducting good enough that ground prop blast with
move much air through a 3" thick rad. Of course loose fin spacing and
low louvre angles will help though. I decided on a 2" thick rad with
extra surface area to get the ground cooling and accept the extra cruise
drag. But then I put a extra effort into ducting to hopefully reduce
cruise drag. 3" rads are definately the way to go for 200mph + cruise
speeds but they will need fans to get good ground cooling. I also figure
it is pretty cheap to have another rad made 3" thick later if I want to
further experiment further. Your labour and effort is going to be way
more than the actual cost of a custom rad! You already know that so
don't hesitate to have a custom rad made by CRracing or Griffon or
someone that does them in aluminum. CR and Griffon will certainly
discuss the "airplane" thing from what I've heard and so did the local
guy that I used.

Radiators called "crossflow" flow faster than "double pass".

An industrial cooling engineer will define double pass as water goes
left to right across the rear of the rad and then comes right to left
across the front of the rad. If engine radiators are ever made this way,
I've not seen it but I would expect at least 10% more cooling from such
a rad for very sound and well documented reasons that I won't get into
unless you ask. My rad is more conventional with water going right to
left across the top half and right to left across the bottom half. Rad
builders are used to this and often suggest it will give a 4 or 5%
improvement but that is somewhat hit and miss. It generally does help as
it tends to reduce the effect of dead spots that have low coolant or air
flow. If easy to plumb I would do that on a 16x23 rad.

OK. Now for the questions. Opinions: Is a 16x23 radiator, two 1-inch
cores, total 3-inch thickness, big enough for a 400HP Chevy?

I think so. In fact if you get the airflow excellant with good ducting
even a 2 inch of that dimension might work and also perhaps give better
ground cooling. Well maybe a little larger if only 2" thick.

Crossflow
versus double-pass? Will the cowl be "pressurized" enough from incoming

air

in flight to prevent flow from the outlet side of the radiator to the cowl
outlet at the top of the cowl without ducting the radiator outlet?

Again No. If you've seen anything like that work it is because they have
other radiators in the system that are in fact doing the cooling.

(Ducting
the outlet would be very, very difficult.) There are elements of the

engine

mount, engine, and engine accessories that will be in the radiator outlet
flow path. Think that will be a problem? Thanks in advance for any ideas
everyone.

Ducting the outlet is just as important as the inlet but ducting can
take many forms and it is not a problem to let the air slowly pass
through the engine compartment as long as the exit is done reasonably
with at least a small area for the air to speed up and reenter the
external high speed airflow. Remember how on a cessna or a Rebel even
just rounding the bottom of the firewall makes a large difference.
Extending the exit ramp several inches aft of the firewall helps a lot more.

FWIW you might want to also consider a wider less high rad in the bottom
of the cowl with airflow straight out under the fuselage. I put a 23 x 6
rad that is 2" thick under the cage on my rebel with the ducting
entirely below the cowl. That is for a 135 hp engine. I believe it is
overkill and will provide unlimited ground and lake (floats) cooling.
But I didn't have any room inside the cowl.
Ken

Mike Kimball (not looking forward to fabricating the cowl)
044SR

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Hi Del

I uploaded an old pic as R119RAD.JPG. The cover over the side of the rad
is not installed. The exit door is just visible angled down hanging
fully open. You can see the side exit ramp outlet up on the cowl where a
small amount of cowl ventilation air exits. The inlet to the rad is down
where it sees a good breeze from the prop and it is located a couple of
inches below the bottom of the cowl so that air goes in rather than
around the opening. The roots of the design goes back to work published
in the 1950's which is when the last meaningful published research seems
to have been done. I'm pretty sure the inlet could be a lot smaller but
I am also after good ground cooling. I still expect the cooling drag to
be less than or equivalent to an aircooled engine but drag was not the
primary motivation here. Hopefully it will work ;)

Mike - The more I think about it the more I think you are on the right
track if you can exit the cooling air out the side of the cowl. Perhaps
make the cowl a couple of inches wider than the firewall?? Again I'm
just trying to share some of what I've learned and that includes being
cautious of anyone who claims to know all the answers... ;) There is
no "perfect" solution and I'm sure mine could have been simpler.

Ken

Schmucker, Del wrote:

Ken:


Interesting discussion do you have any pictures of your installation?



Thank you,

Del Schmucker
Information Systems Manager
Keewatin-Patricia District School Board
807-223-1254
807-221-8769 Cell
807-223-4703 Fax
del.schmucker@kpdsb.on.ca
www.kpdsb.on.ca

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Mike Kimball wrote:

I suspected that the top/rear of the cowl would be high pressure. Thanks
for confirming that.

One thing I have read over and over again is to try to avoid a 90 degree
turn, or any large angle for that matter, in the airflow to the radiator,
yet I keep reading about numerous applications with the radiator horizontal
underneath the engine. One of the reasons I wanted to angle the radiator up
about 30 degrees is to reduce the bend in the incoming air from the front
scoop to the face of the radiator. Thanks to Ken's comprehensive response
to my query I am back to my original idea of mounting the radiator
horizontal under the engine, ducting air from the front of the cowl to the
top of the radiator and then out the bottom of the cowl. But to do that
means a 90 degree turn for the air. Rock and a hard place!

That is actually two 90 degree turns. One or even two 90 degree turns is
not a showstopper especially if the air is slow where it is turning and
the turn is gradual rather than sharp. But it will be more drag than
straight through flow. There can also be more problems with stagnation
and vortices that create areas of the radiator that are blanked with no
significant airflow. The 30 degree angled rad is not a show stopper
either (two 60degree turns) but it will also be more drag than a
straight through flow. Even the famous P-51 radiator was angled as I
recall. An inlet up by the spinner will not have much prop blast for
ground cooling so this might be a 50/50 sort of tradeoff. An inlet like
you originally described will work better for ground cooling. Side cowl
outlets should generally work better than a belly outlet as the side is
pretty neutral pressure whereas the belly will be higher pressure. A low
inlet that flows straight through a custom radiator and then dumps into
the cowl and gently turns and ramps out the sides of the cowl would be
even better I think. I'd recommend a custom rad if it allowed straight
in airflow.

I'm confused about the contradicting comments that "There is absolutely no
way that you will be able to force cruise speed air through a 1" thick
rad..." followed later by "I decided on a 2" thick rad..." and then "it is
pretty cheap to have another rad made 3" thick later...".

Yeah sorry about that -I was in a hurry to get to work. I was thinking
that my duct design is such that I can redesign the radiator somewhat
without changing the duct much. The real point though was that
regardless of what you do, the air going through the rad will be down in
the perhaps the 50 mph range at most. If you do it by brute force (like
holding your flat hand out a window against the airstream) (or an inlet
and outlet the same size as the rad) it will be high drag. If you slow
the air in an expanding duct feeding the rad and then speed it up in a
converging duct after the rad, then it will be low drag. A 3" rad with a
decent duct will have lower cruise drag but poorer ground cooling since
it will be harder to force air though it with limited prop blast.

Ken's comment regarding a double-pass radiator, "I would expect at least 10%
more cooling from such a rad..." I think tells me that double-pass is
preferable to cross-flow. Ron Davis, and Howe racing radiators offer both
types. I get another advantage from the double-pass. It would put the
inlet and outlet on the same side of the radiator which would make hose
routing easier.

I'm guilty again. If you read what I wrote carefully I'm pretty much
certain that any double pass radiator you buy will not be what I
referred to as giving a 10% gain. The 10% gain was for what would more
properly be called a counterflow heat exchanger not for a normal double
pass automotive radiator. Sorry for muddying the water about that. Don't
count on more than 4 or 5% gain from having the inlet and outlet on the
same side but by all means do it if convenient.

Speaking of hose routing. I finished my beautiful heater box assembly,
mounted to the panel brace and installed the instrument panel only to
discover that the inlet to the heater core points right at the witches hat
attached to the firewall. Dang! I can't cut a hole in the witches hat.
Actually, can I? Think it would be a bad idea to cut a hole in the witches
hat and maybe add more witches hat next to it? That would be the easiest
soloution.


Mike

Oh man I know how much work can go into a heater box but it still might be
easier to change it. But I don't see why the witches hat couldn't be cut and
a properly reinforced "doubler" constructed on both sides of the hole but
I'd want to get MAM's (or a trusted engineer's) blessing by faxing them a diagram. You'd have to "double" it against tension/compression and also bending fore and aft.

Ken





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Hi Mike, Maybe this will help, I know it's not an airplane completely
different but here goes in our race car the double pass radiator and water
wetter in the system cooled it approximately 20 to 40 degrees just by doing
those two things from a standard 3 core radiator, We couldn't do much more
to the cooling system to get temperature down further without getting the
oil to cool properly since it seemed to hold temperature longer than the
water did. So just as a reminder I'm sure you have the oil cooler under
control I just wanted to let you know what helped in our situation since it
was about the same engine.
----- Original Message -----
From: "Mike Kimball" <mkimball@gci.net>
To: <rebel-builders@dcsol.com>
Sent: Tuesday, May 24, 2005 3:35 PM
Subject: RE: Radiator Opinions

I'll get some pictures loaded to the archives soon. In the mean time
there
are a couple of pictures on my homepage at http://home.gci.net/~kimball.

Mike

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com]On Behalf Of
Schmucker, Del
Sent: Tuesday, May 24, 2005 6:11 AM
To: rebel-builders@dcsol.com
Subject: RE: Radiator Opinions


Ken:


Interesting discussion do you have any pictures of your installation?



Thank you,

Del Schmucker
Information Systems Manager
Keewatin-Patricia District School Board
807-223-1254
807-221-8769 Cell
807-223-4703 Fax
del.schmucker@kpdsb.on.ca
www.kpdsb.on.ca

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of
Ken
Sent: Tuesday, May 24, 2005 8:10 AM
To: rebel-builders@dcsol.com
Subject: Re: Radiator Opinions

Mike Kimball wrote:

I've been reading dozens of papers on the subject, researching,

talking to radiator builders (hard to do since you have to avoid the

dirty

"airplane" word). I have a need for a radiator that will be about

16x23

total length and width. On the Howe radiator site I discovered that

67-69

Cameros use a radiator that is 21x17. That is about the same size and
implies that a Chevy V8 can be cooled with my 16x23 radiator. I am

also

leading towards a philosophy that I have run across that the best path

for

air through my radiator is to enter at the bottom of the cowl and exit

at

the top of the cowl (or upper sides) since the heated air wants to

rise.
Be careful with this. Air will not exit at the top of the cowl in front
of the windshield as that is a high pressure ares which is why
automobile cabin intakes are there. The truth is that the advantage of
heated air rising is not very significant at all at cruise speed so
don't expend a lot of extra effort to do that.

So
I'm leaning towards mounting my radiator under the engine angled about

30

degrees up at the front. I would then duct air to the bottom of the
radiator and make an exit point at the top of the cowl, probably with

the

capability to vary the size of the outlet.

I believe that even one extra 90 degree turn of the cooling air will be
worse than any "hot air rises" advantage. Again air out the side of the
cowl will work. Air out the bottom rear of the cowl is almost for sure
preferable if you have to turn the airflow more than 90 degrees though
to do anything else. Crossflow does it this way with the rad positioned
as you mention and claim it always works if you have 1" of water head
pressure drop in the airflow across the rad. Not theoretically optimum
but simple.

I have also read that you want
the inlet to be at least three prop blade chord widths away from the

prop to

minimize the turbulence and pulses created by the prop. I can just

make the

three chord lengths.

Yes but as for all of this stuff there may be very little difference
between 2 or 3 chord widths. If 2 or 2 1/2 is a lot easier to do then go

with that.

I'm hoping that the airflow from the prop on the
ground will be enough to keep the engine cool so that I won't need an
electric fan (I don't have enough room). I've made adjustments to the

carbs

on various airplanes I have owned with the engine running and the prop

blast

at idle is impressive! Also a little scary being that close to the

prop!

Although the most common opinion I have found about flow is that slow

flow

through the radiator is best, I have also encountered exactly the

opposite

opinion.

Well define what someone means by slow and fast. There is absolutely no
way that you will be able to force cruise speed air through a 1" thick
rad let alone a 3" rad. It would take more pressure loss than you have
available. Attempting it would create huge amounts of drag and most of
the air would go around it anyway. I personally concluded that very few
installations will have ducting good enough that ground prop blast with
move much air through a 3" thick rad. Of course loose fin spacing and
low louvre angles will help though. I decided on a 2" thick rad with
extra surface area to get the ground cooling and accept the extra cruise

drag. But then I put a extra effort into ducting to hopefully reduce
cruise drag. 3" rads are definately the way to go for 200mph + cruise
speeds but they will need fans to get good ground cooling. I also figure

it is pretty cheap to have another rad made 3" thick later if I want to
further experiment further. Your labour and effort is going to be way
more than the actual cost of a custom rad! You already know that so
don't hesitate to have a custom rad made by CRracing or Griffon or
someone that does them in aluminum. CR and Griffon will certainly
discuss the "airplane" thing from what I've heard and so did the local
guy that I used.

Radiators called "crossflow" flow faster than "double pass".

An industrial cooling engineer will define double pass as water goes
left to right across the rear of the rad and then comes right to left
across the front of the rad. If engine radiators are ever made this way,

I've not seen it but I would expect at least 10% more cooling from such
a rad for very sound and well documented reasons that I won't get into
unless you ask. My rad is more conventional with water going right to
left across the top half and right to left across the bottom half. Rad
builders are used to this and often suggest it will give a 4 or 5%
improvement but that is somewhat hit and miss. It generally does help as

it tends to reduce the effect of dead spots that have low coolant or air

flow. If easy to plumb I would do that on a 16x23 rad.

OK. Now for the questions. Opinions: Is a 16x23 radiator, two 1-inch
cores, total 3-inch thickness, big enough for a 400HP Chevy?

I think so. In fact if you get the airflow excellant with good ducting
even a 2 inch of that dimension might work and also perhaps give better

ground cooling. Well maybe a little larger if only 2" thick.

Crossflow
versus double-pass? Will the cowl be "pressurized" enough from

incoming air

in flight to prevent flow from the outlet side of the radiator to the

cowl

outlet at the top of the cowl without ducting the radiator outlet?

Again No. If you've seen anything like that work it is because they have

other radiators in the system that are in fact doing the cooling.

(Ducting
the outlet would be very, very difficult.) There are elements of the

engine

mount, engine, and engine accessories that will be in the radiator

outlet

flow path. Think that will be a problem? Thanks in advance for any

ideas

everyone.

Ducting the outlet is just as important as the inlet but ducting can
take many forms and it is not a problem to let the air slowly pass
through the engine compartment as long as the exit is done reasonably
with at least a small area for the air to speed up and reenter the
external high speed airflow. Remember how on a cessna or a Rebel even
just rounding the bottom of the firewall makes a large difference.
Extending the exit ramp several inches aft of the firewall helps a lot
more.

FWIW you might want to also consider a wider less high rad in the bottom

of the cowl with airflow straight out under the fuselage. I put a 23 x 6

rad that is 2" thick under the cage on my rebel with the ducting
entirely below the cowl. That is for a 135 hp engine. I believe it is
overkill and will provide unlimited ground and lake (floats) cooling.
But I didn't have any room inside the cowl.
Ken

Mike Kimball (not looking forward to fabricating the cowl)
044SR

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Yeah, I'll think about the idea of entering the air below the radiator and
exiting the air via cowl openings on the sides instead of the top. Now my
only concern is the cabin air inlets I installed in the side panels of the
forward fuselage section. I'll have to move them if I exit air from the
cowl on the sides. There's always a snowball effect. Thanks!

Mike

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com]On Behalf Of Ken
Sent: Tuesday, May 24, 2005 3:18 PM
To: rebel-builders@dcsol.com
Subject: Re: Radiator Opinions


Hi Del

I uploaded an old pic as R119RAD.JPG. The cover over the side of the rad
is not installed. The exit door is just visible angled down hanging
fully open. You can see the side exit ramp outlet up on the cowl where a
small amount of cowl ventilation air exits. The inlet to the rad is down
where it sees a good breeze from the prop and it is located a couple of
inches below the bottom of the cowl so that air goes in rather than
around the opening. The roots of the design goes back to work published
in the 1950's which is when the last meaningful published research seems
to have been done. I'm pretty sure the inlet could be a lot smaller but
I am also after good ground cooling. I still expect the cooling drag to
be less than or equivalent to an aircooled engine but drag was not the
primary motivation here. Hopefully it will work ;)

Mike - The more I think about it the more I think you are on the right
track if you can exit the cooling air out the side of the cowl. Perhaps
make the cowl a couple of inches wider than the firewall?? Again I'm
just trying to share some of what I've learned and that includes being
cautious of anyone who claims to know all the answers... ;) There is
no "perfect" solution and I'm sure mine could have been simpler.

Ken

Schmucker, Del wrote:

Ken:


Interesting discussion do you have any pictures of your installation?



Thank you,

Del Schmucker
Information Systems Manager
Keewatin-Patricia District School Board
807-223-1254
807-221-8769 Cell
807-223-4703 Fax
del.schmucker@kpdsb.on.ca
www.kpdsb.on.ca

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Anybody remember Dave Bangle? He had a Rebel with a Subaru 2.2. Last time
I saw it he had been through several cooling iterations and had settled on
one that he said worked great. It was simple too. He mounted the radiator
across the engine mount tubes near the lower cowl exit and ducted/baffled
between the rad and exit so cowl air had to go through the rad to get out.
The intakes were in the normal place on each side of the prop and there was
no baffling or ductwork ahead of the radiator. I liked it because it was
simple and had cool air in the cowl. Anyone know what happened to Dave?

Joel




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Hi Joel

That worked better than I would have guessed but he did eventually open
up the exit quite a bit and I think extend a lip down to help drag/suck
the air out. Pressurizing the entire cowl with a slow lazy turn into the
rad is not a bad approach but the air warms up going by the engine
before it gets to the rad which is a significant handicap. The flow is
similar to a Lycoming cowl and will be similarly draggy compared to a
good liquid cooled installation. Some kind of exit ramp extending aft of
the firewall would help I think.
Bringing the air into a large inlet plennun over the top of the engine,
isolated from most of the engine heat and then down through a rad has
worked for some guys but I'm also aware of some that couldn't make that
work satisfactorilly, especially on the ground. One example is a V-6
written up in Contact. IIRC he baffled the engine fairly well to create
an upper plenum and initially seemed happy but he subsequently switched
to a belly mounted rad anyway.

Most of the Egenfelner guys claimed great cooling for years. Curiously
they now recommend a very high boiling point non-aqueous coolant which
makes me think there is more to that story as well...

Ken

Joel Jacobs wrote:

Anybody remember Dave Bangle? He had a Rebel with a Subaru 2.2. Last time
I saw it he had been through several cooling iterations and had settled on
one that he said worked great. It was simple too. He mounted the radiator
across the engine mount tubes near the lower cowl exit and ducted/baffled
between the rad and exit so cowl air had to go through the rad to get out.
The intakes were in the normal place on each side of the prop and there was
no baffling or ductwork ahead of the radiator. I liked it because it was
simple and had cool air in the cowl. Anyone know what happened to Dave?

Joel

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I settled for moveable plastic vents in the door windows and I'm
thinking about an intake on the lower leading edge of the wing root
fairing like some of the Cessna's.

Ken

Mike Kimball wrote:

Yeah, I'll think about the idea of entering the air below the radiator and
exiting the air via cowl openings on the sides instead of the top. Now my
only concern is the cabin air inlets I installed in the side panels of the
forward fuselage section. I'll have to move them if I exit air from the
cowl on the sides. There's always a snowball effect. Thanks!

Mike

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