The Official H-Body Internet Community

by **h-bot** » Wed Mar 06, 2002 4:15 pm

From: voodoo_competition_REMOVE_432810_THIS_@yahoo.com

I have been looking into this phenomenon of the
Flex-A-Lite 400 Series Nylon Fan and how it moves toward the
radiator under acceleration. I conducted a couple of
experiments and this is what I discovered.

The
Flex-A-Lite 400 series fan will always move toward the
radiator under acceleration. However, my 16 fin per inch 4
row radiator aggravates the condition. This is most
likely due to the inherent airflow restriction caused by
the dense radiator core.

When installing a
simple 2 row with 12 fins per inch, the fan only moved
about 1/8" toward the radiator. With the 16 fin per
inch 4 row it moves a full 1/4" forward.

I
made a special upper radiator bracket from .080 wall
1/2" square steel tubing MiG welded to a pair of
Chevette Upper Brackets with integral fan shroud
tabs.

This bracket bolts to the core support where the
light duty (narrow bolt patern) radiator was used. I
moved the radiator to the passenger's side 3/16"
because the full-size Cadillac tank on the drivers side
was touching the LF frame rail.

The stock 4
cylinder Vega 2-piece shroud is retained and makes a huge
difference (15Â°) at idle speed.

I also tilted the
radiator slightly forward at the top which improved
clearance between fan and radiator. I know have a full 3/4"
between the blades and the core.

Considering how
the 400 series fan moves around has led me to try
other fans. Nothing else I have experimented with can
match the airflow of the 400 series fan. period.

The movement on the 400 series fan starts right
at the hub. It looks like a custom steel wafer,
covering the front of the fan around its bolt circle,
would solve this problem.

I was looking through
Summit and found a plastic (Nylon?) fan made by Derale
Corporation. It is similar to the 400 series fan but the
pitched (curved) part of the blades extends almost to the
center of the hub, greatly strengthening the fan
overall.

I have never used this fan but I beleive it would
be worth a try. 3/4" is much less clearance than I
would like to have, but I also want a cooling system
that will allow me to idle in the Burger King Drive
Through on a 100Â° day without boiling it over.

So
far, the 13" X 21" X 2.5" 4 row is doing an incredible
job of heat management on this engine. I am impressed
with this because I am preparing to increase my
compression ratio to 10.5:1 in the very near future.

I hope this fan information proves helpful...Robert

[This is message #33701 by user voodoo_competition on Yahoo! Club GM HBODY: http://clubs.yahoo.com/clubs/gmhbody ]

by **h-bot** » Wed Mar 06, 2002 7:31 pm

From: SWT_Racing_REMOVE_807835_THIS_@yahoo.com

Robert,

Just be glad you don't have to fit
two 3" diameter exhaust pipes between the radiator
and engine and try to keep it cool! ;P

Andrew
Slater
SWT Racing/Hangar18
Fabrication
<a href=http://home.socal.rr.com/swtracing target=new>http://home.socal.rr.com/swtracing</a>

[This is message #33708 by user SWT_Racing on Yahoo! Club GM HBODY: http://clubs.yahoo.com/clubs/gmhbody ]

by **h-bot** » Thu Mar 07, 2002 5:43 am

From: erik_norway_REMOVE_961944_THIS_@yahoo.com

Intresting reading Robert.

I have a friend
who have almost got his arm riped off by a
Flex-A-Lite fan that broke near the center.

So I will
kepp away from them, thisa is not to say they all do
cause I do not know.

What I know is a fan like
that robs you hp.
So what I am using is twin
electric fans in front of the radiator.
The front
section were the radiatore used to be is now totaly
rebuilt and new fans from a modern eurpean car is on it`s
way in.

It is controled by a heat
sensor/switch in to steps on low speed one full
speed.

But my real consern now is getting the hot air out of
the engine compartment!

Anyone got a
sugestion?

I will make a air spoiler under the radiator to try
to make vacum behind it so it sucks the hot air out
of the engine compartment and under the
car.

If nothing else works I will install ventilators in
the hood exactly like the one on the rear fender of
the wagon. This to ventilate the hot air trapped in
teh engine compartment.

Man it`s tight in
there

Will take some picture of it this week
end.

Erik
Oslo in Norway

[This is message #33737 by user erik_norway on Yahoo! Club GM HBODY: http://clubs.yahoo.com/clubs/gmhbody ]

by **h-bot** » Thu Mar 07, 2002 2:26 pm

From: voodoo_competition_REMOVE_622306_THIS_@yahoo.com

Erik,
What about using Camaro style fender vents and ducting to let hot air out of the engine compartment. This could easily be installed in the front fenders.

Just an idea...Robert

[This is message #33762 by user voodoo_competition on Yahoo! Club GM HBODY: http://clubs.yahoo.com/clubs/gmhbody ]

by **h-bot** » Thu Mar 07, 2002 2:45 pm

From: b_daddyz_REMOVE_185138_THIS_@yahoo.com

Looking at my 76 I had an idea but not sure how
effective it would be.

I know the cowl area build
some pressure - would it help to make an opening in
the firewall right above where the fan blower box it
and one on the other side between the distributor and
the master cylinder?

This way air would go in
through that grates on the cowl by thw wipers and into
the engime compartment and hopefully down post the
exhasut and out under the car - taking some of the heat
off the exhasut with it.

Just a crazy
thought.

Adam

[This is message #33764 by user b_daddyz on Yahoo! Club GM HBODY: http://clubs.yahoo.com/clubs/gmhbody ]

by **h-bot** » Thu Mar 07, 2002 2:52 pm

From: vegadad_REMOVE_888170_THIS_@yahoo.com

Adam,
It is a bit risky (crazy) as this allows
the engine compartment to vent directly into the
driver's compartment. That vent area in front of the
windshield runs dow next to the footwells and is the source
for the Vent air or outside air for your A/C. No a
good solution to your problem.
john b. (in
Virginia)

[This is message #33765 by user vegadad on Yahoo! Club GM HBODY: http://clubs.yahoo.com/clubs/gmhbody ]

by **h-bot** » Thu Mar 07, 2002 2:57 pm

From: vegadad_REMOVE_200815_THIS_@yahoo.com

Robert,
What about installing those Vents on
the hood on either side of the cowl induction scoop.
If you've ever had the fenders off your Vega there
are indentations in the air boxes just below the
beltline that look like they were designed to accomodate a
scoop of some kind. The next problem would be feeding
the vents from the engine compartment. More
engineering as you don't want to impact the strength of the
wheelwells holding part of your front suspension. Ah yes,
dream a dream.
john b (in Virginia)

[This is message #33766 by user vegadad on Yahoo! Club GM HBODY: http://clubs.yahoo.com/clubs/gmhbody ]

by **h-bot** » Thu Mar 07, 2002 2:57 pm

From: vegadad_REMOVE_855483_THIS_@yahoo.com

Robert,
What about installing those Vents on
the hood on either side of the cowl induction
scoop?
Also, if you've ever had the fenders off your Vega
there are indentations in the air boxes just below the
beltline that look like they were designed to accomodate a
scoop of some kind. The next problem would be feeding
the vents from the engine compartment. More
engineering as you don't want to impact the strength of the
wheelwells holding part of your front suspension. Ah yes,
dream a dream.
john b (in Virginia)

[This is message #33767 by user vegadad on Yahoo! Club GM HBODY: http://clubs.yahoo.com/clubs/gmhbody ]

by **h-bot** » Thu Mar 07, 2002 4:02 pm

From: monzapla_REMOVE_988415_THIS_@yahoo.com

Check out the hood vents i installed in the hood of my 75 2+2 Monza. Pics in "my breifcase" in my profiles. They work!
Perry

[This is message #33769 by user monzapla on Yahoo! Club GM HBODY: http://clubs.yahoo.com/clubs/gmhbody ]

by **h-bot** » Thu Mar 07, 2002 4:31 pm

From: fyrftr50_REMOVE_221348_THIS_@yahoo.com

It certainly was an interesting read. So just how
much HP does a Flex-a-Lite fan take away compared to
your basic solid fan? Just curious as I'm interested
in using a Flex-a-lite for my Buick V6 with a 2-core
rad. I was impressed with Robert's findings about the
massive air movement to keep the engine cool at
idle.
Bryan

[This is message #33770 by user fyrftr50 on Yahoo! Club GM HBODY: http://clubs.yahoo.com/clubs/gmhbody ]

by **h-bot** » Thu Mar 07, 2002 7:32 pm

From: TimMcCabe99_REMOVE_126334_THIS_@yahoo.com

Robert,

Do you think the fan is flexing
forward due to the amount of air it is pulling through
the rad? (like a heavy lift helicopters rotor will
bend upwards as it lifts it,s load)

Can you
add a reinforcement to the center to give it added
strength? I have a 13 inch flexlite fan (biggest fan that
would fit under the intake), but it is metal and does
not seem to bend forward at all..

Tim

[This is message #33777 by user TimMcCabe99 on Yahoo! Club GM HBODY: http://clubs.yahoo.com/clubs/gmhbody ]

by **h-bot** » Thu Mar 07, 2002 7:45 pm

From: crhytec_REMOVE_953382_THIS_@yahoo.com

Well, what about the old drag racer's trick of raising the back of the hood a few inches?

Scott

[This is message #33779 by user crhytec on Yahoo! Club GM HBODY: http://clubs.yahoo.com/clubs/gmhbody ]

by **h-bot** » Thu Mar 07, 2002 7:50 pm

From: wilker1000_REMOVE_146440_THIS_@yahoo.com

few years ago, a car magazine did a test of cooling fans. The winner, which drew the least HP AND cooled best was...The Thermal Clutch fan. No kidding.

[This is message #33780 by user wilker1000 on Yahoo! Club GM HBODY: http://clubs.yahoo.com/clubs/gmhbody ]

by **h-bot** » Thu Mar 07, 2002 8:17 pm

From: pfjk36322_REMOVE_701570_THIS_@yahoo.com

Saw the same test results.And raising the rear of
the hood pulls the hot air into the cowl,hence into
the interior.Hood vents looks like the best
idea,airdam directly under the rad(Eric),followed by front
fender vents(ala T/A or 3rd gen Z/28).
On my'97
Blackbird Ram-Air T/A(no fender vents) the trapped under
hood air actually makes the front end "light" at
140MPH.Not to mention the spoiler creates lift instead
downforce at speed.Mecham in AZ sells a vented hood and
rear spoiler which fixes this problem.Yet,I can find
more uses for the money they want for
them.Well...except if I want to run the Silver State
Challenge.And,I'd rather run that in a Monza!!!Passing a Vette or
Porsche at 120MPH sounds like too much fun.
Sorry,had
to wipe the drool up.LOL!
Frank

[This is message #33782 by user pfjk36322 on Yahoo! Club GM HBODY: http://clubs.yahoo.com/clubs/gmhbody ]

by **h-bot** » Thu Mar 07, 2002 9:23 pm

From: SWT_Racing_REMOVE_527567_THIS_@yahoo.com

That's a perfect analogy Tim. I've seen the same
problem that Robert is having on other cars with 4 core
radiators. It appears that there is a large pressure
differential across the thicker core, causing the fan to flex
forward because of the low pressure area created between
the fan and radiator.

Andrew Slater
SWT
Racing/Hangar18
Fabrication
<a href=http://home.socal.rr.com/swtracing target=new>http://home.socal.rr.com/swtracing</a>

<SNIP>
Do you think the fan is flexing forward due to the
amount of air it is pulling through the rad? (like a
heavy lift helicopters rotor will bend upwards as it
lifts it,s load)

[This is message #33785 by user SWT_Racing on Yahoo! Club GM HBODY: http://clubs.yahoo.com/clubs/gmhbody ]

The Official H-Body Internet Community

Nylon Fans:

Nylon Fans:

Nylon Fans:

Nylon Fans:

Nylon Fans:

Nylon Fans:

Nylon Fans:

Nylon Fans:

Nylon Fans:

Nylon Fans:

Nylon Fans:

Nylon Fans:

Nylon Fans:

Nylon Fans:

Nylon Fans:

Nylon Fans:

Who is online