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Discussion Starter · #1 ·
I have a 400 SBC with a 6-71 blower, when it was on the road before, it was ok when driving, but just a short stop at traffic lights was enough to push the temp up too high for my liking. I had an electric fan at the time, I'm wondering if a mechanical fan might work better. Truck is blown apart now so I can use either, I'm planning to fit a shroud for maximum efficiency, and if I do use electric again it will be a higher CFM than the last one.

Any advice gratefully accepted
 

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I used to fit an electric fan every time for the little bhp you gain. Over time my attitude has changed and I would always choose a well shrouded mechanical where possible.
 

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I'll second that, I've recently had a friend that has warped the head on his motor because of an electric fan failing.
Mechanical every time :tup:
 

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Discussion Starter · #5 ·
Thanks Guys, kinda what I was expecting to hear, I'm going mechanical fan with shroud.
 

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I'm a grown up drunk!
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Had an electric 16" fan that was shrouded and the temp used to creep up in traffic,
Went to a factory 5 blade mechanical fan with no shroud, no issues since then, infact i had change the 160 stat that was fitted with the electric fan to a 180 stat as the motor wouldn't run hot enough!

go for a viscous fan if poss and the horsepower loss is minimal.
 

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Gary, ever heard a motor running with a failed viscous coupling ? Sounds like a vacuum cleaner at full tilt ! LOL
 

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I'm a grown up drunk!
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I used to fit an electric fan every time for the little bhp you gain. Over time my attitude has changed and I would always choose a well shrouded mechanical where possible.
My attitude has also changed for street cars,
All that fancy electric pumps,fans etc is fine on race cars but i've proved street type stuff can work well,
My car has as a mechanical fuel pump, vac-advance dizzy, vac-sec carb and mechanical fan but it'll idle in summer traffic at 180 degrees till it runs out of fuel, delivers 20mpg and runs 12.50 quarters.
 

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My attitude has also changed for street cars,
All that fancy electric pumps,fans etc is fine on race cars but i've proved street type stuff can work well,
My car has as a mechanical fuel pump, vac-advance dizzy, vac-sec carb and mechanical fan but it'll idle in summer traffic at 180 degrees till it runs out of fuel, delivers 20mpg and runs 12.50 quarters.
i agree with all of that gary :tup:
 

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My attitude has also changed for street cars,
All that fancy electric pumps,fans etc is fine on race cars but i've proved street type stuff can work well,
My car has as a mechanical fuel pump, vac-advance dizzy, vac-sec carb and mechanical fan but it'll idle in summer traffic at 180 degrees till it runs out of fuel, delivers 20mpg and runs 12.50 quarters.
Seconded , reliability is key for a primarily street car. Nothing worse than a constant nagging fear of overheating either.
 

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Lowlander
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Call me over cautious but where possible I like to run well shrouded fan with electric fan as backup running off switch usually drops temp by 10-20 deg depending on conditions :)
 

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Seconded , reliability is key for a primarily street car. Nothing worse than a constant nagging fear of overheating either.
One thing about modern engines is the increase in reliablity most modern engines use an electric fan on a thermostat switch.
So reliability should not be an issue!
The other thing that a modern car uses is an expansion tank so coolant can be drawn back into the radiator when cooled.
Not dropped on the road or in an overflow tank

A larger engine produces more heat .
To transfer heat effectively in to the coolant then the right quantity of coolant needs to be available in the first place.
The right radiator size is also important.
Is it unreasonable to expect a larger engine in an engine compartment designed for a smaller less powerful engine with the same size rad to get hot in traffic?
So what is the cfm of a fixed fan
Compared against an electric fan ?
Is it better to push the air in or pull it in?
Sorry guys just thinking out loud .
 

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i run a fixed mech fan and a electric 16" blower too (no shrouds) big alloy 3 row rad and everything keeps cool on a run 160f stat and soon comes down in traffic once the electric fan kicks in at 190f. truck engine bay is pretty big though. thinking of wrapping my headers too because they generate so much under bonnet heat. alloy rad does disperse heat quick and that means its warmer in the cab noticeably so now i need to insulate the cab! another project.
 

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One thing about modern engines is the increase in reliablity most modern engines use an electric fan on a thermostat switch.
So reliability should not be an issue!
The other thing that a modern car uses is an expansion tank so coolant can be drawn back into the radiator when cooled.
Not dropped on the road or in an overflow tank

A larger engine produces more heat .
To transfer heat effectively in to the coolant then the right quantity of coolant needs to be available in the first place.
The right radiator size is also important.
Is it unreasonable to expect a larger engine in an engine compartment designed for a smaller less powerful engine with the same size rad to get hot in traffic?
So what is the cfm of a fixed fan
Compared against an electric fan ?
Is it better to push the air in or pull it in?
Sorry guys just thinking out loud .
Replying ( out loud) :)

Yup, most modern cars use electric fans, ever stopped to consider why ? Most are transverse engines so no other option . Yup, reliable UNTIL they stop working , blown fuse , corroded terminals, sludge around sensor, or low water level. Likewise you need to use OEM parts if you want that level of reliability at OEM prices. Most aftermarket electrics that I've used seem to fail at 12 months and 1 day :(

We don't use OEM though, rather some generic aftermarket unitrather than one built and designed /trialled to suit a particular engine and aerodynamic combination.

We are our own worst enemies by going for looks over reliability ence lack of recovery tanks on most modified vehicles.

Not unreasonable to expect a small rad designed for 1000CC not to cope with 7000cc but that's down to designing the whole thing as a package. " Yes mate, that'll cool 350ci in anything " rads are crap , application and lack of aerodynamic son older vehicles are an important part of designing an adequate system.

Always best to pull it through from cold to warm, otherwise you are trying to cool a radiator with hot engine bay air :)

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UK Hot Rods: News, tech, chat, email group for hot rods, street rods and kustoms
 

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blown fuse , corroded terminals "
Could this be due to incorrect installation wrong cable size,poor earth, badly joined cables, incorrect cable connecting plugs and socket selection and poor maintence ?

sludge around sensor, or low water level could this be due to poor maintenance?
"Likewise you need to use OEM parts if you want that level of reliability at OEM prices. "
Agree with you on this
However the OEM price should be balanced against
that
"Nothing worse than a constant nagging fear of overheating feeling"
An Engine over heat may come at a much higher cost than a OEM fan assembly

" Most aftermarket electrics that I've used seem to fail at 12 months and 1 day "
Its a sad fact of life that you get what you pay for.

like most things its only as good as the weakest link in the case of a fixed fan its the drive belt with is attached to the water pump .
they both have their merit's as well as negative points as you have said if its transverse then your options are limited.
If your engines very low in the chassis then your options are limited.
But its always a surprise when thousands have been spent of a custom or rod that boils on the side of the road after sitting in traffic for ten minutes.��
Thanks for the links KeV ��
 

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Can't disagree with any of that ;) :) Seen the blown fuses happen on multi thousand pound builds , same as poor ( or no ) maintenance. More likely to get corroded terminals on something that spends most of it's life in a garage ;)

With a fixed fan it's on and cooling even when not needed and gives a good head start on maintaining optimum temp, rather than wait til it's getting too hot and try to drag it back again.

It's amazing where some feel the need to cut costs or simply don't do the homework.

:tup:
 

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Discussion Starter · #19 ·
I'm now wanting to fit a mechanical fan to my Chopt Cab, Blown Rover V8, P6 water pump. I could get an original P6 fan and fit it as standard (with spacer to clear blower belt).
I would prefer a viscous fan, but I cant think which one or how to fit it.

Any suggestions?

Many thanks
 
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