electric fan positioning

[LadyScrumpy]

Hello all.
This is my first post.  (clearly therefore massively exciting)

I have a GT6 Mk3 with the usual miniscule radiator.  It's had an electric fan fitted donkeys years ago which is in front of the radiator.  I therefore assume it is a blowy type fan.
BUT Ive heard about "suck" type fans.  which presumably sit behind the radiator do they?

What's the difference in performance?
It seems counterintuitive to put a fan with its case in front of the radiator because it obstructs a lot of the air access to the radiator surely?

The engine has never overheated but then its not been hillclimbing yet....

I'm hoping for some useful feedback on whether some people DO put the fan behind the radiator  or not? and what the pros and cons of doing this are compared to where it is at the moment.

Thanks guys.

Abby

[99176]

I would wait 'til you have a problem brfore you cure it.
It's best mounted behind radiator but space becomes a bit of an issue.
Well documented crank pulley mod usually required.

[smithy]

Abby, your forum name conjures up wonderful mental images of ruddy cheeks and stolen apples. You're not, in actual fact, a bloke, though. Are you?
We had a forum user called Elsie I fell in love with, and he was a bloke, so I hope you don't mind me asking.

Meantime I've got a GT6 Mk3 rad in my heap (and the enjin), and I think that properly maintained flushed and properly loved, (unobtrusively), it's been great and I hope that it's going to continue to perform marvellously, despite my lead-pedalling it, so will be interested in others opinion.
I know a few have swapped out for VW things, and there are a number of "pushers".....  Don't know why....!

[LadyScrumpy]

Um, I am definitely female.  Although 6ft2 and despite being slim we ARE farmers and I DO sometimes get treated like a bloke.
I don't help myself by doing not very ladylike things like taking cylinder heads of landrovers to try and squeeze out that little bit more compression with a bit of planing.  I do also steal apples and have been known to have ruddy cheeks.
Although of COURSE I am usually beautifully pale. ;)  When i'm not drunk on cider.

The fan thing is just to get things set the way i want them.  The fan could easily be moved from front to back of radiator with no trouble at all...I just wondered what the techies thought to it... there's bloody loads of space for it.

[smithy]

Thanks for being so forthright - and be still, my beating heart.  ;)

Here are a couple of good threads for your perusal - and info from a couple of the usual suspects. Hope they help.  :)

http://club.triumph.org.uk/cgi-bin/forum10/Blah.pl/Blah.pl?m-1325950657/s-29/highlight-radiator/#num29
http://club.triumph.org.uk/cgi-bin/forum10/Blah.pl/Blah.pl?m-1324227865/s-3/highlight-gt6+radiator/#num3

[piman]

Hello Ladyscrumpy,

if you put the fan behind the radiator it will still impede the airflow, so there is no gain.

Alec

[Richard B]

5458 wrote:

The engine has never overheated but then its not been hillclimbing yet....

Planning on going up Prescott?    ;)

I wouldn't worry too much. Fans are of no benefit over 30mph and hopefully you will be going up hills faster than that?  :-/


One of the reason for having an electric fan is that it switches off at speed and saves engine power. Do you have the front panels around the radiator (sides and top)? This is very important on a GT6 and often neglected.

Yes the fan should be mounted behind, but does then need to suck rather than blow (behave Smithy :P )  Personally, I must disagree with Alec as I think the shrouding effect of having the fan at the front is more detrimental to cooling than having the fan mounted behind where it can restrict the air exiting the radiator.

[esxefi]

splice a warning light into the fan circuit that illuminates when the fan is running,you can see how often it comes on then and if it is worth moving it.but as said i don't think it will be. :)

[ferny]

Suck, any day of the week - it's far superior to blow. With the fan on the back it will restrict air flowing through it just as it would on the front but, at least air can get to the radiator fins with it not blocking them. If you have room to fit it round the back, then do so. You won't regret it.



Also, Oakham, lovely place. Had a fun weekend there crashing on a mates sofa. He lived five minutes drive from Asda (I think...).

[LadyScrumpy]

Richard_B wrote:

Planning on going up Prescott?    ;)

YES!  And a few others.

Richard_B wrote:

Do you have the front panels around the radiator (sides and top)? This is very important on a GT6 and often neglected.

No I don't.  I bought a load of stuff of a bloke scrapping a gt6.  One of the things in the box is a rad cowl but it doesn't seem to fit whichever way I show it up to the radiator.

Where does one get some decent radiator cowling?

bearing in mind I am hoping to bring a fat pipe of cold air to feed the carbs.  It's got triple dellortos currently with no filtration, just trumpets. I reckonI can squeeze a TR6 air intake pipe into the gap and bring in some decent cold air from the front, so this would all need to fir through the cowling presumably?


A warning light wouldn't be of much use as the fan isn't thermostatically controlled.  it's just got an on off switch on the dash.  It's a switch out of a spitfire, by which I mean the aircraft not the car.  It looks awesome.  Don't really want to tinker with it.
Abs

[Richard B]

[Sorry, link no longer available]

Not sure if Tim has any left. send a pm to bestquality03 to find out.


I would get a Kenlowe switch for the fan, you can use your existing switch as an override then.

[rotoflex]

If not OEM-style, the only way to mount a fan as far as I'm concerned is on the back of the radiator with a fan shroud.  Just like modern auto manufacturers do it for maximum efficiency.

[piman]

Hello Ferny,

"With the fan on the back it will restrict air flowing through it just as it would on the front but, at least air can get to the radiator fins with it not blocking them."

I have to say that is totally illogical, the first comment contradicts the second.  Any obstruction to airflow is an obstruction whether in front or behind, it make no difference whatsoever.

Alec

[jeroensprint]

The best is at the rear. When the fan is not turning the blades do restrict when it's at the front. Fitting at the rear all the air goes through the rad and will find a way out. The shape of the fan frame can cause some airbending of air that will not pas the rad when fitted at the front. Fitted at the rear the air is already through the rad and will be blown away. In other words, everything that sits in front of the rad blocks air getting through. If the air has passed the matrix of the rad the air will escape somewhere and will never be pushed back.

Jeroen

[James]

I have come to the conclusion that if putting the rad behind restricts its size then you're better off going for a front mounted one that will easily cope.

I have fallen foul of this with my saloon!

[ferny]

piman wrote:

I have to say that is totally illogical, the first comment contradicts the second.  Any obstruction to airflow is an obstruction whether in front or behind, it make no difference whatsoever.

Alec

No, it doesn't.

Air between rad and engine - very hot, heated funnily enough by rad and engine.
Air between rad and grille - cool.


Which side would you rather have exposed, the hot or the cold? My preference is for the front to remain clear. although I haven't managed to achieve that on mine for the reasons James has said - I don't have room any more.

[Clive]

this is a perennial chestnut ;D

I have an (unsubstantiated) inkling that more air is SUCKED through the rad than is pushed through via ram effect. If that is the case, then  fan position is unlikely to have any effect.
Jeroen, all the fans I have seen rotate very easily, so much so they spin as air passes through them. I doubt they will create much restriction, maybe turbulence (will that be good or bad?? ) but it is the motor and other fixed bits that are a worry.

Guess the answer is a modern rad, and modern type fan with correct shrouding.

EDIT  Pete, you argument would imply a fan behind the rad needs to work harder as it is working in less dense air, in front it will be more efficient:P

[piman]

Hello Ferny,

you are missing the point, airflow is what cools the radiator and and anything in the airflow be it in front or behind the radiator upsets that airflow. Of course the air after the radiator is hotter, it's removed heat from the radiator but that's irrelevant.

Alec

[uksnatcher]

Also depends on the quality/airflow of the fan you use, a decent Spal or Pacet aftermarket or a OEM fan off a (lets say) German car , which is probably made by Pacet etc will push/pull more air than a shiny new cheepo ebay fan that people tend to buy due to being cheap and belive the marketing blurb....they are utter rubbish, better off strapping a hair dryer set on cool to your car, it would work better.

A quality branded 10"/12" fan will more than cool any triumph either front or rear mounted,quickly and efficiently as Stella Artois says....reasuringly expensive  

Check out the airflow and amp draw from these Spal fans:
http://www.spalautomotive.co.uk/acatalog/12_VOLT_SUCTION_FANS.html

The cheapo ebay jobbies claim to flow upto 1700 m3/hr.....utter complete twaddle...we compaired on a test battery a £160 spal fan with a cheepo and the difference is night and day. The spal will instantly take off if you dont hold it down with a big spark from the current draw, the ebay fan just sat there slowly spinning to max revs with hardly any current draw.

Dont scrimp on the quality of the fan , fit a second hand one if need be...they are designed to last 100k+ on a modern car  ;)

[smithy]

Sorry to distract you all from the thrust of your push/pull arguments, but where's Lady Scrumpy gone?
She turned up - made us all get our perennial chestnuts out - and then disappeared!
I begin to think that maybe she's a ringer. (A hand-puppet? A sock fiend? Whatever it's called).
Possibly Hugh in disguise, supressing his trademark emoticon fetish. We should be told.
Mods, I call upon you to establish some kind of cred. for posters, including a sex test perhaps, to avoid another sordid "Elsie" mistake of the type I made a couple of weeks ago. A short questionnaire on number of shoes and handbags owned should do it, with a clause in to negate the Alan Chatterton effect.

[Clive]

Fret not, wrong part of country for Hugh ;)

Hmm, chatterton effect. That IS a worrying concept :o

[Richard B]

cliftyhanger wrote:

.... chatterton effect. That IS a worrying concept :o

N oo ooo!

[gilesdive]

I knew he had loads of shoes, but the handbags are news to me.  ;)

Back to cooling engines, I would agree with her plans to put a TR6 style inlet or similar to get nice dense cool air into the carbs.
As most people know (but our new member might not) the radiator cowl bits are made of glorified cardboard (you can get polished stainless ones if you have loads of spare cash). Easy to make a hole in to route a bit of flexible trunking through. The TR6 had a metal drum on the end with paper air filter inside, but you can easily get a K&N filter or similar to fit the end of the pipe. Doesn't really matter where it comes out as long it gets cold air, but I would avoid having it so low down that you risk the engine taking a big breath of water when you hit a deep puddle too fast.
The cowls just sit vertically either side of the radiator, with the curved side upwards where they sort of follow the contour of the underside of the bonnet. It means the air has to go through the radiator rather than taking the easy route around it. Fitting them will have a much larger effect than whether  the fan is ahead or behind the radiator.

[LadyScrumpy]

can we have a bit less discussion about my gender.  I might be an oily petrolhead with grubby fingernails but I'm all woman.  I'm not sure that the show and bag count proves anything though.  My friend zoe has about 3 pairs of shoes.  I have about 60...and 2 bags.  Not really a bag person.

I am a sock fiend though.  Well...I like socks.  Nice wooly ones.

Car conked out today.  God knows why. petrol engines can be fickle things, particularly carburettors.
It just got a sniff of a bit of an incline uphill and conked out.  Several times.  Wouldn't start again for about 15 minutes each time.

I suspect I might be a while turning her into hillclimber then!

[Richard B]

Carburettor jet bloacked?

There's a lot of hoses breaking down with this dodgy ethanol attacking the older rubber hoses.