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Electric fan - blow or suck!


trigolf

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Afternoon all.

I'm finally looking to upgrade my Vit elderly 12" 'sucking' Kenlowe fan  for a more powerful/efficient modern model. It's fitted on the back of rad, using the kenlowe original skinny thru the rad BA bolts, which I've never liked. I don't want to fix a new fan thru the rad,with the glorified 'tyraps' that seem to be the default solution. I've found a fan on 'tinternet, specifically listed for a Vitesse,that features proper laser cut mounting brackets that do not fix thru the rad core👍. It's specifically described as a 'blower' fan. I always understood 'blower' fans to be mounted on the front of the rad, which clearly it can't on a Vit. 

Can a 'blower' fan be mounted on the rear of the rad. ? Any disadvantages?🤔

Gav

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Are you sure thats not for a Rover Vitesse as a blower behind the rad would be pretty nonsensical? Unfortunately the space is so limited that anything other than a fan attached directly to the rad adds so much width that youre up against the engine. Also mounting the fan away from the rad, unless with an airtight shroud, loses quite a bit of airflow through the core which is the whole point... 

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my rather rorty Vt6 had the 7 bladed plastic fan  std old radiator  and a non wrapped 631 exhaust and could idle for an hour without faltering 

never any signs of anything more than 1/2 way up the gauge whether idling or driving hard   

it just works as triumph intended 

cant say the plastic fan shifts more air under the bonnet but wildly quieter than the old metal fan at speed 

Pete

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2 hours ago, johny said:

Im afraid your car seems like it was in the minority Pete😁

Must be in a minority of two as my Mk1 GT6, with standard fan, never overheated either, although it did have a recored radiator. If the gauge started to rise at all then turning the heater blower on brought it down again.

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I've always thought an engine side sucker was more efficient especially if you can shroud the fan to the rad. My 12" Spall high flow fan works really well.

Fitting one is another matter!

Iain

Edited by Iain T
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1 hour ago, Colin Lindsay said:

Must be in a minority of two as my Mk1 GT6, with standard fan, never overheated either, although it did have a recored radiator. If the gauge started to rise at all then turning the heater blower on brought it down again.

yes some cars can definitely do it but not the majority it seems. I think it must be the radiator because the water temperature is going up so obviously the heat transfer from the engine is good but then the heat cant be dissipated to the atmosphere quickly enough...

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1 hour ago, Iain T said:

I've always thought an engine side sucker was more efficient especially if you can shroud the fan to the rad. My 12" Spall high flow fan works really well.

Fitting one is another matter!

Iain

Have you managed to squeeze in a shroud as well Iain😲

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20 minutes ago, johny said:

Have you managed to squeeze in a shroud as well Iain😲

No not yet as it's bloomin' tight for space but I accept the challenge once I've finished playing with the suspension geometry and other minor tweaks. I'm sure there must be an off the shelf vac form shroud that I can modify.

Iain

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Just a thought - I would say from my ancient engineering physics stand point - a radiator cooling fan under normal use should be a sucker unless you are going for heavy duty cooling with more than one fan. If you have a fan sucking the air through the radiator it will pull the air through quicker making the cooling more efficient.

Eric

 

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3 hours ago, Colin Lindsay said:

Must be in a minority of two as my Mk1 GT6, with standard fan, never overheated either, although it did have a recored radiator. If the gauge started to rise at all then turning the heater blower on brought it down again

My experience the same as Colin's these past 16 years.

Dick

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Well... obviously Pete, Colin and Dicks cars were Monday morning cars off the line- it's got to be the reason!

I'm still waiting for a reply from the companys' Tech Support dept, as to whether it is actually a 'blower' or 'sucker' model. It's very strange, as they list the TR5/6 kit as a 'sucker' 

I see that James Paddock (not the company concerned) describe a very similar kit for a TR4 as a 'blower'!🤔

I'm even more confused now! I've always thought that the Vitesse engine bay residual heat dissipation was poorly addressed - i.e. no bonnet vents or louvres, unlike the GT6 1 and 2.

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To keep it simple I suppose the question could be:

If you only have a belt driven radiator fan on your Triumph do you ever have any more concerns about its engine cooling than with a modern car? 

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32 minutes ago, johny said:

To keep it simple I suppose the question could be:

If you only have a belt driven radiator fan on your Triumph do you ever have any more concerns about its engine cooling than with a modern car? 

No. A mate of mine back in the 1990s used to run his Mk3 GT6 with no fan at all - I'll be seeing him on Saturday 24th so will ask for details of how he used to do it. (His top radiator hose did explode spectacularly at Stafford one year when he was using the engine to power headlights to light our BBQ) 

I believe in giving the system all the help it can get - uprated or recored original radiator, good hoses and completely clean pipes or waterways, and I have sometimes replaced an early fan with a later one but I only ever had one electric fan, on a Spitfire back in the 1990s and then only because everyone said I needed one, and it soon came off again. 

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18 minutes ago, Colin Lindsay said:

I believe in giving the system all the help it can get - uprated or recored original radiator, good hoses and completely clean pipes or waterways, 

Ah thats cheating Colin - youve obviously must have some concerns about cooling being sufficient😁 In my modern it never crosses my mind to think about my radiator or system condition! 

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Ref engine fan if the engine is doing 700rpm at idle in traffic then the crank driven fan is only doing 700rpm vs 3000rpm for an electric fan. It used to be quite normal here in metro Melbourne on hot days to have to keep the foot on the throttle maintaining over 1500rpm when stationary at the lights in city traffic to help cool the engine, since fitting an electric pusher fan on the daughters Mk2 Spit with an auto thermo switch (82C from memory) it's now fit and forget never gets in the red! Note the elect fan is only a cheapo so efficiency questionable, but an alloy rad 3 core is fitted.

Engine driven fan is even worse if the fan is mounted on the water pump at engine 700rpm likely to be only 500rpm at the pump pulley & fan.

Around 1968 I had a 1200 Herald Conv and travelled weekly from the NE to our London city center offices arriving 10AM Monday and leaving 2PM Friday, I had the mech fan removed the Herald got hot but never boiled, 

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Lateral thinking re Vitesse but I'm sure all small chassis are similar what if you retain the engine driven fan and shroud it? Would that then be as good or at least adequate for today's traffic jams? It would certainly be much more efficient than a standard Triumph.

Anyone tried it?

Iain

Edited by Iain T
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While technically a shrouded, pull fan is the most efficient almost any electric fan, pushing or pulling, shrouded or open should be significantly more efficient than the original mechanical fan.  Not only does it spin faster when 'on' but the fan blades should be much better designed than the Triumph ones (that can be as basic as some slightly angles flat pieces of metal!), it will 'freewheel' when the car's moving at speed so not significantly limit airflow through the rad, and as closer to the rad. a greater percentage of the air it pulls/pushes passes through the rad. rather than coming from around the rad. as with the engine driven fan.

That said if the fan does have aerodynamically designed blades while a 'pull' mounted 'push' fan will normally run the other way and 'pull' air if you swap the +ve and -ve leads it will be significantly less efficient - though likely still more efficient than the engine driven one.  There's also a risk of reducing the fan's lifespan as the blades will be engineered to expect forces to be acting on them in one direct and not for those forces to be flipped.  We're not talking aerospace engineering standards here though, where things are engineered to do specific jobs while being as light as possible so the fan blades will likely to be massively over-engineered to cope with ham-fisted mechanics so have zero impact :)

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And might I add, the sender makes a big difference to what the gauge is reading. Based on tests of senders from 3 different suppliers for the same part number.

Resistance of the senders was as much as 200 ohms apart at cold, this translated to a gauge reading of 1/3 for one and 3/4 for another.

Irrespective of what temperature the system is at, I concluded that some modern parts are crap.

S

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