Intercooler cooling

[Part1cle]

I saw a thread on another forum recently and it made me wondering about Intercooler cooling.

Basically, if the standard Viscous fan is removed, that draws air through the Radiator and I/C, to save the power taken up to drive the fan, would the lack of air being pulled through the I/C and the reduced cooling be self defeating in the HP stakes? Would this be more apparent at low vehicle speed/high engine revs?

Some givens:

Both I/C and radiator are heat exchangers – to work efficiently they need good air flow through them.

I/C’s should work efficiently when the vehicle is travelling at speed due to the “ram” effect of the vehicle travelling forwards.

The I/C will not be as efficient when using higher revs at low speed, such as towing, some green laneing, trials – that type of thing, when lots of torque would probably be needed.

Viscous Fans are designed to move more air when spinning slowly, as engine revs increase they tend to freewheel, doing less work and thus absorbing less power.

The Viscous fan on a Defender/Disco (ours are 300TDi's - that is what this is based on) draws air through the radiator AND the I/C.

A fan can also help remove heat from inside the engine bay when moving slowly.

Now some common beliefs:

A Defender, or Disco, cooling system is more than adequate most of the time without any fan cooling if in good condition.

Viscous fans drain loads of horse power – I’ve seen as much as 12 HP quoted over the years.

Bigger I/C’s will deliver lots more power.

Ok, I would appreciate any comments on the above, but here’s my take on things. I have pondered the use of two fans – one for the radiator and one for the I/C. The radiator fan could work similarly to any production vehicle, it could be thermostatically controlled with a manual override option if thought necessary. The I/C would have a separate fan, with its own ducting out of the engine bay, this fan would only work at low vehicle speed. How the fan would be controlled is open to debate, possibly by a simple on/off switch or by monitoring the temperature going into and out of the I/C. I think at vehicle speeds in excess of 20mph (?) the ram effect for cooling would take over anyway – I’m more interested at what happens when crawling along in low box at medium to high engine speeds.

Has any one done something similar to that mentioned above?

It led me to wonder what happens when Turbo-diesels are put on a Dynomometer, clearly they have engine cooling but is any special cooling provided for the I/C? Has anyone tried to tune for low vehicle speed at higher revs?

I as mentioned at the start of the thread, the above are idle musings, while digesting a super Xmas lunch, and a bit Pie in the Sky! The fact that this forum has lots of folks with practical experience is why I thought I’d post here. I don’t want to start a flame war, but would appreciate reasoned logic and practical experience backed up with facts

Hope it won’t give anyone indigestion after all that Turkey

[Daan]

I saw a thread on another forum recently and it made me wondering about Intercooler cooling.

Basically, if the standard Viscous fan is removed, that draws air through the Radiator and I/C, to save the power taken up to drive the fan, would the lack of air being pulled through the I/C and the reduced cooling be self defeating in the HP stakes?

I doubt it. I never understood anyone who would fit an electric fan to an intercooled off road vehicle. It is the only way I can see to make any use of the intercooler at low speeds. Some challengetrucks now remove the I/C altogether, claiming that there is less lag. Probably true, but if there was an electric fan in the first place, there wasn't much point having it anyway.

I just keep things simple, have the original viscous and intercooler, and make sure it is all sealed wel, so the airflow will go through intercooler and rad.

Daan

[mmgemini]

As I don't use my 300Tdi Defender "off road" I wonder if I should respond.

Well you should see some of the roads I've driven. No tar for miles.

Now on our last trip in Namibis I towed another Defender for 38km...Ambient temperatore at least 40Deg C..if not higher.

Well you see I've been told that many times that I can't, shouldn't, will cause engine damage etc...

Yes I have a Kenlowe fitted. Fitted to Kenlowes spec......

I certainly didn't notice any difference with power or cooling...

Some pictures of the recovery..Ambient temperature at the time was 47 deg C....

[lrfarmer]

this is some thing that i too have been thinking about as my dads shougun has a fan fitted to it's intercooler

so i've been looking out for a fan but there are not many 7"fans about.

[mmgemini]

this is some thing that i too have been thinking about as my dads shougun has a fan fitted to it's intercooler

so i've been looking out for a fan but there are not many 7"fans about.

Look for a computer fan.

[flatback90]

if your looking for small fans and shrouds try looking at motorcross or trials bikes the one on my montesa is about that size

[lrfarmer]

Look for a computer fan.

i've got 3 on the heater thay just don't blow anuff

[reb78]

Brunel Performance sell fans for this purpose:

http://www.brunelperformance.com/ourproducts.htm

chrism on here had one for sale recently with an intercooler. I bought the intercooler, but not the fan (i was happy with just the ram effect). Might be worth dropping him a PM:

http://forums.lr4x4.com/index.php?showtopic=48502&view=&hl=brunel%20intercooler%20&fromsearch=1

[Gremlin]

This was my concern when i put the 200 in the series with an electric fan. I went all the way and put a spal fan on the 200 IC which was activated by a pressure switch at 1 psi, the fan would kick in when boost came on. Now after the rebuild i went with a td5 intercooler and no fan, result...............errrr i do not know, i am still suffering from lower boost pressures after the rebuild, probably unrelated to the fan or cooling. I guess that at low revs than yes cooling across the IC will be lower, but there will be some air movement while the electric fan will have none, time will tell if it is the right way or not.

g

[pinkbeef]

this is some thing that i too have been thinking about as my dads shougun has a fan fitted to it's intercooler

so i've been looking out for a fan but there are not many 7"fans about.

next time your passing a motorcycle shop have a look at the rad fans.

[ejparrott]

Just bought a 7" fan off of ebay, no links to the company, but it came from jap_parts and is a nice piece of work. Admit its a straight vane fan not a curved Kenlowe, but I've had a 14" straight vane rad fan for years and never noticed a problem with it...

[Part1cle]

Thanks to all that have taken the trouble to comment so far.

As Daan mentioned in the second post – I think I’ll just make sure my Viscous fan/cowl is working as well as it can be.

Further to my original thoughts, if the I/C is placed in front of the radiator, as some of the larger ones are, I’d have thought that it would have been essential to keep the Viscous fan for low ratio work, the potential problem here is that due to low airflow at low vehicle speed the radiator could actually pass heat to the I/C. I guess it wouldn’t be so bad if the I/C were fitted at the bottom of the radiator as that is usually the coolest part. It would also seem logical to block the hole off where the original I/C was to ensure maximum flow through the two radiators.

I’d still be interested in the outcome of fitting a fan to an I/C, especially a picture or two, and any findings.

Cheers, H

[David Sparkes]

Further to my original thoughts, if the I/C is placed in front of the radiator, as some of the larger ones are, I’d have thought that it would have been essential to keep the Viscous fan for low ratio work, the potential problem here is that due to low airflow at low vehicle speed the radiator could actually pass heat to the I/C.

Absolutely correct.

... It would also seem logical to block the hole off where the original I/C was to ensure maximum flow through the two radiators.

Absolutely correct, in fact essential.

I’d still be interested in the outcome of fitting a fan to an I/C, especially a picture or two, and any findings.

Cheers, H

When you did the original searching and reading, did you follow up the cross references to the Autospeed site?

The guru there tends to do silly things like actually measuring temperatures before and after changes. He has done articles about the different operating conditions, and therefore the different design characteristics required, between ICs on Petrol engines and ICs on Diesel engines.

HTH

[Part1cle]

Hi David, thanks for your comments.

I’m afraid I have done little or no research into this – only what has been picked up playing with mostly petrol engine cars, until I got my first Landy, and about 40 years in heavy engineering. As mentioned earlier, it was just idle musings after too much Xmas lunch.

I’ve taken the fan off normally aspirated petrols, to some good effect, but haven’t really done anything with our diesels since we’ve had them, its only since adding a Defender to our “fleet” earlier in the year that it even crossed my mind to do any changes – perhaps it’s something in the Defenders make-up?

Thanks for the suggestion to view the Autospeed site, I will take a look at that later. I find this sort of stuff fascinating and that site sounds particularly interesting.

Cheers, Henry.