Outer Limits 4x4 Board

On my Suzuki Sierra, I currently have a 12" thermo that was mounted directly to the radiator by the previous owner, with the factory shrowd on the back. Radiator has seen better days so I have purchased a new one.

My question is to do with fabricating a new shrowd for a 14" thermo fan that I have lying around.

How much of a gap behind the radiator should the shrowd be mounted? Is 10mm enough?

How bad will it be not running a shrowd at all? The 14" fan covers a far greater area, maybe 80% of the radiator, and the shrowd will possibly make the "at speed" performance of the raditor suffer.

My options are to either mount the fan to a shrowd, or just to the radiator.

Opinions???

Thanks

Are you running the orig engine fan also?

Nic

No, engine fan was removed by previous owner.

Fan will be setup between the radiator and engine.

Engine is stock 1.3, not that it matters.

You definitely need a shroud, although to be honest if you could get a used mechanical fan that would be better anyway.

The reason you need a shroud is that it forces the fan to draw air through the radiator. Without a shroud, the fan will suck air from above, below, and the sides, just moving air around behind the radiator rather than sucking it through... and hence not helping with cooling much at all.

I am not sure what you mean about a gap behind the radiator. The best set up for a shroud is that it has no gap next to the radiator, or just a small gap blocked with some closed-cell foam or similar material, just to allow for movement and vibration. The only air gap from fan to radiator should be what's required to allow the fan to turn. Anything more just lets air flow the wrong way..

If you are referring to the gap between the fan and the radiator core then 10mm is fine, and the same would be OK for the fan edge to shroud gap as well. A lot depends on the stiffness of the fan blades.

The idea is to get them as close as possible for efficiency, but allow a bit of room for nasties such as the fan being bent a bit by hitting water in a river crossing.

As Chimpboy said the shroud itself should cover the radiator, but not "blank off" any areas of it.

if you are going to hook up a new thermo fan. i would put a switch inside the car to turn it off when you do water crossings................ saves bending fans etc

The gap that i'm talking about is the amount of room behind the fins to the inner surface of the shrowd.

There needs to be some distance to avoid blanking off the parts of the radiator.

With the current setup, it sucks the air through, but not accross a large enough area, as it only draws trough on the outer edges of where the fan sits (approx 30% of the radiator). But the fan is not needed at highway speeds.

The reason for keeping the thermo setup is because i have two of the already, and I dont have an engine mounted fan.

It's not flash but here's a quick sketch



try and maximse the volume between the shroud and the radiator to improve air flow.

Also, try and minimise the volume of white space in the above post.

Nice pic though mate, try to get that fan away from the radiator a bit like shown, to decrease dead spots where air does not flow.

not trying to hijack but should the thermo be put on the front of the radiator or engine side?
i would be going for a thermatic switch and also a toggle switch to turn it off for water crossings..

Usually put on the engine side, I think most fans work better when pulling air through, rather than trying to push air through.
Some people use both and have a push-pull setup too.

Especially with a well designed shroud, the air would be pulled through the entire radiator, whereas a push though setup could result in 'dead space' areas where the air doesn't really flow through.

Typically on the engine side rather then infront. They pull air more effectively then they push it. ie resistance infront of the fan.

Thanks guys,

It's the 30 - 50mm dimension that i was curious about, as shown on the above pic.

Mudzuki wrote:Thanks guys,

It's the 30 - 50mm dimension that i was curious about, as shown on the above pic.

Thats how far back the fan sits from the radiator. This allows the fan to pull air from all areas of the radiator, and not create hot spots.

For example, if you leave no gap and mount the fan right on the radiator, you have no air flow through the radiator where the centre of the fan is located (motor, bearings etc). This means the middle of the rad will get hot, which isn't good.

The space allows air to be drawn through all of the core.

sweet cheers for the info guys. sounds like engine side is the go. will have to muck around with the standard shroud.. or maybe make one?? :|
will see