electric fan

[new to this]

When fitting a electric fan, i know they should be in the centre of the radiator, but space is tight the front pulley gets in the way, would it still work okay if i offset the fan to the right, im using a Saab radiator

thanks for any help Dave

[sprint95m]

Yes.


(If you look at a Saab 9-3, the fan is offset.)




Ian.

[Carledo]

I've got the Saab rad in the Carledo. there is sufficient room with the Vauxhall engine that i've been able to fit the Saab's matching fan and cowl! As Ian says, the fan is displaced towards the N/S of the car.

When fitting electric fans to Sprints, even with a standard radiator, it's always necessary to displace the fan towards the n/s, even the slimmest of slimline fans will interfere with the crank pulley. I no longer give it any thought, but long ago, I decided that the N/S of the rad gets hottest quickest as that's where the hot water comes in from the engine, so it's the best place to put the fan anyway.

Steve

[GrahamFountain]

When fitting a electric fan, i know they should be in the centre of the radiator, but space is tight the front pulley gets in the way, would it still work okay if i offset the fan to the right, im using a Saab radiator

thanks for any help Dave

Mine is a bit towards the hot side of the rad too, but I don't think the one I have would be a problem mounted in the middle.






However, it's only an 80 Watt motor (supposedly) and I'm not totally happy with it's performance in hot weather and when driving with any strength of tailwind. So I'm going to swap it for a 120 Watt one.
It's been a bit of a pain finding a 120W one that sucks not blows - I know you can run them in reverse, but with the blades curved the wrong way, I think they run stalled - read some of a paper by Sid Camm a while back about the issues in axial flow compressors, which dealt with that. The blades being stalled would mean they'd do more to drag the air round over the surface than lift air through the rad. And my imperfect experiments suggest the axial airflow with curved blades is a lot greater in one direction than the other.
Anyway, I now have one where the blade is reversible. It's not perfect, but better than running the blades backwards.

Graham

[soe8m]

I use Derale fans the last 20 years. Not cheap but having one in your hands the rest instantly look toy fans for Ken's pink car. These derale's hovercraft over the workshop floor when on. Never seen a revotec thingy do that. The fan blades can/have to be switched over when used for push or pull. so either way maximum performance.

Jeroen

[GrahamFountain]

I'm not sure it's necessarily a simple case of higher power is always better, even if the fan is likely to be on for a shorter time when it's wet enough to need lights, wipers, fan, and demister, etc. There will be some issues in blade shape, but as long as the airfoil's the right way around, it should be most about motor power. And some of these fans draw going on 20 amps while running. That's a lot compared with the alternator output at tickover, like stuck in traffic.

So I've been wonder if there's a role for a pulse width modulated speed controller in this - they can be quite efficient. I may try one of the cheap manual ones (£5-8). And if that sort of works, consider finding or building/modifying one where speed is controlled by temperature above a threshold.

If I build it, it will be analogue, not digital and temperature will be measured at the rad outlet, which is a fairly simple measure of how well the rad is cooling; unlike thermostat output temperature, which is complicated.

Graham

[new to this]

When fitting a electric fan, i know they should be in the centre of the radiator, but space is tight the front pulley gets in the way, would it still work okay if i offset the fan to the right, im using a Saab radiator

thanks for any help Dave

Mine is a bit towards the hot side of the rad too, but I don't think the one I have would be a problem mounted in the middle.






However, it's only an 80 Watt motor (supposedly) and I'm not totally happy with it's performance in hot weather and when driving with any strength of tailwind. So I'm going to swap it for a 120 Watt one.
It's been a bit of a pain finding a 120W one that sucks not blows - I know you can run them in reverse, but with the blades curved the wrong way, I think they run stalled - read some of a paper by Sid Camm a while back about the issues in axial flow compressors, which dealt with that. The blades being stalled would mean they'd do more to drag the air round over the surface than lift air through the rad. And my imperfect experiments suggest the axial airflow with curved blades is a lot greater in one direction than the other.
Anyway, I now have one where the blade is reversible. It's not perfect, but better than running the blades backwards.

Graham

I just bought a fan yesterday on Ebay 220w bought the biggest i could get , not sure how good they are but just need to get this car running and see how it works

Dave

[new to this]

I've got the Saab rad in the Carledo. there is sufficient room with the Vauxhall engine that i've been able to fit the Saab's matching fan and cowl! As Ian says, the fan is displaced towards the N/S of the car.

When fitting electric fans to Sprints, even with a standard radiator, it's always necessary to displace the fan towards the n/s, even the slimmest of slimline fans will interfere with the crank pulley. I no longer give it any thought, but long ago, I decided that the N/S of the rad gets hottest quickest as that's where the hot water comes in from the engine, so it's the best place to put the fan anyway.

Steve

Ive got a Saab fan but couldnt get it to fit to big

[Carledo]

I've got the Saab rad in the Carledo. there is sufficient room with the Vauxhall engine that i've been able to fit the Saab's matching fan and cowl! As Ian says, the fan is displaced towards the N/S of the car.

When fitting electric fans to Sprints, even with a standard radiator, it's always necessary to displace the fan towards the n/s, even the slimmest of slimline fans will interfere with the crank pulley. I no longer give it any thought, but long ago, I decided that the N/S of the rad gets hottest quickest as that's where the hot water comes in from the engine, so it's the best place to put the fan anyway.

Steve

Ive got a Saab fan but couldnt get it to fit to big

No you won't get the Saab fan and shroud in front of a slant motor, my Vauxhall engine is shorter, lighter and sits further back than a Sprint engine and the Saab fan and shroud only just goes in. But it's a monster thing in terms of performance, seldom in for more than a minute at a time to drop the temp the requisite 10 degrees C. The only downside is it DOES draw enough current to affect the idle when stuck in traffic, not enough to stop the engine and it does recover itself, whether from cleverness in the ECU or a lessening of load once it's up to speed, I don't know. But the idle drops by a couple of hundred RPM when the fan first cuts in!

Steve

[GrahamFountain]

I just bought a fan yesterday on Ebay 220w bought the biggest i could get , not sure how good they are but just need to get this car running and see how it works

Dave

Well I hope the blades are the right way around to pull air through the rad. I know what nearly (but not quite) all the sellers say about them working both ways, but the fans with blades that are curved in section can't work as well when they're run backwards - that's what the bit about the blades being stalled rather than flying properly means: To pull air through, the part of the blade nearest the rad needs to have the smaller pitch and the part at the back needs to have the larger pitch, so the air accelerates smoothly across the blade as it moves across the airflow. Sorry if that's a bit Janet and John.

There's another argument about blades curved along their length, i.e. whether they should turn with the tips leading or trailing. But I'm not going there.

If because the motor's that big it draws a bit too much current when idling, you might be able turn it down with something like one of these:
https://www.ebay.co.uk/itm/6V-60V-30A-D ... SwxxFfUO~j
If it draws a enough less than 20A at 12-14v, one of these might do:
https://www.ebay.co.uk/itm/DC-9V-60V-20 ... 4035900453. Though I'd worry the margin is a bit small.

For my 120 Watt fan, I'm thinking of one of these:
https://www.ebay.co.uk/itm/12V-24V-DC-M ... 3962329967 But I think I'd also have a switch in parallel with the controller, so if I want I can let the fan run at full voltage - the controller is likely going to drop something like a volt or so, even at 100% mark and no space.

Modifying that to control fan speed off the coolant temperature with a threshold and some hysteresis might be interesting.

Graham

[new to this]

How are you fitting the fan to the radiator , with tyes through the rad, or making up brackets to hold the fan to the radiator ?

Thanks Dave

[SprintV8]

Could you fit a shroud on the Back of the rad to direct airflow thru the fan.
But don’t fit it close to the fins as you’ll block the airflow.

80-120-180 watt motors.
But what do they move in CFM.

There are some really thin fans you could use.
Or
Extend the front out

[new to this]

Could you fit a shroud on the Back of the rad to direct airflow thru the fan.
But don’t fit it close to the fins as you’ll block the airflow.

80-120-180 watt motors.
But what do they move in CFM.

There are some really thin fans you could use.
Or
Extend the front out

Not really enough room to fit a shroud

Dave

P.S how are you working out how much time your working on your sprint upgrade

[SprintV8]

Could you fit a shroud on the Back of the rad to direct airflow thru the fan.
But don’t fit it close to the fins as you’ll block the airflow.

80-120-180 watt motors.
But what do they move in CFM.

There are some really thin fans you could use.
Or
Extend the front out

Not really enough room to fit a shroud

Dave

P.S how are you working out how much time your working on your sprint upgrade

Only counting if I work on the Sprint for more than a couple of hours.
There’s a awful lot tinkering Pondering and working things out at the moment.
Once she’s back home I’ll be able to get more time on her.

[GrahamFountain]

I've just found the problem with my electric fan - the 80 Watt motor one that I thought might be too small.
It still might be, but there's a bigger problem in that while it blows fine when it first comes on, after less than a minute is starts to slow down, and after 5 it's hardly blowing at all, which just sucks. I assume that's a problem with the motor, as the battery voltage is holding up reasonably well. So it's a good job I have a replacement 120 Watt one in the garage.
I hope I don't have to pull the rad to swap them over.

Graham