17 replies to this topic

[inim_repooc]

As we all know - having a belt driven fan will sap a bit of power.. I thought this was about 4hp from what I've heard in the past... 

 

Although - this video I saw today has me wondering just how much difference it really does make - this video is based on a 350 block chevy v8 - though the concept is probably the same - I'd think a given fan will probably take a given amount of power at a certain RPM regardless of engine?

 

Anyway - just thought it is quite interesting!

 

Edited by inim_repooc, 01 May 2017 - 07:09 PM.

[Rapidmini59]

Hi dude
Yes your correct.
Im not running one, once its up and running ill let you know.
Im gonna run an electric kenlowe instead.

[monkey]

How do you run the waterpump without the belt? Is there an electric pump conversion?

[Dusky]

Just don't bolt the fan to the pulley. Still have the mechanical water pump, alternator etc.

[monkey]

Hmm fair enough. I can't be watching the video at the moment but I can't imagine the losses are that crazy, I assumed that you would also do away with the mechanical pump to maximise the reduction in hp loss. Feels a bit half arsed just not bolting the fan on :-p

[Spider]

It is quite interesting and a real eye opener for sure and many thanks for posting up.

 

However,,,,,,,,

 

That test was purely one on how much HP it takes to drive various fans. But what is it the Fan does? Is it just fitted to mealy sap HP from the engine?

 

I hope not!

 

The flip side to it is and what was perhaps missing from those great back to back tests was a measurement of Air Flow in CFM.

 

Fan design can optimise Fan Efficency, ie, less HP for the same CFM, but there's not going to be big gains there, maybe 10%.

 

So, pretty much HP = CFM and this showed up in their graphs that most fans sapped the most power at higher RPMs.

 

Probably to take that to the next level is how much CFM flow is really needed?

 

This also highlights why electric fans on a Mini are little more than junk, though, they are good in traffic and when the engine is turning slow.

 

They mentioned there that an Electric Fan draws about 30 Amps (I've measured them closer to 25) therefore, assuming 100% efficiency in the Electric Motor this works out to be just under 1/2 HP (In reality, they are not nearly that good).

 

So, how can an Electric Fan push enough CFM to take the place of a Mechanical Fan?  With these set ups, it can't.

 

They work with a Front Mounted Radiator as once the car is moving, there's enough CFM usually being produced from that forward movement, but in the case of a Mini, there's a positive pressure in the wheel arch and so they need a Fan to blow enough Air through the core.

Edited by Moke Spider, 01 May 2017 - 10:05 PM.

[Rapidmini59]

How do you run the waterpump without the belt? Is there an electric pump conversion?

I still run all the other bits just no fan itself.
I have a crank pulley,kad waterpump pulley and 70 amp alternator and a belt but no fan.
Less to catch your hands and clothes on when running engine with no front end.

[nicklouse]

Hmm fair enough. I can't be watching the video at the moment but I can't imagine the losses are that crazy, I assumed that you would also do away with the mechanical pump to maximise the reduction in hp loss. Feels a bit half arsed just not bolting the fan on :-p

Why?

That is how the metro worked.

[Spider]

 

Hmm fair enough. I can't be watching the video at the moment but I can't imagine the losses are that crazy, I assumed that you would also do away with the mechanical pump to maximise the reduction in hp loss. Feels a bit half arsed just not bolting the fan on :-p

Why?

That is how the metro worked.

 

 

and it has a front mounted radiator,,,,,,

[panky]

I ditched the fan and water pump for electric versions on my Commer camper to squeeze out a few more horses. It's running a Sunbeam Rapier lump and it goes very well - how much of that is down to the fan and pump can only be speculated but it does help. I did find that the temperature was cycling and the fan was cutting in intermittently so I fitted a small bike rad in the heater return - this did the trick and the temperature dropped about six degrees clear of the fan sensor. Now it only cuts in after a hard run or idling for a long time in traffic, could work on a Mini given the right sized auxiliary radiator.

[monkey]

Hmm fair enough. I can't be watching the video at the moment but I can't imagine the losses are that crazy, I assumed that you would also do away with the mechanical pump to maximise the reduction in hp loss. Feels a bit half arsed just not bolting the fan on :-p

Why?

That is how the metro worked.

the metro wasn't set up that way to maximise bhp, i believe it didn't have a side mounted rad so a fan on the pump would be pointless?

[Spider]

 

So, pretty much HP = CFM and this showed up in their graphs that most fans sapped the most power at higher RPMs.

.....................................................................................................................................................................................................................

This also highlights why electric fans on a Mini are little more than junk, though, they are good in traffic and when the engine is turning slow.

 

They mentioned there that an Electric Fan draws about 30 Amps (I've measured them closer to 25) therefore, assuming 100% efficiency in the Electric Motor this works out to be just under 1/2 HP (In reality, they are not nearly that good).

 

So, how can an Electric Fan push enough CFM to take the place of a Mechanical Fan?  With these set ups, it can't.

 

I found this graph which maybe of interest

 

[nicklouse]

 

 

Hmm fair enough. I can't be watching the video at the moment but I can't imagine the losses are that crazy, I assumed that you would also do away with the mechanical pump to maximise the reduction in hp loss. Feels a bit half arsed just not bolting the fan on :-p

Why?

That is how the metro worked.

the metro wasn't set up that way to maximise bhp, i believe it didn't have a side mounted rad so a fan on the pump would be pointless?

 

err mine was. what about all the mini race cars with no Mech fan just a front mounted Rad and an electic fan. or the many Mini based kit cars with no Mech fan?

[Gr4h4m]

I tried removing the mechanical fan on a side mount and just using an electrical one on the inner wing and it wouldn't keep it cool even on the motorway. Same setup with a two blade fan and i have never had an issue so I have left it alone.

[monkey]

 

 

Hmm fair enough. I can't be watching the video at the moment but I can't imagine the losses are that crazy, I assumed that you would also do away with the mechanical pump to maximise the reduction in hp loss. Feels a bit half arsed just not bolting the fan on :-p

Why?

That is how the metro worked.

the metro wasn't set up that way to maximise bhp, i believe it didn't have a side mounted rad so a fan on the pump would be pointless?
 

err mine was. what about all the mini race cars with no Mech fan just a front mounted Rad and an electic fan. or the many Mini based kit cars with no Mech fan?

Apologies I didn't realise that metros had side mounted rads.

maybe for an all out racer where every hp counts and money isn't a problem then I could understand, but for any road use car, when you factor in the effort and cost of removing the mechanical fan to fit an electric fan, and then the saved hp or two vs the 1/2hp lost on the extra load on the alternator I just don't see the point.

Each to their own though