Overheating - Fan location related?

1nsane!

1nsane!

Senior Member
Joined
Sep 10, 2007
Messages
950
Reaction score
169
Location
Centurion
Ok, so this is one for the specialists.

I have a home built Lotus 7 replica (Locost) with a 1.6 Ford RoCam engine.

I have fitted a Honda Ballade single core radiator with a 13 row oil cooler.

I use the car for circuit racing and if I have clear air in front of me, the water temp is stable at around 85-90C. If I follow someone around for more than 4km, the temps go up to 107C and the water bottle starts to blow out steam.

Even when I pull out and allow some cool air over the radiator and oil cooler, it takes a while to get back below 100C.

Now my question is, the fan is in front of the radiator, does this cause more obstruction that the fan being at the back? My logic says no, but I have found mixed answers on other forums.

Also, what is the next logical step to make the car run cooler? Change to a dual/triple core radiator? Change the angle of the radiator?

Any advice would be appreciated.

Some pics:
cooling setup.jpg
cooling setup2.jpg
 
At what temp does the fan switch on?
Secondly does it suck or blow over the rad as I can't see the blade orientation/angle?

It does look like the fan could obstruct airflow to some degree though.
 
It blows air over the radiator. The fan is set to come on at 92C, but does the fan make any difference above 60km/h?
 
My father drives two 1996 model Land Rover Tdi's, and they used to overheat pretty regularly. A few years ago he got fed up and replaced the stock radiators with one's that had an additional core or two if I recall correctly, and they haven't overheated since then. Extremely reliable considering the punishment they go through on the farm :love:

There is a lot of wasted space on the radiator where no wind is being blown by the fan. That is usually fixed by using a good shroud in puller fans, but I don't know how you're going to get past that with a pusher...
 
1nsane! said:
It blows air over the radiator. The fan is set to come on at 92C, but does the fan make any difference above 60km/h?
Click to expand...

Are you sure. Did you test this with a piece of paper perhaps? Just make sure it mounted correctly. Family member actually did this, took a while for them to realise why their car was constantly overheating.
 
1nsane! said:
It blows air over the radiator. The fan is set to come on at 92C, but does the fan make any difference above 60km/h?
Click to expand...

I'm not sure but I have noticed cars running slightly hotter when sitting in a slipstream behind another vehicle.

Is it possible to mount the fan on the back so it sucks air across the rad and maybe drop the activation point to about 90C?
 
GhostSixFour said:
Are you sure. Did you test this with a piece of paper perhaps? Just make sure it mounted correctly. Family member actually did this, took a while for them to realise why their car was constantly overheating.
Click to expand...

:D
 
GhostSixFour said:
Are you sure. Did you test this with a piece of paper perhaps? Just make sure it mounted correctly. Family member actually did this, took a while for them to realise why their car was constantly overheating.
Click to expand...
Hmmmm, now you are making me wonder... It is an easy test, will quickly do it this afternoon, I have a switch on my dash for the fan.
 
Fit a Spal or Flex-lite fan with bigger blades. That fan blades doesnt look very effective and may cause a restriction.

Also fit a surge tank for your radiator, then you should be good to go.

How many hot laps can you get in on the track?
 
Can't you fit a shroud at the back and move the fan to the back as well?

Or is space too limited?

Also, is hot air allowed to flow freely? Doesn't help if you sealed off the engine bay underneath to help with airflow, if the hot air can't escape properly, then you will get overheating.
 
ACTPerformance said:
Also fit a surge tank for your radiator, then you should be good to go.

How many hot laps can you get in on the track?
Click to expand...
I have a surge tank, that is where the water blows out when it gets too hot (pressurised system).

I did 2 hours at Phakisa, no problems. This past weekend, I was in a very close dice and after 3 laps at Zwartkops (2.4km per lap) it started spewing water at around 107C.
 
ponder said:
:D
Click to expand...

True story. Car kept overheating and said family member tried replacing basically everything, then, one day whilst idling the car the fan switched on and blew a receipt that was on the bumper, or there abouts, off. I think the receipt was for a new water pump or something.
 
The_Librarian said:
Can't you fit a shroud at the back and move the fan to the back as well?

Or is space too limited?

Also, is hot air allowed to flow freely? Doesn't help if you sealed off the engine bay underneath to help with airflow, if the hot air can't escape properly, then you will get overheating.
Click to expand...
My anti roll bar is in the way at the back... I might be able to modify the brackets to make some space.
 
Also, what the_Librarian, fan shroud is very effective and water wetter by redline will help keep the temps down.
 
GhostSixFour said:
True story. Car kept overheating and said family member tried replacing basically everything, then, one day whilst idling the car the fan switched on and blew a receipt that was on the bumper, or there abouts, off. I think the receipt was for a new water pump or something.
Click to expand...

Would have loved to see his face when that happened :D
 
Phew, fan is definitively sucking air from the from and pushing it over the radiator. With a few mods I MIGHT be able to put the fan at the back.
 
1nsane! said:
Won't a fan shroud restrict the airflow of the radiator?
Click to expand...

Hmm, question for someone jacked up on fluid dynamics.

But it might also create a acceleration/low pressure effect that speeds up the airflow from what I've seen in a few scenarios. Anyway I'm kinda sucking this out of my thumb but then why do commercial vehicles come with fan shrouds when they could save money and not have them. Think it helps the fans efficiency.
 
1nsane! said:
Won't a fan shroud restrict the airflow of the radiator?
Click to expand...

I think they help to control the direction the air moves.

Personally (and I am no expert) I would just get as big a fan as is possible in there, looking at that grill photo there is still plenty more space.
 
You must log in or register to reply here.
Back
Top
Sign up to the MyBroadband newsletter
X