Lotus Elan

S4 with wide radiator - OK to drop engine mounted fan?

PostPost by: tdskip » Thu Jul 09, 2020 4:32 pm

Good morning/afternoon gentlemen. With lots and lots of your help I’m getting to the details on reinstalling the engine and cooling system on my 1969 USA Federal car.

As a reminder this car has been partially disassembled since 1991 and the original radiator was beyond cost effective repair, so I purchased a heavy duty wide triumph Spitfire radiator. I’m bringing that to get the neck reoriented to the proper direction, but wanted to ask if you think I can skip using a plastic engine mounted cooling fan . I would run the pressure fan in front of the radiator of course, but was hoping to get some thoughts and coaching from you on this.

I live in Southern California, and it can be warm down here but for the most part this will be a pretty mild weather car and I generally plan my days/routes to avoid rush-hour traffic.

Thank you in advance for the thoughts.
SoCal
1969 Elan DHC
tdskip
Third Gear
Third Gear
 
Posts: 322
Joined: 13 Sep 2012
Location: SoCal

PostPost by: pharriso » Thu Jul 09, 2020 4:38 pm

tdskip wrote:............but wanted to ask if you think I can skip using a plastic engine mounted cooling fan . I would run the pressure fan in front of the radiator of course, but was hoping to get some thoughts and coaching from you on this.


I don't think later cars ever came from the factory with "mechanical fans" attached to the water pump pulley, I think this was an American distributor or dealer mod when owners had cooling issues. There may be a service bulletin on it.
You should be OK with cooling system in good condition & just your functioning electric fan.I would still make sure there are no gaps around the radiator, so air has to go through it, rather than around it.
Phil Harrison
1972 Elan Sprint 0260K
User avatar
pharriso
Coveted Fifth Gear
Coveted Fifth Gear
 
Posts: 2799
Joined: 15 Sep 2010
Location: Long Island NY, USA

PostPost by: nmauduit » Thu Jul 09, 2020 4:41 pm

If efficiency and peace of mind is of the essence, I would source an electrical pusher fan (used if need be) and install that (possibly even remove the mechanical one then)... minimal installation could even be manual switched operation initially.
S4SE 36/8198
User avatar
nmauduit
Coveted Fifth Gear
Coveted Fifth Gear
 
Posts: 1481
Joined: 02 Sep 2013
Location: France

PostPost by: tdskip » Thu Jul 09, 2020 4:51 pm

Thank you for the fast and helpful replies.

I will track down a good electric pressure fan and go from there.
SoCal
1969 Elan DHC
tdskip
Third Gear
Third Gear
 
Posts: 322
Joined: 13 Sep 2012
Location: SoCal

PostPost by: lotocone » Fri Jul 10, 2020 2:24 am

I'd use a pusher fan that is thin because there isn't much room between the front of the radiator and the spring connected to the hood/bonnet. Spal has fans that are not very deep.
Bob
1969 S4
lotocone
Third Gear
Third Gear
 
Posts: 271
Joined: 09 Feb 2010
Location: Michigan

PostPost by: tdskip » Fri Jul 10, 2020 2:57 am

Great tip - thank you
SoCal
1969 Elan DHC
tdskip
Third Gear
Third Gear
 
Posts: 322
Joined: 13 Sep 2012
Location: SoCal

PostPost by: cliveyboy » Fri Jul 10, 2020 9:05 am

Hi Folks (Long time since I last posted)
A decent full width Spitfire radiator will do the job. I have an original S3 Radiator with a dense core 71C/160F thermostat and my Sprint runs cool in 30C heat and fast driving. The only time the temp rises is in slow traffic and when stopped,
I have twin rear mounted electric fans which cool the engine very quickly. The fans are top quality ones which are thinner but can still flow large volumes of air. They will however draw about 8amps each so might want to install a relay.
A rear mounted fan is best location for unrestricted air flow (and the physics of cooling means air pulled through cools better than air pushed through). A front fan can still do the job if that's the only option
As previously mentioned avoid putting a single fan central on a radiator as it fouls either the bonnet spring or the engine pulley. Plenty of space to one side.
If getting your radiator modified think about getting a boss installed to take a fan switch similar to original ottor switch or threaded (M22x 1.5mm is a very common thread) this makes it easy to trigger your electric fan.
I have the bonnet foam that seals on top of radiator but don't use anything at the bottom as my rad sits low. I did make some custom radiator brackets that allowed more movement for better positioning and engine clearance.
For anyone fitting a wide radiator to later models (mine included) you may need to fettle the bodywork underneath but its a very simple quick job.
Clive
1972 Elan Sprint FHC
cliveyboy
Fourth Gear
Fourth Gear
 
Posts: 586
Joined: 22 Sep 2003
Location: Oxfordshire UK

PostPost by: Andy8421 » Fri Jul 10, 2020 9:07 am

Engine mounted fans on most cars are pretty hopeless. You really need it when the car isn't moving to shift air through the rad, and that is usually when the car is ticking over and fan speed is low. When the car is moving, the fan is generally surplus to requirements, yet that is when it moves most air and sucks up most HP.

Viscous couplings are one way to go, my old Landrover has a fan the size of a helicopter, and a great big viscous hub. I guess they plan for mud-plugging, when forward speed is low, but in low-range the engine revs (and cooling requirement) would be quite high.

I would put the engine mounted fan in the bin, and fit one (or maybe two if cooling is marginal) electric fans. As the rad is rectangular, two electric fans fit nicely side by side.
Andy8421
Third Gear
Third Gear
 
Posts: 389
Joined: 27 Mar 2011
Location: Surrey, UK

PostPost by: rgh0 » Fri Jul 10, 2020 9:41 am

cliveyboy wrote:Hi Folks (Long time since I last posted)
A decent full width Spitfire radiator will do the job. I have an original S3 Radiator with a dense core 71C/160F thermostat and my Sprint runs cool in 30C heat and fast driving. The only time the temp rises is in slow traffic and when stopped,
I have twin rear mounted electric fans which cool the engine very quickly. The fans are top quality ones which are thinner but can still flow large volumes of air. They will however draw about 8amps each so might want to install a relay.
A rear mounted fan is best location for unrestricted air flow (and the physics of cooling means air pulled through cools better than air pushed through). A front fan can still do the job if that's the only option
As previously mentioned avoid putting a single fan central on a radiator as it fouls either the bonnet spring or the engine pulley. Plenty of space to one side.
If getting your radiator modified think about getting a boss installed to take a fan switch similar to original ottor switch or threaded (M22x 1.5mm is a very common thread) this makes it easy to trigger your electric fan.
I have the bonnet foam that seals on top of radiator but don't use anything at the bottom as my rad sits low. I did make some custom radiator brackets that allowed more movement for better positioning and engine clearance.
For anyone fitting a wide radiator to later models (mine included) you may need to fettle the bodywork underneath but its a very simple quick job.
Clive


I don't think I agree with the common belief that puller fans are better than pusher based on my understanding and experience with heat and mass transfer system design. Its really a decisioon to be made based on physical access preferences

With a wide radiator two smaller fans can be fitted either side of the bonnet spring if wanted.

I agree fitting a relay for 1 and definitely 2 fans is sensible.



cheers
Rohan
User avatar
rgh0
Coveted Fifth Gear
Coveted Fifth Gear
 
Posts: 7512
Joined: 22 Sep 2003
Location: Melbourne, Australia

PostPost by: Andy8421 » Fri Jul 10, 2020 10:37 am

Firstly, welcome back Cliveyboy.

Are you planning to start producing some of your excellent Elan products again? I left it too late to buy some from you, but have learnt my lesson and won't make that mistake again.

Regarding the push vs pull question, I would have thought any effect is going to be negligible. The thermodynamic effects - heat increase due to pressure difference across the fan, frictional heating of the air, efficiency of the fan in hot vs cold air will be measurable, but tiny. Its not a jet engine.

Just from an airflow perspective, I would have thought a fan in front of rad would be much better - the space between the rad and engine is pretty cramped already.

Andy.
Andy8421
Third Gear
Third Gear
 
Posts: 389
Joined: 27 Mar 2011
Location: Surrey, UK

PostPost by: coolexperts » Fri Jul 10, 2020 1:56 pm

This is our full width radiator in aluminium showing mountings for two fan but only one fan fitted for Northern Europe. With the absence of Cliveboy we have recreated his cast aluminium combined thermostat housing / filler neck and usualy supply the radiator with out a filler neck fitted when this is used. Where twin fans are requested we supply a fused line and relay set to operate the fans. 8)

http://www.coolexperts.co.uk/product/lo ... struction/
coolexperts
Second Gear
Second Gear
 
Posts: 80
Joined: 08 May 2012

Total Online:

Users browsing this forum: No registered users and 14 guests