Lotus Elan

Improving Radiator For S4

PostPost by: William2 » Thu Sep 08, 2016 11:30 am

I am going to fit the full width Triumph radiator to my S4 Elan to improve the cooling and not have to keep looking at the temperature gauge!!
On the science of how radiators work I have read suggestions that having this radiator uprated to 3 cores might not be necessary or a good idea. This is partly it appears to the fact that you are trying to get the water pump to shift more volume of water which it may not be able to do efficiently. Therefore, there is an a case to suggest leaving the rad as the standard 2 core.
I also intend to start off by fitting a single front mounted electric fan and see if that copes ok. My reasoning here is that half the rad is still clear of any obstructions for heat dissipation.
Any thoughts on this and has anyone swapped the narrower S4 rad for a standard S3 with a marked improvement on reducing engine temp?
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PostPost by: pharriso » Thu Sep 08, 2016 1:28 pm

The narrow S4 radiator works well as long as the lower blocker, bonnet foam & recuperator bottle are all in place & functional. We have 100 degree F summer heat & the system works well....
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PostPost by: mbell » Thu Sep 08, 2016 6:29 pm

I have the wide radiator 2 core on mine (modified old Spitfire radiator) with a Clivey boy dual fan setup. I've not gone on any long drives but it has run and sat stationary running for periods in what would be very hot temps for the UK with out issue.

I'd suggest checking the state of your current radiator, as I agree with Phil that the narrow radiator in good condition, properly installed with a good fan should cope ok. It has less safety margin than the wide radiator thou.

I've just removed the water jacket plugs from my engine while its out (1 was rusted through) and there was a pretty alarming amount of crud (sand,rust/etc) in the block. Any of that getting into the radiator would cause blockage issues which would impact it's effectiveness. So you might find a good clean out of you current radiator improves things quite a bit.
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PostPost by: Bombay Racing Green » Thu Sep 08, 2016 7:00 pm

Hi William,

I have just gone through the same for my S4. Really I should have tried one at a time and seen was effect, if any, the mods would have achieved. However, Work and family are thieves of time so I just got cracking. I have to state that the previous owner had the standard narrow radiator uprated to a 3 core unit. It also had a new Kenlowe fan fitted. The fan ran all the time. I eventually found the sensor and thermostatic switch and tried to adjust it to no avail. I then wired a simple switch to the fan and put it under the dash. With the fan off and a good high speed run on the motorway during the high Summer here in Ireland (about 28/9C, don't laugh!) the water temp would be at 100C once stopped. The fan would bring this down steadily but i felt something better be done. I am aware that Stromberg heads run slightly warmer. This is what I tried:

1. Cut two holes in the left wheel arch as per the manual.
2. Straight water with Water Wetter.
3. Bonnet foam strip.

After doing points 1&2 the temperature runs now at about 85C on a long run. Sadly Sue Miller didn't have any bonnet foam at the time of my order but will send it on later. The radiator has the bottom blanking plate. I will be switching back to antifreeze soon to see what the difference is. I suspect only a few degrees but I'd say every little bit helps in a much warmer climate than here.

Rather than having a simple switch for the fan, I now have the switch running a spare Lucas RA6 relay. It is wired through the hazard light so I can have a visual confirmation that the circuit is powered. I want to return to an automatic system so that if someone else is driving the car they won't have to worry about watching the temp. To that end I was coveting one of those excellent cliveyboy thermostat housings. I think he's offline at the moment (I hope everything is OK?) and the one for sale at Burton Power is 70 degrees out in orientation. However, they do have a new casting of the original thermostat housing with a plain blank boss in the top. When I got it I found that it doesn't have enough meat in the boss to mount a M22 thermostatic switch. I have bought a M14 thermostatic switch from a BMW/Volvo/Opel configuration that has a 95-90C range. I shall helicoil the hole so I won't damage the casting when I insert/undo the switch. I have an old radiator that I shall send off for refurbishment and whilst it is there I shall ask them to solder/braze in an M22 threaded hole.

I would concur with the previous posts. Sort the radiator and its blanking off first and see how she goes.

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PostPost by: collins_dan » Thu Sep 08, 2016 7:15 pm

I think if you read through the forum, you will find as many examples of people not finding the narrow rad adequate, as those that do. For me, when the car was moving, it was fine, but when the car was not moving, it was not fine. I think the wide two core should be fine, as long as you add a powerful fan or two. I changed to a wider radiator, but kept the same single 10" fan drawing 7.4 Amps and pushing 850 cfm, and found it insufficient. I switched to two 9" fans, each pushing 2400 cfm and only drawing 4 amps each, so 8 combined and problem solved. I think one large fan would also work, as long as it is pushing 2-3,000 cfm. My 2 cents. Dan
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PostPost by: elanner » Fri Sep 09, 2016 12:43 am


Would you post a pointer to your fan?


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PostPost by: gjz30075 » Fri Sep 09, 2016 8:42 am

William2 wrote: and not have to keep looking at the temperature gauge!!

Guarantee, you'll still look! It's an LBC :lol:
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PostPost by: William2 » Fri Sep 09, 2016 9:11 am

I should have said a couple of extra things in my original post. Engine has been totally rebuilt, narrow rad was uprated with a new 3 core and I have fitted the bonnet foam and blanking panel beneath the rad. My car does have the 2 standard holes on the LH inner wheel arch.
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PostPost by: terryp » Fri Sep 09, 2016 9:54 am

I replaced my standard S4 set up with full Cliveyboy wide radiator and twin fan set up and can say I would not even think about engine temperature anymore.
Previously on my two +2's I would be driving with one eye on the temp gauge and pre switching on the fan on the approach to a built up area.
The fans hardly ever switch on even in 30 degrees
I would throughly recommend changing the radiator as its one more think not to have to worry about. Same as fitting solid driveshafts of some description.

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PostPost by: rgh0 » Fri Sep 09, 2016 10:17 am

A 3 row narrow core radiator adds about 50% more heat transfer area compared to the standard 2 row core. A 2 row core wide radiator adds a similar 50% more heat transfer area. A 3 row core wide radiator adds about 100% heat transfer area than the orginal narrow 2 row core.

If I was going to the trouble of replacing my current 3 row core narrow radiator i would fit a 3 row core wide radiator. In reality a 3 row core narrow radiator should be plenty for a normal road car in even the hottest climate. But a 3 row core radiator will not hurt

Last edited by rgh0 on Sat Sep 10, 2016 2:47 am, edited 1 time in total.
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PostPost by: MyLotus » Fri Sep 09, 2016 11:07 am

Swapping the S4 rad for the longer S3 is the way to go. It worked perfectly for my S4. By the way, I am preparing my 1970 S4 for sale. Will be posting it here soon.
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PostPost by: pereirac » Fri Sep 09, 2016 1:12 pm

I just bought a cheapish third party Triumph radiator ( from TRGB as they were local) and paid another company to turn the top hose connector 108 degrees. Filled a single Kenlow pusher fan to the from and since then overheating neves seems to be much of a problem even in traffic queues... It fitted straight in and I still have the original unit in case somebody is concerned about 'originality' .. Total cost (then) was about ?200, a very easy and worthwhile mod. Looking for a refurbished Standpart radiator now as that would be slightly more 'original'... :D

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PostPost by: William2 » Fri Sep 09, 2016 3:05 pm

Carl, am I right in saying you have fitted the wider spitfire radiator with the standard 2 cores?
Thanks for all the advice. I have managed to find an original wide rad which will need recoring.
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PostPost by: therolfie » Thu Oct 27, 2016 4:38 pm

Ok it's in a +2 but I moved from narrow to wide & the twin rear fans from Clive. Well 1300 miles through Spain & France this summer was excellent in 40oc weather & traffic was spot on, so much so that when I do my S4 I will use the same set up, was very impressed. Hope it helps :))
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