Lotus Elan

wheel arch holes for improved cooling

PostPost by: bcmc33 » Tue Aug 04, 2009 5:31 pm

john.p.clegg wrote:Before I get the hole cutter out, isn't there a big hole underneath the engine bay that the sump dangles through??


My friend, John,

Yes there is a big hole at the bottom and that's where a lot of the cooling air goes before it hits the radiator.

As I see it, there are a number of issues that may or may not be relevant.

To get the maximum amount of air through the radiator requires that all the possible passageways around the radiator need to be blocked. This is a pretty obvious statement, but very difficult to achieve, so you have to do the most practical things with the ultimate objective in mind.

I have seen so many Elans and +2s with foam blanking strips across the top of the radiator, but very few with a blanking plate at the bottom to direct the air towards the radiator instead of it taking the line of least resistance and going underneath.

I am of the opinion that without the side air holes behind the radiator there will be a pressure build-up in the top half of the engine bay and venting under the car will be very inefficient. It is likely that stratification will occur resulting in the lower half of the radiator only working at maximum efficiency.

I?m still of the opinion that a grille in the Bonnet (hood) would be the most efficient.

I guess there?s plenty of room for discussion on this subject.

Air vent -- original fit.JPG and

Air vent -- added holes.JPG and
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PostPost by: stugilmour » Wed Aug 05, 2009 2:33 am

Ian, is your heater core sealing correctly in the off position within the heater box? I have my heater box out of my Plus 2 right now, and the foam on the two flaps that seal the heater core was completely shot from age, coming out as powder and small flakes. I found the car quite warm and stuffy; have not checked it out with the repair in place yet. I can explain more or send photo's if you need. Others have mentioned this issue before, so you may have already addressed it. Thinking of adding a manual heater valve on the hose to ensure the core can be completely shut off in warm weather as well. 8)

Cheers!
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PostPost by: GrUmPyBoDgEr » Wed Aug 05, 2009 8:54 am

stugilmour wrote:Ian, is your heater core sealing correctly in the off position within the heater box? I have my heater box out of my Plus 2 right now, and the foam on the two flaps that seal the heater core was completely shot from age, coming out as powder and small flakes. I found the car quite warm and stuffy; have not checked it out with the repair in place yet. I can explain more or send photo's if you need. Others have mentioned this issue before, so you may have already addressed it. Thinking of adding a manual heater valve on the hose to ensure the core can be completely shut off in warm weather as well. 8)

Cheers!


I'd like to add a word of caution regarding shutting off the supply to the heater matrix via a valve.
I don't know the +2 cooling system but do know that the circuit is different to the Elan's.
I understand that the heater matrix is an integral part of the minor cooling circuit.
It would be worth while finding out if the proposed valve would prevent coolant flow in the engine as well as the heater & if so what the effect would be on the engine.

Cheers
John
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PostPost by: rocket » Wed Aug 05, 2009 9:46 am

Thanks for that John id had the same thought.Im not going to do that anyway as i believe the heat that builds up comes from the engine compartment through the wall by your feet.My heater blows cold air as it should when in the cold position.


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PostPost by: handi_andi » Wed Aug 05, 2009 8:49 pm

Firstly, has anyone out there got an Elan plus 2 heater that works correctly?

Secondly, and more on topic, what about putting a sheet of aluminium on the underside of the chassis from around the back of the front cross member to say a foot in front of the fire wall to act as an under tray as you find on modern cars? This would surely create a venturi opening by the fire wall and aided by the footwells and the airflow under the car would pull a continuous stream of air through the car when moving? This is surely the effect that is used on modern cars to aid airflow?

I am not convinced by the bonnet grills idea towards the windscreen because of the airflow in that region being fairly turbulent as it leaves the bonnet to go over the windscreen. Given that the air intakes are there for the cabin, and they are horizontally mounted, then this would tend to imply that there is a high pressure region there which would not aid in the quest for more flow through the engine bay.

The passenger footwell is always likely to get hot because of the proximity of the exhaust to it, and the same thing occurs on series landrovers for the same reason. Easiest answer to reducing the heat on the passenger side would be to attach heat reflective pads to the foot well on the engine bay side.

Just a few thoughts

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PostPost by: GrUmPyBoDgEr » Thu Aug 06, 2009 7:19 am

Theoretically the under sump venturi could help but the covers that are on modern cars are there for sound deadening purposes. t
I think that any sheet metal used for the purpose proposed would most likely increase the noises from the engine especially those noises coming from the "spinning bits" which could be very unpleasant.

Cheers
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PostPost by: bast0n » Wed Aug 12, 2009 12:23 pm

I have a 1966 Elan SE DHC and regularily go to Italy via being silly in the Alps. Two problems were an overhot engine especially in traffic at plus 35 or higher and a wife complaining of cooked feet!

Solution to problem one - get a Renault 25 fan from a scrappy and you have two huge fans enough for two Elans that push air from the front and mount with through the radiator fin bolts. Rubber stuck under the bonnet to seal the top gap and a cut up rubber floor mat to seal the lower gap glued in place. Also a four core radiator rebuild. An electronic controller in the top hose and an overide switch on and auxiliary panel and of course an alternator. (driven in my case by a twin pulley system so that the waterpump has its own belt and the alternator belt can then be tight - any one wanting details of this mod please contact me)

Problem two wifes hot feet. Fantastic aluminium bubblewrap type stuff available from car accessory catalogues - expensive - fitted all around the footwell under the bonnet, both vertical and horizontal surfaces, attached by stainless self tappers with built in washers. Then under the carpets on her side, front side and bottom, the rubber? sheet that cooker manufacturers use to insulate electric cooker ovens to keep the heat in!

Result - cool engine and cool wife - Bliss......!

PS - why bother with holes that let the muck in? :D
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PostPost by: bcmc33 » Wed Aug 12, 2009 2:27 pm

bast0n wrote:PS - why bother with holes that let the muck in? :D



That's the interesting and informative bit - nothing comes in through the holes only hot air getting out. 8)
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PostPost by: bast0n » Wed Aug 12, 2009 4:36 pm

Brian that may be true, but my chum with holes has found that sometimes muck is heavier than air and does get in. I think that Montgolfier discovered this.....................eh?
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PostPost by: dougweall » Wed Aug 12, 2009 5:15 pm

Just to add my tuppence worth to the discussion, when at CLM in 2008 looking around the racing elan's they had various idea's for getting heat out of the engine bay,
1 a series of approx 12 x 1" holes along the trailing edge of the bonnet.
2 fitted some bonnet clips that could be adjusted for height at the rear of the bonnet, so the bonnet sat approx 1 - 1 1/2 " high at the back.

Does that make sense, :roll: may be not.

Doug.

Incidentally I forgot to mention, another "mod" the racers had come up with, we asked where was the coil, you don't appear to have one.
Oh it gets far too hot under here so we have moved it inside the car under the dash above the drivers feet. I also think with a suitable ( for racing anyway ) air flow around to help keep it that little more cooler. To me that makes a lot of sense.
Last edited by dougweall on Wed Aug 12, 2009 6:26 pm, edited 1 time in total.
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PostPost by: handi_andi » Wed Aug 12, 2009 5:57 pm

Doug

I think it does make some sense as it would create a venturi affect by using the flow over the bonnet and windscreen to draw air through the under bonnet area. Not sure how effective it would be though or what effect it would have on the overall aerodynamics, mind you raising the bonnet slightly might give you some added down force at the front end.

Cheers

Andy
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PostPost by: bast0n » Wed Aug 12, 2009 9:00 pm

Doug- Raising the rear of the bonnet certainly helps but for everyday use you get a lot of hot air over and around the windscreen. DHC only obviously. As regards coils position - I have been let down by coil failure three times in hot countrys - I have repositioned mine above and to the right of my feet, (RHD), and no further problems. Also for those of you who have trouble with the dreadful Lucas rotor arms, Bosch do a replacement and again - no more trouble over several years.

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PostPost by: bcmc33 » Wed Aug 12, 2009 9:13 pm

bast0n wrote:Brian that may be true, but my chum with holes has found that sometimes muck is heavier than air and does get in. I think that Montgolfier discovered this.....................eh?

The Montgolfi?re brothers ? are they the Elite flyers we meet at Classic Le Mans every year?

If I took my Elan mud-plugging then I would probably blank off the holes.

dougweall wrote:Just to add my tuppence worth to the discussion, when at CLM in 2008 looking around the racing elan's they had various idea's for getting heat out of the engine bay,
1 a series of approx 12 x 1" holes along the trailing edge of the bonnet.

It?s worth noting that my second plan to increase flow through the engine bay was to cut a pair of slots in the rear of the bonnet. I sent this picture to a friend recently to show him what I had in mind.
Air vent -- bonnet.JPG and


bast0n wrote:I have been let down by coil failure three times in hot countries - I have repositioned mine above and to the right of my feet, (RHD), and no further problems.

I?ve used a solid state coil for the last two years ? a better bang for your buck and no heat worries. But then, I guess, I don?t live in a hot country.
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PostPost by: redskatejbf » Wed Aug 12, 2009 9:54 pm

I don`t have a under bonnet (hood) heating problem so perhaps I am `shooting the wind here` but rather than cut slots etc. in the rear edge of the bonnet would you not have the same effect by removing the sponge `joint` on the body under the windscreen to bonnet and replace it with two very short lengths of a harder (firm) sponge that has the same effect as giving a tension between the body and the bonnet. This I would have thought would give much the same effect as slots / raised bonnet to let the heat out without to much visual impact.
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PostPost by: bcmc33 » Wed Aug 12, 2009 11:20 pm

redskatejbf wrote:but rather than cut slots etc. in the rear edge of the bonnet would you not have the same effect by removing the sponge `joint` on the body under the windscreen


What sponge joint?

The rear of my bonnet locates down on two pins.
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