Lotus Elan

Fitting an Oil Cooler - S4

PostPost by: AHM » Wed Jun 12, 2013 9:31 am

Hi All,

I want to fit an oil cooler to the S4 - narrow radiator

I've bought a Mocal 13 row oil cooler , and a thermostat/sandwich plate that screws to the oil pump.

I have mounted the cooler horizontally in front of the radiator in the middle.

What is the best way of connecting it up? I have had an initial look but it seems that the pipes either go through sharp bends, rub on something or look untidy.

suggestions?
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PostPost by: rgh0 » Wed Jun 12, 2013 1:22 pm

I run the two connections out of the sandwich plate to the rear and pointing slightly to the outside, due to the angle of the pump and filter the connections also point down at an angle. I then run the lines down and outwards in a loop to come back up past the filter on the outside and up over the front cross member just to the right of the steering column on a right hand drive car passing under the curly bottom radiator hose. The lines then continue to run up and turn to the left and loop down again to connect to the top ports on the cooler. I mount the cooler to the left a little rather than central at the base of the radiator to keep the bends in the hoses not to tight.

I am travelling currently and don't have any pictures on my laptop but I will see if I can dig some out when I get home

cheers
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PostPost by: sutol45 » Wed Jun 12, 2013 1:52 pm

AHM wrote:Hi All,

I want to fit an oil cooler to the S4 - narrow radiator

I've bought a Mocal 13 row oil cooler , and a thermostat/sandwich plate that screws to the oil pump.

I have mounted the cooler horizontally in front of the radiator in the middle.

What is the best way of connecting it up? I have had an initial look but it seems that the pipes either go through sharp bends, rub on something or look untidy.

suggestions?



Is this for road use? If yes, then why would you want to fit an oil cooler?

And this is a serious question as I know there's supposed to be Global warming and all that but an oil cooler (running on a good quality 20W 50 for which the engine was designed) on a road going Elan?

I ran my Elan around the South of France and Italy a few times and my car never warranted the fitment of an oil cooler...

Please tell
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PostPost by: rgh0 » Wed Jun 12, 2013 2:04 pm

Hi Suto

Do you need to fit an oil cooler is a whole different and very interesting question. At one end of the spectrum running a full race engine on the track on 40 degree days - yes you absolutely do. At the other end of the spectrum driving a standard car conservatively on normal roads in the North of England you absolutely don't.

But in general you are right and most of the time in most circumstances for a standard road car you don't need a cooler especially with todays modern synthetics which tolerate higher oil temps much better than mineral oils of 40 years ago did

However In between the extremes there are a whole range of issues and circumstances and usage when you may or may not need a cooler. However fitting a thermostatic cooler just wastes money if you don't need it but may save you engine if you did. You makes your choice and takes your chances in the end.

cheers
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PostPost by: AHM » Wed Jun 12, 2013 3:05 pm

Rohan,
Thanks for your post - I had tried forward and sideways but not backwards!

Pictures would be great but no hurry, I bought the cooler about 10 years ago and only trial fitting it now after the rebuild.

sutol,
Is it an absolute requirement to have an oil cooler - No - I appreciate that the thermal capabilities of the oil and the engine are sufficient without it.

Have I decided that on balance it would be advantageous to have one for the 3 days each year where everything gets a bit hot - Yes

It is more about heat management in general than cooling oil in particular.

Look at it like air conditioning do we need it - No. Is it nice to have on a hot day - Yes.
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PostPost by: Bud English » Thu Jun 13, 2013 2:17 am

Deleted and moved to it's own thread where it should have been to begin with. Sorry. :oops:
Last edited by Bud English on Thu Jun 13, 2013 4:56 pm, edited 2 times in total.
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PostPost by: Grant K » Thu Jun 13, 2013 11:27 am

I read an earlier post by Rohan & fitted my oil cooler per (my interpretation of) his description. It does seem like the best way to avoid hoses rubbing on things.
The only thing they do touch is the cross member. Here, they rest lightly on a self adhesive neoprene rubber pad cut to shape.
I folded a shroud out of light gauge aluminium to direct heat from the cooler under the radiator. Fits well in a +2, but not sure if this would work for an S4. Original fan still fitted - I may change this later.

Did I need a cooler? Hard to say for sure, but it seemed like a good idea - the engine has been modified for more power & it can get hot here in summer.

Hope the photos help.
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PostPost by: prezoom » Thu Jun 13, 2013 4:58 pm

With all this talk about oil coolers, I am wondering just how hot is your oil getting? Has anyone bothered to fit a oil temperature gauge to see if one is needed or not?.. I know, as a result of dyno testing on other racing engines, the most horsepower was achieved with water temperatures just over 200f and oil temps in the 220f range.

I also used water to oil heat exchangers to maintain a constant oil temperature. I found a Setrab exchanger to work extremely well, although it was a bit bulky, especially if trying to fit it to an Elan.

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PostPost by: AHM » Thu Jun 13, 2013 11:55 pm

Grant - Thanks simple when you have a photo.

Rob - The oil doesn't get hot enough for its capabilities to be a concern. I use 5w 40 Fully synthetic.

I'm more interested in how I keep my rebuilt engine and myself cool. I could put the roof down and turn the heater on in the S3, that is not quite as much fun in the S4 as it is a coupe.

The oil has the sump surface area for cooling and the rest of the engine as a heat exchanger. Now if you think where the oil goes, wouldn't it be an advantage if you fed those areas with cooler oil rather than using them to cooll the oil.

Also im hoping that if I cool the bottom end more effectively I will get less heat soak through the bell housing and gearbox - they are still hot long after the end of the traffic jam when engine temp is normal.
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PostPost by: 69S4 » Fri Jun 14, 2013 7:05 am

prezoom wrote:With all this talk about oil coolers, I am wondering just how hot is your oil getting? Has anyone bothered to fit a oil temperature gauge to see if one is needed or not?.. I know, as a result of dyno testing on other racing engines, the most horsepower was achieved with water temperatures just over 200f and oil temps in the 220f range.

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I put an oil cooler on my S4 somewhere around 25yrs ago in an attempt to keep the engine cool - a kind of "if the water won't do it maybe the oil will" approach. I've also had (past tense - I broke it recently) an oil temp gauge reading from the bottom of the sump. The car is only used on the road - no track days or anything and for normal use the gauge reading has been around 50C (+/- 10C summer to winter).

The only time the oil temp gets anywhere near the water temp is when I'm stuck in traffic or when the engine has to work for a living - climbing an Alpine pass for example. I know others have posted different (higher) figures for road use oil temp but that's what my gauge has been reading. I've been meaning to check it against a boiling water std but my "hand on the sump" thermometer suggests it's probably not that far out.

Wrapping the cooler matrix doesn't make that much difference so I'd guess most of the cooling is from general airflow past the sump. The gauge is going to be replaced next time I change the oil so it'll be interesting to see if the reading is much different
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PostPost by: Quart Meg Miles » Fri Jun 14, 2013 8:12 pm

69S4 wrote:
prezoom wrote:With all this talk about oil coolers, I am wondering just how hot is your oil getting? Has anyone bothered to fit a oil temperature gauge to see if one is needed or not?.. I know, as a result of dyno testing on other racing engines, the most horsepower was achieved with water temperatures just over 200f and oil temps in the 220f range.

Rob Walker
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I put an oil cooler on my S4 somewhere around 25yrs ago in an attempt to keep the engine cool - a kind of "if the water won't do it maybe the oil will" approach. I've also had (past tense - I broke it recently) an oil temp gauge reading from the bottom of the sump. The car is only used on the road - no track days or anything and for normal use the gauge reading has been around 50C (+/- 10C summer to winter).

The only time the oil temp gets anywhere near the water temp is when I'm stuck in traffic or when the engine has to work for a living - climbing an Alpine pass for example. I know others have posted different (higher) figures for road use oil temp but that's what my gauge has been reading. I've been meaning to check it against a boiling water std but my "hand on the sump" thermometer suggests it's probably not that far out. ..


I've had an oil temp gauge for forty years, until recently fed through the drain plug so it was half out of the sump. Now I have it mounted in its own sump bush opposite the drain plug and it measures about 10?C higher (screening rigorously from the exhaust not making any difference). Driving moderately to warm up the engine I never fail to reach 50?C (40?C with the earlier mounting) after which I feel free to drive flat out and 90?C is normal in summer, 110?C not unusual. Even in the early, sump-plug years it would indicate over 90?.

So Rob's racing temperature figures support the case for leaving off an oil-cooler for road use provided we are not concerned with engine wear; does anyone have data on that aspect? My engine is absolutely standard tune but a Sprint engine might be another matter.

Didn't one of our fabrication masters advertise an oil-water heat transfer radiator recently, fitting in the thermostat to radiator path?
Meg

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PostPost by: 69S4 » Sat Jun 15, 2013 1:17 pm

Quart Meg Miles wrote:I've had an oil temp gauge for forty years, until recently fed through the drain plug so it was half out of the sump. Now I have it mounted in its own sump bush opposite the drain plug and it measures about 10?C higher (screening rigorously from the exhaust not making any difference). Driving moderately to warm up the engine I never fail to reach 50?C (40?C with the earlier mounting) after which I feel free to drive flat out and 90?C is normal in summer, 110?C not unusual. Even in the early, sump-plug years it would indicate over 90?.


The bulb for my gauge is mounted on the side, about an inch up from the bottom of the sump and opposite the drain plug - so in a similar position to your Mk2 location from the sound of it.The gauge was fitted at the same time as the cooler so I have no idea what the readings would have been before.

I've never had normal road driving readings as high as 90C - 70C maybe on the motorway on a hot day but that would be about it. It's been a constant source of "amusement" to me that while I've struggled for decades to keep the water temperature down it seems to be equally difficult to get the oil temperature up. I'd probably be a lot less stressed if I threw both gauges away and just drove the car in ignorance.
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PostPost by: sutol45 » Sat Jun 15, 2013 1:36 pm

AHM wrote:Rohan,
Thanks for your post - I had tried forward and sideways but not backwards!

Pictures would be great but no hurry, I bought the cooler about 10 years ago and only trial fitting it now after the rebuild.

sutol,
Is it an absolute requirement to have an oil cooler - No - I appreciate that the thermal capabilities of the oil and the engine are sufficient without it.

Have I decided that on balance it would be advantageous to have one for the 3 days each year where everything gets a bit hot - Yes

It is more about heat management in general than cooling oil in particular.

Look at it like air conditioning do we need it - No. Is it nice to have on a hot day - Yes.


OK AHM, that's a good enough reason for me... don't block that water radiator mind!
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PostPost by: JJDraper » Sun Jun 23, 2013 11:01 am

Ok, I'll add my tuppence..! We've been here before, but what the heck, its a slow weekend.

When I refurbed my +2, I junked the Ambient air temp gauge and fitted a similar looking oil temp gauge, with the sensor in the sump plug. I note that the oil takes a good while to get to around 60-90 DegC (5-10 miles), and under normal road conditions runs up to around 90-110. Motorways, at a steady 70mph+ in Summer (or at least what passes for it in the UK) cause the oil temp to climb over 120 or more. So far so good. My first long distance foray down the autobahns to the Alps and beyond saw the oil temp hit the max stop of 140+ on the guage anytime we went up serious gradients, or at serious speed. I was running Millers 20-60 synth, so the oil was running at close to its limit for long periods. When I got home, I checked the accuracy of the gauge with 'tell tales' on the sump and oil filter housing. These are stick on temperature sensitive strips that change colour irreversibly when a temp is exceeded.

http://temperature-indicators.co.uk/aca ... abels.html

I am satisfied that the gauge is accurate to +/- 5DegC, which is still a wide range. For my next trip I fitted an oil cooler in exactly the way described above. Result, the oil temp stabilises at around 90-110 in the UK, on most runs I have undertaken. On a two week haul in Italy last summer, in what even the locals called a seriously hot summer, blatting down the Autostrada and up the mountains, the oil temp got up to 130, tops, never going near the Max-out zone. The gauge usually sat in the 90-110 zone, in normal running, even in the extreme heat. Back home and over last winter, I noted the oil temp was quite sluggish to warm up, so at the scheduled oil change, I removed the cooler. This summer, the oil temp rise is back to the pre oil cooler behaviour. Note that at all times, even when the oil temp was maxed out, the water temp was within limits - mid gauge.

This experience tells me that without any regulation, the oil has no real mechanism to lose excess heat when the engine is working hard. Not hard to imagine given the humble origin of the block which wasn't designed with this in mind. The cooler & built in thermostat was working, evidenced by the normal heat up to 90C, and hunting around this point until it settled down into an equilibrium. For extreme stress, the 13 row cooler is just about adequate, evidenced by the rise to 130+ under extreme conditions, but no further.

What are the implications for all this?

Under normal UK conditions, you probably don't need an oil cooler and in winter it is a nuisance.

Heat transfer from over-heated oil to the water side is not going to be significant, given the small delta T, and limited surface area. An oil cooler, even in the hottest conditions has both a massive delta T and surface area.

Under high stress - 120C+ - you must use a synthetic oil and even then it is running close to its limit.

Is the peak thermal stress under hard use responsible for accelerated engine wear seen in pre synthetic oil days?

Fitting an oil cooler is desirable if you drive at anything like 'normal' modern motorway speeds in hot countries, but is worth removing for autumn/winter use in temperate countries.

Anyone who states you never need an oil cooler in a road going Elan probably has a financial interest in rebuilding engines.

The most important thing for prolonging the life of an engine is clean oil, at the correct temperature. The further away from ideal, the more quickly engine wear occurs. Clean oil is easy to maintain with regular oil & filter changes, but without knowing the temperature of your engine oil, with some degree of accuracy, you are running blind. Are you feeling lucky?!

Now, all I have to do to scare myself again is fit sensors in the gearbox and diff housing with a selector switch in the cabin! Ignorance is bliss, but accurate data is better.

Jeremy

PS once the cooler has been fitted, it is a 20 minute job to remove, or put back on, when you change the oil & filter.
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PostPost by: rgh0 » Sun Jun 23, 2013 12:52 pm

You can get thermostatic oil sandwich plates that only pass the oil through the cooler once it has heated up. If using on a road car for protection in those motorway and mountain climbing conditions in summer you should fit one of these to ensure the oil warms up rapidly and it stays hot enough in winter !

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