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Dual oil cooler, answer to overcooling

139K views 858 replies 110 participants last post by  exigegus 
#1 · (Edited)
In doing research I come across how the dual oil coolers badly overcool the oil. The explanation is simple, the oil thermostat doesn't really shut off oil to the coolers, but provides a bypass and this is not sufficient. Shrug, TADT, cut out an oil cooler, switch to an expensive alternative.


So, in a thread on oil coolers, and low oil temps, someone linked to a mishimoto oil cooler sandwich plate. Nice looking piece. Slightly different layout. Looks like it not only provides a bypass, but restricts flow to the coolers. I dig the sandwich plate I purchased years ago for my twin cam, and sure enough, same thing, but not as nice as the Mishimoto.

Order one up on Amazon.
https://www.amazon.com/gp/product/B009AMOX48/ref=oh_aui_detailpage_o05_s02?ie=UTF8&psc=1

Nice

Ordered a pair of little gauges
https://www.amazon.com/gp/product/B001QJ9JX8/ref=oh_aui_detailpage_o04_s00?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B001QJBDJ6/ref=oh_aui_detailpage_o04_s00?ie=UTF8&psc=1

Set up a little test.

conditions:
62-65 degrees [drops slightly from cracking garage door]
car idling, standstill
the oil temp gauge is too slow to react so the temp measurements are from a handheld non contact thermometer aimed at the oil pan. I have the gauge data, also.


results:

see for yourself. the stock thermostat is a POS, it is bleeding warming oil in just a few minutes, where the Mish. unit basically never does. While it is not that much different vertically, look at the time scale horizontally, there is nearly ten minutes for the stock setup to get across a given temp line, and that is without any air through the coolers. It will get worse when moving. The radiator fan comes on 10 minutes sooner.

At the end of the last test revved the engine up and measured again, the oil coolers do indeed get warm when pushed and hot with the mish unit. I will try it after it cools down again to see if the higher revs and force of the oil pump makes it flow more before the thermostat opens. It will still be far better than stock.

155 bucks all in[actually 136 , I used the stock sandwich plate adapter threaded piece, wasted 18 bucks on the mish piece]
oh, and two m20 to 5/8 BSP adapters and a couple of copper washers,

will use the 1/8 NPT port for the temp gauge
 

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#4 ·
Actually it is more like 8 or 9, but remember that it will get much worse when moving, the factory will cool the oil much more than the Mish unit since the Mish unit is flowing virtually no oil at any point

would you not take 8 or 9 miles more fun ?
 
#5 ·
This seems good. Will you be able to drive the car and report again?
 
#6 · (Edited)
How is keeping cold oil in the oil loop a solution? A hotter t-stat like your 185°F Mishimoto plate is only delaying the return of 60°C/140°F oil (that's too low), not getting rid of it. By keeping twin oil coolers, you are not solving the problem which is twin oil coolers are overkill in these cars!

The solution is to get rid of cold oil in the loop altogether, not restrict it. So, gut the 27 feet of oil line to the coolers, do away with the additional 3.7 quarts of oil in that loop which aren't even purged during oil changes, and mount a single cooler in the rear.

There's nothing expensive about this alternative if you reuse the OEM cooler as I did. I spent less than you did and could have done it for nothing if I didn't need 4 new BSP fittings.

Plenty of us run a single oil cooler in the rear. Shorter oil loop = faster time to oil operating temp = higher oil pressure = stable oil temp.
 
#10 ·
sorry, but no

the problem with the cars is an ineffective thermostat.

the point of the exercise is solving the problem without excessive work or excessive mods.

I am neither a proponent of Lotus engineers as demigods nor as buffoons. Most of the issues I have found with the cars are more related to manufacturing than engineering. It seems apparent that the engineers did the math and wanted dual oil coolers. Someone chose the wrong thermostat which keeps the oil cold. The second oil cooler does not keep the oil cold with a proper oil thermostat. When actually driving there will not be a loop of cold oil, the higher engine speeds and oil pressure will slowly move hot oil through the loop faster than an idle test, but proportionally better than the factory

As with most things I feel the simplest answer is the best answer. A rear oil cooler works well, but is beyond the abilities and mod desires of many. The Laminova is superior, but again expensive and not simple.


This can be done in less than an hour, including picking the car up and costs less than any other alternative. It involves little more than what is involved when changing the oil.

It mods the car in no substantial way so future owners do not have to concern themselves with your engineering prowess, or lack thereof.
 
#7 ·
I think the best answer to oil cooling/over cooling is to replace the oil coolers with a Laminove heat exchanger and get rid of the oil thermostat all together. The Laminova heat exchanger will pre-heat the oil when cold and cool when hot...and...it gets rid of about 30 feet of oil lines in the process. All very good for this engine...any engine...

Quit trying to "Band-Aid" the problem and fix it!
 
#8 ·
Does blocking off the back of the coolers from the wheel well side with some thin plastic, or aluminum plate help?
Just looking for a quick, simple solution. :popcorn:
 
#9 ·
I wrapped one cooler, but have no temp gauge.
 
#13 ·
Exigegus, nice work and thanks for the information. :clap: Your research helps answer the design intent vs. actual results differential that exists with dual oil coolers, and it provides guidance to many Lotus owners for a simple fix.

I eliminated my Exige's dual coolers and installed a single rear oil cooler a few years ago. It proved to be a very productive mod and improved oil temperature management, with higher operating temperatures and a narrower band of operating temperatures. Though, it did require project planning, re-engineering, fabrication and wrenching skills that many Lotus owners don't have...as you pointed out.
 
#14 ·
I'm also a big fan of the laminova solution, but it does requires enhancing the car's water cooling system and it is a more complex install. The results are excellent ….. just my 2 cents.
 
#18 ·
So in order from cheap and least desirable to most expensive and most desirable:

1) Physically block off airflow to one or both OEM oil coolers.
2) Replace OEM oil cooler sandwich plate (aka this thread).
3) Remove OEM oil coolers and lines, reinstall one OEM oil cooler at the rear of the car.
4) Remove OEM oil lines and both oil coolers. Install Laminove heat exchanger at rear of car and install improved radiator.

I think option 2 is a sound option pending further testing. It is the factory engineering, and appears to be easy and cheap aka a simply bolt on modification - I am glad Exigegus is breathing life back into the debate. It is something that can potentially easily help both the street and track folks.
Although they provide additional benefits there is a degree of magnitude increase in difficulty to perform options 3 and 4 compared to option 2. Finally option 4 is the ultimate answer to the issue.

Maybe my option is such because I (falsely?) think that 2008+ radiators don't have the same expansion tank failure problem that earlier cars have... ? If they do then I would lean more so to option 4 as being the only option to take for tracked cars. I keep my eyes open but I don't recall ever reading someone with a 2008+ car replacing their radiator due to failure. Maybe someone can help enlighten me so I know if I need to be concerned or not. ;)

Lotus (accountants?) are not the only ones to screw this up. GM's C5 Z06 oil coolers and OEM thermostat are also a total POS. During cold weather the temp doesn't get to operating temp... in Texas at the track they can't do 20min sessions before oil gets to +300deg. I have three examples of friends that had to install 2 extra coolers + transmission cooler + larger radiator to keep heat at bay - on stock engine cars! This was HARDLY a bolt on fix for them either...
 
#28 · (Edited)
So in order from cheap and least desirable to most expensive and most desirable...
I would also like to suggest this option:

0.5) Bypass front oil cooler circuit altogether, by disconnecting and capping front lines, and fitting U-shaped line between sandwich plate feeds.

I could have sworn someone tried this before, but I can't find the thread right now. I believe this is also closer to be OEM Toyota install in the Celica/Matrix?

And obviously, this is *not* for track use, as you lose all the additional cooling capacity. As has been suggested before, the engineers must've had something in mind when they did the original cooling circuit design.
 
#21 ·
From my 32 years of Lotus ownership I will tell you that half the people will never do the Laminova mod, it will be too expensive, too difficult or too un-original.

There is nothing wrong with the Laminova, and much right, but this is a simpler and cheaper solution. It neither adds nor subtracts any parts so will do little offense to the originality police.

It is not a half measure, but IMO a better execution of the original engineering
 
#22 ·
The Laminova solution has many positives IMHO:

Less weight, which is hard to do in a Lotus. Around 28 pounds.

Optimum oil temperature is reached quickly.

Higher oil pressure.

More consistent oil temperatures.

When you change the oil you change all of the oil, not a portion of it.

Cabin temperatures are reduced (no oil lines in the side sills).

Eliminates the possibility of oil leaks from the oil cooler connections (which have killed some engines).


To each his own.

San
 
#23 ·
Not sure why this has to be more about the method than the results. Someone made a change that addressed a specific problem, and posted some good results and the conditions under which they occurred. Thanks!

I don't think you can say for certain it will take longer to stabilize when the car is moving, that really needs to be tested. unless you are coasting downhill for 20 minutes, a moving car means an engine producing more heat than when it is just idling.
 
#24 ·
Not sure why this has to be more about the method than the results. Someone made a change that addressed a specific problem, and posted some good results and the conditions under which they occurred. Thanks!
I don't think that this is about the method versus the results. There is always more than one way to skin the proverbial cat.

I didn't introduce the Laminova solution to this thread. That being said I feel there are positive aspects, and negative (cost), as EricH already mentioned. I also would like to hear about anyone with a 2008+ radiator that failed, as if the 2008+ radiator is more robust, one could possibly do a Laminova solution for considerably less money.

San
 
#27 · (Edited)
What would be interesting to see is a similar data set for the Laminova.

With enough data, one eventually gets information.

What occurs to me upon looking at the Laminova setup is that running on the radiator hose means that you will get limited oil warming prior to the thermostat opening, which is when you would like it.

Similarly 'higher oil pressure' is a claim without numbers, it would be interesting to see some data on that. Not doubting it, as most oil cooler installations result in some parasitic oil pressure loss. Quantifying it would be interesting.

Anyone with a Laminova setup and an oil temp ga could do it idling in their garage in less than an hour[don't forget to crack the door, we don't want to get the data from your wife]


I will make another data run revving the engine somewhat after the coolant temp ga registers but before oil is hot enough to crack the thermostat, to see how much flow looks like it goes though under higher pressure.

Then I am going to move the temp sender to its permanent location on the sandwich plate. I did not want to do that before I took before and after since the stock plate has no provision for a sender. I anticipate the temp there to move faster than the pan gauge and be more accurate than the non contact thermometer. I was interested to see the highest oil temp readings came from measuring the fins of the oil cooler.


Here is a graph with the oil pressure included, note how the oil pressure drops sooner and it looks like the 150F is the number that brings it to its lowest idle level.
It also shows the gauge readings
 

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#30 ·
Similarly 'higher oil pressure' is a claim without numbers, it would be interesting to see some data on that. Not doubting it, as most oil cooler installations result in some parasitic oil pressure loss. Quantifying it would be interesting.
Why do you need a number for that? Exchanging 30+ feet of AN-10 line for approximately 3 feet of AN-10 line will decrease the resistance in your oil system. Let's say you'll gain 2-PSI of oil pressure...no, no, no...let's say your oil pressure will increase by 1-PSI...well OK, let's say that is will increase by only 0.5-PSI. My point is that I don't think anybody here, not even an engineer, would guess that your oil pressure would drop by removing 30-feet of oil line resistance from your oil system. It will make it better...who cares by how much? Why do you care? What difference does it make if it's 0.5-PSI more or 10-PSI more. It will not be even 0.5-PSI less, now will it?
 
#29 ·
Don't want to high-jack the thread, but I'm about to install a Laminova in my Exige and pull out the oil coolers. Aside from a more efficient radiator, what additional upgrades does the coolant system need to keep pace? I planned to splice it in on the passenger side return pipe so I'm only running minimal -AN lines back to the sandwich plate.
 
#31 · (Edited)
You need to replace the sandwich plate with a plain one without a thermostat. Mocal made the OEM one and Mocal makes plain ones. The other thing, if you get AN-10 fittings for your sandwich plate, then you will no longer have any BAT fittings or those troublesome leaky oil line any more. Just unscrew the center "post", remove the old sandwich plate and then replace with the new, plain sandwich plate...reuse the OEM center "post" to re-fasten the new sandwich plate. Done!

[Edit] Just found this...
http://www.lotustalk.com/forums/f101/mocal-laminova-heat-exchanger-accusump-187794/
 
#45 · (Edited)
I always warm my car at idle before taking it on track, oil temp lags behind water. After approximately 15-20 minutes at idle (car has a 170* thermostat), water is at ~178*F and oil is at ~145*F. Once on track and after a few laps, whether ambient is 55* or 95*F, water will get to ~176 to 185* (depends upon the blanking plates I use for the radiator opening to control water temps) and oil temp is ~ 220-225*F. These temps remain stable for the entire session or 30 minute sprint races that are run in Lotus Cup.

My temps are a little different than your setup... after a good warmup and 4 laps I see water temps around 87c / 188F , a tad higher .. but Oil is only 94C / 201F , so you are running a bit warmer . This is based on a 20C / 68F ambient.
I am running a C43-332 Laminova .
Running a BOE REV400 and have the HEX mounted in the front so difficult to use blanking plates.

Suspect that you are using the smaller C43-182 Laminova ?

Would be good to see the oil temp a little higher .. so may look to go with smaller Lam at the next strip down ... which won't be for awhile hopefully !!!

I love the pics of your car in Red and Black ... I have been looking to redo my car and I keep coming back to your colour scheme ... would you be concerned if the same colour car turned up in the Southern hemisphere !!

Just as a point of interest ,in the K20 Elise race car I am currently building I am running a Dual Core Cooler kit http://www.speedflowshop.co.uk/dual-core-laminova-oil-cooler-kit-3635-p.asp
C43/92 for the gearbox [ EP sequential] and C43/332 for the Engine [K20]
Have deleted the the OEM water Pump and running a CWA200 Pierburg Pump for more flow [ ECU controlled] Will still have a HEX rad sandwiched to the Engine Rad.
It will be interesting to see what temps I get ..
 
#51 ·
My temps are a little different than your setup... after a good warmup and 4 laps I see water temps around 87c / 188F , a tad higher .. but Oil is only 94C / 201F , so you are running a bit warmer . This is based on a 20C / 68F ambient.
I am running a C43-332 Laminova .
Running a BOE REV400 and have the HEX mounted in the front so difficult to use blanking plates.

Suspect that you are using the smaller C43-182 Laminova ?

Would be good to see the oil temp a little higher .. so may look to go with smaller Lam at the next strip down ... which won't be for awhile hopefully !!!

I love the pics of your car in Red and Black ... I have been looking to redo my car and I keep coming back to your colour scheme ... would you be concerned if the same colour car turned up in the Southern hemisphere !!

Just as a point of interest ,in the K20 Elise race car I am currently building I am running a Dual Core Cooler kit Dual Core Laminova Oil Cooler Kit - Speedflow
C43/92 for the gearbox [ EP sequential] and C43/332 for the Engine [K20]
Have deleted the the OEM water Pump and running a CWA200 Pierburg Pump for more flow [ ECU controlled] Will still have a HEX rad sandwiched to the Engine Rad.
It will be interesting to see what temps I get ..
CPH, thanks for the kind words on color (it's a Ferrari color--Corsa Scuderia--Lotus blasphemy I know ;)) I'm still partial to orange, but since I sold my (Bobcat) orange 2-11 to a friend, who is also a member at Spring Mountain, I didn't want to have the same color car and rain on his parade.

As for size of Laminova, I pretty sure we have the same one, mounted as shown in the photo below. Can't explain oil temp differences. I'll check my data and report back on the oil temps for hot vs cooler days.
 

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#47 ·
Mine is on the passenger side of the car, on the lower firewall (engine side). The only time you can really see it is when it's up on a lift. I know Jack has excellent pictures of his setup and I'm sure he'll post them up.

OP, I hope we're not hijacking this thread as I'd like to think we're still in the neighborhood of solving the same problem/issue.

San
 
#52 ·
So, more data.

Moved the oil temp sender to its final location, but continued to measure from same exterior spot on the pan

Again cold start, room was slightly warmer.
double entered last data points so they would be visible

First gap in graph represents approx 60 seconds elevating rpm to 2500 -3000 rpm

second gap 30 seconds revs to 3000 to 5000

higher oil pressure is not forcing its way through system, most temp rise at coolers seems to be thermostat starting to open

I would say oil coolers would not be contributing any useful cooling until thermostat is full open

It is a 185 degree oil thermostat

have a 200 degree on order just because
 

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#58 ·
It occurred to me that addressing the sandwich plate / thermostat issue would still benefit a car that has converted to a single rear oil cooler, such as mine. (Please slap me if I missed a chapter in this discussion. :facepalm)

While operating temps are now higher and in a narrower range, the oil warm up time has been shortened but not drastically so.
 
#59 ·
I just finished installing a single rear oil cooler, I'm in the middle of installing oil temp gauge (oil pan), and I still need to remove the two front coolers and lines. I swapped the sandwich plate thermostat wax "bullet" with a 200*F "bullet", and I wired the Spal fan on the oil cooler to a toggle switch in the cockpit. I like the fact that the oil cooler doesn't add heat load to the coolant radiator, and the fan switch adds a degree of control. I expect I'll mostly leave the fan off when on the street, and switch it on at the track. I don't doubt that the Laminova is a good solution, but since I still have A/C, and drive it on the street, I just wondered if overheating (the coolant) might be an issue on a hot day, stop and go traffic, with A/C on. Situation best avoided, I know.

-Ed
 
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