Possibly Found a Cheap Oil-water Heat Exchanger

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Lotus-e-Clan
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Possibly Found a Cheap Oil-water Heat Exchanger

Post by Lotus-e-Clan »

Image

Looking to replace the oil cooler on the Excel with a heat exchanger.

Laminova exhangers (like I have on the Clan only bigger) would be around £350 (and upwards) new . I know some folk who have used exchangers from other cars (like from some Rovers). So started looking around for one with enough capacity to suit the Excel.

This one is for a Range rover Sport and costs just £44 all inc.
https://www.ebay.co.uk/itm/114678478658 ... SwYjdgJPdp

Trying to think through the snags - because £44 sounds too good to be true!

Haven't researched the oil fittings yet (?JIC) but it looks fairly straight forward.

Any thoughts/comments appreciated.
Peter K

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Re: Possibly Found a Cheap Oil-water Heat Exchanger

Post by DavidOliver »

Not strictly engine oil cooler but a transmission fluid cooler, I recently bought a Mishimoto air/fluid radiator for the gearbox of my Jaguar XJ40 to remove the circuit of coils in the engine Water radiator as water leaks destroy the clutch plates in the gearbox and there is no way of knowing until it is too late.
So try Mishimoto for a water/oil radiator, their prices are very reasonable, a new heat exchanger I doubt will leak coolant into the oil but a pressure test before installing might give you peace of of mind.

Dave the cog.

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Re: Possibly Found a Cheap Oil-water Heat Exchanger

Post by Pete Boole »

Great idea - get the oil warmed up sooner. Can't quite tell how big that one is - take another photo with a scale! The threaded fittings look like 0-ring type (like you might get on air-con fittings) the non-threaded for the water side. Because water is four times as efficient as air in heat transfer, a small unit may well be all you need. Keep us updated!

Pete

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Re: Possibly Found a Cheap Oil-water Heat Exchanger

Post by Lotus-e-Clan »

Image

Found a diagram of the same (I think) on Ebay.

Dave - Looks large enough to be an engine oil cooler rather than a transmission cooler?

I think I may take a punt and buy ... I'll sleep on it anyhow.
Peter K

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Re: Possibly Found a Cheap Oil-water Heat Exchanger

Post by Lotus-e-Clan »

..couldn't sleep so i bought it already.


Will report back soonest!
Peter K

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Re: Possibly Found a Cheap Oil-water Heat Exchanger

Post by Lotus-e-Clan »

:oops: Sorry Dave I think you are right ...I've since found other references to it as a transmission cooler!

I've bought it now so I think I will try it out on the Clan first. The race engine for the Clan is at the machine shop for some work so I have the spare engine in at the moment. Just before I get the race engine back (spring '22 unfortunately) I'll hook up this cooler to the spare engine (which will need a refresh soon anyhow).

In both the Excel and clan I have pre and post cooler oil temp sensors hooked to the same gauge so I'll be able to measure the delta across the cooler. But yes, will it take 7 bar on the oil side? :shock:
Peter K

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Re: Possibly Found a Cheap Oil-water Heat Exchanger

Post by Pete Boole »

What temperature does the oil in the Clan reach before it goes to the cooler? Presumably it doesn't need cooling by much if it's going to end up the same temperature as the engine coolant.

Pete

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Re: Possibly Found a Cheap Oil-water Heat Exchanger

Post by Lotus-e-Clan »

Pete Boole wrote:
Sat Nov 13, 2021 22:56
What temperature does the oil in the Clan reach before it goes to the cooler? Presumably it doesn't need cooling by much if it's going to end up the same temperature as the engine coolant.

Pete
Temps are dependent upon stage of operation and load -which is a product of power output AND rpm.

soooo examples:

Warm-up period - say <15 mins from cold start (obviously this varies dependent on ambient temps)
  • load condition = part throttle pootling, normal gentle rev rise and fall etc.
    Pre- exchanger (sump oil temp) <50C (ie not registering on gauge)
    Evans Coolant = 60- 70C
    post-exchanger (before the oil reaches the bearings) = 55C ( ie the coolant is dumping heat INTO the oil)
Fully warm say >15 mins
  • load condition = part throttle mixed with some WOT but essentially gentle running/ cruise conditions
    Pre-exchanger (sump temp) 75C
    Evans coolant = 82C
    post exchanger = 82C (ie the coolant is STILL putting heat into the oil)
NB. operational oil temp (post-exchanger) has now equilbrated with coolant temp but the sump oil (pre-exchanger) is COOLER because the volume hasn't heat-saturated yet (the sump is cooled somewhat by air flow). And THIS is what you see most of the time when the Clan is driven normally like most road cars.

Stinking hot Now we're getting mental with the throttle and/or holding a VERY high rpm cruise on part-throttle for 15 minutes or longer
  • load condition = lots of WOT and/or sustained rpm above 5k rpm motorway cruise
    Pre-exchanger (sump) = 95C - very hot oil, heated by the underside of the hot piston crown, is dropping directly into the sump
    Evans coolant = 82C-- 85C (depends on road speed and ambient temp)
    post exchanger = 85C (ie the exchanger is REMOVING 10C from the now very hot sump oil)
Obviously there are lots of operational variables and the devil is in the detail but the best DELTA I've had from the Clan's exchanger is 15C. That is, the oil going to the bearings is 15C cooler than the very hot oil in the sump.
This is road-speed dependent too because the faster I go the more the Evans coolant is cooled by the 3 radiators I have in the Clan (one rear rad and two small ones each side of the nose within the front spoiler).

Oh yes, forgot to add that the hottest oil temp I've seen (sump temp) is 105C but that's not normal for my use and set-up.

All of this is specific to the cooling set-up I've developed for the Clan. Things might look different with the Excel - but I'm encouraged by the findings in the Clan to try an exchanger in the Excel. Like you say, quick oil warm-up and oil temp equilibrating with coolant temp are the main advantages. The other revelation is that sump temps don't tell the whole story - you need to know the oil temp leaving the exchanger too.
Peter K

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Re: Possibly Found a Cheap Oil-water Heat Exchanger

Post by Pete Boole »

You keep such brilliant logs Peter! 8). I really like the idea of warming the oil up more quickly but I'd also be happy with it at 105C if the pressure was still OK - assuming a good modern synthetic. I like the idea of boiling any water contamination out of the oil by letting it get hotter than the coolant temperature (and I know opinions vary a lot with regard to this!). My plan with the Elite is to monitor the oil temperature and only fit a cooler if the oil gets too hot to maintain good pressure. Not decided which oil to use yet.

As an alternative to the Laminova the Range Rover unit looks unbeatable! Also excellent that you don't need to put it in the airflow.

Interesting discussion!

Pete

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Re: Possibly Found a Cheap Oil-water Heat Exchanger

Post by Lotus-e-Clan »

On both the Excel and Clan you have to be really pushing to get the oil much over 95C in the sump.

Also consider that these <100C temp measurements are at the sump, or post exchanger, but oil temps at the piston crown will be way over 100C once warmed-up normally (showing 82C post exchanger). The super-hot oil is soon cooled when it drops back into the greater cooler volume within the sump. Any water in the oil is driven off at these hotter surfaces (under piston crowns) that are way beyond the temps measured in either the sump or post exchanger.

So during normal running with oil temp equilibrated to coolant temp you don't have issues with water in the oil.

That said, oil brand is an important consideration. A while back, I ran Gulf Competition 10/60 in the Clan for a short period and thought I was getting coolant in the oil given the mayo film under the filler cap. That was a bit confusing considering I was running Evans waterless coolant.

Turned out it was water vapour from combustion emulsifying into the oil. Gulf competition is an ester-based oil and is very hygroscopic. Sludge found in the sump too. Swapped back to Castrol Edge fully synth and the issue disappeared. No problem with Valvoline VR1 either. I was informed by the engine specialist last week that Duckhams oil did the same thing - sludge in sump, mayo film under the filler cap.

EDIT: When I first started in biomed I got told-off by my supervisor for leaving the lid off a test plate I'd but in the 4C fridge. The plate would dry-out overnight I was told. I said don't be daft the temperature is too low. Got a flea in my ear and soon learned that evaporation does indeed occur at 4C! So even with the sump at 75C I wouldn't be concerned as long as the the breather system is doing it's job too.
Peter K

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Re: Possibly Found a Cheap Oil-water Heat Exchanger

Post by Pete Boole »

Will defo be running a full synthetic once run in. I'll have to look at how the breather system is arranged on turbocharged Esprits. I'll probably run a catch tank if I can find space.

Pete

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Re: Possibly Found a Cheap Oil-water Heat Exchanger

Post by lotushiast »

Great idea!! Where do plumb in the water hoses in the existing system?

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Re: Possibly Found a Cheap Oil-water Heat Exchanger

Post by Lotus-e-Clan »

lotushiast wrote:
Wed Dec 01, 2021 10:35
Great idea!! Where do plumb in the water hoses in the existing system?
You would have to modifiy the Excel's existing coolant hose route.

My Clan has the exchanger within the auxillary /heater circuit using 5/8 'heater hose'. Other Clan owners plumb the exchanger direct into the top radiator hose, or the bottom radiator hose. There are pros and cons for each exchange location.

Locating the Exchanger depends on which outcomes are most important to your application:
  • 1) speed of oil warm-up
    top hose location will prolong oil wam-up when the thermostat is closed -
    heater circuit will reduce oil warm-up time (especially if located pre- heater matrix) as long as you make arrangements for continuity of flow when the heater is off(!).

    2) Working oil temperature
    top hose location will (eventually) maintain oil at a higher temperature -
    bottom rad hose, or the return from the heater, will maintain oil at a lower temperature

    2) target Delta oil temperature value pre and post exchanger
    top hose = coolant heat goes into the oil at low road speeds (esp. traffic) and you get a small cooling delta at high road speeds/high revs when the oil is heated maximally by the very hot pistons;
    heater return hose /botton rad hose = small cooling /heating delta at low road speeds (rad fan on/off in traffic) , larger cooling delta at high road speeds/high revs (max rad cooling in ram-air)
For the Excel I would put the exchanger in the pre-heater matrix circuit for rapid oil warm-up with a larger cooling delta at high road speeds/@high revs/@high water pump speeds. You need then to plumb-in a heater bypass hose for when the heater matrix is shut off.
I've already modified my Excel's system with a heater bypass hose between the back of the head (near No.4 pot) and the heater return hose to reap the benefits to No 4 cylinder cooling when the heater valve is shut off.
This location also means you can have VERY short oil lines from the filter block to the exchanger because the new heater bypass hose will pass close by :wink: .

But there is more than one way to skin a cat so I expect there are other good ideas out there too. :D
Peter K

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