Rear Mounted Oil Cooler project

[jevvy]

Nice work Jonny, a project that has had significant ponder time in my head too so its nice to see you having a go.

I might have missed it but have you considered fitting a low-point drain / valve for the cooler and lines - be nice to increase the oil change effectiveness as a free 'win' with the mod.

[World Citizen]

13 hours ago, Jonny Hart said:

^. But my SC has no fan at the moment.    
 

Re stuck in traffic.   Are you seriously suggesting that an SC tube rad with no fan is better than a bigger modern oil cooler with a fan?   🤷‍♂️ 

Never suggested that but factor in the constraints/challenges a rear cooler installation has then I'm not so convinced

My reasoning is other than the larger cooler with a fan everything else about this installation is adding additional heat into the system a front installation doesn't create

Due to my 'how many ways can this not work that need to be fixed to make it work' 🤔 approach to automotive engineering I'm just raising a few valid concerns and not poo pooing anything here. 

[Phill]

If, for arguements sake, one's system was so far gone it was a viable option to purchase a new, rear mounted kit, could one, for example, reuse the thermostat, if it wasn't fubarred, buying the rest separately?

[flatsix777]

This is a very interesting concept and it would be great to understand how it functions in use. 

My 930 has air intakes on the rear wings which a PO added - they have no functional purpose but a rear cooler could change all that. I fitted a Carrera matrix cooler under the front wing with fan and also a front mounted cooler where the A/C condenser used to live in order to manage temperature on track. It’s compromised but works, although heat is still marginal in the worst standing traffic when ambient temperature is high. An improved solution, using my rear air intakes, is appealing. 

Good work & fair play for getting on with it.

Cheers 

David

[Jonny Hart]

^. The slantnose Turbo cars use a single cooler in front of the rear wheel - of course they have the air intake but when stationary they have a puny fan to assist.   Weirdly, from pictures it looks like the fan is horizontal at the bottom so it is either blowing up or down. 

[Jonny Hart]

[Jonny Hart]

This is the hottest oil temp my SC has ever seen.  This was after 40 minutes of idle in the climate chamber at RIcardo (42 degrees C) during AC testing.  We had two fans at the front to simulate road speed and a duct at the back to blow some air over the engine.  Engine lid was open.   (In case you're wondering, I had just switched the engine off, then wanted to take the picture so turned the ignition on hence no oil pressure)

 

 

[GaryH]

Take it on track at Bugatti for half an hour in the summer and check the temps then Couldn't touch the rear bumper blade it was so hot

[anglophone1]

11 hours ago, Ian Comerford said:

I’m looking forward to you posting this on Pelican Jonny, it will wake up all of the naysayers who went on for ages about your AC not being viable.......

Spot on Ian- this’ll shut them up!

[Ian Comerford]

11 minutes ago, anglophone1 said:

Spot on Ian- this’ll shut them up!

Well, it will probably wind them up initially.......

[8bucksagallon]

Ahh yes, southern california Porsche owners, the cradle of all knowledge......

[Ian Comerford]

I’m not sure they were all from Southern California....

[Kenny Senior]

I'll be following this with great interest. The cooling setup in my 3.6 install isn't perfect and a jaunt to the Nurburgring last year in 37C ambient temperatures saw me struggling to keep the engine cool during steady 80mph autobahn driving despite two matrix coolers at the front with fans and Elephant Racing finned oil lines. 3.6 engines don't have the engine mounted cooler and they suffer for it when they don't have the big cooler and airflow that the later plastic bumpers allow with all those vents.

I've thought about a rear mount cooler like yours which looks a similar size to the 964/993 item they have under the front wing, but couldn't work out a decent solution. I could even recoup some cost selling on the ER lines and sundries. I've come dangerously close to cutting vents in my backdated S bumper but having gone to great lengths to get the look I want I can't bring myself to let loose with a jigsaw.

[Jonny Hart]

All buttoned up, just waiting for oil delivery tomorrow.    I’ll put a guard on after I’ve checked for leaks.  

 

Put a second condenser and fan up front.   AC runs silly cold now.  To the point I’ve had to implement evaporator freeze protection in the firmware.  

Total (dry) weight of the Porsche oil lines, thermostat and oil cooler 12kg.

New oil cooler, thermostat and lines ~4kg.

AC condenser, fan etc  ~2kg.  
 

Will report back on oil temps and performance.

 

 

[World Citizen]

Just seen this on PH, If it's good enough for Koenig Ferrari 512BB.....

[Jonny Hart]

^ Certainly ugly enough. 

[Busybee]

Hope this works for you Jonny. Struggle to see how you'll get any natural air flow in there and whatever type of cowl is gonna need to be tough. But I'm here to be shown the error of my ways. And how exciting if it works. Maybe I can use it on Daisy with her 3.8!

[8bucksagallon]

As busybee says above, interested for the 3.8. I realise that from a production perspective as few variations as possible need to be included, but my particular car has a Turbo tail which seems to have space for a large inter cooler which obviously isn’t there. Does that space have any potential for fitting a cooling radiator, or is it in the wrong place? It would certainly allow for a larger surface area. Which way does the air flow on these cars? Is it out the top, or in the top?

[Busybee]

In from the top, down through the Cylinders and out the bottom. You don't really want to be pushing warmed air in through there though. I'd say the most efficient place would be right up at the nose as in the RS style bumper? 

[Leicestershire]

The oil cooler on my Griso motorcycle is side mounted.

The design of the cover and the shape of the fins make it very efficient at cooling the oil (air / oil cooled engine).

 

[Jonny Hart]

Ok, so I glugged in 10 litres and built some oil pressure just to be sure.   Connected the CDI back up and fired it up.   A good start.  No oil leaks and no dramas. 
 

Out on the road - up to temp which is just under the 90 deg white mark (8 o’clock position).    Fan was not running .  After a few miles it didn’t seem to climb anymore so I pulled over to feel if the 80deg thermostat had opened.  It had.   And as I stood there the fan came on.   Oil temp is now on the 90 deg mark (fan stat is 92C) and then gets pushed down by fan to just below mark again.  Fan goes off. 

Ragged it along a straight a few times and the oil temp rises a bit above white mark.  Fan comes on and keeps temp in check.  Then down to idle, fan keeps running for a few mins then off. 

Didn’t have that much time today so only a short test.  I was also very conscious of oil pressure and leaks etc so easing into it.  What I need to do now is put some more load on the engine.

AC is arctic with the extra condenser. 
 

 

 

[Phil]

Hi Jonny,

Thats a tidy installation. Will it work with a standard exhaust system fitted with a pre silencer ?

cheers Phil

[Jonny Hart]

39 minutes ago, Phil said:

Hi Jonny,

Thats a tidy installation. Will it work with a standard exhaust system fitted with a pre silencer ?

cheers Phil

There’s always a way. 

[Kenny Senior]

I'm really very excited for this if you put it into production. My current setup with two matrix coolers, one in each front wing just isn't efficient. I'd probably look to run this along with the normal offside front cooler if I can plumb it up that way. At least then I can do away with the extra aftermarket cooler in the nearside front arch.

[Jonny Hart]

Ok, some more testing today.  25 deg C ambient.  Did an hour of mixed driving, country lanes, crawl through town and then some A21 fast stuff.  There’s a good hill on the A21 for some engine load.  

Firstly though I got it up to temp and just let it sit there.  Fan comes on at 90C mark and it just sits on the mark forever.   The fan keeps running.  

Then, during normal driving, fan does stay on pretty much all the time, temp doesn’t really move that much.  90C plus or minus a needle width.  Mostly just below. 
 

Onto the dual carriageway.   Quite a bit of traffic today but tried to recreate some high load conditions.  Fifth gear WOT up hill.  Hottest I could get was this, about 100 deg C  

Observations:

1)  the oil temperature climbs and drops much faster than with the original non fan cooler. As well as the fan, I guess there is less oil having no long lines and so less thermal inertia.  
 

2)  the fan pretty much runs all the time once warm.  The thermostat is 82C and I have a 92 deg fan stat.   This shows that the fan is needed without the long oil lines etc.  

3)  I could actually fit a taller oil cooler.  There is room for a few more rows.