Jonny Hart

If you were paying attention you’d have seen that I added 10 litres of oil. There was a bit in the bottom of the engine as I did not have to remove the sump plate. I knew I’d be having less oil but was a bit surprised to find it is quite over filled! So I measure the capacity of the original system. brass oil cooler. 1 litre All external pipes including those around engine. I did not fancy getting messing with these so I took a estimate based on 20mm bore and 5.5m total length. That gives about 1.8 litres. So a total of 2.8 litres for the cooler and pipes. My modern oil cooler is 0.4 litres and I have 2 metres of hose (0.6 litres) so 1 litre in total. So 1.8 litres less than stock. Plus the bit left in the engine explains that then! Out and about again today. Just sits right on the 90 deg mark +/- a needle width.

Cool cab. Your weights aren’t quite right, the IB washer bottle is 8.5kg when full not including pump of pipes. This might be of interest: https://www.classicretrofit.com/collections/other-parts/products/911-washer-bottle-kit

Our for a blat again. 25C ambient. This time with arch liner fitted. As predicted, no change in oil temperature. Next, with the engine already hot, I disconnected the fan and let it sit there. It warmed up and then plateaued just below the half way mark and stayed there. A bit cooler than a 964 with a failed oil cooler fan. Driving with no fan resulted in reaching the half way mark but I didn’t go any higher in normal driving but probably would under more load. Fan connected again and normal state of affairs is resumed as below:

Two steps ahead of you there mate. 🤓

The guard is going back on for round two of testing. I doubt it will make any difference as fully sealed fan arrangements like this do not use ram air. All they need is ample pathway to grab enough air from the input side. My full arch liners are worst case scenario but still allow air in from above and below. A full sealed fan is part of the reason why the fan will run most of the time. Interestingly, having played with a 964 last few days it totally needs the fan also when stationary. I’m ordering an even larger cooler as I can now see a way of fitting it, plus a higher CFM fan. I want to get to the stage where I can push the temp down on demand under prolonged load. I’m treating this like any product development. If you know anything about our products, you should know how thorough we are at testing but it takes time. Lots of time.

@Nige. Well there’s a couple of things that I’m mulling over... Oil thermostat opens at 82C. Looking closer at the fan stat it runs at 88C but has to get down to 79C before it will switch off. I’ve mounted the fan temp stat almost directly on the thermostat housing. This probably explains why the fan always runs. The body of the thermostat and hence the fan stat is always going to be at least 82C. The next move could be to put the fan stat nearer to the oil cooler. I’ll also see what happens with the fan off so I can gauge its performance.

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.

There’s always a way.

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.

^ Certainly ugly enough.

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.

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)

^. 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.

@Phill Must be an oil thing. 😂 Either resto, SSI swap or upgrade from ‘trombone’ or SC type. @Wingnonut, At the moment, it is just supported by the pipes and can be moved out the way quite easily for access to the valve covers. I’ll probably design a stay to secure it but it’s not going anywhere! @Nige, most oil thermostats on ‘normal’ cars are directly attached to the engine block. The 911 already has one thermostat in the centre of the engine for the ‘onboard’ oil cooler. Noted on the rear quarter on early cars. I have elected to run my fan thermostat on the return line to the engine and have gone for 90 deg C. The oil thermostat will let oil into the cooler at 80 deg C. This gap should give me some idea about how often the fan is required and whether the cooler provides cooling unassisted at all.