Oil Cooling Airflow

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casey
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Oil Cooling Airflow

Post by casey » Thu Apr 23, 2015 8:01 pm

Having suffered oil temps of 116 degrees in an ambient of 20 degrees recently when 5-10 minutes into a track session I decided to see if there were any easy way to try and reduce the oil temp under these conditions. If I came off the power, the temps would drop noticeably within ~20 seconds, but ruins it rather the track experience! The temp is measured with an R-Spec gauge with the sensor mounted on an oil filter sandwich plate.

I came across a thread on the RX-8 US site where a number of people had adapted the front inner wheel arches to improve airflow over the oil coolers. It made sense to me, and the claims were for ~5 degree drop in temps in extreme conditions, just what I need to bring the oil temp into a "safer" range (100 ideally, 112 absolute max).

With acknowledgement to RX8club.com, here is the procedure to remove the inner wheel arches and make the mod (I have adapted the procedure slightly, having just completed the mod on my car)

1. I remove the front wheels to make it easier, BUT, you do not have to.

2. Remove the 10 or so black plastic screw nut clips with a small Phillips head screwdriver.

3. Remove the 3 Threaded steel screw nuts near/under the front lower bumper (NOT the ones what hold on the small black plastic wind deflector that looks like a ruler on it's edge).

4. The black plastic guard will now easily come apart from the main one , the removed shield is now the part you will work on.

5. Use a blade saw (or a Dremel in my case) and carefully remove the 3 vent partitions (in the two top vent slits, see the first pic) to lengthen the size so you now only have ONE middle partition vent joiner in each, so it will now look like the bottom two vents.

6. Use the Dremel to create an extra vent at the top slit.

7. Use a rasp file (or suitable Dremel tool) to smooth, straighten and correct all the new openings to match the original ones.

8. Enlarge the width existing vents by about 25% using a Dremel cutting blade (or small saw).

9. Wash off the Black plastic bits.

10. That is all, replace the shield in the reverse order when you removed it.

This is a VERY easy mod....

Note: I DO NOT RECOMMEND THAT YOU ENLARGE THE VENTS TOO MUCH AS YOU ARE THEN EXPOSING YOUR OIL COOLERS TO TOO MUCH ROAD WATER SPRAY/STONE DAMAGE/WEATHER.

Before;
Image

After;
Image

I have a track day at Croft on 5 May. It the weather is hot (yes please 8) ) then I'll report back if the mod have improved the oil cooling!
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Re: Oil Cooling Airflow

Post by duckula67 » Fri Apr 24, 2015 12:49 am

Interesting.
Look forward to the results!
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Re: Oil Cooling Airflow

Post by Clive » Fri Apr 24, 2015 8:19 am

As discussed on the phone I would say you could go a little more extreme and make more of a difference as I did and cut out the bridges between the slots

Also there was somebody selling a vented bonnet this week which will have a dramatic effect on water temps and stop heat radiating out into the oil system -----------or alternatively you could just go slower :mrgreen:

Hope this helps

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Re: Oil Cooling Airflow

Post by bigpete » Fri Apr 24, 2015 8:47 am

I've noticed my oil temps have gone up since fitting the greedy sump, which casey has had fitted not so long ago and wonder if this has bought the oil temp up for some reason?
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Re: Oil Cooling Airflow

Post by casey » Fri Apr 24, 2015 10:44 am

@Clive - driving slower isn't an option :wink: - but I had to at Snetterton after 5-10 min stints in the pm session to keep temps under control :cry: I might open the vents up a bit more after I get some experience as to whether it's had a noticeable effect. I was concerned about stones getting thrown in there from the wheels, although the angle of the slots helps to prevent this. I did see one guy who has removed a whole 10" square section and then cover it with a fine mesh - I might be tempted to try that!

@bigpete - interesting; before fitting the Greddy sump I had occasional water temp issues on track, but not oil temp issues....

Another observation (I believe I saw this at Snetterton) was that the oil temps would tend to stay "in control" up to about 105 degrees (just rising gradually), then the temp would rapidly rise beyond this point - and rapidly cool if I short shifted and kept revs lower

I'm going to change the oil (well, at least 4 litres via Pela pump) before Croft as it's due for a change and the extra heat cylcing might have compromised the oil's properties. Better safe than sorry!
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Re: Oil Cooling Airflow

Post by Nerdstrike » Fri Apr 24, 2015 1:39 pm

The Greddy sump does two things - increases oil capacity, and adds different baffles. I wonder if you get some kind of hot loop in the oil flow and it doesn't cycle as much of the volume? The extra thermal capacity in the sump would slow both rise and fall of temperatures.

Alternatively, what if it were a new regime in the water cooling?

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Re: Oil Cooling Airflow

Post by RickyG512 » Fri Apr 24, 2015 1:51 pm

That RadReleif engine coolant additive is meant to bring temperatures down by 10 degrees!
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