# Upgrade engine oil cooler or radiator first for track?



## m1ac_drew (Apr 2, 2002)

Me again...

For track use, upgrading which component is likely to have the greater reductive effect on engine temperature, the engine oil cooler or the radiator? Obviously in an ideal world, both would be changed at the same time, but I am curious to know if I decide to do one and then the other (or one and not the other), which of the two is likely to yield the colder temps and why?

I know that the engine coolant has a heat exchanger with the transmission oil, but I am rigging up a separate cooler for that as well as the rear diff.

Secondly, is it better to replace the engine oil cooler or add another somewhere else?

Also, bonus question: what is the thing that looks like a radiator directly in front of the radiator and behind the intercoolers? I briefly tried to follow the hoses to see where they went, but couldn't work it out yet. I've indicated it with the blue arrow in the attached photo.


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## WingedBeast1968 (Sep 18, 2009)

Air conditioning


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## m1ac_drew (Apr 2, 2002)

Ah, thanks


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## m1ac_drew (Apr 2, 2002)

Demon Tweaks currently have the Mishimoto MMRAD-R35-09 radiator with a 6% discount, which is the best price I found:

https://www.demon-tweeks.com/uk/mishimoto-performance-aluminium-radiator-mshmmrad-r35-09/

I've got the front bumper off the car, and while it wasn't the hardest job in the world, I don't particularly want to have to repeat it if not necessary, so I may do the oil cooler at the same time. 

I'm wondering if I should get a GT-R specific cooler like this:

https://auto.helperformance.com/nissan-r35-skyline-gt-r-oem-replacement-oil-cooler

Or a high-quality universal one like this and adapt to fit:

STD Proline oil coolers, The widest range of race proven coolers on the market! | Setrab


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## L6DJX (Sep 15, 2017)

oil cooler - all day long

speak to litcho
theirs is cheap and awesome
my oil temps hasnbt been over 95 since


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## m1ac_drew (Apr 2, 2002)

I think the Litchfield cooler is the HEL, they certainly look identical, same price too, within £5 or so. 

I just got off the phone with one company I called to enquire about the Setrab coolers and they recommended I replace the OEM engine oil cooler with a Laminova oil-to-water (he confirmed replace, not add in-line with OEM). 

This surprised me a little as though I have seen mention of them for applications such as the transmission and rear diff, I had never considered one for the engine oil. I'll possibly have enough buffer now with the enlarged radiator, still not sure about the idea...


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## Cardiff R33 (Jan 16, 2004)

Trans cooler is first concern Imo


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## L6DJX (Sep 15, 2017)

trans and engine oil 
depends how much track work you plan to do i guess


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## m1ac_drew (Apr 2, 2002)

Cardiff R33 said:


> Trans cooler is first concern Imo


Agreed and it's in progress; just waiting for parts to arrive


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## m1ac_drew (Apr 2, 2002)

L6DJX said:


> trans and engine oil
> depends how much track work you plan to do i guess


My goal is to go to the Ring, not to do tons of laps, but the laps are very long compared to a 'typical' track, so one lap will equate to 7-8 laps elsewhere.


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## m1ac_drew (Apr 2, 2002)

I sent the HEL engine oil cooler back, ordered one of these instead:

https://www.demon-tweeks.com/uk/setrab-proline-engine-transmission-oil-coolers-501330/

34 rows vs 14, 264mm height, same width and depth and stock.

Even with the brackets, fittings and the return postage for the HEL, it's still over £100 cheaper and should be way better.


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## m1ac_drew (Apr 2, 2002)

The Mishimoto's core is approximately 10mm deeper than the OEM; should help things, including providing cooler fluid to the transmission heat exchanger.









I have a Setrab SLM 14-row 420mm wide cooler going on for the transmission. Another 1-2 coolers going on for the diffs. Want to do one cooling circuit for the two diffs, with one cooler at the front and possibly another one at the rear.


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## Hugh Keir (Jul 25, 2001)

Gearbox temps are a real issue on the GTR and given the expense of getting your gearbox fixed, it would be one of the highest priority items for me.

I use the HKS kit, but have also seen that dudersvr on the GTR Forum has developed a very efficient gearbox cooling system.

Be interested to see how you mounted your engine cooler once complete?

Cheers

Hugh

.


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## m1ac_drew (Apr 2, 2002)

Yes, I've been following dudesvr's design with minor alterations. He's been really helpful since this is my first DIY car plumbing project. I have nearly all the parts and have modified my shroud to accommodate the cooler. Just need a few more AN fittings and small sections of hose.

Will indeed post up pictures of the engine oil cooler once fitted. I checked the OEM duct last night and it will fit with some Dremel modification. I'm waiting for the brackets to arrive plus I have sheet metal in case I need fab anything. Have attached some pre-install photos (smaller cooler is for the differentials).


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## m1ac_drew (Apr 2, 2002)

Brackets have arrived...


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## m1ac_drew (Apr 2, 2002)

Turns out I mistakenly ordered the brackets for the diff cooler and not the engine oil cooler, so I'm having a go at creating my own brackets with the sheet metal. These are my first attempts at shaping and cutting...























The thickness is spot on, but need to get a longer sheet.


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## m1ac_drew (Apr 2, 2002)

My lower cooler bracket was quite corroded, so I removed and went at it with a metal brush on an angle grinder to take off the rust and loose paint:























I'll prime and repaint it by hand with some high-build all-weather paint. I also re-tapped the threads and will order A4 stainless steel bolts to replace all the OEM bolts I've removed.


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## dudersvr (May 7, 2003)

Interested in seeing the difference the rear diff cooler makes, I think the front is a little overkill.


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## m1ac_drew (Apr 2, 2002)

I'm going to be cooling the rear and front diffs together on the same circuit, in parallel; the Mocal oil pump is pretty heavy-duty and should be able to handle them both easily. Just one pump and one cooler.

The additional cost of cooling them both this way (vs rear only) is negligible, just some extra hose and a few extra AN fittings. The AN-10 hose in and out of the pump and cooler is roughly twice the size of the AN-6 hose in and out of the diffs:









I haven't decided yet how I'll switch on the pump. I see Willall Racing turn on the diff cooler from the transmission temperature switch. I also considered having temperature switches on both diffs and turning on the pump when either reaches its threshold. I'd also like to have gauges for their temps. Will be fitting the diff cooler last, so still have some time to decide.


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## m1ac_drew (Apr 2, 2002)

Time to resurrect this thread!

Not much has happened with the car over the past few weeks. I had to come up with some custom parts to complete the plumbing:

* An oil flange to M22 adapter for the engine oil cooler













* A rear differential drain plug with a banjo bolt thread







* A rear jack point extension to provide enough clearance for the banjo







* A pump bracket for the transmission oil pump








Will be hoping to make some more progress over the coming days and weeks...


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## m1ac_drew (Apr 2, 2002)

Bracket for the differential cooler, to be mounted directly above the windscreen washer reservoir:















I made this out of a piece of mild steel sheet: folded, cut, drilled, primed and painted - having great fun learning how to do all this! Bolts and washers are marine grade stainless steel.

I cut the Setrab bracket to provide easy access to the two mounting bolts:









All the plumbing is complete, and I hope to start refilling the oils today.


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## m1ac_drew (Apr 2, 2002)

Some WIP pics:


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## m1ac_drew (Apr 2, 2002)

Front diff connections:















Slightly marred the fittings, but these aren't visible, so not too bothered (the only two visible connections are to the transmission cooler, and I was more careful with them).

Was a real challenge to fit the front diff fill hose, as there is not much space to work with, but I managed to use a straight fitting instead of a banjo bolt. Had to make a custom tool from an old spanner:


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## dudersvr (May 7, 2003)

I think front diff is totally unnecessary, it just does not do much work and has no way of effecting the other components temp wise, for best cooling logic says trans, rear diff, engine coolers and radiator all work in harmony to lower temps across the board.


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## m1ac_drew (Apr 2, 2002)

BAILIYAT said:


> I've got the front bumper off the car, and while it wasn't the hardest job in the world, I don't particularly want to have to repeat it if not necessary, so I may do the oil cooler at the same time.


It gets easier each time you do it. I put mine on and off twice today while checking for space around my new coolers. I also made sure to cover up the wings this time. 

I think I need to trim a bit off the bottom left corner of the engine oil cooler bracket; need to see if it clashes with the front tray, bumper itself is fine.

















Refilled the engine with new oil today: six litres exactly with the cooler and filter change. I realised she probably won't have another opportunity for such a thorough oil change, so decided not to put the old oil back in...


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## m1ac_drew (Apr 2, 2002)

Checked the clearance of the bottom of the cooler last night and it looks good.

Just ordered sheet aluminium to make the new air ducts. I thought about hacking around with the stock engine oil cooler duct, but decided I could do better building a bigger one from scratch.

Baliyat, I have a spare pair of the flanges that enable plumbing an aftermarket oil cooler. PM me if you're interested.


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## gtr mart (Mar 29, 2004)

dudersvr said:


> I think front diff is totally unnecessary, it just does not do much work and has no way of effecting the other components temp wise, for best cooling logic says trans, rear diff, engine coolers and radiator all work in harmony to lower temps across the board.


I tend to agree it's probably overkill, however is there a possible benefit in that it will warm the front diff fluid more and also improve rear diff cooling by increasing the thermal mass / quantity of fluid going through the rear diff?

Certainly interested to see the results although wont be easy to test


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## dudersvr (May 7, 2003)

gtr mart said:


> I tend to agree it's probably overkill, however is there a possible benefit in that it will warm the front diff fluid more and also improve rear diff cooling by increasing the thermal mass / quantity of fluid going through the rear diff?
> 
> Certainly interested to see the results although wont be easy to test


Front diff cooler is separate to rear so nothing can be warmed up and rear diff is separate to trans so is not really being warmed at all to any degree, thats why the drag cars are run on stands or driven around the paddock.


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## m1ac_drew (Apr 2, 2002)

My front and rear diffs are parallel plumbed into the same cooler so yes, they will share whatever warmth they have. Inline oil filtering is also an advantage.

The circuit is like as follows:

Two diffs (drain plug) > one filter - one pump - one cooler < two diffs (fill plug)

I haven't fitted any temperature sensors to the diffs, so won't be able to measure impact directly. Their pump is activated by the temperature switch on the transmission sump, same as the pump for the trans fluid.


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## dudersvr (May 7, 2003)

m1ac_drew said:


> My front and rear diffs are parallel plumbed into the same cooler so yes, they will share whatever warmth they have. Inline oil filtering is also an advantage.
> 
> The circuit is like as follows:
> 
> ...


Are the diffs filtered? so if you lose the front it does not pollute the rear?


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## m1ac_drew (Apr 2, 2002)

The only filter I have added is the in-line one before the pump. It's the SUSA 150 micron filter with a magnet too. This collects debris from the oil output of both diffs via an AN Y-connector, so no notable cross-contamination can occur.


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## m1ac_drew (Apr 2, 2002)

There's another Y-connector after the oil cooler to split the lines heading back to the two diffs.


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## gtr mart (Mar 29, 2004)

dudersvr said:


> Front diff cooler is separate to rear so nothing can be warmed up and rear diff is separate to trans so is not really being warmed at all to any degree, thats why the drag cars are run on stands or driven around the paddock.



LOL you need to read the messages John. He joined the two circuits.

As for the filter, that sounds like if you have an issue with the front, then it stands to contam the rear as suggested. Would be worth putting another filter on. if there aren't measurable benefits I would be tempted to keep them seperated.


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## m1ac_drew (Apr 2, 2002)

Neither diff can contaminate the other with anything magnetic nor with anything bigger than 150 microns. Worst-case scenario is that I lose a diff and have to clean/replace the filter element.

How often do these diffs fail? I'm assuming it's obvious when they do, there should be some sound or feeling through the controls?

It's always more efficient to cool multiple heat sources on the same circuit provided that the total heat produced doesn't exceed the thermal transfer capacity of the cooler. This experience comes from building liquid-cooled computers with multiple CPUs and graphics cards in hot countries. PC components can be plumbed in serial because the heat exchangers are sealed; central heating systems work on the same principle. I opted for parallel because the diffs have breathers, making it impossible to maintain pressure through them both in series, I also didn't want the heat from one going to the other before passing through the cooler.

Two filters would only be required if the two diffs were plumbed in series, which isn't possible anyway.


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