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Discussion Starter · #1 ·
I am thinking of adding a litchfield DCT cooler and maybe the diff cooler along with a duel pass radiator and they recommend a secondary radiator too.
My question is if anyone has any pictures of the DCT cooler fitted? How much do they cut on the underside and in the wheel liner?
I’ve got a picture I took when at litchfield of the cooler installed
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but they had none of the under body panels fitted.
 

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Was a guy on here running both the DCT and diff cooler. They worked but not as well as a cooler mounted up front.
He removed them and went AMS setup I believe.

I went for HKS in the end.
 

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Discussion Starter · #3 ·
I have looked at the complete AMS kit. It looks very good. Price is good in the USA but could imagine the import duty’s being high the hks looks a good option . My car looks reasonably stock. That’s why I would like to see the cuts required for the litchfield unit.
 

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I just searched my photo library and can't see any unfortunately other than the underfloor which has the exit duct fitted (the photo below was before I fitted the diff cooler as well, you can see it mounted on the driver's side with the inner arch removed.) The inner arch just has a cut placed in the acoustic lining that sits over the inlet duct. The exit vent(s) are quite discreet, it's just an aluminium louvre that's riveted into the underfloor rear quarter panels. I've also included a photo of the additional gearbox / coolant heat exchanger radiator which sits discretely out of the way under the car, it's a fairly new Litchfield product and I saw a noticeable improvement using it on track, and the supplementary radiator I've fitted.

I've fitted both the gearbox and diff coolers. They both help, undoubtedly. The diff as I'm sure you know, has no temperature sensing, so it's all guesswork and wishful thinking that it's not getting too hot. Also, it's not a huge capacity of oil either. So fitting the diff cooler does add a significant volume of diff oil, which also can only help as the fluid isn't working so hard, same as the gearbox cooler circuit adds volume.

The AMS cooling kit I've heard all kinds of wild claims about, but as is so often the case, no data or onboard laps with telemetry showing a car being driven hard and the coolant temps to decide for yourself before parting with a massive chunk of change... I'm totally past that. They (AMS) also use a dual pass aluminium radiator, but given that the dimensions are exactly the same, I simply don't see how it can be significantly better than the Litchfield dual pass radiator, which is also made from an extremely high quality core and is also dual pass, and beautifully made too. That being the case, running just an aluminium dual pass radiator still wasn't enough for me and I needed a supplementary cooler in the left front bumper (where the HKS heat exchanger fits...) So having a front mounted gearbox cooler wasn't going to be any use to me as I needed the real estate to fit the supplementary cooler- might be something to bear in mind before going for an HKS gearbox cooler.

The AMS kit does use a much bigger laminova for the gearbox cooling. I gather there's a further upgrade that adds an additional radiator too, but it would be very interesting to experiment with a bigger laminova for the GTR. I know how efficient it is because we tried bypassing the OEM laminova on mine, just in case it was overloading the engine coolant system, and apart from taking 15 miles for the gearbox temps to rise to a safe temperature (even in Portugal!), the gearbox temps just climbed and climbed on track to over 135 degrees until I aborted the session, even with the additional cooler fitted... So the OEM gearbox heat exchanger really is efficient and does a huge amount of the work to cool the gearbox.

A lot of my cooling problems are caused by running a race intercooler, so whilst that's still a work in progress, it's always a trade off on a GTR. If you drive it hard on track you will run into temperature management problems. Better rads, extra rads, vented bonnets, coolant additives, bigger thermostats... Done it all and we've still not cracked it fully. Even if you can control the engine / gearbox / IAT temps, your brakes will be dead after 3 laps too.

If you want a long and boring read of everything we've done to try and solve these heat management issues, the build blog is here and it has onboard video and telemetry too; CBA LM800 - The path to 900bhp

And for what it's worth, most of the track days here are about 18-20c ambient, so that also explodes the myth that GTR's only overheat in hot climates.

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This is the only photo I have of the rear of the car with the gearbox cooler duct visible. The Diff cooler is a mirror image on the right hand side. As you can see they're pretty discreet. You have to look quite hard to spot them.

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Discussion Starter · #6 ·
Thanks for the info. My gtr has only ever been to litchfield. It’s got there lm1000 with there log manifold with a well built gearbox. I have carbon ceramic brakes and there suspension and handling kit. So at the min it’s cooling that needs attention.
i got a price from them for duel pass radiator the extra radiator in the front. And the transmitter cooler. But was wondering how the transmission cooler looks. Underneath and in the wheel liner.
The first picture of the heat exchanger beside the drive shaft is that working better than the oil only cooler?
 

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My car is at Litchfields at the moment so unfortunately I can't send any pictures, but I can assure you it's very discreet, you barely notice the underfloor exits. It doesn't involve any cutting of the expensive bit (the carbon underfloor itself), only the side plastic pieces which are cheap as chips anyway. The cooler itself and the pumps are all hidden from view too, the pump sits in the space between the bumper and the inner exhaust heat shield along the side of the car. It's been really well thought out. Litchfield did my gearbox cooler installation when they built the gearbox, but I did the diff cooler installation myself, took the best part of a day.

The extra heat exchanger by the prop shaft was designed to take advantage of a bit of extra space for reducing the coolant temps, basically anywhere you can get airflow through a cooler matrix helps as space at the front of the car is at a real premium. As the gearbox heat exchanger (the 'laminova') leans on the engine coolant a bit, if you can run a cooler gearbox it will help engine coolant temps too. That said with this setup I never end up with really high gearbox temps, and the Titan Fuchs FFL-R is good for 135-140c.

You have the same manifold setup as me then, only difference is I am only running 850bhp on EFR6758's, but you will also have external water cooled wastegates which add to the cooling burden (although I'm assured it's way better to cool them to avoid the diaphragm splitting.)

Re carbon ceramics, you may get away with that, depends on the track and how hard you are on the brakes. But generally cast iron rotors are better on track, as the brake temps you can generate can oxidise carbon ceramic discs on a heavy car like a GTR. All depends on driver and track really.
 

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Litchfields have all the fitting instructions, just have them emailed to you.

There does’nt look like there’s much alteration and nothing that can’t be put back to std.

I think it’s the plastic panel underneath each rear qtr that they cut.

Nissans std radiator is pretty good, if you have a big race intercooler fitted it might struggle to get airflow.

Secondary cooler is not a bad call, it’s only a wasted space in the front bumper anyway. That’s where Litchfields stuff stands out, using space that’s not important and wasted.
 

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Where do you thinks a better placement?
High pressure area i.e. front bumper but it's already used by some of the guys for an additional coolant radiator from LM so not an option.

HKS diff cooler is interesting as it's a NACA type duct to a low pressure area under the car (rear undertray) so hot air should be sucked out as the car drives forward.
Maybe the LM stuff has the same idea given the 'exhausts' are in a similar area but the 'intakes' in the wheel arch liners, I dunno.
Wheel arch CFD is very complex.
Under the car is complex (couette flow here?)

I'm genuinely interested so if someone knows for sure, be delighted to hear.

@Litchfield are users on here. Maybe Iain will chip in.
 

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As you state, the front is occupied by the secondary cooler for the external waste gates more often than not.

I see turbo smart have gone onto electronic gates now so the possibility may be an option if there’s room on the Gtr for them And freeing up the frontal again. would you need to increase the venting on the undertray for the additional airflow as it’s really poor.

I don’t know if the long aluminium pipes that carry the water front to rear have been exchanged for a cooler by someone before? Maybe somebody else might have seen it.

Ive also wondered if they would be best run as two separate systems as well.
 

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The secondary radiator picks up straight after the turbo outlet. I've tried separating the engine coolant circuit from the gerabox cooling circuit and just relying on the gearbox cooler, and it's nowhere near enough. Also the laminova does warm the gearbox up very quickly, which you lose if it's not in the circuit. The additional gearbox cooler I posted previously sits in the engine coolant lines below the car. No idea how turbulent the flow is under the car but it did make a small but measurable improvement.

I've got a pressure sensor that I can move around to various locations, primarily to check the pressure at various points in the underfloor for brake cooling, but I could easily relocate it to the rear inner arch to check the local pressure there too. I'd hazard a guess that most of the airflow under the car is turbulent.
 

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I was thinking of leaving both coolants in place for the box.

joining the two hoses on the rear of the engine or having a pipe made in metal to do the same job To seperate the two.

Replace the long aluminium pipe will a long cooler which I’m pretty sure I’ve seen somewhere before and can’t remember. A water pump with temp switch fitted And maybe a reserviour in the arch somewhere.

The litchfield underfloor cooler was just a rip off of the Dodson one.

Theres also an extra vent for cooling on the later cars in the undertray, does this actually help?
 

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I could easily relocate it to the rear inner arch to check the local pressure there too. I'd hazard a guess that most of the airflow under the car is turbulent.
That'd be ace.



I'm out on tack on Monday. Can report back on the front mounted DCT cooler- transmission temps was what was stopping me last time.
On the road, it's never gone above the thermostat temp of 80°c regardless of how hards it's pushed.
 

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What about the time it takes to warm up the gearbox though? It took 15 miles with the laminova bypassed. I think the OEM laminova does a huge amount of work keeping the transmission cool, and when it was bypassed the engine got just as hot just as quickly anyway... I notice that AMS use a bigger laminova to cool the gearbox, that must be worth looking into?

The vents under the floor from what I hear, do more to cool the fuel tank than the gearbox.
 

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Replace the long aluminium pipe will a long cooler which I’m pretty sure I’ve seen somewhere before and can’t remember. A water pump with temp switch fitted And maybe a reserviour in the arch somewhere.

Sounds like what the AMS setup has albeit in a different location.
 

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On the road, it's never gone above the thermostat temp of 80°c regardless of how hards it's pushed.
To be honest neither did mine, in fact just driving around in the damp on track, 10 seconds off the pace, is enough to solve the overheating. But the minute the track grips up and the lap times come down, the overheating comes back. It's almost impossible to drive a GTR hard enough on the road to have a temperature issue I reckon. A lot of people never have the issue on track either, but then you see they're driving the car 10 seconds a lap slower than it's capable of going. I think that's part of the problem.
 

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On the road, it's never gone above the thermostat temp of 80°c regardless of how hards it's pushed.
To be honest neither did mine, in fact just driving around in the damp on track, 10 seconds off the pace, is enough to solve the overheating. But the minute the track grips up and the lap times come down, the overheating comes back. It's almost impossible to drive a GTR hard enough on the road to have a temperature issue I reckon. A lot of people never have the issue on track either, but then you see they're driving the car 10 seconds a lap slower than it's capable of going. I think that's part of the problem.
 

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I’d leave the Laminova fitted, just look at the options with it.

The extra vent in the later eba undertray flows directly onto the box, having an earlier tray means you can cut it and install one where you feel is best.

Would I be correct in saying that the v spec undertray has more venting than the std one?
 
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