2GR cooling

[Ash Kelly Barr]

Hey guys just want to get some thoughts from those that are running 2GR setups.

Background:
2GR in AW, highlander with towing option (oil-water cooler)
Suspect the rad is a bit to small.
Still NA on OE denso ECU

Good:
normal driving around town is sweet, water temp sits between 87 and 94, no big deal

Issue:
Giving it stick and maintaining RPM between 3500 and 5500 (even less) for sustained amount of time water temp sky rockets!
It keeps going up and up until I back off and haft to chill in 5th for several minutes for it to return down to 90-95 again.

Not only is it water temp issue but because the oil is water cooled I feel the oil is getting to hot and is thinning down to much.

Understandably I want the motor to last, so I want to make sure the oil is staying within it operating temp

Solutions:
So a bigger and/or sectioned radiator will help coolant temps, and help them get back down quicker after a thrash

But I'm also wondering if I ditch the water cooled oil cooler in favour of a standard oil cooler?

As water temp rises, oil temp is rises as well, water returning is heated by the oil and there's a sort of compounding effect.

I'll be getting an oil temp sensor/gauge to monitor it.

So what's people thoughts on splitting the oil cooler system away from the coolant?

Has anyone got any data logging of temps on their setups?

[lasersooby]

Hi Ash, have you tried emailing Marc at frankensteinmotorworks. He has done a lot of work around the 2GR installs in both the AW11 and the SW20.

Try contacting hime through his webpage, see below:

http://frankensteinmotorworks.squarespace.com/

Regards, Mo

[Mr-Paulio]

Hi Ash, I don't mean to hijack your post but also wondering if anyone has just tried upgrading the existing cooling system?
When I refitted my 4AGZE I fitted an aluminum radiator from redline, obviously new water pump and fresh coolant, and with the AC gone wired the condenser fan to the radiator fan so they both operate on the cooling system.
I know it's only a 1600, but the cooling system really does not work hard at all now. This is vastly noticible over the way it was. The car has to be stationary idling for quite sometime before the fans operate. (Initially it worried me) And even then they only run for about 10 seconds.
Maybe worth looking into also?

[85AW20v]

When was the radiator last cleaned out - and I mean by a radiator shop with the tanks taken off and the tubes rodded? That could be all it takes as the AW radiator is rather large compared to the size of motor - about 150% bigger than my son's 1600cc Civic. I would think capacity would be fine once that was done.

[mickeyduck]

Simon has a very fair point Ash. Copper radiators actually shift heat more efficiently than aluminium ones (thermal conductivity of copper is better) but new aluminium ones are squeaky clean inside whereas 25 year old copper ones are half gunked up. Get a copper one professionally cleaned and chances are it'll be twice as efficient.

Or do what I did for my HR Holden after I race worked it (to Bathurst XU-1 specs). I went to Western Radiators in Henderson and had them make me a new radiator with a core that was twice as thick, so it bolted up just the same but shifted twice the heat. Did the job real well, cost me a few hundred bucks.

If I ever trick up an AW I'll be getting a rad made from copper that's twice as thick cos I know for a fact it works. Your motor is twice the capacity. Give it twice the rad. And decent fans.

And vent the bonnet perhaps too so the heat can go away easier? If it isn't already (I don't remember).

[GDII]

I found this a good read. Additional information to what you provided Charlie.

http://www.onallcylinders.com/2012/12/1 ... -radiator/

[mickeyduck]

Very interesting indeed! Nice.

I wonder if anyone makes custom Aluminium radiators? Or if you are restricted to buying what you can find on the market? That was one good thing about a copper one - hand made to spec, twice the capacity of a standard one. From the sounds of it if you can get an aluminium one made twice as thick as standard, you'd be SWeet.

[GDII]

The place I have got radiators from says they make custom ones. I haven't had one made there though. There will be quite a few places around who will but for the cost of one from another car that can be made to fit it's not always viable. But as it's an important part of the car it's probably worth it if that was something that needed to be done.

Just like a custom intercooler made to fit your car. Sure it can be expensive but when trying to make an intercooler fit into a car that never had one or had a very small one like an SW20 then that is also a good option. Like HyperTune in Australia making custom CNC'd end tanks to fit a specific application or even an intake manifold or adapter plate. Getting off topic now.

[Malcolm]

I found this a good read. Additional information to what you provided Charlie.

http://www.onallcylinders.com/2012/12/1 ... -radiator/

Jeez what a lot of nonsense! Sounds like the guy from the Summit technical department is about as clued up as your local pimply-faced Repco salesman. I can't believe any technical article would propagate the myth that coolant moving too quickly through a radiator gives you worse cooling.

To answer the original questions, Ash; I agree that you should definitely check out the state of your current radiator - the AW11 one is virtually identical to the SW20 and they're both more than adequate for your power plus quite a bit extra.

As for the oil cooler - first step there would be to look at oil temps - generally you can handle oil temps up to 130-140 degrees C, but if you're hitting that on the road then it probably means you'll be massively overheating it if you take it to a track. If your oil temp is close to coolant temp or even below it, there's no point separating the system off.

And a few general comments about the physics behind radiator/cooling system sizing: generally, there are diminishing returns for increasing radiator size and/or coolant flow rate: a radiator that is twice as wide will not reject twice as much heat, a radiator that is twice as thick will not reject twice as much heat, a coolant flow rate that is twice as high will not reject twice as much heat. This will always be true, but how steeply diminishing the returns will be for each change is hard to know without actually testing.

To understand the reason for these diminishing returns you need to realise that radiators are all about temperature differences. When air first hits the radiator it might be 80 degrees cooler, once it's traveled through 10mm of core thickness and absorbed some heat the temperature differential might be 50 degrees, once it's gone through a further 10mm of thickness the differential might be 30 degrees. For every bit of extra thickness you add, the more hotter the air becomes and the less efficiently it cools.

From my experience with cooling system testing on various cars and similar vehicles, the biggest limitation tends to be airflow through the radiator. Because air is much less dense than water/coolant and has a lower specific heat capacity, you need a shitload of it in comparison to the coolant flow, and usually it ends up being the biggest limitation. Interestingly, this can lead to the situation where making the radiator thicker, and therefore creating more resistance to airflow, can actually cause the cooling of a vehicle to get worse! Not likely the case on your average road car with a large frontal area and thin core, but if your starting point is a 38mm core and you replace it with a 76mm core, it can happen (I witnessed this on a vehicle I was involved in the development of a couple of years ago)

[Malcolm]

crap I did that thing where I went to edit but clicked quote instead and now there's a silly double post, plus this one explaining it

[Benckj]

Deleted previous post for you.

[mknz]

What Malcolm said, the exact same shit pops up in computer cooling.

[mickeyduck]

Diminishing returns, sure. Double the thickness may not mean double the cooling ability. But nobody ever fitted a smaller radiator to a car that had overheating problems.

If your thicker radiator isn't doing the job then yes you might need more air flow to cool off the larger dose of heat that is in that thicker radiator, which is why I mentioned fans. And yes at driving speed you might perhaps also need a larger air intake.

The point of a larger radiator is to use the ability of water / coolant to convey the heat to a larger surface area, for a larger volume of air to then dissipate.

Aim at that simple idea and it will work.

Making a thicker radiator is simply the easiest way to increase its surface area within the confines of a vehicle without butchering the car. After that, as I said originally, just add more airflow for idling conditions (look at the fans). Going full noise you'll likely find there's a ton of air going through it anyway.

[mknz]

Like the others have said though it's best to start with the easiest/cheapest stuff first before you start swapping parts especially with many people swapping 2GRs and not much cooling issue reporting.
Flush/Check there is no serious flow blockage (especially in the radiator because it reduces the effective SA)
Run 50/50 coolant/water if you're not already (or run less antifreeze and more water but keep the anti-corrosion the same) (water is a much better conductor)

The above two are if the water at the hot side is 'much hotter' than at the cold side (that can imply lack of medium/heat transfer) while if both are 'close' in temperature that can imply inadequacy of the radiator's SA, airflow or both. (definitions are loose, cold and warmed up give different results obvs, blah blah blah).

Doubling is fine for 'thin' (definition of thin gets complicated) radiators as not much more pressure is needed for the air to flow through. However once you start getting 'too'(same shit) thick the amount of airflow decreases because more pressure is required. To increase airflow you can either space out the fins more(defeats the point of a bigger radiator as less SA) or have fans that generate more pressure or utilise a push-pull configuration. After a point though you will be forced to run two radiators(but that is a serious amount of heat to dissipate).



***I have left things simplified, cooling system design is hugely dependant on which parameters can be changed and by how much. I can give you too many engineering books if you wish on the subject

[mickeyduck]

Like the others have said though it's best to start with the easiest/cheapest stuff first... Flush/Check there is no serious flow blockage

Agreed. As stated earlier.

Doubling is fine for 'thin' radiators as not much more pressure is needed for the air to flow through. However once you start getting 'too' thick the amount of airflow decreases because more pressure is required.

Yep. But driving down the road you tend to find there is quite a lot of pressure and quite a lot of air passing through. Unless your air intake is absurdly restrictive. When you're stuck in traffic that's when you tend to find you need serious fans to pump enough air through there.

I can give you too many engineering books if you wish on the subject

Ash may be interested Michael, and good on him if he is. Me, I'm just going on my experience of race working an old Holden to divide its 0 - 100 kmh time by a factor of three, and what worked to bring the extra heat generated by the extra herbs back under control in the most cost effective manner available to me.

I didn't have engineering books to consult. Just a bunch of experienced old professionals that built race cars and dragsters, and some experimentation and evolution while observing the results.

I'm not out to claim I know better than anyone else, or that I'm more learned. I'm merely trying to pass on some stuff I learnt through my own practical experience in the hope it helps someone else. But if that paints a target on my back, well hey... Call me a dummy and let's leave it at that.

This is Ash's thread anyway so let's just hope he manages to cure his overheating issues. That's all that matters here.

As we all started out by saying in the first place, and as you seem to have reiterated, Ash should probably start by sending the radiator off to have it professionally cleaned out and go from there. Certainly the cheapest option. Or at least it used to be before things were made in China...