Radiator questions (upgrade for 1UZFE Lexus V8)

[-Nemesis-]

--------------------------------------------------------------------------------
I've been doing as much reading as possible on radiators to keep my 1UZFE cool in my 94 4Runner. Before I fork out a grand or whatever for a custom jobby....

I found a post on here from way back someone saying they put a FJ75 series cruiser radiator in theirs for a commo V6.

So anyways i've been scouring the eBay stores as they have all the measurements on their auctions from one seller who is a radiator shop.

For arguements sakes the original radiator in mine has a core dimension of 476x528x48 and it's a double core.

Anyways out of interest I started reading more, and clicked on a HJ75 Diesel radiator. Now it's dimensions are 495x530x65 and it is also a 4 core. Making it 2 inches taller than a FJ75, or an inch taller than the 4Runner.

http://cgi.ebay.com.au/TOYOTA-LANDCRUIS ... dZViewItem


So 3 things....

*Do people in the know think this will cool the 1UZ? Keeping in mind the 4Runner radiator can almost keep up. Normal road driving with a good thermo usually keeps the temp in check. But too much load or constant climbing pushes the temp up.

* What is the pros and cons of a 4 core thats close on an inch thicker?

* And, how is the price on that auction>? Adding freight it sounds good to me for a new one, but I haven't shopped around.

[pongo]

Is the 4runner rad your using now a diesel one ? . I heard that the diesel ones have an extra row in them.

Im only speculating so dont rely on this

[-Nemesis-]

Yeah i've heard the diesels have a triple core, but mines the V6 one which is 2 core. Wasn't sure if that'd be enough though, as I want it to be as cool as possible.

I've concluded that diesels must run hotter than petrol as all the radiators i've now looked at are bigger for the equivalent diesel model of a truck. But that's probably already common knowledge hehehe.

[jeep97tj]

Are u running a shroud with your thermo?? if not a shroud and the 3 core diesel radiator should have u covered, unless the 4 core is an easy fit, then u may aswell go that. But either way if u dont have a shroud i would put that on first.

[-Nemesis-]

There's no real room for a decent thermo and shroud on the inside which is a problem, and that's with the original 2 core radiator. So i've resorted to the big 16" thermo on the outside, which according to 50% of people is better anyways.

Fitting I can make happen, the reason i'm looking at these 75 series ones is they're the same width. That's the letdown with the runner is it can't really be any wider than original, but an inch or so taller should be no drama.

I've just being doing basic calcs, and although the whole core isn't filled with coolant, if it was; the combined volume of the core and headers on the HJ75 diesel rad puts it at just shy of double the 4Runner one

My main concern is i'm sure i've heard some negatives about 4 core radiators, as it is less efficient as far as ariflow goes as they're so thick? Or something like that....

[jeep97tj]

Is it auto or manual? if it is auto u could install a separate oil cooler and fan to take some of the load of the engine cooling system.

[-Nemesis-]

It's a manual, I have looked into oil cooling though. But for the cost it's probably easier to go a big bling alloy radiator that will keep it frozen. But the $ are important as i'm ahh getting married in 3 weeks!

[shakes]

if there's someway you can shoehorn a shroud of some sort in there. That would be my first point of call.

air will always take the easist route first... most of that air coming in goes around rather than through the radiator. a better larger radiator will help but you will most likely find some sort of shroud even basic ducting of some sort on the front will help no end.

cheers

simon

[jeep97tj]

But the $ are important as i'm ahh getting married in 3 weeks!

Thats perfect u havent given her the ring yet...... well off u go, down to cash converters

[Zeyphly]

I had a custom four core radiator in my hilux with 253, but it was nearly too big. The previous owner was running an engine fan and went through some deep water and sucked it in to the rad. I had a five core rad out of a landcruiser that i tried to fit but no way it was going in there. I got a Radiator out of some sort of cruiser that is another three core but a heap longer. I am running two inches body lift and it is sitting in the standard height up top but the bottom tank still just comes down below the cross member.

[-Nemesis-]

What do you mean by too big? As in it won't fit? Or to do with the whispers i'd heard about too big a core thickness vs airflow etc?

[MissDrew]

I run a desiel rad and mine cools fine on the highway even on a 42 deg day towing a trailer (hottest it gets is 98 deg). But when going slow like in 1st low it gets hot fairly quick so I think most of my problem is air flow. I`ll over come this by just dropping another rad on the tray with a 16 inch fan and shroud.

2 things I think you will need are bigger water compasity, this can be done by just more pipping and more efficent air flow.

[Zeyphly]

I couldnt get a larger as in thicker one to fit in well enough for me to be happy with it.

[-Nemesis-]

Well if the 4 row cruiser can fit with a fan up front I should be laughing. No one has confirmed what I heard rumours about large core thickness. Funnily enough I also found the HJ75 radiators in 3 core which are a bit thinner and cheaper. So not sure if that eBay one above is meant to be an upgrade or OE replacement.

[awill4x4]

One other thing to remember is the size of the core tubes. Most of the brass/copper radiators use either a 12mm or 16mm deep tube so if your 4 core has 4 tubes equalling 48mm and your 3 core has 3 tubes equalling 48mm there's no nett gain.
My own aluminium one in my GQ is only a 2 core, but each tube core is 26mm deep giving a core thickness of 57mm including clearance between tubes.
Regards Andrew.

[-Nemesis-]

Those eBay ones claim to have a core depth of 65mm, so assuming that includes the gaps thats pretty good yeah?

I might go to the local wreckers and measure up a 75 series one myself to be certain....

[slosh]

I read an ancient 4wd monthly that had 1uz in dual cab hilux(must've been one of the first), used a HZ holden radiator, can't remember whether 3 or 4 core. Bearing in mind that this had to cool the old 308 V8 originally, it might go OK with 1uz.

[HotFourOk]

Most of the brass/copper radiators use either a 12mm or 16mm deep tube so if your 4 core has 4 tubes equalling 48mm and your 3 core has 3 tubes equalling 48mm there's no nett gain.

If you use the 12mm tube compared to the 16mm (but have the same amount overall) there will be more surface area for the fluid to transfer heat to with the thinner tube.
The more the fluid can touch the metal the greater the heat transfer coefficient.

In your example, wouldn't the 12mm 4 core radiator dissipate a greater amount of heat?

[awill4x4]

If you use the 12mm tube compared to the 16mm (but have the same amount overall) there will be more surface area for the fluid to transfer heat to with the thinner tube.
The more the fluid can touch the metal the greater the heat transfer coefficient.
In your example, wouldn't the 12mm 4 core radiator dissipate a greater amount of heat?

Sounds good in theory, but you end up with a thicker radiator and by the time the air gets to the last row of tubes it has heated up so much that very little cooling is done. I was advised of this by PWR when I enquired about building an 85mm thick (3 rows of 26mm) custom aluminium core radiator for a supercharged Big block 34 street rod. I took their advice and used their 57mm thick core (exactly the same the supercars use) and it worked perfectly.
Regards Andrew.

[-Nemesis-]

Ahh yeah see that's what I was talking about. So what about 65mm 4core then? Too thick?

I think it's OEM in the FJ75 etc so it must work for them?

[awill4x4]

Ahh yeah see that's what I was talking about. So what about 65mm 4core then? Too thick?
I think it's OEM in the FJ75 etc so it must work for them?

Nemesis, if you think you can fit it in and the hose plumbing is suitable to your needs and the price is right, then give it a go.
One added benefit is the extra volume over your original one so that's a plus. It's a shame you can't fit the fans behind the radiator with a neat shroud as a properly designed shroud is often the heart of a good cooling system.
I know that PWR have 57mm thick aluminium complete radiators listed but their prices range from $800 upwards so they're not a cheap excercise.
Regards Andrew.

[ozrunner]

Nem

I'll be the devil's advocate

There's a lot more I could mention but this probably sums it up.

I've just being doing basic calcs, and although the whole core isn't filled with coolant, if it was; the combined volume of the core and headers on the HJ75 diesel rad puts it at just shy of double the 4Runner one

You're therefore planning on doubling your water capacity as a fix, so ask yourself this simple question .

If you current fan can't keep the volume of the thinner V6 rad cool in slow going, how is it going to cool double the amount of the same hot water in a thicker rad !!!!

JD

[-Nemesis-]

Actually it can, just not under a constant heavy load like on the thick sand etc.

Having said that, my thermo is possibly the highest rated one available shy of paying for a full on racing one worth more than the motor. It's an ICE (Unipoint) 16" rated at just shy of 3000cfm.

You can tell this radiator is just purely not good enough, as it will run fine around town etc etc.... But as soon as that hard load is placed on it the needle moves, meaning it's maxed out just to keep it cool enough for normal duties.

I could always just run a diesel 3 core like Guts said, but for the same money i can get the 75 one

I think the FJ75 will be the easiest to fit as it's cores HxL is the the same as a 4Runner/Lux. Just has bigger header tanks and a thicker core.