Outer Limits 4x4 Board

I'm looking at fitting a new radiator to a 75 Troopy with a boosted 1HZ. There's a few other things to do first but I think with the turbo I have exceeded what the cooling system can handle, hence a bigger radiator.

Is a PWR the way to go or should I look at someone else. A bit of googling didn't show great reviews from desert cooler. Are there others to consider?

I'm after results so budget isn't really limited if a product works.

Ideally a bolt up fit but considering all options.

Alloy radiators arent all they are hyped up to be.

The reason oem manufacturers are using alloy is because its cheaper.

The reason most people put aftermarket alloy radiators in is for bling, or because they think it will be better than the copper core oem, but they are usually wrong.

I would look at putting a HDJ79R radiator in. Toyota did all the engineering for you, you just need to make it fit.

shadow: have you had bad personal experiences with aluminium radiators? like most things you can argue black and blue for either.

is a factory hdj70r radiator the same whether factory turbo or n/a? i have no idea but something worth asking.

Canyonero 4x4: if your going to fuel up your turbo then i'd say a factory radiator won't cut it, that's going on patrol experiences (depending on how much fuel too)

What are you boost and egts like? Got a intercooler ?

Lepa wrote:shadow: have you had bad personal experiences with aluminium radiators? like most things you can argue black and blue for either.

I've done alot of research on alloy rad's, particularly the cheaper aftermarket options, as I am in need of a custom/bigger than stock radiator to cool the LS1 in my project FJ45.

Lepa wrote: is a factory hdj70r radiator the same whether factory turbo or n/a? i have no idea but something worth asking.

Canyonero 4x4: if your going to fuel up your turbo then i'd say a factory radiator won't cut it, that's going on patrol experiences (depending on how much fuel too)

Not entirely sure, but the HDJ79R radiator was designed by toyota to cool a turbocharged engine and ive not heard of any of the factory turbo 79's having cooling problems.

also the HDJ79 radiator has a good chance of being the right width to fit a hzj75 body.

also, if you make use of an OEM radiator, and you break it, then its very easy to get a replacement.

It's a GTurbo, so generally around 16psi but can hit 17 or 18 when pushed. It's ran quite lean (21:1 AFR if not leaner) EGT's rarely exceed 500deg pre turbo.

Fitted with a CrossCountry top mount W2A however as I used the FRP sports bonnet, the cooler does not yet seal properly against the bonnet. I plan on getting thicker foam to seal it properly as I suspect that the hot air off the motor is being drawn back through the cooler.
I also plan to fit a new OEM viscous hub fan.

Is it worth packing up the back of the bonnet to let hot air out (will look shit but so does crawling up a hill because you don't want to cook the motor.)

A2A**

A quick look on Toyodiy.com shows different part numbers between radiators for HZJ75, HZJ79 and HDJ79. I guess there is a difference so if anyone can shed some light on this that'd be great.

As well as OEM gear I'm after any recommendations or experiences on other set ups regardless of vehicle, hence why I posted in Gen Tech, not Toyota. There gotta be a way to get her to stay cool. I'm about to tow a trailer and 6 bods to Vic on the June long weekend and don't want to cook it but don't want to do 80km/hr all the way.

Canyonero 4x4 wrote:A quick look on Toyodiy.com shows different part numbers between radiators for HZJ75, HZJ79 and HDJ79. I guess there is a difference so if anyone can shed some light on this that'd be great.

The HDJ radiators have more rows of tubes across the radiator.

Hamo

Firstly i'd consider lowering your glycol content. Pure water has a far higher ability to transfer thermal energy than 50/50 so run the lowest concentration you are comfortable with. Don't worry about the anti-boil part as this is mostly taken care of by system pressure. Water at 14psi of pressure boils at about 120 degrees.

Copper is technically also better at transferring heat so stick with a copper rad, the biggest you can fit.

The design of your engine when fitted with a turbo dumps a LOT of heat into the water jacket instead of using it to make more power. When my brother fitted a FACTORY 1hdt turbo engine to my old red truck that had previously had a 1hz with turbo the temps never moved off the 80 degree mark no matter how hard we pushed it. That was a factory cooling system that had previously not coped well.

The only other thing i suggest is to drill three or four 7/32" holes in the thermostat body. This will let your engine sit about 5-10 degrees lower at normal operating ranges and give you a bit more of a buffer as it warms up. Not the best solution but it worked for me.

Canyonero 4x4 wrote:A quick look on Toyodiy.com shows different part numbers between radiators for HZJ75, HZJ79 and HDJ79. I guess there is a difference so if anyone can shed some light on this that'd be great.

.

That's because they are all totally different trucks. 75 was a superseded model compared to 78/79 so even if they're the same to look at or even the same part they're likely to have different part numbers. Compare a hzj79 with a hDj79 for a more accurate idea. even then it only needs a tiny change like intake pipe positioning for it to be a different part number for what may be an otherwise identical system

Hamo wrote:

Canyonero 4x4 wrote:A quick look on Toyodiy.com shows different part numbers between radiators for HZJ75, HZJ79 and HDJ79. I guess there is a difference so if anyone can shed some light on this that'd be great.

The HDJ radiators have more rows of tubes across the radiator.

Hamo

Surface area trumps fin/row count/depth/thickness every time. Cooling works by differential temperatures. So the second row in a rad receives air pre-heated by the first row and will accept less heat transfer. the third row is worse and the fourth row is next to useless. A radiator that has double the surface area will have far more coolilng capacity than one half the size and with two rows. This doesn't help those of us with 70 series trucks and their abominable available surface area for cooling.

Increasing the Frontal surface area is always the best solution, but a 4 row cooler is still better than a 3 row cooler, it is a diminishing return as you suggest, but it still increases the air to copper surface area.

The air exiting the radiator rarely reaches 60 degrees and even if its at 60degrees as it passes the 4th row, it is still cooling the water which is at 100degrees, just less effectively than air at 30 degrees passing the first row.


Im not 100% sure on the layout of a 75, but on my 45 on 80 chassis it would have been possible to fit a wider radiator that sits above the chassis rails and encroaches behind the headlights. (except my steering box is now also in the way)

Milo. You're a wealth of knowledge. Got the new fan clutch and extra oil, fitting tomorrow with new thermostat and will definitely drill it out. Fitting it in the morning. Worked out a way to seal the TMIC to the bonnet. Pick up rubber on Monday. I'll give the lower glycol a go and see how that goes. I'm very eager to see some good results. Next step I guess would be to see if I can get a custom rad made up. Cheers all for the input.

Canyonero 4x4 wrote:Milo. You're a wealth of knowledge. Got the new fan clutch and extra oil, fitting tomorrow with new thermostat and will definitely drill it out. Fitting it in the morning. Worked out a way to seal the TMIC to the bonnet. Pick up rubber on Monday. I'll give the lower glycol a go and see how that goes. I'm very eager to see some good results. Next step I guess would be to see if I can get a custom rad made up. Cheers all for the input.

Forgot to mention that you should drill the holes in the outer ring of the thermostat, not the inner body that moves. There's plenty of meat in the outer ring but not a whole lotta space in that middle section

Done. Didn't get it back together yet but when I do I'll post some feedback

Dont forget fin pitch. A finer pitch is more efficent at transferring heat on paper, but if the air dams up and cant pass through at a good rate then it can have a negative effect. Water rate is another, you dont want the coolant passing through the rad too fast, it wont get time to rid its heat. Another place to look is engine bay. The air cant get through the rad if it cant get out the engine bay.

uninformed wrote: The air cant get through the rad if it cant get out the engine bay.

This is absolutely critical. There MUST be a path for the air to escape and as easily as possible. I got rid of the plastic/rubber flaps that seal the inner wheel well to the chassis. The down side is that those flaps stop mud and crap from getting in the engine bay so it gets messy in there real quick if you're a fan of bog holes but i'm certainly not so it didn't bother me. I also made sure my engine bay was as neat and uncluttered as possible. Bonnet scoops for intercoolers can actually add to the problem by increasing engine bay air pressures and the inward air/added air pressure flow from the scoop can fight against the air that the engine fan is trying to pull. Interesting to note that for all the bad sides to a body lift, one positive advantage is that there us greater room behind the engine between the firewall/floorpan and the drivetrain allowing for more airflow. I wouldn't go adding a BL just for that reason but, especially on a troopy

How did you go with it mate?

I've been flat out and haven't gotten back to it yet. I should get a chance over the weekend. I'll Yeah the engine bay is beginning to look a bit cramped with the turbo, cooler, AC, batteries etc and not much I can really do about it. As much as I don't want to, I might pop the bonnet up at the back 10/15mm and see what difference it makes.

I finally got it back together yesterday with brilliant results. It's now happy to sit around the 82deg mark. That's new fan clutch with extra oil, new thermostat with 4x2.5mm holes, 25% glycol and sealing the IC to the bonnet. With that said it is shit weather at the moment and no real load but runs so much cooler over all now so will see how it goes down the freeway with a bit of weight behind it. May still look at raising the bonnet a bit at the back yet.

Glad to hear it. It takes the joy out of driving a bit when you have those sorts of issues in the back of your mind all the time