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Discussion Starter · #101 ·
Great thread.last year was towing light trailer east of Dalby triton started over heating couldn’t understand why.fairly likely I didn’t replace bottom plates.so I have a questio,does it make a difference if the bottom plate (or plastic/ rubber) go’es all the way to the diff/axel centre.not real practical for a patrol but anyway
Hey mate, not 100% sure on your triton however i will share something i found today on an 80 series, these bits of plate either side of motor on the chassis could easily be called a "guard" of sorts i guess however there is nothing OEM closely positioned behind them for them to be protecting anything, based on the angle/orientation, apparent strength and positioning i can only presume these are aero related - i plan to take some measurements to see if anything changes with a set of these on my GU.

remembering that our OEMs will not spend money they do not need to in order to satisfy the criteria they work to, those bits of tin are a lot of money considering the amount of vehicles made and sold over time.

All these little bits and pieces can add up, and as our OEMs work to a criteria to ensure that the same stock vehicle can be dropped in the middle of the snow or the middle of the desert and still do a reasonable job in both, that unfortunately means it wasn't really optimised for either IMO.

I would lean towards re fitting anything that seems to be aero related unless you are modifying the way it all works or other mods have made the OEM aero stuff ineffective.

It may be the little things that get it over the line in terms of not "running hot" when doing work in our generally hotter conditions here in Australia.

as for the bottom plate/air dam - on an IFS vehicle we would want it to be more of a bash plate/under tray type arrangement i would imagine as the diff is not live.

In saying that - I have not yet done any testing on a non live axle 4WD, only live axle and road car.

Since getting into aero stuff i have really started to notice all the different things OEMs are doing.

On that note, Does any one have a Y62 they could look at and verify weather the vents on the side are just a gimmick or if they actually vent the air out the engine bay here?

Cheers





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Discussion Starter · #102 ·
Been a while in between posts, But we have had a bit more in the pipeline in terms of improving airflow through the engine bay of the GU.

Just haven't had time of recent to execute finishing some of the bits and pieces properly but so far, we are currently investigating and finding what appears to be further improvements with the following:

* Turning vane on TMIC intercooler (nothing new or groundbreaking here at all but some with a TMIC may not be yet aware and this can help them if they desire lower IAT)

Example of this can be seen on 200 series Landcruiser i believe, the plastic grille on top of the core has 2 of these towards the front of the core from memory.

* Plate under gearbox to clean up airflow that wraps around under diff as it is deflected by air dam (this plate is skinny and goes from the sump to just behind the cross member. (stay tuned for final verdict but so far looks to do a bit for engine bay pressure and even flow of air through the TMIC)

Also have been investigating a little of how the air pressures behave towards the rear of the vehicle (say for example under the tray of a Ute)

So far i cant find a lot that i believe would have a decent notable effect on the airflow out of the engine bay on my car but i have a few theories to test on this when i can get the time to get a few different utes and wagons to get numbers off.

Theory is there is potential for bad under body aero at the rear to possibly affect the way the air is drawn out of the engine bay.

For most people we should definitely stick to just sorting the front as improving that has a decent effect on everything no question, but as i am interested in how far these little adjustments can take me - i will keep looking.

To create a low as possible pressure under any car, we want the air speed nice and high and the flow to be as laminar as possible, this is why a full undertray is used on race road cars typically.

obviously this is not really practical for us, however if we can "clean up" some of the air flow under the vehicle with "bash plates" this theoretically can yield more gains as these plates should help in reducing a bit of turbulent airflow under the car.


That being said - here is an example of a mock up that actually seemed to make things worse. thought id share this as to me it looked great in theory based on the above. I have learned aero theory from a few books but this example is why its so handy to test air pressures. So this saw an overall increase in engine bay pressure which is NOT what we are after when doing a modification behind the bay which has the intention of lowering the bay pressure.

On the contrary if an increase in bay pressure is found from improving the airflow into the bay (eg take spot lights off or thin up radiator core) this is a good thing.

Wheel Tire Automotive tire Plant Hood


The skinny plate that seems to help is positioned forwards, this plate is obviously back a fair bit.

This here is another example of the inner guard or skirt mod, this is a 3 1/4 inch hole on my car. I have welded an egg ring back in here.
Motor vehicle Gas Automotive exterior Engineering Auto part

I wanted to cut this whole area out but have settled for this as per experienced smash repair dudes instruction.

He pointed out that over the years from the GQ to the GU he seen many "changes" in this area of the body which he says is likely due to the body being prone to cracking through here.

the GU have the brace which is spot welded on, which was removed for access to cut this hole and will be re fit today.

This mod along with a hole in the bottom of the outer guard and flare, and then a good mudguard on the bottom of the flare in front of the hole definitely helps, however keep in mind the strength of the panel to avoid potential cracking issues and perhaps even consider fitting a GU brace to your GQ when/if you do this as the GQs were apparently far more prone to cracking the body and i am led to believe they dont have this brace from factory..
 

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* Turning vane on TMIC intercooler (nothing new or groundbreaking here at all but some with a TMIC may not be yet aware and this can help them if they desire lower IAT)

Example of this can be seen on 200 series Landcruiser i believe, the plastic grille on top of the core has 2 of these towards the front of the core from memory.
To add to this a bit of an explanation to what Turning Vanes do Improving intercooler flow using turning vanes.

This here is another example of the inner guard or skirt mod, this is a 3 1/4 inch hole on my car. I have welded an egg ring back in here.
Motor vehicle Gas Automotive exterior Engineering Auto part
I wanted to cut this whole area out but have settled for this as per experienced smash repair dudes instruction.
Are you going to vent this directly to the outer panel via a tube.

For I believe from my Tech Days that the Wheel Arch becomes a High Pressure zone and without proper ventilation will decrease down force (from my race track days), while yes this will apply mainly to race cars if your hole is not vented to the outer skin of the car and vented in such a way to create a vacuum effect in the pipe your mod may add to the under bonnet pressure.
 

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Discussion Starter · #104 ·
To add to this a bit of an explanation to what Turning Vanes do Improving intercooler flow using turning vanes.



Are you going to vent this directly to the outer panel via a tube.

For I believe from my Tech Days that the Wheel Arch becomes a High Pressure zone and without proper ventilation will decrease down force (from my race track days), while yes this will apply mainly to race cars if your hole is not vented to the outer skin of the car and vented in such a way to create a vacuum effect in the pipe your mod may add to the under bonnet pressure.
It vents out the bottom of the flare/guard so its shielded from the wheel well high pressure by the mudguard. I have also observed/confirmed wheel well to be a high pressure so yes, we do not want to vent here we, want to keep it sealed up.
 

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The temp underpan never looked like it would work. Looks more like a shovel. Makes me want to get my underbody protection sorted sooner than later though
 

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Me old Troll is going into holiday mode for a couple of months, as I do some long over due work on the drive line.

But while waiting for the bits and pieces to arrive I thought lets do a bit more Aero on the front of the old girl.
Tire Wheel Vehicle Automotive tire Grille

As you can see not much to stop the air going into the Rad area,but behind the grill is another story all together.
Water to Air Intercooler Rad, Air Condenser, then a 3 Core Rad only due to the fact my factory Rad needs a
re-core, after 30 years its started to weep.
Tire Wheel Vehicle Automotive tire Motor vehicle
Automotive tire Motor vehicle Engineering Railway Gas

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Now I've done all the normal things as making sure the factory rubbers are all in place, sealed the gaps between the Rad Support
and the Rad, cleaned the old viscose fan oil out and replaced it with new and made sure fan shroud was complete and in place.

Now to fill in the Air Spill points before the Rads and behind the Grill.
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This I hope will stop the air from spilling out to the sides of the Rad.
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While these I hope will stop the air from going over the Rad.

As with all things to do with cooling the kettle time will tell. As winter is now upon us the results if any will only show up when the heat comes back.
 

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Discussion Starter · #108 ·
Low Ambients are definitely not helpful for determining how good your aero is as the bigger difference in temperature or the larger "Delta T" means less airflow can remove a given heat load.

I have just returned from Toowoomba QLD today back to weipa, and with toowoomba's ambients i reckon i would never have been prompted to go after my cars aero as the ambients just mask the issue too well. This i suspect is likely one of the reasons that so many people seem to think they don't have an issue in regards to ECT control as no symptoms show up until either the load or the ambient are much greater.

For anyone who may be interested, if you measure your bottom radiator hose temp under varying conditions and over time you can use this as an indicator of the impact of your aero mods, positive or negative. Obviously the lower you can get that temp under all conditions the better and you CANT have it too low in a system that has adequate bypass coolant flow. If you have no bypass whatsoever (not ideal IMO) then yes this can be too low. (remember to monitor ambient temp while you monitor this) With proper bypass flow and a good cold water supply the thermostat can literally temper the operating temp of the engine against a load.

While we are at we may as well talk about "why" as this is always the big one for those who need to self motivate.

THERMOSTAT: (by definition a device used to REGULATE the ECT and the engine temp)

The only way a thermostat can have proper control over these things, is with an endless cold water supply - like what we have in an outboard engine. So the aero/airflow over the radiator core is essentially determining the quality of the cold water supply, the cooler the water coming out - the more control the thermostat can have. (This is of course with consideration to the orifice size of the thermostat and with all other things being up to the task like water flow) Another neat positive of this is the cooler the feed water the higher the density and therefore the greater the NPSHa to the pump, which your water pump will love you for and can then move more water. (good)

The higher the coolant temp coming back out of the radiator in the bottom hose the more the thermostat has to open its main orifice and close its bypass (if fitted) to attempt to regulate the engine temp.

Once the stat is fully open (and if fitted bypass fully shut) our system is now "unstable" and you are at the mercy of nothing other then airflow and ambient temps so load and ECT will go up together, the magnitude of which to be at the discretion of the ambient air temps.

for any condition where our thermostat is not yet 100% open our system is "Stable" and with all other things being good it can attempt to closely regulate the ECT and engine temp. Remembering of course that the hot hose temp will be higher under load due to this being the path of the excess heat leaving the system. (about no more then 4 degrees variation is good but the lower the better)

In a lot of production engines, we will find the operating temp is arranged in a manner in which the thermostat opening temp is a "floor" for lack of better term on the operating temp and/or otherwise a warm up device and the engine fan/thermo fan can be arranged to come on at sometimes a 10 degree hotter ECT then the stat temp (ceiling). This give us what we call the "operating range"

I suspect our later generations of engineers have lost touch a little or are working to criteria's and budgets and as usual are making engineering decisions based on many factors including the non obvious and ultimately being told yes or no by the bean counters (poor bastards aren't allowed to do a fine job)

In addition to this i believe our OEMs realise that even though our GU skinny radiators can be rated to 200hp with correct airflow, the reality of things is - we will likely never get this airflow unless we hold it out the window and don't drive any slower then 100.

A key part of fixing our "aero" and "cooling system" or as i prefer to call it "heat management system" :rolleyes: - we are going from having an operating range to having an operating temp. This is what i and i suspect many others have managed to achieve with aero and understanding this, i think is important for the people like myself who as "why" a lot. (i have had many people tell me they "dont have a heating problem" one day then tell me that they were running 10 degrees above stat temp on a trip at a later date - This IS in my eyes a problem or if not a problem an area that can be improved to give us more headroom again)

Measuring bottom hose temp and using this as your indicator to get your aero as mint as possible is a great way of ensuring you never again have any pre desert trip anxiety or fear of summer :ROFLMAO: (because last time she got a bit hot) as you will have confidence that you now have more up your sleeve, even if your mods and testing were done in the winter time where the ECT in the stat housing doesn't change at all with airflow mods because the ambient are so low the stat can have control with poor airflow.

Cheers
 

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That’s an interesting intake manifold you have there.
Its a water to air intercooler off a 6BT.

Measuring bottom hose temp
I also measure the Rad Cold side before it gets back to the motor.

You can tell when the bypass is closed and after a while you can figure out how much the bypass is opening just by the return temp to the motor. This was how I figured out I had a problem with the GU and the bypass not fully closing when it was taking longer to return to normal temps Engine running hot TD42???.
 

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Discussion Starter · #112 ·
Here is a way to get some more radiator into your wide rad style GU. This is an ebay W2A heat exchanger mounted down low (in between chassis rails) so that it doesn't block or mess with air flow to the main stack (which is full of seeds and crap again from pushing tracks)

The idea of this is to allow the free air section on the wide rad shrouds to be blocked off - resulting in the fan being able to have more purchase on the radiator at low speed.

This is to eliminate chance of air recirculating and to take advantage of the available space between the chassis rails which evidently flows a lot of air at speed and nissan seemed to agree there as well when looking at TB48/TD42Ti GU's

This new additional heat exchanger is now our high speed radiator instead of the old free air section being our high speed radiator, and at speed it certainly does flow a lot of air and allows the thermostats to open a lot less against a typical load to stablise the ECT. (they now have more headroom and control)

So the main radiator does less work, and has more up its sleeve.

The reality of things is, we need to get the air flowing through heat exchangers as well as possible, but with a car wrapped around them, a bullbar infront of them and a lump of steel behind them its not ever going to be 100% perfect or easy. Taking advantage of areas that have great airflow potential is a good way of getting "more radiator" for the guys with more cooling needs.

More power, higher ambient, IDI (less efficient engine) and the size of that, higher loads are things that can call for "more cooling needs"

It is surprising how much of an effect a rather small heat exchanger can have on things, if you give it the airflow it wants. This being said, you can clearly see this one is being blocked by a winch, however the low pressure created by the air dam directly below it mean that the air doesn't have much of an issue making its way around the winch to pass through the core.

We opted for this on the 6.5 GU as the free air section (draft flaps in this case) of the shroud can never work properly with the fan penetration depth required for this bay/motor setup to flow air well enough. I would not be blocking any free air sections on OEM cars as a rule of thumb, with of course the exception to doing so while in conjunction with this aux rad mod, as if in the case that blocking the free air section of an OEM wide rad nets some gains, the issue was still likely else where (low pressure side)

With this setup he can now tow his 3.3 tone plate reef boat down corrugated dirt roads in high ambient at 100kph and the temp will peak to 97C in the hot hose and then stablise at 96C in the hot hose. Something he wouldn't have even dreamed of doing even in winter at night time, prior to everything we have done to this car.

Although this mod is mainly a high speed helper, it does help at just about all speeds, the amount of which varying with the actual speed the car is doing.

Because we have stayed with a thin main radiator and a powerful engine fan that moves a lot of air, not only is our "active cooling" more effective but the recovery time is very quick, which is far more desirable in my opinion then having more passive cooling (heat storage in more water and metal) but suffering a ridiculous recovery time, which is what a massive thick and heavy radiator does.

The loaded ECT or hot hose temp will always be high during a big load event with 6.5 litres of turbocharged IDI diesel, however the block temp is stable and given that simply lifting the foot for a few seconds can see the hot hose temp return to the stat temp (88c) with minimal if any change to our block temp shows us that our heat management or cooling system is doing a great job of sending excess heat to the radiator and the aero is doing its job of putting that excess and unwanted heat into the atmosphere.

There is no coasting to a stop with the ECT not budging off 110C and having to pop the bonnet and bring the revs up while waiting for things to calm down.

The second main reason i thought i would share this, is because this heat exchanger could be an oil cooler, or a nice spot to move your W2A heat exchanger to improve flow through your main stack. The space is not huge, however with the amount of airflow potential it has, it doesn't need to be. You can see in this one that it comes up to about the bottom of the condenser so you could argue it is restricting airflow to the rad slightly, but it is by no means any where near the same as switching back to a 65mm radiator core. (yuck)

The bash plate/air dam underneath it is strong enough to drop the car on, so we aren't worried about damage.

Cheers








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Nice idea, it will work as you say a higher speed option and is well protected from damage due to its location.

On my GQ that is fitted with a Water to Air system the Rad for it is too big by half. I could do with cutting it in half with little to no lose in performance, but as they say "if it ain't broke, don't fix it".

In the future if I buy a larger camper or Van then I will look into either cutting in in half or splitting it into two Rads one in-front of the main stack the other lower as your example shows.
 

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Discussion Starter · #115 ·
So i thought i would go ahead and share my opinions and thoughts on materials and mediums. While i will quote some facts i will also be sharing my thoughts/opinions which may or may not be 100%

Radiator materials: ahhhh, nearly as bad as the FMIC vs TMIC debate, and for good reason - they both have advantages and disadvantages.
The general thing i am hearing from all the wisdom the local pub has to offer is that "you want a copper brass radiator, they cool better" or something to that effect. Now on the other hand we have a lot of people on the ally band wagon and getting good results - including my TD42 ute.

So basically with the materials, i look at 3 things, the "specific heat"
The "thermal conductivity", and the "actual specific heat" of the material (so the specific heat with consideration to the physical weight, or the thermal mass)

So basically our specific heat means, how much heat can i fit in this material, and each material is assigned a value to represent this, however this is not the true specific heat, the true or actual specific heat depends on the weight of said material along with the material itself.

Ally - 0.22
Copper - 0.09

So ally can fit more heat in it, simple.

However, this is for X amount of material by weight, so if we have around 2.4 x the weight in copper, we have an equal actual specific heat capacity.

So how important is specific heat to our radiators?

In my opinion, not as important as you would think, however more of it doesn't hurt.

So see the main thing i see with copper/brass radiators is 2 things, 1 being that they are usually as thick as a brick home so this makes them physically heavy which brings actual specific heat up. (yay winning) however if you have read this thread you will know that, no this is not winning because the thicker core will generally mean it cant flow as much air, depending on cores rows and FPI and all other aero things. (oh no!)

So one situation where a low actual specific heat is ok is a situation that has excellent airflow, as we do not need as much room in the material to fit heat into if we are actively removing this heat to the atmosphere well.

This is a good chance to discuss 2 terms i like to use these days to help explain this, "Active cooling" and "passive cooling"

Active cooling involves the rate of which and the amount of heat we can REMOVE from a material so this generally relates to airflow over our radiator core or other exchanger.

Passive cooling more so relates to the specific heat capacity of a material or medium, and involves the rate of which and the amount of heat we can STORE in said material/medium.

OK so lets talk thermal conductivity. To me, this means how fast can a material or medium absorb heat. For our radiator, the quicker the better right?

Copper vs ally, copper smokes ally. it will absorb the heat much faster however for a given weight it will not be able to store as much heat as the ally can.

copper - 397
ally - 226
brass - 117

So given with copper we have a high thermal conductivity and a low specific heat, provided the radiator itself is physically heavier then its ally counterpart - this is likely (2.4x heavier) for a given design (cores, rows and FPI) the copper will be much better matched to a setup that has good aero/airflow as we can dump our excess heat from the engine into the atmosphere a lot quicker.

But here's the thing, How much of this radiator is copper and how much of this is brass??? and where is the copper and where is the brass... As we can see above brass has a poor thermal conductivity compared to ally. (perhaps someone can chime in who is in the know of radiators specifically) So something to consider.

Obviously copper brass is a little easier to fix in the bush, which is ironic given that most of them i see are quite thick, meaning the fan is about 5 x more likely to take a bite out of it during a water crossing or something. Also, ally are not unfixable on the tracks, just cant really fold some cores over with a set of long nose pliers and off you go.

In conclusion, I feel as though they can be treated fairly equally when talking materials, with a slight advantage to a copper brass core, provided it works aero/airflow wise. So its better to look at the thickness of the core, to make sure you get the appropriate fan penetration depth, look at the fin count or FPI, look at the rows and cores ect ect. get those things right and get as much air flowing through it as possible and you will be laughing.

Heat transfer.

Heat transfer is governed by 2 main things, the nature of the materials/mediums and the temperature differential between the thing giving away its heat and the material/medium receiving the heat

simply put, the hotter the hot thing is relative to the cold thing, the more net heat energy can flow to the cold thing. "cold" in itself is a misnomer as it is simply a term we use to describe an absence of heat, there is actually no such thing as cold, however we will use it to keep things simple.

so this is one reason why we can achieve a more stable operating temp against a modeate load, using a higher temperature thermostat. the fact that the radiator is hotter means that we can transfer more heat to the atmosphere or air passing through it. we can give away more heat energy.

Does this give us more headroom? No. This gives us less fluctuation or more control over the operating temp of the engine in normal situations. (moderate loads at speed)

This also makes the engine more efficient, as the delta T between combustion temp and coolant temp is less (hotter coolant means we suck LESS heat out of the bang, this is good.)

Which is a great Segway into mediums and my theory.. Many people in the industry will tell me that you will get no better medium (coolant) then straight water... Lets have a look at its numbers

water thermal conductivity @ temperature

70C - 659.69
90C - 672.88

the hotter we get water the rate of which we can give heat to it diminishes. Makes sense seeing water has a specific heat capacity as well and can only fit so much heat into it before it changes state.

Now given that the industry collectively agrees on hotter being better (provided you can keep it stable) and given that the reason for this is to stop us from having to much of the heat from the bang getting into the coolant rather then doing work at the treads, i believe it is not unreasonable to argue that going back to a coolant is a better over all move for those who are serious about their aero. A coolant will dumb down the ability of the water to absorb heat, now this doesn't necessarily mean that it also dumbs down its ability to let go of its heat once it has collected it from the head.

Given that the rate and amount of heat transfer is more so governed by the receiving material and the temperature difference between the 2 materials/mediums then it is the material that holds the heat, we can see a few advantages a coolant offers over a straight water setup. (maybe OEMS arent so silly after all!?)

1: Lower top hose temperature in general : top hose is where the thermostat is sending excess heat, if the medium grabs more heat, we will see more heat here under load.

2. Hotter block/engine temperature relative to coolant temp: again, we are keeping the heat in the pot do drive us down the road and we are also getting more heat to the metals of the engine itself (remember the engine is also kind of air cooled after the liquid cooling) so we theoretically have a little more "radiator" with a block temp that is closer to the coolant temp and great aero.

3. More power/efficiency: For a 100% load event, because the coolant is dumber compared to water, it wont suck up as much net heat energy as quickly meaning more power (in theory)

4. more stability in temperatures overall: just due to the fact that we have much better heat management (in a bypass system)

Now i have spoken to industrial chemists, engineers ect and from what i can gather all the theory is fairly spot on. So along with the anti boil/freeze thing, in our bypass systems that have excellent control due to great airflow - it seems that gains are to be had in switching back to a coolant.

The reason i say this is i believe straight water can be along the lines of a band aid in a system that has poor airflow and in adequate bypass, giving some symptom relief provided both the radiators specific heat capacity and the actual specific heat capacity of the water are great enough, allowing for more passive cooling of the engine. (massive thick ally 7 row radiator that holds 37 litres comes to mind)

In reality, a heat management system with excellent active cooling ability is 99 x out of 100 far superior to one that uses the radiator as a heat sink rather then a heat exchanger.

It is quite cool watching the heat enter your top hose but seeing your block in various points stay stable when at 100% load -and watching the heat disappear when the foot lifts.

Remember this isnt really a thing with poor airflow, infact nothing is.
 

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Discussion Starter · #116 ·
Water Plant Hood Motor vehicle Cloud





Keeping the aero/airflow discussion moving forward, here is an example of what we can call "hood louvers" or "bonnet vents"

Couple of websites in the states mainly like racelouvers sell similar things to this for the purpose of allowing the high pressure under the bonnet (generated by the engine fan and road speed air) to escape to the low pressure over the exterior of the bonnet.

So then this goes a little further then that. With the correct angles on the louvers (there abouts will work) you end up with a venturi effect across the louvers (many of you would allready have found this with perhaps shop air over a fluted vent or something of that nature while holding a rag)

For those that havent, the venturi effect means the air from the engine bay will be sucked out as the road speed air flows over the bonnet/louvers. (yay enhanced aero things)

I haven't spoken with this bloke in particular to determine weather he thinks these work or not on his particular 6.5 100 series, however i had solid results in testing a few different bonnet mods on a 94 festiva that was an aero mod test dummy. (what a beast that car was) :ROFLMAO:

Things to keep in mind when doing this is to keep the vents forward as possible, but just behind the radiator (stay well away from the windshield if possible)

Think about components underneath with rain exposure. (race car stuff)

This sort of thing is pretty much 100% necessary for a 6.5 as there is basically no where for the air to escape, and in theory can improve your TD radiators performance a fair bit, as i have measured a considerable pressure difference in these areas. (S4 GU)

Its on the cards for my main car, however i want to try and make it look a bit less race car then this if possible and with a cooling system as happy as mine, along with a reasonably fresh paint job on my car - I'm not particularly in a hurry to go cutting holes in my bonnet.
 

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Discussion Starter · #117 ·
Wheel Car Tire Sky Land vehicle



So im on the move from weipa headed south, we have load sharing leaf springs on the trailer with minimal up travel left in them. (its yuck) She's loaded. not sure exactly how much but basically the box on the trailer is a 2400 x 1200 wood box and it is packed to the brim with heavier gear as if it was a game of tetris. Of course the box on the draw bar is around 100kg before it is filled with gear and while it is loaded its not tetris loaded like the wood box on the rear. Im moving town and i don't really want to buy stuff again so i have gotten rid of minimal. i would have to be north of 6 tonne all up i would imagine.

So why should you care? Well i have a Ti radiator so the skinny little one (32mm/18 ish FPI) and currently 250cc of water meth injection on top of what ever i am making now days at 28 psi boost on a not so great turbo with drive ratio likely north of 2.5 at this boost (dont ask but my cruise boost is 20 and above 🥴) and it has been a great trip so far down in testing the "cooling system" up and down these ranges in the heat of the day. (looking forward to hitting towoomba ranges at full load will just have to watch my speed)

I've had plenty of opportunity to be at 100% load for decent periods at full boost going up steep gradients with the aircon on and these were in the heat of the day.

The hottest i have gotten my coolant in the top hose is 98/99C and that was nearing the top of a range in 5th gear with the vehicle at maximum speed/load point (wouldn't pick up any more speed or revs, and held here for a decent amount of time)

Not sure how fast, however way too fast for the corner coming up at the top, luckily you can slow down quickly going up steep hills..... It was great to observe the hot hose temp having a super quick recovery from this sort of 100% load situation. (Once corner is taken with the outside mirror touching the ground and then a lighter load cruise condition was on the engine with airflow still being decent)

The engine did not give a **** what i wanted it to do, its basically not able to be "overheated" in my opinion provided you have the vehicle at speed. In saying that i cant really push it hard enough in the sand to get it to play up either. It was never a shocker before i got obsessed with heat management but i would have been sweating hitting these hills like this if this was 3 years ago.

- Block temp was never an issue

- Recovery was instant, seconds once the foot is lifted

- i never lose coolant because my static pressure is low (due to good airflow and good de aeration/expansion tank setup)

- Pyros at full load are about 750c at their most (not sure on AFRs as i have been to busy fixing other peoples cars to worry about getting mine micky mouse with current turbo)

- Radiator is not brand new and had plenty of grass seeds that wouldn't move with air or pressure cleaner last time i had it out.

- Rad would have been dusty/dirty as well

So for some interesting comparison. VJD Landcruiser weighing about the same (towing big) will easily see 105C + ECT on the scan gauge monitor, however it wouldn't be haulling as hard as the TD does (only got a remap and an exhaust and snorkel) Now obviously these cruisers have engine management and under this condition the needle on the dash hasn't started to move yet at all. Its not an issue at all. The reason i say this is because even with our inefficient heat wasting TD "junkers" we can make more power and still keep reasonable ECT if we get enough airflow through them.

What we are comparing is IDI vs modern day CRD things. There is much more aero mods i can do to my car to improve it further, i just don't really "need" to as of yet however i would like to.

I am not using a bypass switching thermostat, so my bypass flow is indirectly controlled by the opening of the main orifice on the stat. If i wanted to i could restrict a bypass circuit a touch more (nutsert in heater hose barb) and this would potentially get my max hot hose temp down a few degrees however it may hinder the performance of the pump slightly and its really not that necessary at all. The hot hose should get hot under load and its going to be hotter the more output you have.

Its like this: hot hose = heatload x time take away heat losses (airflow)

Heatload = engine load x output x time

sort of like that any way. ( i think )

I recall people paying out on a car that made around 300rwkw because the coolant temp was up around 130C in photos (if my memory serves me correctly) however i don't see this as an issue anymore really provided the coolant hasn't failed at that temp and also what people tend to forget is you don't have airflow on a dyno so its really a **** spot to be doing this type of testing (a worst case scenario)

I am using a derk pump and a UFI gen 2 fan for full disclosure, but i also had zero damage to my timing cover when i removed the genuine pump. I do want to play with the fan to try and get it to start locking up a little hotter/later for fuel econ reasons as i run mine hotter on the stat then what they were designed for but i think the gains would be marginal.

Perhaps Ti radiator conversions could be a viable option for GQ and early GU owners who do not want to go the aux rad mod route and want the sort of performance i am getting.

I have obviously done lots of field testing since tinkering with a few different vehicles but i would have to say these are the steepest gradients so far i have had the opportunity to 100% full load this Ute on for decent enough time periods and I'm looking forward to some even steeper and longer ones if i can find them. Lots of these climbs i ran out of road well before i ran out of hot hose 👍👍
 

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2005 TD42Ti ute
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Discussion Starter · #118 ·
Hood Motor vehicle Automotive design Trunk Gas


What is an expansion tank, what is their function, why are they sometimes a good idea?

This is my current setup, PX Ranger expansion tank with some mods. (its a bit dodgey, but mark 3 should be better.)

An expansion tank is different to a header tank, and also different to an overflow bottle, all three of these terms i have heard people use interchangeably. While that is not super important, it is good to clear up what they all are meant to do and how they should work.

A well setup expansion tank is basically a substitute for a lack of volume in the top tank of a radiator. This is what we call a "non recovery system" The expansion tank itself is meant to always have an air pocket in the top of it and it is connected to the system directly, not on the other side of a spring radiator cap. A header tank is also connected to system pressure, but only via one hose on the bottom of it, basically all it does is acts as a remote fill point. An overflow bottle is what we get factory on GQ and TD42T GUs. a bottle that isnt connected to system pressure, but is apart of the system when the cap operates. This is what we call a recovery system.

With these tiny skinny radiators like the TD42Ti one, we have basically no room available in the top to run a decent enough air gap to keep the coolant in the system once its got some heat in it. The function of the air gap is to act as a shock absorber on the system, smoothing out the way the water moves throughout the system as well as to provide a bit of room for our coolant to expand into as we heat it. Its also designed to be a remote mounted high point in the system to allow full self bleeding, to trap any aeration that may become present due to pump cavitation, steam, and other air issues that motors can have during operation.

Failure of coolant.

The expansion tank itself helps prevent failure of coolant in a few ways. Firstly, it helps provide a higher NPSHa to the water pump by feeding it back only de aerated and more dense coolant. Secondly, it traps any air in the top of it where it can remain controlled and help our waterflow as our shock absorber. This in turn reduces chance of pump cavitation which means the water can keep moving.

Some anecdotal evidence.

Just about every TD42Ti that i see with the water pump removed has minimal damage if any to the timing cover, except for the ones that have a large impeller to timing cover clearance.
The TD42Ti motor in GU patrol ran a "semi recovery" system, which consisted of both an expansion tank and an overflow bottle (what a bloody show that is, but it kinda helps a little). Lots of older TDs especially in GQs i find have more chance of having damage to the timing cover. Perhaps its not unreasonable to suggest that the expansion in the Ti GU's is helping keep the pump fed and the water moving nicely, so it has less chance of cavitating.

Static system pressure.

For anyone whos ran pressure gauges on their cooling system in various points, we have noticed that we have some dynamic pumping pressures like discharge and suction, but we also have an overall system or static system pressure which is the air pressure in the top of the system. This air pressure is normally produced by the heating of the coolant, as we warm it up it expands, the volume of the system however does not so the pressure goes up. Its fairly normal. A high static pressure could be a head gasket issue, a nucleate boiling issue (poor waterflow), an airflow issue or a system air volume issue.

Basically, if there is no air gap the water doesnt have any where to expand into so the old "should run on cap pressure" 🤦‍♂️ can become a thing and you can be pushing out a tiny amount of coolant at operating temp, for no real good reason.

Engineers have gone away from recovery systems all together with lots of later model cars and its a good move if you ask me. Recovery systems just scream bandaid, and in a well setup cooling system with decent airflow, they are not required at all, they are better in the bin which allows more airflow through the bay in some cars (ironic given more airflow reduces the chance of it being needed to catch coolant getting pushed out)

How does airflow affect static pressure?

As we drop the temperature of the system via means of airflow though the radiator, we can see our static pressure decrease due to the coolant becoming more dense and contracting as we actually apply the airflow to the radiator core. If you ever get a chance to test this for your self, you will be quite surprised as to just how much this contraction of coolant drops the water level in the system when decent airflow is applied to the radiator core. This could be also due to dynamic pressure differences (pumping pressures) increasing as a result of pump cavitating.

When is an expansion tank a good idea? Basically nearly always. This comes back to the body shape of the vehicle. We just cant really get a bigger top rad tank into vehicles with the shape of the bonnet/body the way it is, so remote mounting the top tank is what we can do. Lets also keep in mind that this ranger tank is quite large (it works quite well) but it also can fall into the bay clutter category, as more **** basically slowing down the flow of air through the bay.

If you have a vehicle with plenty of under bonnet room, you could just have a much larger top tank (provided this tank is the highest point out of the whole system) and this does away with the need for the expansion as we can run a decent air gap in this.

Some key takeaways

- any decent cooling system should be 100% self bleeding (this also means it is pro active with aeration) It drives me up the wall when people think you need to bleed a cooling system. It may be a true statement but it screams poor engineering to me, and it also shows that it cannot be trusted if there is chance of aeration in the system. While we aim to have zero aeration in the system, its good engineering in my eyes to allow for it to be controlled and utilised if ever produced for one of the many reasons that it could be.

It is a bit of a laugh that the rangers have such a good exp tank given their history of being fairly leaky motors. At least with a slight head gasket issue, an expansion system will get you home, perhaps you wouldn't even realise you had an issue, as it is an area for combustion gasses and coolant to seperate, so the coolant can keep on doing its job to keep the motor in once piece and the gasses can just keep venting out the spring cap while you tip toe home. Double bonus being that by nature, the expansion tank is generally of aid to the water circulation which can reduce the risk of a damaged head gasket.

- Static pressure can help pump feed, however too much of it is a good indicator you may have a problem.

- With an expansion setup, you don't do the coolant smell thing any more. (its nice that all the coolant stays in the system, and you don't have to keep topping it up like some with recovery systems and poor airflow find themselves having to do)

- It aids in water circulation due to increased NPSHa and the shock absorbing effect the air volume has over water which is incompressible.

Will this sort of mod help your car run cooler?

No, sort of but im going to say no not really in contrast to sorting your airflow. This is of course the case provided you have decent water flow and temp gradients to start with, which is probably not the case if your car is completely standard.

The reality is, improving the pumps ability to provide reliable pressure and water circulation can have a multitude of positive effects on all sorts of engines for all sorts of reasons.
Water circulation is perhaps the single biggest area of most engines today that is usually completely overlooked and misunderstood, and our OEMs have not done a good job of water pumps at all for many many many years now as its clearly evident your average water pump impeller these days was likely designed by an accountant.

Even then with all this being great - "no amount of waterflow will bandaid an airflow issue" just as "no amount of airflow will fix a waterflow issue"
 

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Well this has certainly got me thinking. I will be having a serious look at my setup. I have a 2001 4.2TD and it doesn't matter if I am towing a box trailer filled with rubbish, a 2t camper or a 3t Sharkcat as soon as I hit a decent hill the temp soars. I will start with the lower air dam and leaking air in front of the radiator and see what happens.
 

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Discussion Starter · #120 ·
Well this has certainly got me thinking. I will be having a serious look at my setup. I have a 2001 4.2TD and it doesn't matter if I am towing a box trailer filled with rubbish, a 2t camper or a 3t Sharkcat as soon as I hit a decent hill the temp soars. I will start with the lower air dam and leaking air in front of the radiator and see what happens.
Report back with pictures and results if you like.

Not sure if u are using an aftermarket temp gauge (not really that necessary from my assessment of factory gauge efficacy) but if you are let us know how many degrees difference you get. If not let us know approx difference on factory gauge.

Obviously a lot off different inputs are determining the ECT and block temp and where we measure these needs to be taken into consideration but the general consensus with corrected or improved areo is any where between 5 and 14 degrees difference typically.

Not to mention the multitude of other subtle improvements we see to all other aspects of under bonnet things and even theoretical vehicle drag coefficient (I know that's a bit of a laugh, but it's still a thing)
 
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