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There is a possibility that the standard pump is adequate for the job, once other restrictions in the system are removed. It is also possible that while a modified pump does not reduce any temps recorded in the standard system, if fitted in conjunction with other modifications, improvements may be found. Removing restrictions will effect how both standard and modified pumps work.

This will be tested in due course.
If pump is cavitating, what other restrictions can be removed to rectify this, without replacing the pump?
 

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Discussion Starter · #142 ·
There is a possibility that the standard pump is adequate for the job, once other restrictions in the system are removed. It is also possible that while a modified pump does not reduce any temps recorded in the standard system, if fitted in conjunction with other modifications, improvements may be found. Removing restrictions will effect how both standard and modified pumps work.

This will be tested in due course.
Yep

In an open system we can help a pump run back on its curve by choking the discharge until it does so.

Not sure how this will relate to our closed system but I will have to read up on it.

Either way - clean water flow with as much volume as practical (within reasonable means) is where I am still at, regardless of all other variables.

Perhaps you can get that with a stock impeller.
I can't.

Would like to mod one and test one day but it is hard to be motivated to fix something that isn't even remotely close to being an issue any more.
 

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Perhaps you should do some reading up on closed systems and why cavitation happens, or more correctly how cavitation occurs in a closed system. To help you out a bit, with an open impeller, design dependent, cavitation on the interference face can be two things one being clearance is too large which is common with a TD and aftermarket pumps and the other is the pump impeller cannot draw enough water. Cavitation on the blade tips and blade tip interference on the scroll is from too much head pressure, or in our closed system to much restriction for the draw suction. In some cases you will see evidence of both due to clearance issues. Engine design engineers worked out a long time ago a closed system like ours doesn't need a fancy impeller, as i found out in the mid 90's hence a bent tin open type impeller with correct clearances is more than adequate for pressure and flow in most cases, and more than adequate for OEM's up until very recently.

I decided to do an edit as i think this bit is important and you the OP and some others will get it. Generally speaking an open impellor is for high fluid volume output with little pressure. A closed impeller generally speaking will generate respectable volume flow with high pressures so is good for pump fluids up hills or mountains or driving pressure sprays etc. Not such a wise thing in a closed system as the rpm operation range to pump performance curve is quite small so has a limited rpm range. An open impeller has quite a large operating rpm range and will still be effective at pumping volume either side of its performance curve without head pressure issues. So well suited for a closed system. Now our TD pump its a single flappy blade impeller that runs in 2 scrolls so we have two outlets either side of the block one scroll is 3/4 circumference and the other is about 1/4 circumference. Great idea but the system needs to be balanced as this configuration is not great at pressure but can be and is in this case higher in volume compared to a full circumference scroll. Our TD engineers didn't quite get the balance right. They had the right idea for an IDI with its heat chambers in the head main water gallery requiring considerably more water flow to cool those chambers but for this twin scroll pump the system has to be free flowing to compensate for the reduced pressure or resistance overcoming outlet pressure. We have enough holes in the block to head for distribution and the head water galleries are quite large compared to other IDI heads. But the stuff up is the thermostat housing itself. It simply is putting to much resistance on the pump which then causes suction volume issues in our hot side thermostat configuration. If you get this you should understand why a supposed bigger or more efficient pump just cannot flow any real extra volume because the twin scroll system wont allow more pressure to overcome volume flow losses. Then to feed the pump to make higher volume flow values its not happening due to the design of the housing. If you could fit a bigger hole thermostat and send all the water through the rad it can work but the area before the thermostat or the hole feeding the thermostat is tiny and no way to enlarge it significantly enough. Even a external bypass which can work but it has to be before the feed hole before the thermostat housing and you need more pressure to drive the system or balance the flow values thermostat to rad and bypass but it can be done and can work. But the twin scroll pump is not designed for this pressure volume requirement. I know this is a bit of a ramble but the points are clear and well proven.

For the very modern high output turbo diesels where displacement is reduced and economy is just about the highest criteria, engineers are now designing fancy impellers because they know running higher temps with fluctuations less than a couple of degrees in any condition brings economy with diesel so the closed system has to be a lot more stable and flow rates controlled very precisely usually with electrics and electronics. Even the very modern small displacement turbo petrol are seeing performance and economy gains from very precisely controlled temps.

Our TD is a dinosaur compared to these very modern engines, but still, being IDI it can see some very impressive benefits in performance and economy, if our cooling system can be controlled and stabilized in the 94 to 96C range especially in the block area. I would not of though this was a big ask for a TD but it has a few design issues, "its good enough engineering" or it works good enough for a N/A diesel @85kw engine if its lucky. Some of us treble that output at the engine and wonder why we have cooling system issues.

Sure your aerodynamics incentives can help stability or extend the out of control temp stability quite effectively. I for one did most of your suggestion and encouraged such things in this forum, except holes in the inner guards, when you were in nappies. I take nothing away from you there, as i think what you have done, tested and suggested is commendable.especially for an electrician ;):).

It may come to pass that a STD pump is more than capable of flow rates to control treble engine power values and stable, and maybe it "isn't even remotely close to being a issue anymore" we will find out one day.

In the past i have been guilty of "its good enough engineering" or it works good enough and my GQ did cool good enough with all your aero suggestions done in 1990 with a yanmar marine engine closed impellor which was too much suction, But it worked good enough for 200 rwkw's. Now i want to fix the issue properly or have a go at fixing the issue regardless of the aero stuff as that's just a logical bonus.

Now I want real stability and to have a go at those 1%er performance and economy bonuses as our fuel prices these days is hurting the pocket. Or maybe i get the sh#ts and fill the tray with batteries and convert the old near new GQ to full electric :rolleyes:;). Yeah right. My electrical engineer brother has been getting in my ear lately, after we have been designing conversions for 60 meter car carrier catamaran to full diesel electric. These new 500Kw air cooled marine electric motors are really tiny, they are smaller than my TD and weigh a bit less without couplings and the 2 tons worth of switchboard..
 

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Discussion Starter · #144 · (Edited)
Haven't had my head in the litterature for a while Pete had a bit on but I guess another way of saying what on mean in regards to pumps is that in depth theory is great but real engineering is where the rubber meets the road so to speak. So I'm in support of what you and Shayne are aiming to achieve but as you can only think your way through something so far sometimes, as it's not what you think about that is the issue it's the stuff you didn't.

On paper a closed impeller seems silly in ways you describe but I know of a few who swear by this type of thing. I have been hearing you out on the bottleneck thing for quite a while now even to the point where I have a near daylighted factory lower stat housing with other re directed coolant flow to fit which should help improve flow in that area. Will that translate into better results? Hopefully but how much better do you need.

I can keep my motor in one piece and not even see the factory gauge start to rise considerably at 700EGT with EMP probably at 2/2.5 as you suggested from the current turbo I have while making over 660nm and 240 hp for minuets on end. 🥱 This is a recipe for a full blown kettle episode is it not? Imagine with a set of manifolds that flow and a turbo that doesn't keep the heat in the motor!

Meh shel be right mate l get to it one day.

I'm not sure if my ute is fixed fixed but it I'm certainly not one of these "I made a purchase so I'm gonna stand by it even though it doesn't work," type people who are evidently all throughout this forum. And it's certainly not a case of "oh it works here but then doesn't work here" apart from running a bit too cold in lower ambients. Maybe I need a hotter stat or a bit of cardboard to block the front :ROFLMAO:

I'm not sure if that's what other TD people are after or if they really care about near on inevitable slight nucleate boiling that can be symptom mitigated with a sound layout and good enough air flow. A wait on a decent water pump is nealry a lifetime and if what you guys are doing works well your next question is it commercially viable and are you ready to be on the phone 24/7 to half cranky customers who can't get it to work because they think improving the water circulation is going to magically make up for the need of any sort of decent airflow?

As far as my system goes I can pull over and remove the radiator cap after cruising at light load at operating temp and a hiss will come out, no water comes out. I must be doing something right because that isn't what you normally get with these cars even in a GU layout which is better then a GQ layout.

If what you are suggesting is true with water flow, it could render my theory of airflow as being our step 1 in any bypass flow thermostat controlled system being not as important and everyone should focus back on water flow as a step 1. I'm eagerly awaiting the results. Certainly something I can't achieve with my resources. Action is better then no action!
 

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Discussion Starter · #145 · (Edited)
If pump is cavitating, what other restrictions can be removed to rectify this, without replacing the pump?
Perhaps the ranger expansion tank mod, a daylighted or high flowed lower stat housing, a thermostat with bigger throughways and better flowing - anything that encourages a higher volume of coolant at a lower velocity to the eye of the pump.

Also pre pressurising the system could mitigate as nascar does. Just to re discuss cavitation again for the sake of anyone interested. It's the boiling of the medium on the back edge of the impellor due to the pressure here becoming lower than the liquids vapor pressure. if the system static pressure is manually made higher (like before the engine is started) and kept higher, this is a cavitation band aid of sorts as the increased system static pressure works to overcome this drop in the liquids vapor pressure at the trailing edge of our open impellor splishy splashy washing machine drain pump boi, preventing it from changing state and force feeding the eye of the impellor. that's part one of it, part two is the energy it releases as the bubbles collapse. this is what creates the noise and damage.

Some noteable things with impellor design, Standard is open, something like derks is semi enclosed and is sold with instruction to get it as close to timing cover as possible, Others are enclosed.

In theory its absolutely possible that if we can keep a standard pump fed, it would be up to the task. however it could still have efficiency issues at high heat loads due to the amount of recirc it has by being an open impellor. Could we be using external feed lines to the water pump housing to keep the volume up to this side of the open impellor? this would make the over all feed size to the pump greater.

Since we arent pumping rocks and rabbits, and closed impellor designs are capable of "respectable volumes" at high pressures with high efficiency, this again leads me full circle into my thoughts of what is the propper ratio of pressure and volume in the head to eliminate nucleate boiling?

Id love to see the theory on engineering this process. It would have to be a compromise to some extent as both headload and pump speed vary in our TD and they do not allways share a linear and or proportional relationship being IDI turbo diesel.
 

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So more aero testing;
Removed air dam, and I didn’t re-install genuine Nissan bashplate under winch..
Once again no change in pressure readings infront, between stack nor in engine bay!
BUT, water temp down 1° in all conditions across the board, aswell as recovery times twice as fast as before!
So it looks like a slot is needed in the front of my air dam to help let air into this free air section of the Rad below/behind my winch…
 

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Discussion Starter · #147 ·
So more aero testing;
Removed air dam, and did t re-install genuine Nissan bashplate under winch..
Once again no change in pressure readings infront, between stack not in engine bay!
BUT, water temp down 1° in all conditions across the board, aswell as recovery times twice as fast as before!
Will be interesting to see your findings once you have opened up the front of the bash plate area to allow air entry to the free air section while still utilising the air dam itself to push the remaining road speed air under the diff and create what i guess we call a venturi or low pressure of sorts behind the rad.

As we all can agree that more airflow results in lower bottom hose temp for a given condition - i think that your initial design must have been taking away the high pressure available to the front side of the rad core at the free air section, while the air dam itself wasnt as critical because the diff wasnt sticking out a lot to start with. (just my thoughts) Got to love custom making things sometimes, I've done remakes of things like 3 or 4 times regularly, before i was happy - story of my life. :ROFLMAO:

I often advise mock ups for aero related stuff as it can be annoying at times to fully fabricate something nice that doesnt end up working real good.

For a mockup test, a rectangle sheet of something like ally could have one fold in it, and just bolt it to the rad protection member via the 3 holes, (as your air dam + splitter) and see how that gets on. My money is on some good results.
 

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Haha you said it mate, same here, gotta love DIY fab work, and doing it again, and again sometimes!
That’s okay mk2 coming up soon and see how we go!
I built that late last year with the knowledge I had at the time, I know a bit more now and its on the right track, but there’s no substitute for real life testing!
All good, just thought I’d share so others can learn from my mistakes too 👍
 

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Discussion Starter · #149 ·
Haha you said it mate, same here, gotta love DIY fab work, and doing it again, and again sometimes!
That’s okay mk2 coming up soon and see how we go!
I built that late last year with the knowledge I had at the time, I know a bit more now and its on the right track, but there’s no substitute for real life testing!
All good, just thought I’d share so others can learn from my mistakes too 👍
100% mate its super important for discussions sake and would be appreciated by anyone looking to attempt to do something similar.

If i shared my collection of mistakes this thread would be perhaps 3 times longer allready.

example: I used to love my genuine bar as i put so much time into it modifying it to accommodate a high mount winch which it did in respectable style leaving the terminals on the winch motor within mm of the grille without having to cut it and having the terminals in the cut away part of the grille where additional existing clearance was available as if the winch setup was engineered for the oem application.

It was however apart of my issue with airflow unfortunately. Big 10mm gussets that ran from the main winch plate surface back to the mounting points obstructed lower half of rad airflow and additional bars across the front seemed to do a similar thing as well. Also, a high mount winch is a lot more winch in the bar and as much as i miss the sound of that thing and the way it would make you laugh as you were scull dragging yourself our someone else effortlessly, it was not in full support of my airflow related business like the TJM bar is.

Just to again reiterate for anyone interested, core flute is a good material for mockups and can be secured with gaffer tape in many ways. don't be afraid to get proper dodgy for mockups, as long as you make sure it stays on the car when you're driving (buy good tape and zip ties) but basically whatever supports firstly allowing for firstly a low pressure behind the bay and then a high pressure in front of the stack is how we want to be making our modifications.
 

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Nice mate! Same here! I had high mounts on all my GQs and miss them for the reasons you mentioned, that external brake pawl clicking is music to my ears!!!
But on this GU I also decided to keep lowmount purely for packaging reasons and conscious of airflow from day one…
 

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If pump is cavitating, what other restrictions can be removed to rectify this, without replacing the pump?
As Oldmav has detailed, indications from testing is that the thermostat housing is the culprit. Simply put, the pump can only work well if the coolant available to it is sufficient, and not restricted.

Mike has made a number of modifications to his system to get it working as it is now, whereas my testing is based around standard parts. So in this respect, we are comparing apples and oranges a bit. My aim is to fix the issue with hopefully a bolt-on part that requires no maintenance, never needs replacing, and will fit GQ & GU TD42 engines.
 

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You have stated often in other thread you are more about discussion of concepts that statement of supposed truths.

I presented a few ideas for discussion more than theories of facts or evidence to suggestions. You seem to have dismissed the invitation. Much of what i write or propose is to gauge a perception or to incite a different view to ponder on, You know often the best ideas come when other view points are taken into consideration even the silly ones.

One discussion point you have mentioned a few times which is the GU rad system is better than a GQ. Reading between the lines i think you are referring to the skinny rad with top down flow. Not sure that has evidence to support that in the engineering world. Considering top down has limiting fitment issues and frontal area issues. But besides that top down is usually used in big core arrangement where space and frontal area is not a issue. For cars and our 4x4's we have limited space for frontal area and designing in a dam space on low bonnet cars which is for aerodynamic improvement issues for resistance etc. Hence the cross flow design was adapted to get lower bonnet lines and easier to design in wide frontal dam area.

There is evidence to suggest crossflow is more efficient due to the action of hot fluid flow dynamics in tiny tubes and the cold water sinking in both side tanks creating a more effective thermal flow. Probably just theory but their seems to be evidence to support the concept. Its sort like the proposed debate on copper brass V alloy radiators, except in this case its a proven fact good alloy radiators are more efficient and way stronger than the very best copper brass assembly for the same area..
 

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Discussion Starter · #154 · (Edited)
Hmmm. My intention isn't to dismiss any invitations to discuss this stuff, I may just be challenging ideas in a non diplomatic way or something. I hear you on gauging perception, there is a few things that I think you allready know I am already aware of, but I don't mind discussing them again.

Much of what I have looked into is built of what you have allready written about on here apparently some of which when I "was in nappies". Hmmmm yes well I don't wear nappies any more but I've still found myself in a few situations over the years where one could have been handy.

The idea by my suggestion that GU > GQ layout is in regards to mainly yes the down flow radiators and the use of the remote expansion tank. These layouts much better lend themselves to de aeration of coolant due to buoyancy of all mediums in the system and hot rising cold falling or convection I think it is. In regards to the GU and more notably the later GU layout with the tall skinny radiator we see that we have considerably more airflow potential provided the car modifications around the stack lend themselves to allowing this airflow as intended by Nissan .

The greater airflow relates to the waterflow indirectly by means of increasing the NPSHa to the pump due to the coolant being a lot more dense at the bottom of the radiator as a result of this airflow removing a lot of heat.

Along with being able to just pop my bonnet and take my rad cap off at any given pull over off the road, I can drop the bung out of the radiator straight after key off and have my hand under the water running out of it with the hot hose ECT at 80/82 degrees and only have to pull my hand away after the first 4 or so litres has drained because the bottom water in the rad is cool.

The GU layout also steps in when/if things go a bit funny like what happened to me recently with the bursons type A coolant I had in. It decided to break down and turn into a foam fest.

I did my last full load test up the range towing with this foamy crap in and still the motor didn't care. (this is the one that I took video of for anyone I have sent this to on facebook). Since removing this and flushing and being back on straight water for now, I am getting even lower temperatures. 82c stat holding at 80 with + or - 2 variation under normal driving conditions and highway loads/speeds. Better then my previous + or - 4 in these conditions.

The expansion provides an area in which it can control bullshit like foam and air, separate it out from the stuff that cools the motor while not allowing this to get back to the pump like a crossflow can lend itself to doing so, assist the feed to the pump, and act as a shock absorber (theoretical) for our system.

Not to mention it is a good visual indicator of water in system (not that you ever really have to do anything with it unlike a recovery system)

As expected though being on straight water again the hot hose rises faster under high heatload and my block won't come up as much as I would like it too under high heat load. (Subtle and really not that important to me at this point)

On a side note I have one mate who is currently getting a decent expansion tank set up in his GQ with the cross flow.

With this expansion plumbed up correctly the cross flow will be fine in my opinion and if your theory is correct it could be better over all compared to the GU?

The engineers didn't put the bleeder tube on for no reason, and placing an expansion here with the return going back to the pump suction certainly won't hurt regardless of how you choose to make the water move.

If we can keep the motor further under the surface of the water there is less likely to be any air that bleeds up to the top to be recirculated back to the pump.

The trick then is making sure the system lends itself to allowing a propper self bleed which isn't really hard when we all know that air wants to go up and water wants to go down.
 

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For those interested, having removed my AC condenser’s thermo fan and power steering coolers, has again made no change to any of my previous airflow and temp results, as expected. There’s a solid 90-100mm space now between my FMIC and AC condenser.
This may be just in the mind but I’m sure this may be a 0.5%er, a marginal gain to be had for someone already on the edge with their cooling setup, one less thing to disturb air to the Rad. On it’s own may be worth bugger all, but along with no spotties or other basics, on a 42° day may make the difference one needs.
Cheers
 

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Discussion Starter · #156 ·
For those interested, having removed my AC condenser thermo fan and power steering coolers, has again made no change to any of my previous airflow and temp results, as expected. There’s a solid 90-100mm space now between my FMIC and AC condenser.
This may be just in the mind but I’m sure this may be a 0.5%er, a marginal gain to be had for someone already on the edge with their cooling setup, one less thing to disturb air to the Rad. On it’s own may be worth bugger all, but along with no spotties or other basics, on a 42° day may make the difference one needs.
Cheers
The a/c condenser I found have very little pressure drop accross it at speeds over 60kph. I remember it being quite the surprise to me that even my own condenser which has bent fins every where and is really not in the best Nick, that it wasn't really a restriction what so ever at speed.

Also I'll talk again as I did further back up about things like spotties and or items that can obstruct high pressure air flow to the stack.

If you remove them and get a good result, the issue is likely NOT actually the spotties. It's more likely the low pressure side of the radiator.

Once the low pressure side is mint then we found that spotties really don't do much If they are on or not. Maybe they help being gone just a touch in extremes but really neither here nor there on a mint setup.

The factory thermo fan was a bit of a restriction at highway speed but not a deal breaker. It's gone in the bin on mine years ago and will never need to be back on because of how much the UFI fan draws at idle compared to factory. Its doesn't need any help at idle any more and now with it gone its better at speed as well. No problems with condenser pressure/temperatures at idle on a hot day or anything like that.

I think the main hold back on yours is the big front mount but with the right tinkering it won't matter at all and you should get some really nice low EGT at cruise once it's sorted good

The space I between exchangers in the stack seem to help change the amount and way air flows through the stack. The further apart and the thinner the exchangers are (like how the a/c condenser is so thin) the better airflow we got through the stack.

Having them further apart allows for both some air bypass of exchangers air going around them when the fan is drawing and needs more air to the radiator)

while in theory cleaning up the drafting characteristics of the air flow through each one as it passes by.
 

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I removed to give it a good clean but figured may leave off and test just for piece of mind! Power steering coolers will go back on, thermo will stay off👍
Definitely, I’m losing about 40pa from my FMIC. Like everything else, it’s a compromise with pros and cons. Il definitely take that 40pa hit for its benefits. I contemplated replacing it with 57mm core but don’t see much gain for the expense. If it ever needs replacing then a thinner core ‘cooler forsure. Atm I’m Better off putting that effort elsewhere on some damming strips behind grill to stop spilling out near the headlights, and modify my air dam
 

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Reading Oldmavs post above about him doing airflow mods in the 90's got me thinking about when I first thought about it myself. Long before I owned a Patrol, I had a much modified Mitsi 4wd ute in 1996. From factory it had a normal slim chrome bumper bar with a big slot in it in front of the radiator. When I replaced that with a much bigger bull bar and driving lights it effected the temps.

So I took the lights off which didn't do much. Not wanting to cut up the bull bar, I had a look and a head scratch. I decided to try and get some of the air that was going under the bar and beneath the car, and direct it back into the part of the radiator that was covered by the bullbar. In the end I made an air dam between the bullbar mounts that deflected air up itno the radiator, and after that it made no difference what lights etc I used. When fitting a bullbar to my next 4wd I did the dssame thing.

On my GQ this is not really a practical option. My vehicle has a two inch body lift, so the radiator sits higher than normal, so it is not going to be easy to do or very effective. So rather than try and direct air in, I focussed in stopping air getting out. So blocking off the gaps was the solution in my case. But I think that either way, if you get the "air dam" in front of the raditaor working well, then your condensors etc will not be a problem.
 

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Reading Oldmavs post above about him doing airflow mods in the 90's got me thinking about when I first thought about it myself. Long before I owned a Patrol, I had a much modified Mitsi 4wd ute in 1996. From factory it had a normal slim chrome bumper bar with a big slot in it in front of the radiator. When I replaced that with a much bigger bull bar and driving lights it effected the temps.

So I took the lights off which didn't do much. Not wanting to cut up the bull bar, I had a look and a head scratch. I decided to try and get some of the air that was going under the bar and beneath the car, and direct it back into the part of the radiator that was covered by the bullbar. In the end I made an air dam between the bullbar mounts that deflected air up itno the radiator, and after that it made no difference what lights etc I used. When fitting a bullbar to my next 4wd I did the dssame thing.

On my GQ this is not really a practical option. My vehicle has a two inch body lift, so the radiator sits higher than normal, so it is not going to be easy to do or very effective. So rather than try and direct air in, I focussed in stopping air getting out. So blocking off the gaps was the solution in my case. But I think that either way, if you get the "air dam" in front of the raditaor working well, then your condensors etc will not be a problem.
Nice mate, nothing like ingenuity, do you have any old pics out of curiosity?
Agreed mate, always good to see positive changes from tinkering, that’s why I’ve done one thing at a time and constantly made note. I not like to assume, Real life testing always teaches us what works and what doesn’t! Unfortunately my genuine Nissan bar doesn’t have the space under the winch like Mike has, and I don’t really want a shovel-style contraption to jamb air in either as my Gu is only 2”/33s now so ground clearance for Vic high country is a must for me. Hence why my air dam won’t ever be hanging down too low below diff either.
But I believe a slot in the front most section of my air dam will expose lower Rad under the which and maybe plate it up internally to channel air over that lower chassis member of the series IV tall skinny Rad setup….
 

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Discussion Starter · #160 · (Edited)
With a tall skinny downflow rad and a 2 inch body lift, if we could have our free air section at the top of the radiator instead of the bottom, and perhaps a bonnet vent exit - we have a better airflow layout at the hot coolant enters the top so we have a larger temp difference so we can remove more heatload.

This also means the fan clutch would perhaps engage less as it will see less heat and only engage as the airflow through the top free air section stops working so at low speeds.

The factory Ti with the free air section at the bottom is great though as it sort of after cools the coolant with speed. I just theorise that we could move more heatload if the free air section was at the top due to greater temp difference between ambient air and radiator temp.
 
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