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Mar 29, 2017 17:17:30 GMT
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I worked for an OEM manufacture testing cars in a wind tunnel for 13 years and although I left the industry 8 years ago I've managed to retain some information in my tiny mind. The golden rule of cooling is "temperature difference is the driving force of heat exchange" you want as big a temp difference between the rad inlet temperature and the air blowing on the surface of the rad as possible. If the rad is at 99°c then obviously air at 10°c will cool better than air 75°c. Now as Blown imp said the 2nd rule of cooling is "airflow is king". If your rad is fitted with no sealing to the frame, when the fan kicks in it can actually recirculate the air sucking air from the engine bay back over the rad instead of fresh air from the front. This is where you'll get air at 75°c trying to cool the rad instead of ambient air at 10 to 20°c. As airflow is king your thin large surface area rad will cool a lot better than your thick small surface area rad. As air passes through the rad it warms up. The air cooling the rear half of the rad is now cooled by air a lot warmer than the air cooling the front of the rad so it is now a lot less affective. To add one more point a radiator at 90 deg (vertical) to the air flow can seriously affect cooling - you actually benefit from a slight tilt - you want the heat transfer from the hot fins to the cooler air and having tit go straight thro doesn't help the transfer process I've never done any work comparing different angles on radiators but did do some with a vertical radiator and tilting a puller cooling fan. We tried different an angles and found it did improve the cooling as it would direct the air down towards the opening in the undertray rather than direct at the engine. As Blown imp said earlier the cooling fan has very little effect whilst the vehicle is moving. The air flow produced with the fan on is only very slightly above where it would be with the fan off, but hardly enough to make a difference. |
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Mar 29, 2017 17:22:24 GMT
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So... shall I spacer the top of the fans a bit, with the aim of getting the airflow under the engine/car.
Whilst I'll be doing some aero to make for a low pressure area behind the radiator, or doing some kind of Gurney flap business, that only seems to help when moving, what can I do to aid cooling when stationary?
I'll look at what I need to do to seal the rad, I'm worried that I'll end up creating some kind of heat soak from the intercooler, there is about an inch gap between the two with everything in its current positions, with the intercooler mounted lower than the rad, but still significantly overlapping it in air flow.
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Mar 29, 2017 18:12:05 GMT
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They only thing you can really do is fit the biggest fan you can. Don't fit after market. They're curse word. Fit an oem fan. Car manufacturers spend millions developing them. They're the best for the size and power at moving air. Same goes with rads. OEM spend millions developing cores that get the most heat out of a system for the smallest size and weight as that the constraints placed on them by the vehicle manufacturers. A small cottage industry doesn't do this or ford would buy rads from them.
You could make a fan cowl with blown flaps so air is scked across the whole core at low speed but they blow open at higher speeds.
If you have an under tray you can cut a slot in it behind the rad with a strip hanging down to create low pressure when the vehicle moves. It gives the air somewhere to come out at idle also to top air stacking if the engine bay is cramped.
I don't know if tilting the fan will make much difference in your case you'd have to suck it and see.
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Last Edit: Mar 29, 2017 18:13:26 GMT by jonsey
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mattiwagon
Part of things
Just got a work truck
Posts: 445 
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Mar 30, 2017 21:02:26 GMT
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I once got told the depth of a piece of corrugated cardboard is sufficient.
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If they cant be nice f**k em!
84 low t25 panel 1.9td beige and rust combo
97 Goped Bigfoot G260RC with clutch conversion
97 Impreza turbo 2000 builders wagon 76k sold
04 Fabia vRs 50mpg pocket rocket
04 battered T5 pickup in blue!
Chainsaws lotsa Chainsaws
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scimjim
Club Retro Rides Member
Posts: 1,503
Club RR Member Number: 8
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Mar 30, 2017 22:20:13 GMT
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A quick question. Intercooler flush to rad, or is it okay with a bit of a gap? Follow on question  Is your intercooler in front of, or behind the rad and can you monitor IC inlet/outlet temps? |
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Nathan
Club Retro Rides Member
Posts: 5,650
Club RR Member Number: 1
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Just thought I'd mention, mine overheats with the IC in front of the RAD it is why I moved it to the lower valence section.
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Mar 31, 2017 18:21:20 GMT
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My kit car is renowned for overheating. Normally uses a standard ford escort rad just hanging on brackets in the engine bay. I changed to a smaller Honda Civic rad and ducted the air into the rad core instead of allowing it to bypass straight into the engine bay, worked wonders considering the Civic rad takes up less than 2/3rds of the room the escort one used to. I added a header tank and a fiesta mk2 cooling fan into the mix but it's normally pretty well behaved. Some of the other chaps have used the polo rad you mentioned earlier on 2 litre zetecs and pinto's. Someone said you may be able to use these. Not sure if they are correct for your car or not.   They have been in the loft of my shop for at least 20 years, packed in what appeared to be genuine Datsun boxes that have seen better days. No idea what they are worth so if you are interested make me an offer and I'll get a quote for shipping them down. The o/s one is mint, the n/s one has surface rust. |
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1988 DUTTON LEGERRA MK1 - SPARES DONOR
1989 DUTTON LEGERRA MK2 - CURRENT PROJECT
1990 DUTTON LEGERRA ZS MK2
1990 DUTTON LEGERRA ZS MK2
DUTTON PHAETON S2 - Resting
DUTTON PHAETON S4 - Resting
DUTTON PHAETON S4 - PROJECT X
DUTTON SIERRA S2 - Resting
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Dez
Club Retro Rides Member
And I won't sit down. And I won't shut up. And most of all I will not grow up.
Posts: 11,790
Club RR Member Number: 34
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Mar 31, 2017 23:56:13 GMT
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Wind back a few steps.
You say you have no idea if/how your heater matrix is plumbed? Or bypassed? Having had two head gaskets fail from blocked/bodged heater setups, I'd Personally I'd be looking at getting that right before I spend a lot of time re-engineering the rest of the cooling system. Where and how it is plumbed can make a huge difference to an engines cooling capabilities, and it's ability to purge air from the system.
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Before wasting money on fitting the polo unit I would spend a few quid on tape and stuff making sure that every bit of air that goes through the grille, goes through the rad and not around it. Also make sure the coolant is going through the rad as sometimes people take the thermostat out so a lot of the flow goes through the heater circuit or bypass instead of through the rad. I agree Dez. I've seen systems where the coolant avoids the radiator through bypassed heater cores etc as it takes the path of least resistance |
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Update with some photos. First thing first the replacement thermostat pipe work arrived, the original had been modified (for space or hose fitment I think) and I believe this was the cause of a leak that I've had trouble tracking down as the hose attached to it was deforming. In fact it is tracking down this leak the prompted me to take apart the entire cooling system rather than just slap on a couple of huge fans and get on with my life to try and sort out the over heating.  I put it in place to check clearances and things when I put the rad back in and tested fan locations. Whilst it was out I tested the thermostat that was in the car and it seemed to work fine, the part when I ordered it from eBay came with a whole thermostat and housing assembly, so I tested that one too, and it seemed to be a bit newer and in better condition, so I've put that one in the car.  I actually need to work out how I'm going to do the gaskets on this, I've got a couple of other connecting parts that need gaskets, but I'm not sure I want to spend £150 on a complete gasket set for the engine, any ideas? Cut your own gaskets? Checked the rad in place for clearance on the pipe, this is a photo with the fan on one side, but it fits on the other one too  Need to get a bit of new hose, although I'll see if the old one can be persuaded to fit.  I spotted this on the rad, where some wires had be attached to the intercooler/rad mount so had been sandwiched between the two. I've moved them so they run along the top of the front valance, which is where they were connecting to anyway. :/  On the other side of the engine bay I need to start working out what I'm going to do about this manifold/intercooler/air filter pipe work... the red line is how I'd like the intercooler pipe to go, and I'd like the air filter pipe to be at a slightly steeper angle to accommodate this a bit better. However it will require some connectors on the turbo manifold to be at different angles, any ideas people? The one for the intercooler pipe will have to come straight out, rather than turn up at 90 degrees for a start!  Heater matrix pipe work! :  Both the pipes marked in blue go into the bulkhead and I assume into the heater matrix... I have NO IDEA where/how/what to check on these to make sure they are working properly. The one that runs across the engine is a little kinked but not bad, this used to be more kinked, I shortened it a bit a little while ago and made it run in a more sensible manner, I'd replace the whole thing with a better formed bit of hose, but I don't know where it goes once in the bulkhead, or how to get to it to replace that end of it. Cool air plans! So here is what I'm hoping to do to add some cooler air. There is a gap under where the intercooler sits (outlined in blue) that I can add a small air dam behind the air dam that is already there to bring some air up on to the face of the rad, and create that low pressure area to suck the air back down again afterwards.  Also if I remove the two lights in the grill and replace them with ducting and sealing on to the radiator face (so it comes in behind the intercooler) I think that will aid in getting cool air there, particularly if the fans are doing their job of sucking.  Still more bits to order and work out how to fit. However it isn't looking like an impossible task to get this back together and tested. Current list: Order another fan and a fan controller Work out how to mount fans (maybe order universal mounting kit), and how to change turbo manifold stuff (not 100% required) Measure hoses for radiator and intercooler changes then order Fit it all up Hook up fans to electricals Test fans Fill up coolant Start car Hope it doesn't overheat and make me sad. |
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bstardchild
Club Retro Rides Member
Posts: 14,971
Club RR Member Number: 71
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Heater matrix pipe work! : Both the pipes marked in blue go into the bulkhead and I assume into the heater matrix... I have NO IDEA where/how/what to check on these to make sure they are working properly. The one that runs across the engine is a little kinked but not bad, this used to be more kinked, I shortened it a bit a little while ago and made it run in a more sensible manner, I'd replace the whole thing with a better formed bit of hose, but I don't know where it goes once in the bulkhead, or how to get to it to replace that end of it. Well if both pipes go thro the bulkhead that will be the flow and return for the heater matrix One should get hot when the engine is running and the other should be hotter I'd be tempted at this stage while the car isn't running to remove both pipes and flush the matrix with a hosepipe Of course if water is put to one side and nothing comes out of the other then the matrix is blocked They frequently block up when stuff like K seal or rad weld is used to fix other things and if they are blocked then the coolant circuit is not doing what it should |
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I'd be tempted at this stage while the car isn't running to remove both pipes and flush the matrix with a hosepipe This sounds like a good plan, seeing as the heater in the car doesn't work it could be related... I need to track down my service manual to see if it gives me details on how to remove those pipes without breaking/cutting them  |
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Dez
Club Retro Rides Member
And I won't sit down. And I won't shut up. And most of all I will not grow up.
Posts: 11,790
Club RR Member Number: 34
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If those pipes go through and connect to a heater matrix as it appears they do, but the heater doesn't work, that's bad. It's enough on its own to make an engine overheat. You have to think of the heater matrix as a small auxiliary rad that can provide a good 10-15% of your cooling. On most cars until the thermostat opens its actually all of your cooling, and it being blocked will restrict proper coolant flow.
10-15% is more than you will gain any other way so you really should be looking at that as a priority.
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Last Edit: Apr 3, 2017 8:47:14 GMT by Dez
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Regarding the heater circuit, during the 90's Nissan deleted the water valve in the heater systems on cost issues. They choose instead to just bypass airflow around the heater to give you full cold at the heater. The heater circuit is the bypass for the water pump when the stat is closed. If the Datsun does have a heater valve, when its closed(and the engine is of the newer design) and the stat is closed, there is nowhere for the coolant to flow so the water boils in the head until the stat opens
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Last Edit: Apr 3, 2017 9:01:37 GMT by jonsey
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New bits!!  And  That is another fan, a selection of mounting bits and a thermatic switch. Will try and get the fan test mounted and then see where we are for ordering coolant hoses and re doing the intercooler intake. |
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 Just a little mocking up, mounts need to be cut to size etc. Need to work out how I'm going to bracket the bottom in place but it looks fairly doable. Missing the connectors for the thermostat thang at the moment, should be able to pick those up easily though. Then gaskets for new coolant connector bits. Then new coolant pipe work and intercooler pipe work. Then fill it up with coolant and give it a whirl Oh yeah and find what is going on with this heater matrix pipe work. |
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wow...way beyond my skills!....great work. It inspires me how you worked through the issues and resisted the urge to just patch it up and move on....it would have certainly just bitten you later!
JP
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I know its spelled Norman Luxury Yacht, but its pronounced Throat Wobbler Mangrove!
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May 17, 2017 21:17:25 GMT
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Update time Fans are now fitted, process looked a bit like this :      I then offered up the radiator to check clearances against the spinny bits of the engine.  A little bit tight, however I'd left enough room for adjustment so managed to move it over. Which has left it abutted to the inter cooler pipe work on the other side.  But I can jig that around a bit. Then I cut some gaskets (hopefully these will be fine for water/coolant use.  Yes I did put a suitably shaped hole in the middle. All of which leaves me to sort out the pipe work on the entry pipe and its relationship to the intercooler pipe work and then get it all fitted together. I also have a new digital fan controller to fit and the heater matrix to double check. Getting there though. |
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May 17, 2017 21:31:37 GMT
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Bleedin nora , i wouldn't be surprised if that ally piping wasn't leaking , it looks like a gibbon has welded that !
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Bleedin nora , i wouldn't be surprised if that ally piping wasn't leaking , it looks like a gibbon has welded that ! I'm hoping to be able to replace that with some suitable Samco hose, ideally I'll re-route it, but space is tight in there so need to do some measuring. What I really need is a load of hose, bends and connector pipes of various sizes to spend a morning fitting and arranging to see what works. Sadly that would waste a bunch of money if I bought a load to do that, and no shop is going to let you fit a bunch of new hose/pipe work to test it before deciding on something else... |
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