p7rider Posted February 28, 2019 Report Share Posted February 28, 2019 I WILL BE FITTING A REVOTEC ELECTRIC FAN KIT TO SPITFIRE 1500, THEY SUGGEST PLACING THE TEMPERATURE SENOR IN THE BOTTOM HOSE. TO ME THIS SOUNDS A GOOD IDEA AS YOU ARE THEN MONITORING THE COOLED WATER TEMP. BUT I SEE THAT MOST PICTURES I'VE SEEN OF PEOPLES CARS WITH E FANS THEY'VE PUT THE SENSOR IN THE TOP HOSE. IT HAS AN ADJUSTABLE HEAT RANGE SO I SUPPOSE I CAN SET TO A TEMP I'M HAPPY WITH . WOULD BE INTERESTED IN PEOPLES OPINIONS.. Link to comment Share on other sites More sharing options...
rogerguzzi Posted February 28, 2019 Report Share Posted February 28, 2019 Hello p7rider! I run 2 fans on my 1500 Spitfire with a sensor switch fitted to the bottom of the radiator and it has 2 temperature ranges 82/79 & 88/82 Plus a manual override switch but to be honest only the lower temperature one ever comes on(except when stuck on a Spanish motorway in 30+ degs) I upgraded to a full width radiator and the switch boss was already fitted you can see it in the photo Roger ps it has been like that for 4 years and 20,000 miles with no problems Link to comment Share on other sites More sharing options...
p7rider Posted February 28, 2019 Author Report Share Posted February 28, 2019 Good to have proper screw in fittings . Also at the bottom where the water will be cooler ? Link to comment Share on other sites More sharing options...
Colin Lindsay Posted February 28, 2019 Report Share Posted February 28, 2019 I'm assuming the Op has a standard setup? Put it in either and adjust the setting accordingly. Top hose will be hotter; bottom hose cooler. The only Kenlowe I ever fitted (years ago to a Spitfire) had the sensor in the top hose and I suppose this location makes for a better monitoring of the actual engine heat, as opposed to how well the radiator is cooling; but for one of my other cars I bought a sensor that fits into the actual hose, which meant that the top hose would be too short to take the pipe it was set into and it had to go in the bottom one, with the sensor then fitted for the optimum temperature range. So: from that, I don't think there's any hard or fast rule. Link to comment Share on other sites More sharing options...
dave.vitesse Posted February 28, 2019 Report Share Posted February 28, 2019 If you have a thermostatic switch screwed into a short piece of a pipe type then this fits into the bottom hose. This type has a pre-set operating range. The earlier Kenlowe type used a sensor in the top hose. On this type you have a control where you can set the operating range. Nice job Roger, just don't open the bonnet if the fans are on! Dave Link to comment Share on other sites More sharing options...
p7rider Posted February 28, 2019 Author Report Share Posted February 28, 2019 Thanks for confirming. I thought the top hOse would be a bit short to cut. I'm changing from a kenlowe which as mentioned had a capillary sensor in the top hose . The kenlowe has seen a good 25 or more years service . Link to comment Share on other sites More sharing options...
rogerguzzi Posted February 28, 2019 Report Share Posted February 28, 2019 7 hours ago, dave.vitesse said: Nice job Roger, just don't open the bonnet if the fans are on! Dave Hello Dave Why? Link to comment Share on other sites More sharing options...
dave.vitesse Posted March 1, 2019 Report Share Posted March 1, 2019 Roger, You get blow over with the volume of air. Dave Link to comment Share on other sites More sharing options...
rogerguzzi Posted March 1, 2019 Report Share Posted March 1, 2019 Hello Dave I have no doubt you are right but when I was setting up my EFI I had the bonnet open most of the time and the fan would cut in for a short period then stop so it was doing its job! I also did a scientific test to see were the air was blowing(a strip of news paper held in different parts of the engine bay!)and it was flapping at the rear I used to have the n/s fan as the lower temperature one to come and blow over the alternator but I changed it around so its the o/s one that comes on at the lower temperature as I found the new 4 branch manifold was getting hotter than the old one so I thought it may as well have the air flow over it(it is thinner gauge tube than the old one but the old one would not let me fit the EFI runners) Roger 1 Link to comment Share on other sites More sharing options...
Anglefire Posted March 1, 2019 Report Share Posted March 1, 2019 Location of the thermostat has been discussed on here before. It sort of depends on what you are trying to achieve. Located in the inlet to the rad and you will maintain the head temperature at about the setpoint (Say 85'C) - the return to the engine will vary depending on load. Located on the outlet, then the return to the engine will remain largely constant, but the head temperature will vary. On balance, I would say the best place is the inlet as it will probably run more efficiently. On the other hand, the fan should only come in when its really hot as the normal thermostat should do most of the work. 1 Link to comment Share on other sites More sharing options...
Peter Truman Posted April 25, 2019 Report Share Posted April 25, 2019 A friends factory TR8 had factory fitted dual fans with the first cut in slow speed (fans in series so running at 6 volts) temp sensor mounted in the LH side rad tank halfway up, whereas the high speed (fans in parallel 12 volt each) had the sensor in or near the head from memory. My daughters first Sprint had an aftermarket elect fan with the sensor mounted similarily in the rad LH side tank halfway up. In her current Spit Mk2 we mounted the sensor in the thermostat cover tapped into the side boss (Part No.134681), It runs a 78C thermostat with the sensor 85c cut in & 80C cut out. The sensor is a cheap Chinese unit cost with free postage around $5Aus. I brought 3 as security, but unit has proved reliable and fan plus control copes with over 40C here in Aus, it has a manual cut in switch in case! Oh by the way the fans a 10 inch pusher. Anyone have any thoughts on the turbulence in front on the radiator affecting the fans performance caused with the open horizontal area between the chassis legs, one day I might try covering it so the air is directed from the front only. How's this for a twin elect fan installation seen on the Triumph Enthusiasts web site recently a very nice setup (I want one!!) Link to comment Share on other sites More sharing options...
Peter Truman Posted April 25, 2019 Report Share Posted April 25, 2019 Error Read Triumph Enthusiast as "Triumph Experience.com" Spitfire & GT6 Forum, Cooling Fan Section. Peter T Link to comment Share on other sites More sharing options...
p7rider Posted April 30, 2019 Author Report Share Posted April 30, 2019 I've just fitted the Revotec kit and the best place for their supplied sensor is in the bottom hose. I don't think you'll have the space to fit it in the top hose. I then ran the wires along the supplied mounting frame and fitted the relay on the left side of the radiator support frame , using a hole that was already there. This kept all wires and supply running along the left hand side. I bought some of the braided mesh sheathing 6mm I think to protect all my wiring . This matches What Revotec supplies. Link to comment Share on other sites More sharing options...
68vitesse Posted May 1, 2019 Report Share Posted May 1, 2019 Use a revotec adjustable sensor in the bottom hose of my Vitesse it seemed to me better to use the temperature of the water about to enter the engine rather than that leaving it. Unless others know better. Regards Paul Link to comment Share on other sites More sharing options...
Guest Posted May 1, 2019 Report Share Posted May 1, 2019 Hello Paul, I have used sensors in the top hose and fitted to the bottom of the rad in various classics - all have worked and all have cooled the water ensuring no overheating issues; as such job done. There is probably a slight advantage in one over the other, whichever one that may be. But for many owners I think it is a case of what fitting is the easiest at the time and what their personal held belief is. The difference between the two sensor positions is probably a few degrees. My Vitesse uses a top hose position and has dealt with significant heat in France - it also has to deal with the under bonnet heat of the six cylinder engine. The Daimler has a viscous fan, which seems to work fine - although that will be replaced at some stage with an electric unit with a sensor in the bottom of the rad. As you can see, no fast & hard rules for me - as long as the fan does what it is meant to do. Regards. Richard. Link to comment Share on other sites More sharing options...
Mjit Posted May 1, 2019 Report Share Posted May 1, 2019 Theoretical the top hose is the best place, as you start cooling the water as soon as it reaches temperature/stop as soon as it cools. Bottom hose you've got to wait for the hot water to flow through the radiator before it reaches and triggers the switch, so it takes longer/engine gets hotter before you start cooling and you cool longer/engine gets cooler before you stop cooling. Practically you're probably talking about 1 or 2 degrees difference between the two positions, which will make naff all difference and still be way more controlled/consistent than using a mechanical fan, so put it in the most convienient position. Link to comment Share on other sites More sharing options...
NonMember Posted May 1, 2019 Report Share Posted May 1, 2019 1 hour ago, Mjit said: Theoretical the top hose is the best place, as you start cooling the water as soon as it reaches temperature/stop as soon as it cools. Wrong conclusion from the lemma. You don't want to start blowing air through the radiator as soon as the top hose is hot, because the bulk of the radiator isn't hot yet so the bit you're cooling doesn't need cooling. Also, the further up the top hose you go, the more you're looking at the first glob of hot water released by the thermostat, which you really don't care about. There's no point running the fan until the water feeding into the engine, from the bottom hose, needs to be cooler. So, theoretically the BOTTOM hose is the best place. Practically, the difference is a LOT more than two degrees. Under the conditions where it makes a difference (i.e. during warm up and before you really want the fan on) the top hose may be hand-burning-hot while the bottom one is still cold. Once fully up to temperature the difference will still be non-trivial. However, it's easily compensated for by tweaking the fan on threshold. Link to comment Share on other sites More sharing options...
Nick Jones Posted May 1, 2019 Report Share Posted May 1, 2019 1 hour ago, NonMember said: Wrong conclusion from the lemma. You don't want to start blowing air through the radiator as soon as the top hose is hot, because the bulk of the radiator isn't hot yet so the bit you're cooling doesn't need cooling. Also, the further up the top hose you go, the more you're looking at the first glob of hot water released by the thermostat, which you really don't care about. There's no point running the fan until the water feeding into the engine, from the bottom hose, needs to be cooler. So, theoretically the BOTTOM hose is the best place. Completely agree with this and most OE installs measure temperature after the radiator. That said, my Vitesse has the cooling fan controlled by the engine management ECU and that is using the coolant temperature sensor in the thermostat housing as it's reference. What I learned when setting this up is that to prevent the fan coming on unnecessarily I had to make the set point really quite high (somewhere in the mid 90s IIRC), which I found slightly alarming. In practice it seems to work fine though. For my GT6 I will be using a Golf GTI radiator (because it cost a 10th the price of re-coring the original and weighs about 1/4 as much) and that has a threaded connection for a fan switch right next to the radiator outlet, which I will be taking advantage of.. Nick Link to comment Share on other sites More sharing options...
Ian Foster Posted May 1, 2019 Report Share Posted May 1, 2019 When I had my GT6 rad re-cored (to try and retain originality), I had a boss added into the top tank, to take a standard fan switch. (Can't quite remember what temp rating I'm using) This works well, but as I have wired the fan to run on with the ignition off, if the engine is switched off whilst the fan is still running, it can take a while to switch off as there is no circulation from the pump and hot water is trapped in the head and top tank. Easy enough to control by just allowing the engine to run until the fan switches off. A manual override is also very worthwhile and can be used to pre-empt the fan switch. Ian Link to comment Share on other sites More sharing options...
rogerguzzi Posted May 1, 2019 Report Share Posted May 1, 2019 Hello All I fully agree the thermostat should be in bottom of radiator(screwed in) I have been running Spitty like this for nearly 4 1/2 years with a dual thermostat as I use 2 x 9" fans that come on a different temperatures(only the lower temperature ever normally comes on) Just now and then when stuck in traffic in Spain and 30+ degs heat Roger ps I was always told you want the whole engine at working temperature for best thermal efficiency and engine life(no mayo in the rocker cover!) Link to comment Share on other sites More sharing options...
johny Posted May 1, 2019 Report Share Posted May 1, 2019 5 minutes ago, Ian Foster said: When I had my GT6 rad re-cored (to try and retail originality), I had a boss added into the top tank, to take a standard fan switch. (Can't quite remember what temp rating I'm using) This works well, but as I have wired the fan to run on with the ignition off, if the engine is switched off whilst the fan is still running, it can take a while to switch off as there is no circulation from the pump and hot water is trapped in the head and top tank. Easy enough to control by just allowing the engine to run until the fan switches off. A manual override is also very worthwhile and can be used to pre-empt the fan switch. Ian As long as the thermostat is open don't forget that the thermosyphon effect will still give a certain amount of coolant circulation. Mine needed a bit of choke on a restart after quite short stops until I adjusted the fan settings..... Link to comment Share on other sites More sharing options...
NonMember Posted May 1, 2019 Report Share Posted May 1, 2019 46 minutes ago, Nick Jones said: Completely agree with this and most OE installs measure temperature after the radiator. That said, my Vitesse has the cooling fan controlled by the engine management ECU and that is using the coolant temperature sensor in the thermostat housing as it's reference. What I learned when setting this up is that to prevent the fan coming on unnecessarily I had to make the set point really quite high (somewhere in the mid 90s IIRC), which I found slightly alarming. Quite a lot of OE installs are "cost constrained" and therefore do what you've done on the Vitesse. I used to work for Rover developing fuel injection software and most of ours were like that. You need to have the engine temperature sensor for fuel calculations, so why spend the money on a second one? You can control the fan quite well based on in-engine coolant temperature if you also know a bit about what else is going on. But you do end up with high threshold temperatures - the K-series fans didn't switch on until 104 degrees. Link to comment Share on other sites More sharing options...
68vitesse Posted May 1, 2019 Report Share Posted May 1, 2019 The only thing that worried me initially was the high temperature shown on the gauge after a short stop and the fan not running. But as the gauge sensor is reading the temperature just as the water leaves the head decided it was not a problem. Regards Paul Link to comment Share on other sites More sharing options...
NonMember Posted May 1, 2019 Report Share Posted May 1, 2019 High engine temperature after a short stop is normal. It's called "heat soak". Without the water pump running, the heat from the cylinders conducts through the head into the water making the top of the cooling system very hot, but there's almost* no flow to move that heat away anywhere. * there is a little bit of flow due to thermo-syphon effects but it's not very much Link to comment Share on other sites More sharing options...
johny Posted May 1, 2019 Report Share Posted May 1, 2019 I think if the electric fan is set up to run on after engine stop the thermosyphon effect will be considerably increased at least until the wax thermostat closes 1 Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now