Nick B. Posted March 29, 2007 Share Posted March 29, 2007 Has just been browsing the archives - there is a lot about fans. It seems most people are fitting electrical fans to solve an overheating problem.at the same time an increase in HP is mentioned. Can anyone say if this increase in HP is really existing, or is it just rubbish. The spit mk3 fan is not moving a lot of air as I see it, so I can't really believe that it puts a lot of strain on the engine. Reason I am asking these questions is that I am considering putting an electric fan on the spit - to free up a few HP. I am not really in need of much cooling as I have the wide radiator and a freshly flushed block - cooling should be fine.so in short - is electric fan worth the money when talking performance? (not racing, just fun road)RegardsNick Link to comment Share on other sites More sharing options...
Spitfire1500 Posted March 29, 2007 Share Posted March 29, 2007 I am considering the idea myself, but I've heard fitting a new fuse-box with extra fuses is in order to spread out the load on it when fitting an electric fan.David Link to comment Share on other sites More sharing options...
willcolumbine Posted March 29, 2007 Share Posted March 29, 2007 Okay - the old fan debate. Actually there isnt much of a debate anymore! Its pretty much like this...If your cars overheating then you need to be flushing all the crud out, getting a new radiator, thermostat etc. If you cant remember when you last had a radiator then it's time for a new one! Chances are the water pump housing, hoses and crappy return pipe will need doing as well. All fitting an electric fan will do is mask the problem - far better in the long run to sort it out properly!If on the other hand you dont have a particular overheating problem but you're greedy for power then you can get an increase in the region of 2 or 3 horses from loosing the mechanical fan and going electric. This is becuase the fan creates drag at higher rpm when it dosent need to spin as fast as it does.The debate comes in about where to mount the fan. In front of the rad will block airflow and create the overheating problem it's supposed to solve. Mounting it directly behind will have the same effect so probably best to leave as big a gap as possible between rad and fan. Ideally they'd be a fairly large gap and a shroud around the lot like a modern car but this is a tight spot on the spitfire! Link to comment Share on other sites More sharing options...
Nick B. Posted March 29, 2007 Author Share Posted March 29, 2007 ahem, yes - I am greedy for more power. Has anyone actually experienced the mentioned 2-3 horses? allready has ported head, HS4 and proper exhaust. Is fan the wrong place to look for more horses?RegardsNick Link to comment Share on other sites More sharing options...
heraldcoupe Posted March 29, 2007 Share Posted March 29, 2007 Fitting an electric fan to the small 14" radiator usually causes overheating problems rather than solving them. Fit a full width 21" radiator before even considering an electric fan. Modern OEM installations are engineered into the design of the car, they are often front mounted with a full shroud. These systems usually work well, but the keywords are "engineering" and "design". This is not the same as throwing what you can find into the engine bay of your car. For our purposes, the sensible solution is a rear mounted fan which does not obstruct airflow into the radiator.Cheers,Bill. Link to comment Share on other sites More sharing options...
Nick B. Posted March 29, 2007 Author Share Posted March 29, 2007 Hi BillI allready have the wide radiator - just been recored. So in any circumstances, cooling will not be a problem. I a just questioning the increase in HP. Is this upgrade wothwhile when it comes to power. RegardsNick Link to comment Share on other sites More sharing options...
willcolumbine Posted March 29, 2007 Share Posted March 29, 2007 Well now that question depends on the state of your engine! Basically if you've got a ported head with big valves, webbers, balanced internals, electronic ignition, decent filters and a good single box exhaust with a nice tubular header then it might well be worth it!If not then it'll still increase power but your money might be better spent on other things that will increase performance for less cash. Link to comment Share on other sites More sharing options...
Tim Bancroft Posted March 29, 2007 Share Posted March 29, 2007 Gotta agree with Bill and Will.I have one fitted between the engine and the rad in the GT6 and it works well. I loathe the engine driven fan as it saps power and is unnecessary at higher engine speeds. Also if thermostatically controlled it can help to prevent latent heat build up when the car engine is switched off.I'd fit one, but only after the I was sure that the cooling system is working correctly.If fitting one, go for a Pacet- relatively cheap in comparison with Kenlowe. Link to comment Share on other sites More sharing options...
Nick B. Posted March 29, 2007 Author Share Posted March 29, 2007 Well, I have got everything apart from webber (I run HS4), and the exhaust is double, not single box. Still big bore though. Looks like i am in the market for a new fan then. Might just give paddock a call - according to Dr. Sideways Pacet fans with revotech controlls ought to be best buy.RegardsNick Link to comment Share on other sites More sharing options...
willcolumbine Posted March 29, 2007 Share Posted March 29, 2007 Yep sounds like fan modding is worthwile for you then! The kenlowe ones are a rip off - a huge fan, klunky switch and shonky mountings. Dave knows what he's talking about. Much better to put something together yourself from parts. The pacet is nice and slim and you can get it mounted up properly with the temp control running in the radiator hose for a very neat installation. Link to comment Share on other sites More sharing options...
Mac Posted March 29, 2007 Share Posted March 29, 2007 Did some virtual engine graphs with mechanical and electric fan, all other things same.Up to about 5000 rpm little or no difference, more difference right at top of tuned rev range if your engine's up for it. 5-10 HP more from 6-7 thou.Here ya go, with mechanical fan Link to comment Share on other sites More sharing options...
Mac Posted March 29, 2007 Share Posted March 29, 2007 With electric fan Link to comment Share on other sites More sharing options...
rotoflex Posted March 29, 2007 Share Posted March 29, 2007 I agree that for horsepower, headwork will be first (& not really that hard to get improvement).If you must change the fan to electrical, as it's been mentioned here the key to keeping things cool is a fan shroud, as seen in OEM fans mounted behind the radiator in modern cars. It encompasses the whole radiator area in the rear, then closes it down tightly to around the fan. I had cooling problems with the XK140 in summer in this climate, even after boiling out the block & cleaning the head at engine rebuild. I did a lot of research which pointed to the key to cooling effiiency was a fan shroud. I fabbed a fan shroud up from sheet aluminum for the existing radiator & mechanical fan, voila, ran cool as ice cream.I'd say if you must, get the largest, highest volume electric fan that you can engineer into a design which will allow you to place it a few inches behind the radiator & construct a fan shroud.Edit:Allternatively, measure the radiator & clearance behind, then go to a junkyard & spend a day prospecting for newer cars with integrated fans/shrouds, & see if there's a transplant candidate that can be adapted. Link to comment Share on other sites More sharing options...
rhodes Posted March 29, 2007 Share Posted March 29, 2007 I'm not in the XK140 premier league, only the 1500 championship and no hope of promotion. Fan in front of standard 1500 radiator has tendency to overheat but cool as a cucumber with wide radiator. Kenlowe sensor is nbg and replaced this with a thermistor on the thermostat housing and a simple bit of electronics driving a relay. Used separate feed to fan with in line fuse. Don't know if if makes any difference to hp or mpg, but seems the sensible thing to do. Link to comment Share on other sites More sharing options...
rhodes Posted March 29, 2007 Share Posted March 29, 2007 PS to my previous post. Bit too cool in winter, so running winter thermostat. Fan not run much for ages, but I don't block the air entry grille with the number plate hanging down from the bumper. Oil cooler covered over in winter. Its thermostat seems to open too early. Link to comment Share on other sites More sharing options...
Straight Six Posted March 30, 2007 Share Posted March 30, 2007 Quoted from heraldcoupe but the keywords are "engineering" and "design". This is not the same as throwing what you can find into the engine bay of your car. quote] :D How many other performance 'modifications' can this be said of?! :D Link to comment Share on other sites More sharing options...
rotoflex Posted March 30, 2007 Share Posted March 30, 2007 Quoted from rhodes I'm not in the XK140 premier league, only the 1500 championship and no hope of promotion.I only mentioned the XK140 because it had cooling problems, not the least due to this climate & its old-fashioned honeycomb-type radiator, that I had success in remedying.I no longer have it, we didn't really bond. It was GORGEOUS, but not as fun in the sack as the GT6. Link to comment Share on other sites More sharing options...
Nick B. Posted March 30, 2007 Author Share Posted March 30, 2007 Yes, that was a nice graph Mac, Thanks! How did you do this?Looks like a quite small increase (if any) when not spanking the engine thoroughly. Im off to the parts-pusher real soon. In teh meantime I can stant pondering about whether my sparkrite electronic ignition really is good enough.RegardsNick Link to comment Share on other sites More sharing options...
Mac Posted March 30, 2007 Share Posted March 30, 2007 Those are for a 1200. Download Engine Analyser (free fer 15 days methinks) and use Daves settings fer 1300, change any that aren't applicable to yours then try different things such as with or without mechanical fan.Here's a thread with more info:http://club.triumph.org.uk/cgi-bin/blah/Blah.pl?,b=spit,v=display,m=1172738132,s=,highlight=analyser Link to comment Share on other sites More sharing options...
JimM Posted April 1, 2007 Share Posted April 1, 2007 Hi, I'm also probably going to go the electric fan route when I rebuild my 1500. Can anyone tell me how much room there actually is between the radiator and end engine so I can start scouring the scrapyards for a suitable fan candidate. (My car's in about 3000 bits and I forgot to measure before I stripped it)ThanksJim Link to comment Share on other sites More sharing options...
Nick B. Posted April 11, 2007 Author Share Posted April 11, 2007 Hi JimCan't tell you how much room, my engine is not in the right place at the moment - sorry. I was investigating the electric waterpump option as weel now I was trying to get a few extra HP with the fan. Ouch - electric pump kit is £300 ish. That will have to wait a while.RegardsNick Link to comment Share on other sites More sharing options...
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