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Inline cooling fan for engine bay


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I'm approaching refitting all the engine bay air ducts, so I have the opportunity to fit an inline fan to improve airflow.

I would have thought that when the car is moving, this is not an issue but when stationary, in traffic etc it could be beneficial. I'm sure I alos read somewhere that someone had wired one up so that it ran on for a few minutes after the engine is turned off.

Is this worthwhile at all?

I dont know how I would wire this, certainly dont know how to do the time delay thing. Any thoughts, advice, wiring diagrams please?

"Intellectuals solve problems; geniuses prevent them." Albert Einstein

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I was thinking of doing something similar on my S1. As you say, when the car is moving the warm air gets sucked out from underneath. In fact my car runs really nice and cool above 30 mph. I just wired in a manual trigger switch for my radiator fans so I could use the now redundant otter switch to trigger the engine bay fan. If directly feed from the battery it would keep running after the ignition key is removed and until the the coolant temperature has dropped enough to close the otter switch and cut the power to the fan. Very simple to wire up as the otter switch and battery are about 3 feet apart in an S1. Only thing to consider would be what size fan and how to mount it.

Cheers, Gavin

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Unless you are doing a large amount of idling in heavy traffic, which you should try to avoid, I think simply opening the rear hatch, lifting the engine cover, and just letting the hot air dissipate naturally is enough. I realize that this only works when your drive is over but it does get the heat out of the engine bay quickly. And, I always use a trickle charger so Im back there anyways after each trip. It wont hurt, but I wonder if the real gains are worth it?

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Mine has a inline fan built into the ducting to extract air. This runs on for 15 minutes once switched on (as a separate switch) and engine off to aid hot starting, it also comes on with the main radiator fans when switched on either by the otter or when I hit the override. Was put in by the previous owner and part of the under dash which he added below the binnacle. It also has two other switches, one for engine bay light and two for the fire alarm warning.

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I have got a fan on both exit ducts on the Mutant which come on as soon as the engine starts and continue to run for 15 minutes after switching off the engine.

This was done the help improve hot starting and to reduce engine temps when stuck in traffic, this was when the car had carbs (which was quite some time ago), but it is suprising how much heat is pulled out by the fans.

Probably been on the car for 8 years now with no issues.

For the amount of effort involved fitting fans it is well worth doing.

Hilly

1981 S3 4.2 V8 6 speed (The Mutant)

Mutant V8 Conversion Thread

Knowledge is power .................... apparently.

 

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Hilly, do you have wiring details for this mod?

How do the fans run on?

Which fans did you get?

"Intellectuals solve problems; geniuses prevent them." Albert Einstein

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Hi Simon.

This may be of assistance, when i installed two extractor fans to my engine bay i powered them through a sensor probe which was positioned in the engine bay, not in or on the engine coolent system....This picks up the air temp in the engine bay and will switch on and off independant to the cooling system. This can be hard wired so it will switch on and off with heat soak , wether or not the engine is running.. .You could fit through a timer to isolate after a pre determined time when ignition is off.. The temp setting is adjustable . The kit is available from Demon Tweeks and comes with wiring diagram / wire / fuse and instuctions..... Except for the timer which isn't rocket science..

Hope this is of help

Dave

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Dave, that makes alot of sense. Thanks.

Which system did you use - its seems that the Kenlowe or Revotec ones might be correct. They are obviously designed for the water cooling system but I'm guessing would work in air also.

"Intellectuals solve problems; geniuses prevent them." Albert Einstein

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Kind of crazy, but ...

Too bad our engine bay release isn't similar to the front boot mechanism so that when stuck in traffic we could unlock it and then re-lock it when we're underway.

Rich

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Slewthy,

The Delay Timer I am using can be configured for use on 12 to 24V systems, with positive or negative trigger logic. Positive triggers can be as low as 4.5V. Setup is quick and easy with thumbwheel time delay adjustment between 1 and 60 seconds or 1-60 minutes. A quick jumper setting converts the time from seconds to minutes! The Timer can be configured to activate once for each trigger, or free-run as soon as power is applied. Relay can be configured to be normally on or normally off. Specifications: Operating Voltage:12 to 24 Volts DC. Current Draw: 40 mA DC with relay on. Time Settings: 1 to 60 Seconds or 1 to 60 Minutes. Relay Contacts: Form "C", 7A @ 30VDC, 10 A @ 125VAC. Size:3" x 2.2" x 1" (Fits Standard. Snap Track). Trigger Voltage: 4.5 - 24VDC. With detailed instructions and 10 different applications diagrams.

See my fan installation in Lotus Forums GARAGE", 88 Esprit Turbo. Plenty of ideas.

Cheers

John

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John, great info and I like the job you've done on the fan ducting - very neat.

I've bought an inline fan, similar to the one you have, some flexible ducting and a Kenlowe temperature control circuit.

The fan only really fits on the offside over the tank board.

The Kenlowe unit has an override input so your outline of the time run-on could be plumbed in here so to speak.

DSCN2177.jpg

This was fom ebay. They come in 3 and 4 inch diameter. £20.

Its rated at 120cfm and i've run it - really packs a punch and not too noisy.

I'll drop in some pics of instalation soon

"Intellectuals solve problems; geniuses prevent them." Albert Einstein

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Pah! The S2 had this as standard in 1978. A thermal switch on the airbox controlled a fan which pulled air out from the engine cover and blew it out of the right-hand "ear." Mind you, I don't think the switch ever worked on mine.

S4 Elan, Elan +2S, Federal-spec, World Championship Edition S2 Esprit #42, S1 Elise, Excel SE

 

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Pah! Just hot air?

I'm planning to add coloured smoke to mine......not grey or black though.

Rubber mounts - good point I'll do that today.

"Intellectuals solve problems; geniuses prevent them." Albert Einstein

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The previous owner of my car fitted a pair of similar fans in mine, on the tank board on the left side...which in USA is right behind the driver's head! Sounded like a bloody hair dryer from Hell behind my head! The wiring that powered them was a bit dodgy and their usefulness was questionable, so I ripped them out.

"If you can't fix it with a hammer, it's electrical." -somebody's dad

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