engine lid fans

[adamh]

ive been mulling over engine lid modifictions for a while, it dawns on me most cars dont have fans in the engine lid, mine shouldnt be that different , other cars cope, i dont need a cool charge so...

i have another idea and hope it will save me a load of hassle. im going to just remove the drip channeling under the existing vents (minimal cutting). and lash a fan and shroud under there, big enough to cover the vent, try it out, see how it behaves with a thermostat set at 45 and a closed lid.

q, is it better to put a sucking fan on sucking upwards toward the vent or to turn a pusher upside down and push up towards and out of the vents?

[Phaeton]

Complete uneducated guess would be to suck the hot air out of the engine bay which in turn will pull cooler air from underneath the car. With the shape of the MR2 I would have thought that if you tried to suck air into the engine bay there's going to be lack of air there when you are running, a sort of void created by the rear window. This of cause my all be total bollocks & somebody who actually knows will be along shortly I'm sure.

Alan...

[cdwood2010]

Nope, I agree, we've fitted fans to Johns Mk2 lid and as we understood it the fans assist the natural hot air rising which in turn pulls cool air up into the engine bay.

C.

[snowtigger]

there was some nifty laser cut alloy shields with space for the fans for a mk2 not long ago on here and sucking is best mate all men should know that.

[Spook]

RE 'a sort of void created by the rear window'

That void is a low pressure zone designed to pull hot air up through the bay when moving, its a deliberate bit of aerodynamic design for cooling, not just to look good (to some).

It also creates another problem as you dont really want too much low pressure zone above your rear wheels at great speed, so the bigger or higher a rear wing is sticking up into the air stream (or out to the sides), then the better.

But only so much big or hi wing is a good idea, you can start getting the front to lift with too much pressing down at the back, so have to add something more at the front end, then you get into adding too much drag and need more power to pull it along!

Its a balancing act.

But a fan would only aid cooling in this case mate, especialy when in traffic jams...
unless you go along the lines of the infamous Brabham fan car, which would be all kinds of cooool.

[MMaddict]

But a fan would only aid cooling in this case mate, especialy when in traffic jams...
unless you go along the lines of the infamous Brabham fan car, which would be all kinds of cooool.

Its awesome predecessor:

2382

[Torero]

As mentioned, the stock engine bay fan is a heat sink meant to draw hot air out of the bay. The design of the rear window area is made specifically to create turbulence over the engine lid and assist flow of air out ouf the vents.

A few have others have tried the fixing a fan inside a stock lid and have had notable success and accosrding to the Rogue Engineering website their kit has:

"two 10" Spal puller fans, each capable of flowing 640 cubic feet of air per minute, and testing shows that it will reduce the engine oil temperature by around 4 degrees centigrade.""

Well worth it with the V6 in the arse end of the car, Adam, you can even have it manually switched.

John.

[Limeymk1]

I've been considering this for the Engine lid on my Mk1, Paul's TD lid should be I deal for mounting a pair of fans in. I already have an uprated fan in the side intake to blow cold air into the bay.

[Spook]

RE Its awesome predecessor

yeah, Chapparal, what a machine, liked it more with the tall wing though!
looks like the bastard offspring of a washing machine and a sportscar

fans so powerfull they blow stones at people behind attemting to overtake though would just be two brutal, ha ha

[adamh]

a lid with some nice big shapes like pauls is perfect, i would have , or an sc, but i wanted to retain stock look from outside. after having a chat with a spal man he said suction is good if the fan is mounted ideally outside of the lid, thats not for me, he suggested using a pusher and bolting it to the lid underside pushing out. any shroud needed? A: no, just bolt the fan straight on. OK, i will do that

heres the area , fan wont fit easy on the right not much depth because of intake plenum. plus.. if i go for left it should draw the air all the way over from the engine bay intake fan right around the manifold, poast anything else warm like the heads and out the vents. it's not perfect but its a compromise to retain the original lid. the next size down from 9" was a 6". im just going to try a 9 see how it works out.

http://www.twobrutal.co.uk/forum/images/recovered/2013/01/289.jpg

http://www.twobrutal.co.uk/forum/images/recovered/2013/01/290.jpg

john which fans do you have ? pull?..

[gavsdavs]

Out of interest, why are you fitting fans (to SW20s) ?
Genuine cooling issues or something I don't know ?

[adamh]

for a mk1, less room in the bay. last summer i drove to netherlands/france in 32 deg, apart from the coil dying in the heat, when i opened my petrol flap after long drives, fuel steam vapour came from it and petrol was pumping itself up the little vent in the filler flap, coming out like little waterfall, with key off. i proped the lid up 3" with an evian bottle cut in two, and that helped the ignition spark again, and the fuel issue not to happen.

resulting work = heat shield to cover tank area and fan for traffic, the stock fan was always on in anycase.
all that really does is circulate the hot air.

never seen anything like it, i know mk1's have a reputation for vacuum when opening the tank, mine sucked for about 5 minutes, the fuel had heated up. very scary when petrol is pumping itself up the little vent pipe , had to put the flap on enough to stop it splashing out, yet not completely shut so it could vent.... it was like standing next to a cobra hissing for 5 minutes or more.

i tried and tested a number of times in hot and cold weather, i found the issues to be repeatable with no airflow (lid Shut) during hot weather

[Torero]

john which fans do you have ? pull?..
Yes Adam, I have the pull type. They are mounted on a shield that attaches to the underside of the engine lid and face up toward the lid vents thereby pulling air from the engine out.

NOTE: it is not the actual position of the fan body that is important but the direction in which the impellers spin.

[snowtigger]

I've got Paul's lid which is great as I dont need it to look standard but even I'm thinking of fans for summer, I've never had the problems Adam has had but I think the heat of the 2gr saps the power.

[Torero]

Out of interest, why are you fitting fans (to SW20s) ?
Genuine cooling issues or something I don't know ?
Nothing too serious, I didn't have a plug on my 3VZ loom for the engine bay fan, Gav so I am fitting an auxilliary pair that will be manually switched. I've also got A 60mm ally racing radiator and fan shroud which is the nuts but I have an ambition to run around Europe to Hungary during this/next summer (my wife is Hungarian) and I think this is a safety blanket for me.

[adamh]

hear ya, those lids are great. ive a feeling a heatshield on its own will cure my issues, other 1.6 have been reported ok, but, not all did 1000 mile through 30 deg+ upto 33 in NL. i dont expect to be doing that every year, but it must be fit for purpose, stat will control fan. uk is no test for heat come on... we should be so lucky

[adamh]

Nothing too serious, I didn't have a plug on my 3VZ loom for the engine bay fan, Gav so I am fitting an auxilliary pair that will be manually switched. I've also got A 60mm ally racing radiator and fan shroud which is the nuts but I have an ambition to run around Europe to Hungary during this/next summer (my wife is Hungarian) and I think this is a safety blanket for me.

i wired the bay fan always on since loosing the control from the loom. good shout i think i will control both with my Diy stat