fans on bonnet ?
Turbo Mini Forums

ok i notice that lots of folk run with their bonnets up proud next to the window. i dont want to do this, but dont want the problems of trapped heat. would this idea work of mine, i hope the picture loads full size

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MikeRace, Mini13

Dammit !!!!!!

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MikeRace, Mini13

Four holes, and the original ERA bonnet vent.



Also, Nice blue car on your signature :)

http://home.online.no/~lyngset/myold77mini.cfm

Edited by Vegard on 12th Dec, 2005.

You dont _have_ to run a bonnet with any holes. the holes onthe front of the bonnet are usually just there for intercoolers. If you mounted this elsewhere, you could leave your bonnet totally standard, ala TurboDave

the 4x 2" holes on the front are more than up to the job

in my motor fitting these reduced the engine temp over the stat setting some 10 deg....

vegard what did you finish the cutouts with ??
they look so neat.

richi i fitted the extra cooling vents as i have a top placed intercooler

which looking back is a mistake as it suffers from a big heat soak at traffic lights etc,.... mind you i was on a budget then !

but now iam gona improve things.

in the near future

Edited by BENROSS on 12th Dec, 2005.

Vegard I 8nt seen that car since i was 13 ! and it was british racing green when i had it looks very nice now mate. the intercooler will be behind the grille low down

also yes mate hope u dont mind, i used gialloflys too nice looking cars....the red one is my old mini j reg, had 25k genuine miles, i sold it to a 65 year old lady who wrote it off 7 days later !!!

Edited by Richie on 13th Dec, 2005.

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MikeRace, Mini13

I was thinking of the four holes below the ERA-vent, not the ones in the front Alex.

I think the fans in the bonnet are a cracking idea as long as you have them sucking in and blowing down to keep the exhaust heat away from your carb.
The ERA vent faces backwards to capture the negative air pressure just infront of the windscreen and this negative air is pulled down over the carb by the bigger negative pressure running under the car at speed so drilling holes on the front is kind of defeating the point and an increase in under bonnet air pressure will have a negative effect on carb heat soak problems.

So fans in the bonnet sucking IN and no holes in the front is the way to go IMO.

Let us know how it works out.

Two things are infinite: the universe and human stupidity; and I'm not sure about the the universe.

ok... you say u want air sucking in, i was thinking along the lines of sucking hot air out ? either way it dont matter as it could be controlled via switch to opertate both ways :)

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MikeRace, Mini13

If you want to suck ALL that hot air from around your turbo and manifold past your carb to get it out then you can do that. Im just saying the ERA bonnet VENT was to let air in during normal driving conditions and this air would be drawn down over the carb and turbo by the greater negative pressure under the car.

Ive been down this road before with a Lotus Esprit Turbo in the middle east where the temperatures on a cool day are around 40c and believe me its better to have the HOT air vented down and away from your carb than dragged over it whilst trying to get it out of your engine bay.

Sorry for the lack of apostrophes but the SQL server dont like them.

Two things are infinite: the universe and human stupidity; and I'm not sure about the the universe.

psml nee botha i can only give it a whirl, hope it works as my bonnet will have 4 useless holes in i wont be using the era vent, just 4 holes with mesh over them thenthe fans mounted underneath....i have used these fans in paintball to inflate baracades with great success so they dont half turn over some air...it should work IT WILL WORK !!!!! have faith Richie lol !

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MikeRace, Mini13

The problem we found with heat on our motor was the heat soak from the turbo to carb when the car was stopped after a run. We never have a problem once air is moving around. To solve the problem we we cut holes at the back of the bonned above the carb to release the heat. Never had a problem since, even on 30degree days.

http://www.twin-turbo.co.uk
http://www.hillclimbandsprint.co.uk/default.asp

A man without a project is like a like a woman without a shopping list.

my bonnet runs tilted just so the air filter would fit, im hoping to get it flat for next year without any holes.

is it a definate that im going to get fuel evaporation?

mine is always difficult to start when hot it made a hugh difference when bonnet tilted up at rear and with bonnet off starts up even better so id sy you defo need some sort of vent or gap but might be wrong

no longer a series, but still 1.3 turbo.

On the hot starting debate, I am going to try running a carb vent filter on my car, the thinkng being that as the turbo boils the petrol in the carb, the vapours can escape out of the carb float bowl. Then, when you try to restart, there will be an influx of fresh cool fuel to the float bowl.

Will have to wait to see if it works or not..........

on my old torbo bonnet (as seen on Turbo phils car) i cut holes inder the era bonnet bulge to let heat OUT when stationery, holes at the front were for the intercooler when under way.

Here for the craic..

Supercharged Arden powered

Edited by turbodave16v on 14th Dec, 2005.

Dooder is right...

think Lotus Elise and where its radiator is.

Alex

AlexF

So, I,m thinking Lotus Elise, and now I,m thinking where the radiator is. And now I,m thinking what do the big holes in the bonnet do?

And now I,m thinking they let the hot air out and not suck cold air in.

Is this right?

I say this because when I drove my brothers after hit had been standing in the rain, all the rain water that collects around the radiator suddenly covered the windscreen at around 50mph; so there must be a reasonable flow or air out of the vents.

Have I got the wrong end of the stick again?

Wil

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

I,m thinking you,ve got to stop all that thinking ....

well surely if you had a scoop, then the cold air would be forced in whilst driving, cooling the carb, turbo ect.....

then whilst the car is stoped the hot air will escape out, causing the desired effects

Its somewhere with my thermodynamics notes Dave...


ALex

AlexF

oh, from when you were at university?

I've just seen an elise rad - and thought "205GrpB"

That is a completely different situation.
The VERY high air velocity over the nose of the bonnet on the Elise suddenly ends when it meets the vent. Air 2" above the bonnetline probably doesn't change - result: a slight reduction in air pressure (velocity dependant) and a small rolling vortex generated in this area. - just like you have on the top rear of the tailgate on a block-like estate car like a volvo - and why these have a minor diffuser added to the top lip, to try to make this a laminar, not turbulent airflow.
Back to the elise, you have a huge amount of air being forced through a rad, and into a channel towards the lower air pressure - air will simply want to occupy this space, hence a nice flow through the rad once sufficient airflow has been attained.

Edited by turbodave16v on 14th Dec, 2005.

Quote:

I`d sure like to do a mock-up of a mini in this area and put it in a wind tunnel - My interpretation was exactly the opposite to yours. Well, not exactly, but kinda...

I interpereted the ERA vent as actually creating a genuine negative pressure directly behind the vent - simple venturi effect.
The fact that the mini has such a huge open grill area pushes plenty of air over the clutch housing - and fills the whole of the area around the carb with air - just as when standing still. Now, as we have a slight negative air pressure behind the ERA vent, the higher air pressure wants to `fill` the partial vacuum, and hence is drawn towards it.

Whilst i appreciate there is a reputed lower air pressure underneath a car when in motion, it can`t be so great on a vehicle with a relativly large ground-clearance? An F40, sure - but a mini?
I`m not disputing what you`re saying - just that i`ve always understood it a different way - just by thinking about it. No proof at all... LOL!

We need a student to do a project on this at college methinks!



oh, AlexB - I have holes in`t front for the air intake, and have the ERA vent at the back
Edited by TurboDave on 14/12/2005.


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Last week I used a program called 'Fluent' to compute the air flow, pressure and velocity surrounding a car with different items like spoilers, front skirts etc.

Much much quicker and cheaper than using an wind tunnel, and it visually shows with colours the transitions.

i cant post pics on here, in fact ill put some in my msn group thing so you get the picture...geddit?

http://groups.msn.com/minimadmonkey/joholt....msnw?Page=Last

If i have any spare time before going back to the island for xmas, ill try and knock up a mini profile and post the results.

if i dont have time before xmas, and if you guys are really interested, remind me in jan.

"Turbo's make torque, and torque makes fun"

"did you know you can toast potato waffles?"