bonnet flow
Turbo Mini Forums

for anybody that may be runnig a thier bonnet open at the back,heres some pics of the airflow pattern on johns 1312 turbo hes just got on the rd ,congrats john!.. they show the air moving into the gap for the majority of the edge ,but out of the gap at the 2 ends ,this was at about 50 to 60 mph .regards robert.

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

Who's idea was that Robert? It can't have been John's,lol. :)
Good thinking tho

Roland

http://photobucket.com/albums/y139/Skinns46/

so i presume an era vent (in the middle of the bonnet) would suck air in....interesting

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

"did you know you can toast potato waffles?"

Something so simple as a few pieces of yarn!

So Who is going to do this on an ERA vent for us?

so, out of interest, what is this showing? :s

Look at the way the pieces of string are bending. they are being sucked into the vent gap in the middle over the carb, and air is being forced out of the gaps neer the outer edges of the bonnet.

Previous Engine: 1040cc Morespeed engine, 1275 turbo head T2 Turbo Mirage Manifolds Megajolt
Previous engine: STD metro turbo, megajolt
Drives: 399bananahp (flywheel) Honda Civic Vtec b18c4 T28 Turbo 1968 Mini

Megajolt maps to download: http://www.jamesfawcett.co.uk/cms/index.ph...&gid=3&Itemid=3

to be over critical, its not exactly a 'fair' test as the bonnet has those holes drilled in it that could affect the flow, want to mask them up and do it again? LOL

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

"did you know you can toast potato waffles?"

thats very very interesting because i have my bonnet like that and my supercharger sits right at the back nearly touching the bonnet! hmmm. i might try this out. what speed were you going at the time??

balls to the blower!!!



1330,stage3 head, gt1549, canems ecu, S/C box and drops

oh yeah 50-60. duh!

balls to the blower!!!



1330,stage3 head, gt1549, canems ecu, S/C box and drops

I've been thinking about this a bit. I will have my bonnet raised at the back. I have holes at the front of the bonnet. The IC (Cossie 2WD) will be ducted from the holes. I will also duct the from the back of the IC to outlet at the rear of the bonnet.

I think what is to blame for the air flowing back under the bonnet is the lip on the back of the bonnet. Working completely off intuition and guesswork, the lip cretes a bubble of air (like Mythbusters demonstrated with the pickup tailgate). This then forces the air over a longer path than the air above the bonnet. Therefore, it creates an area of relative low pressure under the bonnet and this pulls air under the bonnet.

So, in about 5 years I will cut th lip off my bonnet (and possibly attach a Gurney flap pointing upwards). I'll then attach some string and report back

On 12th Nov, 2009 Paul S said:

I think Gary OS has taken over my role as the forum smart arse

I'd always thought the air flowing under the car created a depression that sucked air out of the engine bay, and under the car?

Yes it mostly flows out under the car, they proved this at MIRA in that Racecar Engineering article

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

www.twin-turbo.co.uk

In this case it is the front windshield that create the high pressure which force air going into a less pressurides area, the strings show that it prefer going under the bonnet that over the windshield, and then allow it to escape , where windshield create les pressure , on his sides.
A citroen sport guy told me that they had better result with sub windshield air induction that taking air in front airvent because this area see more pressure

Edited by fab on 10th Apr, 2010.

Great post Robert. Could with that aero paint Mclaren sometimes use.

Edited by Jason G on 10th Apr, 2010.

Fair points abou the air flowing under the car, but I did plan on isolating the IC flow from the rest of the engine bay by essentially ducting from the bonnet holes to the IC and then from the back of the IC to the exit at the rear of the raised bonnet.

I think fab is probably right that in this case, it will be the windscreen that will cause the flow the enter back under the bonnet.

I really need to get those Racecar Engineering articles

Edited by GaryOS on 11th Apr, 2010.

On 12th Nov, 2009 Paul S said:

I think Gary OS has taken over my role as the forum smart arse

Yes i moved to the darkside

Instagram @jdm_brett

Would that mean I need a scoop facing the windshield to get a good cold air ram ?

I guess so.

But then I would have to build a water box in order not to put overly damp air in the engine when driving in the rain ...

Rusty by nature

free water injection :)

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

Yes i moved to the darkside

Instagram @jdm_brett

I did blow the head gasket when I changed to a DCOE, so maybe you are right

EDIT: Brett, I actually don't know what the ERA vent looks like. I've never seen one. I wouldn't be surprised if the idea was stolen from Vizard though

Edited by GaryOS on 12th Apr, 2010.

On 12th Nov, 2009 Paul S said:

I think Gary OS has taken over my role as the forum smart arse

On 12th Apr, 2010 GaryOS said:
I did blow the head gasket when I changed to a DCOE, so maybe you are right

EDIT: Brett, I actually don't know what the ERA vent looks like. I've never seen one. I wouldn't be surprised if the idea was stolen from Vizard though

Yes i moved to the darkside

Instagram @jdm_brett

Ah, that looks very similar to the one Vizard does a cross section diagram of. That one was taller to allow big bram pipes on an IDA though. I think it was on page 138

On 12th Nov, 2009 Paul S said:

I think Gary OS has taken over my role as the forum smart arse

What is on the site :

Special bonnet vent designed not as intake but to let hot air out of the engine bay. A hard pushed turbo unit can glow red hot so a through-flow of hot air is essential to avoid damage to non-metal components.

So I really don't know what to think anymore ..

Rusty by nature

maybe they made it based on one theory and it worked ( interestingly backwards) but they never questioned it

Yes i moved to the darkside

Instagram @jdm_brett