would bonnet vents on a track Clio work?

[chris blue]

Will get round to drilling large diameter vent ports behind the front number plate soon, as the engine bay gets so hot on track
Don't like the permanent bonnet lifters that raise the windshield end of the bonnet an inch or 2

Anyone tried fitting bonnet vents angled to the windshields for a decent throughput of air? Would it work

Have tried it on a previous motor, and it dropped the temperature by about 20 deg celsius

 

[JamesBryan]

Have you monitored coolant and oil temps to see how hot it's actually getting?

If it's just track sessions at 20 minutes a time, they're not really needed.

Maybe look at what @Tomotek has done on his race car. They need to be in a low pressure area for them to work, can't just slap them anywhere.

 

[chris blue]

Have you monitored coolant and oil temps to see how hot it's actually getting?

Maybe look at what @Tomotek has done on his race car. They need to be in a low pressure area for them to work, can't just slap them anywhere.

No. not monitored temps yet.
Yes- Only for 20 minute sessions, but it does get f'ing hot under there

My assumption was that heat rises, and would place them higher up the bonnet. There would be a fair draught thru.....

 

[-Jamie-]

Bonnet vents are very effective, if they are put in the correct place

 

[JamesBryan]

No. not monitored temps yet.
Yes- Only for 20 minute sessions, but it does get f'ing hot under there

My assumption was that heat rises, and would place them higher up the bonnet. There would be a fair draught thru.....

Try removing the seal between the bonnet and scuttle panel. That's a low pressure area and the speed of the air moving over the top of the windscreen might be enough to create a slight suction to help pull hot air out.

 

[Darren S]

Just go full Scooby scoop on top and be done with it.

As @JamesBryan says - I'd be investigating into where would be the best location for it. Wasn't there a thread a while back that was going on about ambient air pressures and temp within the engine bay?

Do you still have your under-tray on too? I've always left mine on as a daily - though if it was a track car, I'd be taking that right off.

 

[andybond]

Try removing the seal between the bonnet and scuttle panel. That's a low pressure area and the speed of the air moving over the top of the windscreen might be enough to create a slight suction to help pull hot air out.

The air doesnt actually flow that quickly in the area you are describing. Its in a turbulent area as some of the air acutally swirls and goes down towards the bonnet

Like that.

Your best bet is create the lowest possible pressure area inside the bonnet and behind the rad. Also introduce shielding /shrouding around your rad ( if not there already ) to force the high pressure air from outside through your rad into the low pressure under the bonnet.

I would also closely take a look at your water and oil temps. Is there really an issue or are you being a bit sensative?

 

[Djw John]

You know the crash bar is right behind where you plan to drill? So unless you drill that too then it won't do a single thing. It won't do much anyway imo, maybe help the rad out slightly but it's not needed.

 

[andybond]

I dont know on the clio if there is enough space to put in a post rad duct like on the some motorsport applications to get rid of the heat straight from the rad.

Like this :

 

[Tomotek]

I run a completely bespoke rad layout which enables me to run a smaller rad to allow me to get the air inlet for the engine fed from the kidney grille on the bonnet

I have angled it forward and added a duct on the front to feed all the air from the main grille into the rad

I then run bonnet vents positioned nearer the front of the bonnet (infront the cam cover and behind the rad) to draw the hot air exiting the rad out of the bonnet, using the low pressure air passing over bonnet

As previously said, to far back and the airflow is turbulent and high pressure.. also the airflow is blocked by the inlet above the cam cover

 

[1985michael182]

@Tomotek what rad is that your using out of interest please. I've got a VW polo one I think in mine because of the bodies. Lower down out of the way also make life easier getting to things at the front of the engine. The front cross member blocks off around 50/55%% of the rad aswell...