Thread: Will a bonnet scoop reduce heat in the engine bay?

just as a follow up on my previous over technical pointless post, i just rang a ceramic coating place. he said for a double black coat on exhaust manifold and sating black single on inlet manifold, i'd be looking at between $330 to $360 + GST. for anybody interested.

i am looking at getting one of those billet turbo cartridge upgrades with the more efficient fins and ceramic coat. i have just serviced the car so would wait till next oil change is due before doing it. gives me time to save up. then after this i would install better intercooler. even though IC is probably better going in before. just too expensive for me right now. finally i would look into getting scoops or louvres if still required.

Originally Posted by blackrangie

The actuated vent sounds like a great idea

really? or is that sarcasm. i was expecting a lot of criticism and jokes at my expense for that idea

Originally Posted by CU55TM Disco

Attachment 135022

My Dad used to have a set of these fitted the the windscreen cowl of his RRC back in the day.


Also, I REALLY like that bonnet scoop on the rangie bonnet posted earlier!!!

Yes, its going to be a winner that bonnet scoop, I have the same vents on side of my bonnet, will upgrade to some custom milled alloy ones when i get a chance.

Originally Posted by Fausto79

really? or is that sarcasm. i was expecting a lot of criticism and jokes at my expense for that idea

Really its a great idea ...as sometimes you really need a lot of venting, like heavy sand work or towing uphills

Originally Posted by Phil B

Thanks Vern
Do you have any before/ after EGT or pre / post intercooler temps?
Very interested.
Phil

No intercooler temps. But when i changed from my top mount to my water to air, high end egt's dropped by about 70°. Tune remained the same.
One day i might set up some guages to measure the temps

PhilipA

Genuine question:

The efficiency of a radiator depends on the pressure drop front to back.

Can you please explain why?

and then you post this:

thing I did for slow going was to fit a humungous Mercedes cooling fan pushing through the RAD to replace the little aircon ones.
Regards Philip A

The calculations to determine the efficiency of a radiator in this context, are very complex and involve a lot of variables. But 2 basic variables are the flow rates of both the fluid and the air. As you have found with your humongous fan, increase the air flow and you increase the efficiency, or transfer rate of heat from the coolant to the airflow. As another poster has stated with his electric coolant pump, he can increase the flow to the extent that he needs to control the speed of it to obtain a satisfactory operating temperature.

I don't understand the aerodynamics. Is the aim to:
Stuff more cool air in the front?
Vent more hot air out the back?

Cool air in or hot out it’s the same question, with two different purposes. I agree with how you stated your questions DiscoMick.
Mass balance is always required.
As the gas heats up the density decreases so you need to remove more volume to remove the same amount of mass (heated gas/air).
If you want to cool the radiator more effectively use the bonnet vents (not scoops) as per Clarkson and the Evo Lancer. Assist with removing the heated air from behind the radiator.
If you want to cool the engine bay put a scoop in the forward half of the bonnet (forward of the high pressure zone and in the fast moving laminar air flow) and push more air down into the engine bay to exit under the car/trans tunnel. Note the Evo design, scoop for the inter cooler. This requires forward velocity to generate the air flow.
I think the temp controlled open close vents are a great idea, particularly to increase radiator effectiveness at higher temperatures. It may also work effectively at slow road speeds due to the thermo (electric) fan pushing air through the radiator.
Why not jump the vent switch from the thermo fan? ... it’s late and I have had wine ....
Vents - utilise lower pressure on the out side to remove (let’s say suck) gas from the inside.
Scoops - use higher pressure from the outside to force (lets say blow) gas flow on the inside.
Pressure differential means high pressure gas always wants to move to a lower pressure.
I will re-read in the morning....