lets see you vented bonnets

[fostersice]

ok so les the a week away before the car gos to paint and im looking to get my bonnet vented before paint.

so looking for ideas.

 

 

i was thinking 3 x 3 at the front in the middle part of the bonnet pushing air in

 

then 2 x 5 =5 ever side of the bonnet a 1/4 the was up the bonnet again push air in

 

i though ever side as it push air over the airfilters whether i go for carbs or turbo

 

and then 14 x 2 = 7 ever side of the bonnet 3/4 the way up the bonnet

letting the hot air out of the back of the engine bay

 

let forward to your input and pictures

[Vista]

I'm interested in this too, the only one I've seen recently is Darrans (escort tec) orange mk2

 

[JP.]

Vent is on the back !!!!, Cowl inducted letting fresh air into the engine bay.

My cooland temperature is cooler with this.

While driving fresh air is forced into the engine bay with the same speed as the airvents in the dash. In combination with the air coming trough the grille the warmed up air by engine heat and radiator heat is forced to leave under the car.

While idling warm air can vent by the cowl induction.

The big hole in the middle came later on when I found some engine componends that didn't fit under the hood................

 

Mostly just above the hood there's vacuum so there's no place for letting air in only letting out of the bay ( vacuum sucks air out).

Remember when your driving in the rain, always wondering why your hood still stays wet with little pools of water not cleared by the driving speed??? cause there's vacuum by the aerodynamics of the car.

 

If you want to test were the best spot is to make vents, just make a smoke bomb and take the fan from the livingroom. Place it in front of the car and see where the smoke goes.

 

On his example you can see that even the lower smoke line ain't touching the hood while it does touch the roof. Its an example of the vacuum spots on the car.

[Vista]

That wind tunnel diagram doesn't account for the air the enters the engine bay through the radiator grill, fit some vents in the bonnet and it will allow it to escape out of the bonnet cooling hot surfaces that are high in the engine bay as it goes.

[Conor]

If you're going to do it, please get them stamped into the bonnet rather than cutting a hole and sticking those plastic things in.

[fostersice]

stick ons please so 1970 lol

 

stamped or not at all

[w p e]

in me siggy

[emu]

I beleive that Forward facing vents need to be huge to have any real effect. Think how big the bonnet cowls are on scooby imprezas and Land cruisers etc.

 

However, the same size vent facing the rear have much more of an effect at sucking out the hot air because of the vacuum effect that has already been covered.

[Retromotorsport]

technically theres not a vacumn effect on the bonnet..if the was the water would move as the speeding air would be pulled down to it ..or the smoke,

what is there is whats known as the ' boundary layer' .. which is a layer caused by the air sticking to the surface so causing it to 'stall' .. on any flat surfave the only thing that is pretty flush with the surface that will move air is the NACA duct.

 

Which to be at its best needs to be carefully designed, but even an off the shelf NACA duct works better at moving air than lourves or vents.

 

The Cossie bonnet vents are not there to work while the cars on the move but to allow hot air to leak out when staionary

[Vista]

on any flat surfave the only thing that is pretty flush with the surface that will move air is the NACA duct.

 

Which to be at its best needs to be carefully designed, but even an off the shelf NACA duct works better at moving air than lourves or vents.

 

ooo-oooo I know someone with one of them

 

[vibrating_Cake]

technically theres not a vacumn effect on the bonnet..if the was the water would move as the speeding air would be pulled down to it ..or the smoke,

what is there is whats known as the ' boundary layer' .. which is a layer caused by the air sticking to the surface so causing it to 'stall' .. on any flat surfave the only thing that is pretty flush with the surface that will move air is the NACA duct.

 

Which to be at its best needs to be carefully designed, but even an off the shelf NACA duct works better at moving air than lourves or vents.

 

The Cossie bonnet vents are not there to work while the cars on the move but to allow hot air to leak out when staionary

 

 

what about the higher centre part of the bonnet closest to the windscreen.... does this help???

i'd have thought this part of the car was a high pressure spot and adding more air wouldnt help.... at all? especially to the aerodynamics

 

also, using a radiator duct that comes from the front of the car, and raises up through the bonnet before the cambelt of the engine and through the bonnet to fresh air, so coming OUT of the bonnet any good?

like onn erm, nascar engines (i think?)

 

both being methods ive seen. only thing im interested is cold air feed to carbies, that exhaust manifold heats things up nicely under there and twin 45's aint easy to buy a cold air feed for!

[DEP]

Here s mine

[john_3.0s]

on any flat surfave the only thing that is pretty flush with the surface that will move air is the NACA duct.

 

Which to be at its best needs to be carefully designed, but even an off the shelf NACA duct works better at moving air than lourves or vents.

 

ooo-oooo I know someone with one of them

 

 

that looks like its raised above the bonet profile to me so its not a true submerged intake in the spirit of the NACA duct research, be interested to see how good that would fair in the tunnel

[Vista]

that looks like its raised above the bonet profile to me so its not a true submerged intake in the spirit of the NACA duct research, be interested to see how good that would fair in the tunnel

 

It wouldn't perform at all mate as they're only dummies and there's no actual opening (though some owners have opened them up). The base of the black section is below the bonnet line though.

[john_3.0s]

that looks like its raised above the bonet profile to me so its not a true submerged intake in the spirit of the NACA duct research, be interested to see how good that would fair in the tunnel

 

It wouldn't perform at all mate as they're only dummies and there's no actual opening (though some owners have opened them up). The base of the black section is below the bonnet line though.

 

would make it worse then! looks cool tho and thats the main thing

[Retromotorsport]

the best thing for moving air out of the engine bay above a turbo is the NACA , it the only shape that will allow to be sucked out by the passing layer, and yes i would imagine keeping out of the high pressure area at the bottom of the screen is a good idea, but NACA's dont look as cool as lourves on older shaped cars.

 

The biggest problem we have with turbo cars is the ammount of air we let into the front, the front gets opened up to maximise the airflow to the intercooler, this air then has to go somewhere, and with a closed bonnet you get massive air volumn increase going under the car ...something which we dont want as this creates lift.

Heres something I created a few years to combat that. Half the rads surface area is ducted up to the bonnet, the other half still swirls around the engine doing the exterior cooling effect. If you totally close off the air supply around the engine componants soon get super heated. On Mk1's the curve of the bonnet speeds the air up as it goes over the curve, so there is a slight vacumn there.. but this oulet is designed to get air out by using the incoming air to push out the outgoing air.

 

 

 

 

 

 

With carbs you need to ideally seal them up and have an inlet tube to the front of the car, the 'airbox' and there is some quite cheap ones on the market now with blank plates to allow the fitment to many carb/TB set-ups

[Guest cortinamad-gonetoo]

 

[Mk2Jo]

Try these guys - they are near me in Alton in Hampshire.

 

http://www.coollouvres.com/main-page.htm

[vibrating_Cake]

 

 

 

 

 

 

With carbs you need to ideally seal them up and have an inlet tube to the front of the car, the 'airbox' and there is some quite cheap ones on the market now with blank plates to allow the fitment to many carb/TB set-ups

 

oooof thats nice, howd you go about making that then!!!

thats really tempting!

and what do i search for "on the market" for these carb airbox thingys?

ive been debating making one for a long time (one to muffle the sound out slightly ) and the other for a cold air feed + the ram effect of the continuous flow of a block of air in the single pipe.

[bomber1]

so these cars with the rear of the bonnet raised up an inch or 3 does this let the hot air out of the engine bay whilst on the move or stationry?