Bonnet Vents

[Boydie]

Has anyone installed a Bonnet Vent/scoop in their bonnet as in from a Nissan, Mitsubishi or a Toyoya (wash my mouth out) and caused air to flow down over the alloy inlet manifold?

It strikes me it wouldnt be very hard (once the rubber cover was permanently discarded) to tig weld 9 off 3mm x 15mm high x 350mm long alloy strips onto the raised areas of the inlet manifold. If a scoop in the bonnet then caused air to flow over these "additional cooling fins" installed on the manifold and then down onto the turbo additional cooling would occur. Obviously there would only be a cooling air flow effect if the vehicle was moving at say 60KPH and over.

It would certainly assist in the delivery of cooler air into the cylinders and cheaper and easier to do than installing an expensive aftermarket intercooler, which in any case if installed would also benefit from any method of keeping the inlet manifold cooler.

[muddy]

A mate of mine has a subaru type scoopy vent jobber on his 90 and says it runs cooler since he fitted it.

Will.

[fozsug]

Tel put an Isuzu Trooper scoop in his Disco

[Boydie]

Interesting, I was thinking of something more "aggressive" - such as a Subura WRX Type STi or the Nissan Patrol to entrain even more air when the vehicle is moving. My thoughts were to cut the bonnet in such as way as to make radial blades to direct the entrained air down onto the manifold.

Has anyone tried the idea of "finning" the allow inlet manifold?

[tacr2man]

Effectiveness would be affected by the airflow coming thru rad which would tend to pressurise under bonnet area , depending on how much airflow could get out from round engine and out underneath , so you might not get much flow thru the bonnet vent , also would depend on flow over bonnet , if staying laminar to bonnet top to impact front of scoop . On a defender the rear of bonnet area is a low pressure area , if spare wheel fitted ! Cooling underbonnet it was found effective in OZ to cut flaps in rear of lower wing area side ( not disco afaik) HTSH

you might get a similar cooler charge just by taking air in at snorkle top height instead of from under wing

[Boydie]

I finally found a suitable vent on EBay, cut the bonnet and slotted it to direct the air flow onto the inlet manufold and over a flat highway run I took two measurements, with the vent closed and with it open, the result was the inlet manifold was 25 degrees C cooler.

[22inch roller]

Surely this idea could be bad if u go threw a lot of water means unwanted water in your engine bay

[Boydie]

Not too sure about that, being a deisel the only electrics that could cause me concern is the supply to the fuel cut-out solenoid.

On our recent trip to Birdsville we crossed the Cooper and the Diamante Rivers as well as several un-named creeks where the water level was almost above the bonnet without any problems, the trick of crossing deep rivers is to wrap the front of the car with a tarp, fit the wading plugs and tape up the doors with duct tape, and when crossing build up enough speed to cause a bow wave which in turn pushes water away from the front of the vehicle, with these precautions we had minimal water entry and then only in the footwells and nothing that didnt dry out in a couple of hours of 45 degrees C heat.

As for water entering the bonnet vent this would, I think, actually be a bonus as the moist air would increase the cooling effect on the alloy inlet manifold as well as increasing air flow around the turbo. Oh, and the car already has a safari snorkel fitted

[Boydie]

A picture (or in this case three) is worth a thousand words