Can anyone tell me if the MY94 WRX air vents on the bonnet are supposed backed by a thin plastic shield? My friend has one and his vents are actually blocked by (removable) plastic backing.

It's a bit hard to explain but it means that no airflow actually occurs from under the bonnet - it does mean that no water gets in either!

Is this a problem, should the plates be removed?

My friend has been saying that the car has been running a bit strange, but his temp guage hasn't been rocketing up or anything.

Enlighten me, oh wise gurus of Scoobynet!

 

aesthetic only IMO.
The plastic backing stops water getting on the battery and air filter (if you have an induction kit that is).
Some Scoobynetters remove the plastic backing above an induction kit for more air during summer.
The rumour is however, that removing it draws hot air from the downpipe area, straight past the filter.

 

My MY93 doesn't have the backing on and you can see heat shimmer rising out of the vents when stationary, so they obviously do let heat out, but probably backs up what was said above regards drawing hot air past the air filter.

 

AFAIK the vents were put there for homologation purposes for the early rally cars. I have replace the vents on my bonnet with scoops to force cold air into the bonnet

 

Hi guys

Im doing a track day next month so u think it would be better to remove the backing above the air filter for more cold air or just leave them on?

Sy

 

I take the battery one off in Summer only - rain is nightmare, and my HKS is directly under the other.

No real value for me than in really hot weather, but thats where the water spray comes into its own.

 

so do we recon by reducing the engine temp u could acheive a much higher bhp figure?

 

My cuzz bought his STI V with the blanking plates removed. We noticed the rain pouring all over the battery and electrics one day so bought some from Grade A spares and fitted them. He's had no probs with cooling since.

My MY 2000 UK car does fine with the blanking plates in place too. Never seen the temp go over the fixed midpoint even when really revving or long fast motorway journeys. It's nice having a cool engine- my sodding GTI6 had an inherant cooling prob!

Cal

 

Cheers guys, thanks heaps for all your replies - I'll let my mate know not to bother taking them out.

 

If you open the blanked off air vents on a standard car the under bonnet temperature will rise. That is why on a standard road going car they are blanked off. The car is designed to take in air over the radiator across the engine and aided by the bonnet scoop it exits down the transmission tunnel.

The vents are there to allow homologation of rally cars, some of which have isolated air boxes, gathering cold air from the front of the car, including space between the headlight and the bonnet. In this case, the vents allow the induced air to exit and ensure there is always a flow to the filter area which is below the vent. Unless you make an appropriate air box for your filter to breathe below the vent, removing the cover plate is a retrograde step.

 

The vents are designed to extract hot air out of the engine bay. Notice wich way they are louvered.

Fast air moving over the bonnet is low pessure, the higher presure air in the engine bay is forced out. This also means there is less air pressure behind the radiator so more air flows through the radiator and/or FMIC and furthur aids engine cooling.

On the road car during road conditions they were not required so Subaru blanked them off to prevent any problems with the ingress of water.

Those mini scoops are ok if they are directing cold air onto an induction kit but probably do not work as well as reducing underbonnet temperatures as the standard vents without blanking plates. It could well be argued that if you push to much air into the engine bay then you will reduce the flow of air through the radiator, it is far better to get hot air out than to try and push cold air in.

The intercooler scoop is ducted so it does not interfere with the engine bay pressure and air is directed straight through the intercooler.

Lee

[Edited by logiclee - 4/8/2003 11:07:55 AM]