can anybody make any suggestions / your views as whether to remove the bonnet vent covers (not the intercooler scoop) underside of bonnet during these 'warmer' summer months. i.e should I shouldn't I - looks like they are made to be removed, - better engine cooling ?, making turbo run better - I know they prefer cool weather.....don't they?

tell me...

cheers Rob

 

No.

 

Hi Barry,
You wouldn't be able to tell us the reasons, would you, or anyone else, as I am interested in this suggestion.

WREXY

 

I wouldn't

Purely for reasons of water getting into the air system, and hydraulicing the engine. Ie, pistons try to compress water and go bang when it doesnt compress.

If you want some more heat flow, then remove place washers between the plates on the vents and the bonnets creating a gap round the outside.

it would be safer.

 

If I remember correctly these blanking plates have drainage holes so water gets through anyway! I don't fully understand their purpose either.

 

I remove mine for Track Days to aid engine cooling. Stef does too I believe as well as others.

Water shouldn't get into the engine on a standard airbox - don't know about cone filters, but never heard of it.

On a day to day basis, I wouldn't worry about it.

 

already creating some interest,hmmmmmmm, so I take it the current suggestion is...if it ain't broke don't fix it, theres absolutely no need to do it & it's up to me if I wanted to on a track day!.

In honesty, my biggest concern is that the engine remains bloody hot for a long time after usage....therefor I considered removing these for days when I might hit a bit of stop start traffic when the temperatures are right up there in the 80's-90's (lol), but I take it the engine is perfectly capable of ' looking after itself !' & I run no risk of damaging my turbo ?...

well enough b@[[@ks, keep my eye on this to see what else develops..

g'luck out there...
Rob

 

Hello again,

Thanks for the info everybody.
With a Greek hot summer 35deg celsius plus, no clouds, almost everyday and with an APS cold air induction kit, with a K&N filter, which sits in the front guard i.e. in between guard and mudguard, me thinks maybe 'tis a good idea to remove the vents as it is also common practice in Oz I was just told. Only for the summer though. Plus I'm running 1.2 bar peak boost so it may help

Cheers
WREXY

 

I have run without blanking plates for nearly two years now, winter and summer, and no problems...but I should add that as a precaution I have a piece of plastic sheet neatly covering the MAF and battery, both directly under each vent (MY96). I have a standard airbox with panel filter.

If you have cone filter you can make a deflector, out of some old plastic container, and attach it under the vent with spacers. I did this once and it worked fine.

[This message has been edited by stratman (edited 15 May 2001).]

 

Great insight through the many replies, but what are they for, why are they blanked in the first place. I have had the same thoughts myself. What would a dealer say? I'm in for a 30k service Thurs. I guess I can ask.

 

Good points there Stratman about the plastic sheets covering the MAF and battery. Will do.
Good question John. Maybe they're blanked for the MAF and battery not to get wet, cause they're not blanked on the race cars. Let us know what the dealer says m8.

WREXY.

[This message has been edited by WREXY (edited 15 May 2001).]

 

I think the group A rally regs don't allow the rally car to have holes where road cars don't. Not sure why they're covered on road cars though.

Richard

 

Do you Prodrive chaps know anything about the rights and wrongs of this?

MIKEY

 

My guru Morray McKenzie took off his blanking atire and installed Japanese take away lids instead and these worked for him!

My personal option was to drive quickly to move the air through the engine bay quickly so the ambient air could get into the engine!

 

Sorry, this is particularly sad but I've set up thermocouples in the engine bay and on the outside at the front of the bumper to measure this.

The result is when the weather is cold there is 2-5 degrees difference between outside and underbonnet at 10MPH and above. When it is warmer (summer) there is 10-14 dergrees difference at 10MPH and above. The faster you go the less difference.

But come to a standstill and the underbonnet temps rise dramatically typically 50+ degrees. All measurements done with UKAS calibrated kit.

The conclusion is, once the car is moving from standstill there is enough air movement with the blanking plates on, to cool everything sufficiently. It is only when the car comes to a halt that the hot air will pool in the engine bay and cause a problem - the solution is to open the bonnet after a track session to cool down. OK.

F

 

But come to a standstill and the underbonnet temps rise dramatically typically 50+ degrees.

F[/B][/QUOTE]



Blood yell

See, now that suprises(and concerns)me. I feel an Off for summer, On for winter type attitude coming on

MIKEY

 

A 3-Door Cosworth has no blanking plates. In fact the slats in the vents are so large that you can almost get your hand through. Water also streams through when washing and doesn't cause any problems.

On an RS turbo the vent is directly above the distributor and doesn't cause a problem.

The Subaru is the only car I have had that has plates fitted under the vents. Basically I think the vents were just put there origionally for cosmetic purposes as the MY01 has none.

As long as the battery terminals are well greased and all connectors in the area under the vents are coated in petroleum jelly there shouldn't be a problem.

Just don't stick a pressure washer nozzle down them.

[This message has been edited by Scott.T (edited 16 May 2001).]

 

93 WRX.

I have removed the drivers side plate, I have a HKS Greenmushroom induction kit which is directly below the vent, no problems so far, plate was removed last spring & not replaced, cos I have lost it, The car can sometime stand in the rain for best part of a week not being used and it fires OK, I keep the passenger side [Battery etc] covered unless its very nice day [Last Saturday] then just undo the plat but put it back when parking up for the night.

Cheers

 

In winter is big difference how long take before engine warm up if I remove covers. So I suggest remove it only when is hot enough like me. Ususally is removed fom end of March till October/November if you use kone filter remove it at other side only. For cover at filter side use some screw spacer between bonnet vent and cover this could be enough for heat recirculation.

Erik

 

I drive around all year through any weather with these on and haven't had a problem with water ingress or hydraulicing (SP?):-)



Several other people are using these scoops and I haven't heard of a problem yet. Mine has a Blitz induction kit sat right underneath the drivers side....

 

I was wondering when you were going to comment on this Stuart

I, like barge have HKS induction kit, and will have soon the mini bonnet vents (thanks Stuart!). I'm going to run the drivers side one with no blanking plate, and fairly sure I'll do the same for the passenger side, whose blanking plate actaully has a hole to let water through anyway.

 

I think that you are all missing the point. I've been warned that removing the plates or creating any larger gaps around the plates puts you at risk of melting plastic components/ wiring in the vicinity due to the hot air from the whole engine looking for the easy way out (particularly when you come to a rest). Scooby have designed the underbonnet area for the air to find a way out that doesn't cause meltdown, although of course they do recommend that you let the car idle after a hard run etc.. I'm on the side of the guy above who says park up and open your bonnet with the engine running for a while after a hard run/ track outing etc.

Just my tuppence worth

[This message has been edited by Fat Boy (edited 17 May 2001).]

 

i removed the drivers side under plate on my MY97 last year! had no problems so far with the K&N induction kit etc! pulls the air in??

Phil

 

Phil,

I'm not sure, but I think the reversed direction of the slats (certainly on the early bonnet) helps pull the air out.

Stuart

 

IMHO:

The reason I measured the temps was to see if it was worth putting in some sort of cold air induction in or would there be any benefit from removing the blanking plates. The conclusion still stands that there would be very little gain once moving. Putting a scoop over the vent to direct cold air to the air filter would probably cause more turbulance and drag, outweighing the gain from the cold air. You would be kidding yourself if this kit were to try and give some positive pressure onto the induction, perhaps the best gain in doing this would be the looks (if you liked it of course).

The best way to get any colder air to the induction without upping the drag from bodywork additions is to draw the air in via the bottom vent on the bumper and remove the resonance box under the wheel arch. Many have already gone this route.

This is not intended to offend anyone, especially Stef and Stuart (who have bonnet thingys, which look the part IMO), I just test and display results/findings.

F

 

I take my plates off for the summer and put them back on for the winter. No problems. I think it makes a difference in the Summer.
Greg