Intercooler or bonnet scoop or both?

[stevetubbyturbo]

Ive managed to aquire a Subaru WRX inetrcooler for next to nothing and ive also got a bonnet scoop off a Isuzu Trooper (i just seem to collect all sorts of stuff) and i was thinking of fitting them the reason being ive got a 2.4 and their known for the cylinder heads cracking surpossedly from high intake temps.

Ive had a body lift so i can fit the intercooler if i want but fitting it will effect insurance costs where on my policy i can do as many cosmectic mods as i like without effecting the policy.
The question im asking is if i just fitted the scoop over the engine do you think it would help in keeping the engine cooler therefore ruduce the risk of the head ever cracking?

What are your veiws?

[dirtydog]

Depends where you mount the scoop I suppose, after a long chat with Rick (Vagrant No.2) about it the general view was that it will only help if it is rearward facing to create throughflow of air.

[marky]

Ensure the air comes out of the scoop as you are drawing air in from the front.
You need to let the hot air escape

[laser_jock99]

Ensure the air comes out of the scoop as you are drawing air in from the front.
You need to let the hot air escape

Given the large size of the gaps under and around the engine- a small aperture in the bonnet lid will have minimal effect. I'd face it forward to help create turbulance around the engine sending even more hot air Down & Out (i.e. where the rest of it coming past the fan goes).

Nevillef

[BUSHWHACKER]

I would have thought that if the bonnet was gulping in huge amounts of air(especially when travelling at speed) through a scoop, then this would reduce the efficiency of the rad fan.
Better to have the scoop rear facing to let the hot air to be pushed out by the fan/travelling.

[Chillitt]

we took 2 identical scoops and fitted them to 2 identical surfs, one facing forward, one facing backward.. the one facing back got an oily windscreen. (i didnt really..)

[laser_jock@work]

I would have thought that if the bonnet was gulping in huge amounts of air(especially when travelling at speed) through a scoop, then this would reduce the efficiency of the rad fan.
Better to have the scoop rear facing to let the hot air to be pushed out by the fan/travelling.

I've seen rearward facing snorkels but never a rearward facing 'scoop'. I'm not saying it won't help at all- it's just not normal!

Nevillef

[That Ruddy Squirrel]

I've not seen a rearward facing scoop, but it makes sense, let the cold air come through the rad, then pass the engine before leaving via the top of the bonnet.


Trev

[BUSHWHACKER]

Exactly, and you can feel the hot air gushing out through the vents after a drive.

[wibblywobbly]

Err umm...

I recall surfing the web looking for info on this as I had a bonnet scoop on the last Surf that I bought.

It looked great but did nothing for the cooling.

My research told me that if you have scoops then they should be rear facing, in which case louvred vents are the preferred option. If vents/scoops are front facing then engine bay air pressure is increased to the extent that the cooling fan is trying to suck cool air into a high pressure area, and that goes against all of the laws of physics. Front facing scoops became fashionable as they were the rage for supercharged engines (which work on sealed forced air induction). These scoops are sealed to the induction manifold even though they look as if they are stuck on the bonnet.

The best place for an intercooler is down by the radiator, which is where I believe Allspeed fit them. Some claim that the longer pipework increases turbo lag but according to other debates on other threads on this forum, this is not the case with the Surf.

I would also take care with fitting an untested intercooler. The capacity and airflow needs to be matched to the Surf engine and it may not be a suitable fitment. I would try and pick the brains of Allspeed or one of the other firms on the web before doing more harm than good.

Hope this helps

Rob G

[Cumbrian]

I recall surfing the web looking for info on this as I had a bonnet scoop on the last Surf that I bought.

It looked great but did nothing for the cooling.

My research told me that if you have scoops then they should be rear facing, in which case louvred vents are the preferred option. If vents/scoops are front facing then engine bay air pressure is increased to the extent that the cooling fan is trying to suck cool air into a high pressure area, and that goes against all of the laws of physics. Front facing scoops became fashionable as they were the rage for supercharged engines (which work on sealed forced air induction). These scoops are sealed to the induction manifold even though they look as if they are stuck on the bonnet.

The best place for an intercooler is down by the radiator, which is where I believe Allspeed fit them. Some claim that the longer pipework increases turbo lag but according to other debates on other threads on this forum, this is not the case with the Surf.

I would also take care with fitting an untested intercooler. The capacity and airflow needs to be matched to the Surf engine and it may not be a suitable fitment. I would try and pick the brains of Allspeed or one of the other firms on the web before doing more harm than good.

Hope this helps

Rob G

So why do Toyota build them forward facing as standard equipment on the 3rd gen Surfs?

Just wondering since mine has one and is forward facing with intercooler on top of engine right under bonnet scoop.

[da SLUG man]

So why do Toyota build them forward facing as standard equipment on the 3rd gen Surfs?

Just wondering since mine has one and is forward facing with intercooler on top of engine right under bonnet scoop.

the standard intercooler is mounted on top of the engine, so the scoop flows the air through it...
aftermarket ic's are usually mounted below the rad so you don't need a scoop.

vented bonnets for engine cooling usually have rearward facing louvres (like on the ford cosworth/renault GT turbo) these increase the airflow through the engine bay.

on the highly tuned "hot hatches" you will usually see the front bumper cut away to expose the larger intercooler.

[wibblywobbly]

I would also bet that...

I would hazard a guess that the standard engine mounted intercooler is sealed to the scoop when the bonnet is closed. This would force all cool air onto the intercooler without creating a high pressure zone in the engine bay.

Rob G

[Bear Ona Bike]

IMHO
Intercooler scoops face forward mainly because they look better that way.
With that said; they sould also work better for the following reason -
There are so many large gaps around the engine bay that it will be almost impossible to create a high pressure area inside it no matter how powerful the radiator fan or the speed of the vehicle... theoretically... The Bernoulli effect of a body travelling through a fluid/gas should mean that the pressure in the engine bay should be lower than the surrounding air... so a forward facing scoop should work.

..... but I could be spouting complete BS...

[BUSHWHACKER]

Sounds impressive, possibly feasible, but what the surf needs is a release of hot air from the engine bay. anything to prolong the onset of the dreaded overheating problem.