undertray under engine
26 November 2008, 09:46 AM
#2
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From memory API David advises against removal on the grounds of the scooby engine relying on air being drawn out the back from underneath. Removing the undershield messes up the venturi effect creating a stagnant condition in the engine bay and therefore not cooling the engine or the intercooler properly.
My opinion is that a piece of plastic is not going to protect your engine from any knock bigger than running over a rabbit, it is not a sumpguard. Subaru didn't spend time energy and money designing and fitting it for a laugh. As it is not hard to refit mine stay in place.
That said, the choice is yours.....
My opinion is that a piece of plastic is not going to protect your engine from any knock bigger than running over a rabbit, it is not a sumpguard. Subaru didn't spend time energy and money designing and fitting it for a laugh. As it is not hard to refit mine stay in place.
That said, the choice is yours.....
26 November 2008, 05:19 PM
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I'm sure bob rawl did some test with his old newage STI and found the oil temps were down when running without it.
I removed mine when I fitted a FMIC and couldn't be arsed to refit. It's been running fine for over three now
I removed mine when I fitted a FMIC and couldn't be arsed to refit. It's been running fine for over three now
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27 November 2008, 01:19 PM
#12
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And whilst we're on it...WHY couldn't they make some decent bolts for this that don't shear off?
Going to end up cable tieing mine back on!
27 November 2008, 03:18 PM
#13
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Removing it will no doubt lead to reduced temps due to increased air flow under the bonnet. On the negative side (and probably why its there), you will have increased drag (higher fuel consumption, slower acceleration, lower top speed) and loss of stable airflow under the car will negate the venturi effect and cause a loss in downforce (less stability at high speed). I'm sure its there for aerodynamic purposes rather than under bonnet temperatures!
All IMHO of course
All IMHO of course
27 November 2008, 04:13 PM
#15
Removing it will no doubt lead to reduced temps due to increased air flow under the bonnet. On the negative side (and probably why its there), you will have increased drag (higher fuel consumption, slower acceleration, lower top speed) and loss of stable airflow under the car will negate the venturi effect and cause a loss in downforce (less stability at high speed). I'm sure its there for aerodynamic purposes rather than under bonnet temperatures!
All IMHO of course
All IMHO of course
quite agree
27 November 2008, 06:40 PM
#16
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Could be another possible answer. Don't think anyone knows the real answer. I was just quoting API David from memory.
On the subject of the seized bolts, isn't it worrying that on supposedly regularly serviced cars these bolts corrode so badly they sieze and shear off? On all mine so far I've had to drill and tap for replacemnet bolts, yet, with a dab of copperslip, they have not seized since.
On the subject of the seized bolts, isn't it worrying that on supposedly regularly serviced cars these bolts corrode so badly they sieze and shear off? On all mine so far I've had to drill and tap for replacemnet bolts, yet, with a dab of copperslip, they have not seized since.
Last edited by his-n-her-scoobs; 27 November 2008 at 06:41 PM.
27 November 2008, 08:18 PM
#17
LOL,
Its just a splash guard guys!
- to keep water and crap (literally) out of the engine bay. Its main purpose is to keep the engine bay cleaner, just like the equivalent on other cars.Its not some form of cheap sump guard or amazing aerodynamic device.
They were only fitted by Subaru om MY98 cars onwards, so if your car is older, it wont have one. The detail used to be over on the SIDC site in the FAQ section, but the new web version does not have it.
A well known tuner has tested the underbonnet temps/oil temps, and as per my first post, you can save upto 5deg of oil temp on a run.
So removing it will:
1. Make your oil temp drop lower,
2. Let your engine get dirtier - quicker.
27 November 2008, 09:46 PM
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[QUOTE=Hol;8305857]LOL,
Its just a splash guard guys! - to keep water and crap (literally) out of the engine bay. Its main purpose is to keep the engine bay cleaner, just like the equivalent on other cars.
Its not some form of cheap sump guard or amazing aerodynamic device.
They were only fitted by Subaru om MY98 cars onwards, so if your car is older, it wont have one. The detail used to be over on the SIDC site in the FAQ section, but the new web version does not have it.
Interesting that I've got a pre MY98 car with one fitted!
Its just a splash guard guys!
- to keep water and crap (literally) out of the engine bay. Its main purpose is to keep the engine bay cleaner, just like the equivalent on other cars.Its not some form of cheap sump guard or amazing aerodynamic device.
They were only fitted by Subaru om MY98 cars onwards, so if your car is older, it wont have one. The detail used to be over on the SIDC site in the FAQ section, but the new web version does not have it.
Interesting that I've got a pre MY98 car with one fitted!
27 November 2008, 10:42 PM
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Yep, both my pre MY98 cars have them 
So what does the one under the gearbox do? Keep the gearbox clean?
Why doesnt the diff have one? Surely that needs keeping clean too?
So what does the one under the gearbox do? Keep the gearbox clean?
Why doesnt the diff have one? Surely that needs keeping clean too?
Last edited by his-n-her-scoobs; 27 November 2008 at 10:46 PM.
28 November 2008, 10:53 AM
#23
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You really mustn't take it off - especially if you have a V5 onwards rear spoiler.
It acts as a "hidden" front spoiler under the car and increases front downforce.
If you take it off there is nothing hold the front of the car down and with v5 onwards spoilers this is very likely to happen.
Don't remove engine cover or this will happen
It acts as a "hidden" front spoiler under the car and increases front downforce.
If you take it off there is nothing hold the front of the car down and with v5 onwards spoilers this is very likely to happen.
Don't remove engine cover or this will happen
30 November 2008, 11:15 AM
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Great footage....
I think the porsche's problem was he needed to go faster so that when he flipped over he would have landed back on his wheels!!!
He wanted to be going 2.87mph faster an then im sure he would have pulled it off.
I think the porsche's problem was he needed to go faster so that when he flipped over he would have landed back on his wheels!!!
He wanted to be going 2.87mph faster an then im sure he would have pulled it off.
01 December 2008, 09:40 PM
#26
Bit of history, 
Oil temp....
https://www.scoobynet.com/drivetrain...il-cooler.html
MY97 on was with a factory undertray, not My98 as stated. Although ive seen fresh import versions 3's without them....
https://www.scoobynet.com/private-sa...rbo-p-reg.html
Oil temp....
https://www.scoobynet.com/drivetrain...il-cooler.html
MY97 on was with a factory undertray, not My98 as stated. Although ive seen fresh import versions 3's without them....
https://www.scoobynet.com/private-sa...rbo-p-reg.html
