The question of air dams...

[gldgti]

hey everyone

i've just completed a little experiment wiht my diesel, and i think its relevant to ALL mk1 drivers, so i shall share with you the questions and the answers now...

some of you may know what my diesel looks like, i've posted pics a few times. you may or may not have noticed the terribly gaudy silver home made "duckbill" spoiler addorning my front end. i think its in my avatar... see?

anyway, i've had it there for about 18 months and havnt driven it without it really at all.

...until 3 weeks ago i removed it, as, coming to my senses, i found that i actually didnt really like it that much, and thought that its functionalitly were nil.... WRONG!!!

for the past three weeks, my drivin habits have been the same.... the weather has been no different generally from the last 18 months, and nothing else about my car changed - except for removing the spoiler. the result? significantly higher running temperature!!!

what do i mean by significant?

consistently, winter, summer, wet, dry, with the spoiler on, my guage goes to points right at the edge of the whilte box..

consistently, past three weeks, wet, dry, cold, hot, spoiler off, my guage would be steady at half way between the white box and the red box.

i did some driving today around town and in some 80 and 90 zones. still up around halfway.

this arvo i put the spoiler back on, went for a drive and there it was, down at the white box again!!!

as far as this translates to actual temperature, i would guess its about 5-9 degrees.

as to the actual reason, i can only guess, but here goes:

1) the spoiler prevents a certain amount of air going under the engine bay, which causes a lower pressure below it, aiding to suck hot air from within the engine bay

2) the spoiler changes the flow patterns at the front enough to aid in extra air going into the extra holes behind the bumper bar, making the radiator more effective

whatever the cause, i'm 99% certain it works. i will be conucting further tests.

tell me your thoughts guys.

cheers,

Aydan

[el_foolio]

nice discovery mate! seems to make sense really!

[smithy010]

If you're ever in need of a CFD assignment for uni, talk your lecturer into letting you do this!

.... edit.. oh, and for the benefit of all those real engineers out there, who have no idea what CFD is, It's Computational Fluid dynamics.

[roccodingo]

1) the spoiler prevents a certain amount of air going under the engine bay, which causes a lower pressure below it, aiding to suck hot air from within the engine bay

Give the Lad a star...good work mate..



Now if you can find a Scirocco "Storm" front spoiler it may even run cooler !!

[brackie]

...Make the observation...Construct a hypothesis... Control all variables except the one being tested...Collect data from both the control and the experiment...Replicate...Compare data and support or refute your hypothesis...If necessary re-write and re-test your original hypothesis....

WOW! Looks like we (ex and present) science teachers are having a beneficial effect!

Good on ya Ayden You're a credit to the forum.

[gldgti]

thanks guys, i appreciate the encouragement.

i thought this experiment might help some people running well modded petrol golfs etc, since it seems to me that increasing the efficiency of whatever cooling system you have is going to be better than using a larger capacity cooling system at lower efficiency... so i was thinking, any guys having trouble with cooling (where we arent talking about serious overheating, but just general overall temps) should try doing this.

my "air dam" is simply this:

a piece of 70x1.5 sheet cut to the width of the front. it is held in place with 4 little bits of steel strapping and some 3/16 gutter bolts.

the steel strapping brackets are long enough that the spoiler need not follow the curvature of the skirt under the bumper, but is (about 2 feet in the middle) straight and angled forward at about 60 degrees from the horizontal, however i believe it will work just as effectively if vertical.

[smithy010]

Can you post some pics?

[gtimk5]

When racing my golfs oil temp would teach 125 degrees and water (with a TDI radiator) would reach 120. I ran the early mk2 front spoiler. However just running around the streets or in road rallies on stages would be around, oil, approx 100. Water 90. On the racetrack you are getting a lot of extra heat off the other cars if you are behind them. I wonder with the mk1 GTIs if thats why they also ran an oil cooler?