I have been looking into moving the fans on the ST205 to the front of the radiators to free up a bit of space in the engine bay. But as I have been researching I have noticed that alot of cars have some kind of shroud for the fans, regardless of where they are in front or behind the radiator. These shrouds look like they block off airflow to some of the radiator somewhat and only allow airflow from the area that the actual fan takes up. So how exactly does this work, I notice TTE did it too, there is obviously some science behind it but I am at a loss to explain how it works????

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ST205

If you look at the OEM shrouds you will notice some depth between fan and rad with a nice smooth aerodynamic shape to allow easy airflow to all the rad.
the fan produces pressure against the restriction of the rad and the air will tend to flow to even out that pressure. Just like an inlet fannymold.

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If at first you don't suck seed, try drier grain.

Fyi - A long time ago (when it didn't snow end of March), there was a TTE engineer on the Swiss GT-Four forums. I talked a lot with him about cooling issues and he told me they eventually switched from pushers to pullers because they found pushers to be actually blocking the air flow at higher speeds.

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René - Carlos Sainz 2433•5000
Turbocelica.nl | ST185 CS restoration and full rebuild

If it ain't broken.. it soon will be

Aha, OK, I will stick with pull fans then Thanks

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ST205

That may be partly down to the shape of the shrouds, they are only a nice aerodynamic shape on the radiator side !!


I know from experience that on the standard setup, the fans run a fair bit even when driving along normally ( I had a bent shroud for a while which made a racket when the fans were running ). Maybe the shrouds cause a fair bit of restriction to ram air.

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If at first you don't suck seed, try drier grain.

The shrouds should actually assist in maximising the airflow through the radiator. Without the shroud the air will find any route to escape around the side of the radiator and avoid going through it. Equally, if not more important, is the escape route for air once it has passed through the radiator core. With the ST205 there is empirical evidence that pressure builds up in the engine bay at speed with the rubber headlight surrounds popping out in a forwards direction after a spirited drive. The ultimate solution is what you see in the current crop of WRC cars where the radiators vent straight through tunnels to the top of the bonnet. Not really an option with a GT-Four! The bonnet profile of the ST185CS/RC and ST205 is designed to create a low pressure area above the bonnet vent and thus extract hot air from the radiator/turbo/engine bay. It looks like its not adequate for all situations.

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Don
GT4DC Chairman
1994 Toyota Celica GT-Four ST205WRC JDM 269bhp @ 0.9bar
1994 Toyota Celica GT-Four Special GT 590bhp @ 1.8bar
1989 Van Diemen RF88/89 Formula Ford 1600
2008 Nissan Patrol GU 3.0L ZD30DDTi 154bhp

Hi,

a shroud is one of the best things you can do, but let the fan behind the radiator

the fans redirect the air and some mm later he must flow threwe the straight fins of the radiator, the air ain't not want this and creates a backpressure, a pushing fan has
just 70% that power of a pulling one in front of this
have a look to the corolla wrc and you will notice that they changed the fan setup, even space was limited too

on the bonnet, the edge in front of the opening is not high enough and just covers 1/3 of it, the solution on EVO's are great, slots cross the air flow, i built something like
this for my bonnet

pictures are -> after the gt-four meeting 09

viewtopic.php?f=1&t=2908&start=60

greetz

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KEEP COOL UNDER PRESSURE

street legal?.....perhaps in tschibuti

Sunny you have posted 2 / too many IMG tags!

please go back and edit your post to just one set!

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ST165 turbo 4WD
ST185 GT-FOUR RC Carlos Sainz Limited Edition 825•5000
ST185 turbo 4WD Carlos Sainz Limited Edition 2541•5000

^^^ Corrected

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GT4DC Events Co-ordinator
1996 ST205 UK

Hi,

sry, was posted in the old forum which had no problems with it

greetz

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KEEP COOL UNDER PRESSURE

street legal?.....perhaps in tschibuti