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2005 forester STI
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29 Posts
Discussion Starter · #1 ·
Looking for some advice folks. I've purchased a larger intercooler from an Impreza STI blob eye. Has anyone adapted the Forester bonnet scoop undertray so the airflow isn't restricted to the larger cooler? I did get the undertray from the Impreza but it doesn't fit in the foz bonnet scoop. I'm looking for the easiest solution, whether it be changing the scoop or adapting the undertray.
Thanks in advance.
 

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2004 Forester STI
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309 Posts
I've thought the same about mine. Very tempted to modify my scoop under tray to direct air to more of the FSTI intercooler. Andrew Carr told me to just get an Impreza STI IC on the car and ditch the FSTI unit as it's just an STI badged WRX IC. Which if you look at the sizes, he's right.
 

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2006 STI
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7,013 Posts
I've thought the same about mine. Very tempted to modify my scoop under tray to direct air to more of the FSTI intercooler. Andrew Carr told me to just get an Impreza STI IC on the car and ditch the FSTI unit as it's just an STI badged WRX IC. Which if you look at the sizes, he's right.
Size wise, yes. They're not quite the same though... you couldn't straight swap I don't believe.
 

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2005 forester STI
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29 Posts
Discussion Starter · #5 ·
I've just had it mapped by Andy Forest and I'm getting 370/370. He said the icing on the cake would be an Impreza intercooler. Just wondered if anyone had done this mod and how they went about it.
 

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05 Forester XTEn Manual, Two SG9 FSTi’s
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412 Posts
I bought a scoop and undertray from a bug Impreza Sti and had the scoop painted when the car was re-sprayed. It bolts straight on the SG9 and the under-tray aligns well with the impreza sti intercooler. I'm yet to fit it though, another job before winter.
 

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2005 Forester Sti
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354 Posts
The Impreza Sti intercoolers are a straight swap, The blob/bug ones tilt to the right very slightly and only use one bracket bolt but I think the hawkeye Sti allows both bracket bolts to be used as the outlet to throttle body spacing is different.

I modified my Foz scoop to cover the entire new unit, this is before I tidied it up and also added a flexible foam lip to seal against the intercooler but you get the idea....
 

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2008 GRB 20th anniversary 6 MT
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6,625 Posts
I had a hawkeye STi intercooler and Subtle Solutions undertray/splitter fitted to mine.

If you could modify/DIY the undertray as pointed above you would save quite a few £££ though.
 

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MY04 FSti MT6, MY07 Cross Sport MT5
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929 Posts
As an interesting aside, old Ken at the village garage had a turbo diesel pickup in t'other week, which had a fan fitted underneath and a bit to the side of the intercooler, was on some kind of thermostat, came on after a bit when idling or moving slowly, presumably to stop the IC getting heatsoaked by hot air rising from the engine.
 

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Don, King of the parts diagram
MY11 WRX STi Sedan 6MT
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6,056 Posts
The Impreza Sti intercoolers are a straight swap, The blob/bug ones tilt to the right very slightly and only use one bracket bolt but I think the hawkeye Sti allows both bracket bolts to be used as the outlet to throttle body spacing is different.

I modified my Foz scoop to cover the entire new unit, this is before I tidied it up and also added a flexible foam lip to seal against the intercooler but you get the idea....
All to do with the DBW throttle body.

Which is why the Forester STi intercooler differs from the WRX in that the two mounting brackets are nearer the front edge.

537127




 

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MY04 FSti MT6, MY07 Cross Sport MT5
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929 Posts
I modified my Foz scoop to cover the entire new unit, this is before I tidied it up and also added a flexible foam lip to seal against the intercooler but you get the idea....
Nice one, good to see some DIY fabrication. Have you considered putting in one or two intermediate baffles though to spread the air evenly-ish across the IC and stop it all wanging towards the rear of the cavity? I've not done the sums in detail but experience of counterflow exchangers in other disciplines suggests to me that for maximum cooling you'd want slightly more air flow per unit area toward the front of the IC than at the back.
 
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