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2008 STI Hatch.
I've been told the airflow over the bonnet rises over the intercooler scoop at speed. When my engine's back in the car I hope to test this. However there's some logic there. I would like the intercooler to be more effective but want to avoid the hassle (insurance etc) of a fmic. Does anyone know of a larger scoop or other way of improving the airflow into the existing one?
Thanks Don
That's a new one to me and may help. It's certainly something to consider, provided it fits my car of course.
I've been told the airflow on the hatch rises over the bonnet, starving the scoop of air. Not sure if this is true. A few bits of cotton, tape and a dual carriageway will show. I was hoping for an extension to the existing scoop to collect more air if possible.
If there's a problem with the intercooler on any impreza, it's not the scoop but the fact that the intercooler sits above the engine and turbo. Heat soak really only occurs when stationary or in slow traffic, and this has been proved by measuring charge temperatures. I've not noticed any issues at high sustained speeds so it would be interesting to see where hatch hood issues have been investigated. Or was it heresay?
I have been told the hatchback has an airflow problem into the TMIC. The theory is that at speed, the air rises over the bonnet and continues up over the intercooler scoop.
It sounds plausible but I wanted to see it. Not having my own wind tunnel, I mounted a vertical rod at the front of the bonnet and tied lengths of cotton to it.
Result is the theory is wrong. Air follows the curve of the bonnet in laminar flow into the scoop. In fact the opposite occurs. There's a compression effect as the air passes over the bonnet into the scoop.
I've got pics to show this and will upload later.
22 November 2019, 09:38 PM
Uprating hatch bonnet air scoop
. might take a look myself
