I need some air flow to my turbo ..

[CorvallisBMW]

I'd build a heat shield. You really don't want to cool your turbine housing, you want to keep the enthalpy in your exhaust as high as possible. It'll increase your turbine efficiency.

This.

The best thing you can do is to keep the heat inside your exhaust system, as heat = energy, and energy is what spins the turbo.

Use things like ceramic coating on the turbine housing and downpipes: http://www.jet-hot.com/
Also get a heat wrap for the turbo: http://ptpturboblankets.com/home.php
And heat wrap for the downpipe: http://www.jegs.com/i/DEI/186/010119/10002/-1
You can also add reflective foil to the underside of your hood to prevent it from getting too hot: http://www.jegs.com/i/DEI/186/010393/10002/-1

Think about all the modern BMW turbo V8s. They have the turbos inside the vee. Talk about zero air flow! But they make it all reliable by keeping the heat inside the exhaust and limiting how much escapes in to the surrounding environment.

[gearheadE30]

Hmm, I posted in this thread 5 years ago... my turbo blanket disintegrated after about 2 years, and when I took it off, the turbine housing had corroded. The usual OEM method is a sheetmetal heat shield, which is what I'd recommend if you're really that concerned. You just need a thermal barrier of some sort.

[chondamx]

But they make it all reliable by keeping the heat inside the exhaust and limiting how much escapes in to the surrounding environment.

It is really a shame they're still so horribly unreliable.

I am running one of these over my turbo: http://www.zcarsource.com/hood-vent-...989_56318.html

Now, nobody steal my cool old school JDM naca hood vent idea ;)