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beepbeep beepbeep is offline
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Join Date: Jun 2001
Location: Sweden
Posts: 5,564
It's not just flow numbers. It's also combustion chamber geometry and head temperature.

While being quite OK for a 2-valve design, aircooled 911 heads just aren't most optimal for turbocharging. This is the reason Porsche left aircooling and went water alltogether.

With other words, just beacuse you might get away with turbocharging a Miata w/o lowering C/R, it doesn't mean it will work on 911. There is no moderating effect of watercooling, there is no pentroof design, the distance that flame propagation front has to take is quite big, no knock-detection etc.

So yes, you can probably survive with boosting stock SC engine with 8.5 C/R but you have to be careful. Also, forget about linear raise in power just beacuse you boost 1.6 times the ambient pressure. VE just isn't there and turbocharger and CIS inefficiencies will eat a great deal of power.

With other words, IF you chose to turbocharge a stock 3.0 SC engine with stock CIS, you have to be very careful with fueling and temperatures.

I suggest intercooling, low boost and AFR logging run to begin with as you have no safety features.
Thank you for your time,
Old 11-23-2007, 04:57 AM
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