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Jim2 Jim2 is offline
7.0:1 > 11.3:1
 
Join Date: Oct 2003
Location: Calgary
Posts: 1,839
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930gt A couple things to think about. Each component upstream of your turbo which results in a flow loss means you have to make the turbo work harder to get the charge into the cylinder: inlet charge tubing (especially 90 degree elbows), intercooler tanks and core, throttle body, intake manifold, port, valve...

The throttlebody is one item which can be somewhat easily changed. If the turbo is producing say 19 psi to achieve 15 psi at the intake manifold (assume 2 psi drop for the I/C and 2 for the TB), it means the turbo discharge temp is going to be higher, there will be more exhaust back-pressure and cylinder dilution as a result of the turbo working harder, there will be a little less temp drop from the intercooler now that the charge temp is higher, and of course the turbo will take a more time to spool to 19 psi.

My objective with was to have the same cross section area as the inlet plumbing leading up to the throttlebody, even accounted for the butterfly shaft area. On first drive I noticed the throttle is more sensitive at low openings but I had no problems driving. If needed you could rework the arm geometry on the the butterfly to alter the throttle opening rate.
Old 04-20-2007, 09:29 AM
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