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Old 01-06-2011, 11:30 AM   #13
LS7 427
10.17 @ 140.2 mph
 
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Drives: Black & Yellow 2SS/RS LPE LS7 427
Join Date: Mar 2010
Location: Redcliff, Alberta
Posts: 688
Quote:
Originally Posted by SSE 4 2SS View Post
Cool, and this is only a question, does the increased port size slow down the intake velocity, or is it a wash...I can certainly see where the charge would be cooler, less resistance... But does this also equate to less pressure...

I'm starting a twin turbo build, and wanting to know everything I can...

Thanks and this is a beautiful car...I love the paint scheme...

There would definetly be a velocity increase at the node where the air passes through the non ported intake into the ported head. The non ported intake would act as a choke or restrictor to the flow and would create a higher pressure upstream of the node. The flow is certainly more laminar and less turbulent after porting.

With regards to less pressure...If we agree that there is a temp drop (which we appear to) and volume (area of the chambers) of course is constant then;
(Pressure X Volume = Temperature) or P = T/V

Ex.1)
Temp @ 150F, T=150
Vol @ 3L (assumed), Vol=3

P=150/3
P=50

Ex.2)
Temp@ 140F, T=140
Vol @ 3L (assumed), Vol=3

P=140/3
P=46.6

These are hypothetical numbers but as you can see in the examples, buy reducing Temp, Pressure has to drop.

Last edited by LS7 427; 01-06-2011 at 12:23 PM.
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