flow vs pressure (porting vs boost)

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Nov 30, 2016 | 11:38 AM

#26

RGHTBrainDesign

Banned. I got OWNED!!!

Joined: Aug 2012

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From: San Jose, CA

Quote:

Originally Posted by JZG

You would think so but in my experience you are more likely to bend seals due to over heating as the turbine back pressure/boost ratio goes above 1:1. More overlap generally means richer mixtures are required to keep the apex seals under their critical temperature.

eMAP:MAP Ratio is always over 1:1 unless the exhaust is SUCKING... A really good system would be like 1.2:1. Anything over 1.5:1 needs exhaust/turbine housing modification/optimization.

Nov 30, 2016 | 01:50 PM

#27

JZG

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Joined: Jun 2009

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From: 3116

Quote:

Originally Posted by SirLaughsALot

eMAP:MAP Ratio is always over 1:1 unless the exhaust is SUCKING... A really good system would be like 1.2:1. Anything over 1.5:1 needs exhaust/turbine housing modification/optimization.

I probably should have specified I'm referring to manifold gauge pressure, not absolute. Once turbine back pressure (gauge), is higher than inlet manifold pressure (gauge) there is a lot more intake charge dilution with hot exhaust gas. The more overlap the engine has, the more dilution takes place.

Dec 19, 2016 | 09:31 AM

#28

TitaniumTTRE

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Joined: Mar 2011

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From: In my shop

Quote:

Originally Posted by SirLaughsALot

eMAP:MAP Ratio is always over 1:1 unless the exhaust is SUCKING... A really good system would be like 1.2:1. Anything over 1.5:1 needs exhaust/turbine housing modification/optimization.

Stock REW twins from 0-10psi stayed around 1:1. From 10-15psi boost the ratio climbed to 2:1

Current setup stays VERY close to 1:1 all the way to the 26psi range

JzG is right on the money for everything that I have experienced as well

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