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Old 02-14-2013, 06:02 PM   #6952
amalgrover
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Member#: 183480
Join Date: Jun 2008
Chapter/Region: South East
Location: Valdosta, GA
Vehicle:
2011 Audi A3 Quattro
2009 Forester XT

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Quote:
Originally Posted by 02RexWI View Post
I doubt you're maxing out the stock fuel rails at that power level, but you're probably getting close, so it wouldn't be a bad idea to upgrade while you have it apart.
I doubt he is even anywhere close to maxing the stock rails. There are plenty of people pushing well over 100whp more than what he is on the stock rails right now.

Also, your walbro 255 is maxed out probably around 180lph with the boost pressure you are probably running and if you are running the stock wiring and everything (closer to 200lph with a pump re-wire). That equates to approximately 75% IDC (85% if you are re-wired) on your 1000cc injectors (assuming 100% IDC = 1000cc). So, if you are seeing over 75% IDC (85% if re-wired) now, then your fuel pump is maxed, which means that the fuel pressure and injector flow is dropping. This requires you to hold the injector open longer to get the same afr, which means IDC is going up significantly.

If you got a bigger pump and bumped fuel pressure up enough (approx 55psi base pressure), you should be able to get to the power level you are looking for...REMEMBER THOUGH...as fuel pressure increases, fuel pump output decreases. This means that if you bump fuel pressure up to 55psi and run 27psi of boost, you are looking at 82psi of fuel pressure. This means that the fuel pump output at 100% IDC now has to be approx 275lph.
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Last edited by amalgrover; 02-14-2013 at 06:08 PM.
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