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Message started by Sam1 on Feb 12th, 2009 at 9:28pm

Title: gauge vs. absolute pressure
Post by Sam1 on Feb 12th, 2009 at 9:28pm
Hi

If I connect a fuel gauge to measure fuel pressure at KOEO and it reads 40psi, would that be gauge or absolute?
I would say it should be gauge pressure since the gauge reads zero setting on the bench and 40 when connected to the car.
hence, the absolute pressure when connected would be 40 + 15 = 65psi
hence the pressure difference across the injector (behind the injector and infront of it "intake manifold") would be 40psi. with me so far?

NerdCDII Fuel Delivery Testing > Part One > 6:35 indicates the the pressure differential would be 40 - 15 = 25psi.

I must be missing something. please help me understand this.

Title: Re: gauge vs. absolute pressure
Post by Tom Roberts on Feb 12th, 2009 at 10:34pm
Sam,

If you have specific questions on The Nerd Series, it is best just to email those to me.

I think the word gauge made that confusing (nobody's perfect).  I was talking in terms of absolute pressures.

The concept is that to maintain an equal differential from KOEO to 20 inches of manifold vac the fuel pressure must be reduced 10lbs.


Title: Re: gauge vs. absolute pressure
Post by Sam1 on Feb 12th, 2009 at 10:51pm
Thanks Tom, :)

I am enjoying those  CDs a lot, I am learning from them things I never knew before, what a great value.

Title: Re: gauge vs. absolute pressure
Post by Tom Hardaway on Feb 13th, 2009 at 5:22am

Quote:
I am enjoying those  CDs a lot, I am learning from them things I never knew before, what a great value.


I second that.  :)


Tom

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