Gas mileage saga continues (Sorry, QUITE LONG)

[Marteney, Steven J.]

One of the changes made mid-way through the my tuning was injector constant.
My BLMs were 150-160.  I "fooled" the computer by telling it the injector
constant is around 18 lb/hr.  That brought the BLMs down to 128 and
DRASTICALLY improved off-idle.  The injectors were cleaned and flow matched
by Rich at Cruzin Performance to 2% of each other and verify to be 22lb/hr.

Not sure what you mean by "way under the curve for operating rpm vs. VE."

(As a side note, the headers drastically improved cold-start.  Car fires up
after about 2 seconds of cranking.  Before, sometimes I didn't think it was
going to start.  Injector PW vs. Battery Voltage also helped that.)

Steve (still learning, still having fun)

-----Original Message-----
From: Bruce Plecan [mailto:nacelp at bright.net]
Sent: Tuesday, October 31, 2000 12:56 PM
To: gmecm at diy-efi.org
Subject: Re: Gas mileage saga continues (Sorry, QUITE LONG)



That is enough cam, that it would be very responsive to intake and exhuast
tract changes.  Also, getting to where starting to get peaky (at least
compared to a stock cam).
Might take an injector constant change, and VE/Timing changes to get things
lined up, properly.
Also, might now be way **under** the curve for operating rpm vs VE.
Bruce

>Well, I responded to this email over the weekend and realized I never saw
it
> hit the list.  I've adjusted my equations for the square root thing and it
> slightly raised the calculated AFRs to between 12.0 and 12.5:1.

> To answer the cam question, the cam is the ZZ3, 208/221 at 050 w/ 0.484
and
> 0.510 lift, 112 lsa.  Not radical at all.
> Steve

> From: Tedscj at aol.com [mailto:Tedscj at aol.com]
> smarteney at xlvision.com writes:
> > 1) 22 lb/hr * 48psi / 43.5psi = 24.3 lb/hr effective injector flow rate
> I think the increase in fuel delivery is the square root of the increase
in
> fuel pressure.
> 1)22 lb/hr*SQR(48psi/43.5psi)=23.1lb/hr
> Also,
> possibility one for decreased MPG:  what's you lobe center on your cam?
> Over
> scavenging maybe? (probably not)
> Possibility two:  Laying into the gas a little more while having fun with
> your new headers? (much more likely!)

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