Gas mileage saga continues (Sorry, QUITE LONG)

chetwagner at uswest.net chetwagner at uswest.net
Wed Nov 1 20:32:04 GMT 2000


I may have missed a bit of what is going on, but I noticed something 
about taking a while to start. If I may ask, what kind of vehicle is this 
on and what computer\code is being used?  Depending on what 
computer/code is in use, there is a way of fixing things to the point 
that the engine fires up in less than a second.

On 31 Oct 2000, at 15:48, Marteney, Steven J. wrote:

> 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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