Re: General tuning question - fuel economy

["Bruce Plecan" <nacelp@bright.net>]

> Dual pattern - 208 I, 221 E @ 050, Lift is 474 I, 510 E with 112 LSA.

355, 224 @ 050, 470 Lift, TBI (cross fire), long term MPG was about 24.6 as
I recall.  Stock heads, first EFI calibration, Walker 3" exhuast..
Grumpy

>
> Your mileage figures are obviously a testament to your a) heads, b)
personal
> tuning, c) well flowing exhaust, d) others.  Those numbers rival factory
LS1
> F-body specs.  If it's in the 4x4, then I'm doubly impressed.
>
> My average WAS about 19.1, is now about 16.3.  The mods were the cam,
10.2:1
> flat-top pistons, balanced rotating assembly, 3-angle valve job.  My
biggest
> problems are the stock manifolds, heads, TPI, single cat, and no tuning
yet.
>
> Steve
>
> > -----Original Message-----
> > From: Mike Rolica [mailto:mrolica@meridian-mag.com]
> > Sent: Tuesday, June 13, 2000 4:00 PM
> > To: 'gmecm@diy-efi.org'
> > Subject: RE: General tuning question - fuel economy
> >
> > Well, do you have any cam specs??? With my single pattern, 208 @0.050"
> > 278adv and .555 lift with 112 deg lobe center on a l98 (350tpi) I get
> > 30mpg.  300miles out of 10impgal  Or for you us guys 27 mpg.@ 85 mpg,
> > 2500rpm
> > Mike Rolica
> > Plant A,
> > Magnesium Products Division
> > Strathroy
> >
> > (519)-245-4040  Ext. 265
> >
> >
> > -----Original Message-----
> > From: Marteney, Steven J. [SMTP:smarteney@xlvision.com]
> > Sent: Tuesday, June 13, 2000 3:09 PM
> > To: gmecm@diy-efi.org
> > Subject: General tuning question - fuel economy
> >
> > Not having really any engine "tuning" experience I stumble
> > on some of the
> > basic concepts (such as when to add spark advance).  My
> > rebuilt 350 TPI
> > F-body gets about 20% less highway gas mileage with its
> > bigger cam (GM ZZ3)
> > and stock computer.  I figure more air in at X rpm requires
> > more fuel to
> > appease the O2 sensor, hence gas mileage goes down.  How do
> > I compensate, or
> > can I?  I noticed there are some Hiway mode parameters, such
> > as Hiway spark
> > add (?), in the 165 ECM that I could take advantage of.  Or,
> > is the only way
> > to get better mileage mean changing the target AFR?
> >
> > However, I also thought that this engine cruises at about
> > 2200 rpm on the
> > highway at 75 mph.  I'm wondering if the different cam (and
> > valve timing)
> > has defeated the ram tuning effect of the runners and made
> > the engine less
> > efficient on the highway.  Any thoughts?  I'd appreciate a
> > little basic
> > help.  Since this car is my daily driver (70+ per day) I'd
> > like to keep fuel
> > economy in mind when tuning.
> >
> > Thanks,
> > Steve Marteney
> >
> --------------------------------------------------------------------------
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