Mileage with a Motor Home

[Clare Snyder]

Raymond C Drouillard wrote:
> 
> >> >-----Original Message-----
> >> >From: Dave Balfour <balfour at bushnell.net>
> >> >To: diy_efi at efi332.eng.ohio-state.edu
> ><diy_efi at efi332.eng.ohio-state.edu>
> >> >Date: Friday, March 27, 1998 9:56 PM
> >> >Subject: Re: Mileage with a Motor Home
> >> >
> > Will it not take more than headers to pull the max torque down by
> >nearly 30%?? Even a 454 may tend to lug at 1800RPM on a machine the size
> >of your MH. If it lugs, the vacuum drops, and with it fuel economy. The
> >reason MAX torque RPM gives best fuel economy is because it allows
> >highest sustained cruise vacuum. Anything above or below tends to drop
> >off vacuum if running anywhere close to rated load.
> 
> Maximizing vacuum increases mileage?  What about pumping losses?
> 
> If I find the speed of maximum torque on my 360 Jeep engine, should I set
> it up to run at that speed when I am cruising?
> 
> Ray Drouillard
> '89 Grand Wagoneer
> Holley Pro-Jection, Jacobs ignition, Edelbrock performer manifold, Engine
> Guard pre-luber, 3" exhaust system, 30x9.5 tires, stock 2.72:1 axles
> 
> _____________________________________________________________________
> You don't need to buy Internet access to use free Internet e-mail.
> Get completely free e-mail from Juno at http://www.juno.com
> Or call Juno at (800) 654-JUNO [654-5866]
You will note I "qualified" my statement by saying something to the
effect that it holds true if running close to the "rated output" of the
engine. If you have a monster V8 in a small car, or a light, unloaded
pickup, you can get better mileage at lower RPM as the engine is not
lugging. Running the Celica at 85 MPH, around 4200RPM, requires pretty
close to the amount of horsepower available at that RPM. On the 454
MotorHome, I suspect there is a little bit of leaway, but heading into
the wind at 1800RPM, the engine will NOT produce enough horsepower to
maintain headway at 65MPH. Running free at, say, 2800RPM, there will be
enough horsepower available without opening the enrichment system, and
you will likely still be running on the primaries. Regardless of how you
figure it, or what is behind it, with a multi-staged carbed engine, if
you can run with the secondaries not opening, and the power valve not
actuated, in the highest possible gear consistent with required speed
and the previous conditions, you should get your best mileage. Open the
secondaries OR the power valve and the "sucker" really sucks more gas.
Low vacuum opens the power valve and the secondaries on a carbed engine.
Regardless of "pumping losses", if you want driveability and economy
from a carbed engine, this is true.
IF the engine is fuel injected, it can be fooled into running in many
different modes. With electronic spark integrated with the fuel control,
super lean , super advanced, low vacuum cruise may be possible. This
will give better fuel consumption assuming you have more power vailable
than you need, and better fuel consumption period, because closer
control of the combustion process is possible.
-- 
                               _/\_
                       --|-----([])-----|--
                         S    0/  \0    B
         Alls well that ends well!! www.snyder.on.ca is back
                  E-Mail service is back to normal
                  To avoid bouncing E-Mail messages
                    Reply to Clare at snyder.on.ca
                                OR
Remove the R from clsnyder in my E-Mail Address to reply. Stop the
spammers!!!
It's hard to soar like an eagle when your stuck with a bunch of
Turkeys!!!