FC 3208 NA Performance Data

[Jeff Miller]

Not quite sure what doesn't add up, but something doesn't.

At 2200rpm in 4th, 5.29:1 gears you should be running around 49mph.
Certainly should get better than 10mpg at that speed.

If your speedo and tach are accurate, then it would suggest that you
have between a 4.63:1 and 4.44:1 ratio.

I ran a 4.63:1 in a couple of my 'Birds, including my '77
FC31/3208na.

It allowed me to run 70mph plus, and to get into 3rd gear at a
higher speed for hill climbing. My speed over Mont Eagle actually
increased with the taller gears.

It didn't seem to impact my fuel mileage, since I was running 10mph
faster most of the time the aero drag increase at least offset the
lower piston travel/mile of the taller gears.

This was running clean on a '77 with a well tuned Na. If I were to
suggest gears for a much heavier coach like an '82, towing, it
depends on the terrain you're traveling and what you expect from
your coach. A couple of guys have gone to taller gears on the late
Na, but remember that the '82 FC35 is the worst power/weight
ration 'Bird made, you need to address that for performance also.

On our '84 250hp FC35 the 4.63:1 gears were too short for flatlands,
I would like to have run 4.44:1 instead. The 4.11:1 on our '88 /
300hp was a bit tall, especially with the .83:1 overdrive and 12R
tires, again 4.44:1 would probably have been optimum when towing
with that rig.

In all I feel that changing from 5.29:1 to a taller ratio (first
step is the 4.89:1 such as in the '83-'86) is a substantial upgrade
to any coach unless you're really going to spend a lot of time
climbing mountains. If climbing is your game, get a turbo engine,
you can't afford to lose 3% of your hp for every 1000' of altitude
with the Na.

- Jeff Miller
in Holland, MI
(we have hills here too, but we fill them all with water)


--- In WanderlodgeForum@yahoogroups.com, "davidkerryedwards"
wrote:
>
> Good info, thanks for posting that. What effect do you think the
> taller gears would have on top end power? In other words, would
you
> feel different if you were driving I-70 instead of I-40?
>
> Kerry
> 82 FC 35
> Denver
>
> -- In WanderlodgeForum@yahoogroups.com, "orbitalsolutions"
> wrote:
> >
> > At 15,000 miles the valves have fully seated on the "New Cat."
> >
> > After running 1590 miles, on roads ranging from running east on
I40
> > from Kingman, AZ to Flagstaff, AZ (Without having to stop to
cool
> > down). Taking secondary departures to see big meteor impact
sights
> > and the Hopi Indian ruins, along with the winding paths that
weave
> > through the Ozark Mountains, and other stop and goes, this is
what
> > the numbers say...
> >
> > The old bus has consumed 152 gallons of fuel oil. That equals
10.46
> > miles per gallon, pulling a Ford Ranger with enclosed aluminum
bed
> > shell, loaded pretty much to the gills.
> >
> > The motor is currently down less than a quart of motor oil,
(none
> > has been added). That's why I know for sure the valves are
finally
> > comfortable.
> >
> > The majority of running time has been done at 2200 Rpm's at an
> > average speed of about 60 miles per hour.
> >
> > All I can say is I want higher gears! My bus has the original
5.62
> > (I think, or what ever Blue Bird put in it) They are too short
for
> > sure.
> >
> > The only running gear modification I want to make is to get some
> > longer legs in the pumpkin. I am convinced that it would make a
> > HUGE difference.
> >
> > Hopefully, I can find a garage that I feel comfortable to do the
> > work. I would have it done tomorrow If I could.
> >
> > Can't wait to see what the cruise speed will be at 2200 rpm's,
or
> > the fuel milage at reduced revolutions.
> >
> > So there are some real world numbers for anyone that may find it
of
> > interest.
> >
> >
> > James
> > 78FC33SB
> > Bull Shoials AK (But feeling ready for a drive)
> >
>