On Wed, 7 Apr 2004 18:15:28 -0500, "RB"
wrote:

I've had several boats with big single and twin o/bs in the past. I
remember most as having a "sweet spot", which was just down from wide open
throttle (WOT). Many of you are probably familiar with a sweet spot. Cars
and trucks have been known to have them. Seems like going to WOT can eke
out a little more speed, but things are straining, coming back down a little
seems to let everything harmonize and get in the groove, and run more
smoothly.

The question I have is: assuming a boat with o/b has a sweet spot, is my
fuel consumption more efficient at the sweet spot than wide open? Sounds
like it would be -- a little bit---as you come back on the throttle to get
to the sweet spot. Or, is it that there's no real reason to run at the
sweet spot, other than it "feels right", and good?

Just curious



The "sweet spot" you're probably referring to is the point just before
the secondaries open on a 4-barrel carburetor. Not sure about o/b's
though. With fuel injection, it's a bit harder to tell what optimum
cruising speed is by feel, but just keep it in the manufacturer's
reccomended crusing RPM range and that'll be about right. If you
really want to know, get a fuel flow meter or sometimes you can plug
into your fuel injected engine's diagnostic port and get this info
with the right equipment.

"Slambram" wrote
If you
really want to know, get a fuel flow meter or sometimes you can plug
into your fuel injected engine's diagnostic port and get this info
with the right equipment.

They also make fuel flow meters that can link with output from common GPS
units for miles per gallon read-out . I can't remember what that link is
called - all I remember is that my (fairly old - maybe 10 years) GPS doesn't
have it. Of course, this stuff isn't cheap, but for a gadget freak, it
would be worth it, I'd guess.

G

On Thu, 8 Apr 2004 14:50:24 -0800, "Griss" wrote:

"Slambram" wrote
If you
really want to know, get a fuel flow meter or sometimes you can plug
into your fuel injected engine's diagnostic port and get this info
with the right equipment.

They also make fuel flow meters that can link with output from common GPS
units for miles per gallon read-out . I can't remember what that link is
called - all I remember is that my (fairly old - maybe 10 years) GPS doesn't
have it. Of course, this stuff isn't cheap, but for a gadget freak, it
would be worth it, I'd guess.

NavMan makes a unit like that. It's actually not all that expensive,
considering the price of fuel these days--and considering the difference
throttle setting may make on actual fuel economy.

I have the fuel meter alone, not the one that talks to the GPS. IF I ever get
around to installing it, I'll let you know how it works!

http://www.navman.com/marine/products/fuel/

Joe Parsons