The cruise RPM seems consistent with the old Yamaha's. You used to run at
about 68% of max RPM with the Yammies, and you now run about 70% of max RPM
with the Suzuki's. I'll bet that when you reprop, that number will fall
quite a bit.

So, you have lighter, quieter, more fuel efficient engines that don't need
oil...and you've given up a little top end (maybe).

Sounds like you "done good".



"Gene Kearns" wrote in message
...
On Tue, 12 Aug 2003 15:21:38 GMT, "NOYB" wrote:

Nice looking setup Gene. Have you gotten past the break-in? What's the
top
end? Cruising speed? RPM at cruising speed? And, most important, FUEL
ECONOMY!


I'm past (initial) break-in, but, as I said, there are some rigging
issues. The throttle controls are not in sync. I have gotten 6300
RPM on the starboard engine and 6500 RPM on the port engine. Redline
is 6200 RPM, so I quickly pulled back the throttles without checking
all of the stuff I'd like to know. It looks like different pitch
props may be a necessity, as I went from Aluminum 13.75 X 17 to SS 14
X 17. Pretty hard to rationally discuss apples and oranges, but over
rev is over rev.

RPM, now calm down..... gets really strange. Bear in mind there is a
huge difference in torque curves. These engines are only 125 Cu In
and develop their HP with RPM. With full fuel (200 Gals = 1200 lbs.)
two adults aboard and full water and gear.... (Old Yamaha figures in
parenthesis) Cruise looks like (3800)4400 RPM at (30)30 MPH.
All of this is subject to change if subsequent runs indicate that a
different prop is in order.

Engines: (V6)Inline-4 Cylinders, (158)125 Cu In, (475)415 Lbs.,
(5600)6200 Redline.


I'd expect you to see about 40mph with the weight and wind drag of that
hard
top, no? Fuel economy should be about 2.5 mpg? Let me know.


My hull is the old style hull, limited to 350 Hp Max and did get the
advertised 45 MPH prior to changing engines. From what I have seen, I
would expect to see 40 MPH with these engines. Fuel economy isn't
really clear yet.... I know the installer put *some* time on the
boat, but don't know how much. Before I cranked the engines the first
time, I installed hour meters so I *know* that *I* have put 7.5 hours
on them. I would have done more, but the weather has really sucked...
waterspouts, thunderstorms, and threatening clouds..... plus, the
better half has had a bout with kidney stones..... (when Momma ain't
happy, ain't nobody happy.....)

Break-in regime is:

15 Mins - Idle
1 hour 45 mins - Less then 3000 RPM
1 hour - 4000 RPM
Next 7 hours at any RPM, except not at Max throttle for more than 5
min.

During the last 4 hours I have not babied the engine, wanting enough
BMEP to insure break-in. So.... for 7.5+ hours use it appears I have
used about 40-45 gals fuel. Assuming an average speed of about 14 MPH
(which may be low), 2.5 MPG seems reasonable.





"Gene Kearns" wrote in message
news
On Mon, 11 Aug 2003 23:15:48 GMT, "NOYB" wrote:

Good luck with your engines. When are they getting rigged?


They're rigged and in the water, now! I've got a few hours on
them.....

See:

http://myworkshop.idleplay.net/Cavern/My_Boat.htm






--



Grady-White Gulfstream, out of Southport, NC.

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