[SPLASHED] I/O (Sterndrive) Conversion to Outboards

[tpenfield]

Where did the mercruiser #'s come from? ( took the V-P #'s and applied some magic, based on what I was seeing on my boat before the conversion)

scott's link looks like the VPs are closer to your current setup than the stock OB setup. Yes, I think the dual prop (Bravo 3) makes a difference in coming up on plane. thus the lines on the graph are closer. Sort of indicates that getting the stock OB version would not have been a good move as far as planing speed, etc.

Anybody have the skill to overlay all 4 graphs? No . . .

Ted, do you have a GPH graph of your new setup yet? No . . .
Also interesting on the VP test that there isn't too big of a MPG hit from going from 3500-->4500 rpm/ 30 --> 42 MPH

See comments above . . .

 

[Scott Danforth]

Those merc engines are interesting. They basically look like a gen 1 and gen 3 had a one night stand

It's more like a Gen I Chameleon.....
All GM Gen 1 parts inside a merc casted block and heads

 

[Pmt133]

It's more like a Gen I Chameleon.....
All GM Gen 1 parts inside a merc casted block and heads

I just realized the valve cover is an adapter plate. It really is mostly a gen 1.

Wonder if the 4.5 crank will fit my 4.3. Another winter project.

 

[tpenfield]

Heading out to the boat this AM for some more running & data recording. Hopefully the info will determine next steps in tuning. Mike indicated that 5,000 RPM is the minimum and they shoot for 5,500 . . . 6,000 being the maximum.

Plan for the day . . . depending on sea conditions.. . .

1) Run at 4,000-5,000 RPM, trim up to the 75-90% range. See if there is any difference or sweet spot.

2) Use some remote cameras to get a look at the ventilation plates while running.

3) Get some fuel (maybe 30 gallons) and pump-out the waste tank.

4) Anchor near shore, drink some beers.

 

[alldodge]

Get some fuel (maybe 30 gallons)

Not going far or long

 

[Pmt133]

5500 makes sense, that's the rated speed for max power output of the engine.

 

[tphoyt]

It’s beautiful over my way. It was a bit windy early this morning but vineyard sound was like glass. Hope you find the same conditions.

 

[redneck joe]

4) Anchor near shore, drink some beers.

Need snacks. I like KFC dark meat. Assuming you have a fridge in there, get it good and cold...

 

[tphoyt]

I have a craving for fried chicken at 4:30 this morning. I’m going to take this as a sign that I need to make some fried chicken.

 

[redneck joe]

good call.

 

[tpenfield]

Wind is pretty calm

I did a quick run; got 50 mph @5300 RPM trimming up to 80%. $6.12/gallon for gas ️.

I’ll try some more running on the way back from the anchoring spot (Bassett Island)

 

[tpenfield]

Not going far or long

I have 75 gallons,(half a tank) after adding the 30 gallons. I think I’ve burned 30 gallons in 7.5 hours of mixed speeds. (4 gallons/hour)

 

[flashback]

Wind is pretty calm

I did a quick run; got 50 mph @5300 RPM trimming up to 80%. $6.12/gallon for gas ️.

I’ll try some more running on the way back from the anchoring spot (Bassett Island)

 

[tpenfield]

A little more choppy on the way back . . . but I ran the boat at 4000 RPM 35 mph. . . The display was saying 1.0 mpg, which may be suspect, because it does not seem to be using that much fuel.

I know there has been some Internet chatter about Honda not calculating fuel usage correctly.

 

[alldodge]

With a boat your size I would expect something close to 1.0 mpg, mine is half you size and weight a bunch less and my best cruise is around 2.3 mpg

 

[tpenfield]

I was getting 1.25 mpg with the Mercruisers, but outboards may not get as good fuel usage.

 

[tpenfield]

Overall, the boat is awesome . . . it comes up on plane easily and runs nice and flat. Being able to tilt the engines up out of the water at the end of the day is a real treat.

If we take the boat out tomorrow I should be able to get some video of the ventilation plates.

 

[tpenfield]

After paying $6+ for gasoline, I am getting a fuel transfer pump. The Admiral buys our groceries at a local chain store that also has gas stations. You get fuel discounts for buying groceries. She typically gets between $1.00 and $1.50 off per gallon / 20 gallon limit. Much of the gasoline that I've already put in the boat was at a net cost of under $3.00 per gallon.