Re: [omc-boats] OMC V6 Motor, sterndrive

Hi Lee,

 I appreciate your comments, but there's more going on here that isn't
entirely obvious. I know it sounds like overkill but I'll try to explain my
rationale.

It's not about absolute top-end speed, but more about mid-speed throttle
response and torque. That's where a small-block Chevy will shine.
I don't expect I'll push the boat much past 36 - 42 mph with a 215 - 225hp
V8. About the same as the OMC 1968-70 16-footers w/ V6's would do.

1) Where we do all our boating ALTITUDE is a power-zapper. At 7000 ft ASL,
Air Density sucks an easy, 20% power penalty.
Where others can swing an 18-inch pitch prop, we pull 14's. It's like having
the performance of 120-hp, I-4 Chevy at sea level.

2) We typically carry no less than 1000 pounds of passengers, fuel and gear.
That puts the in-water, hull displacement close to (or over) 3000 pounds and
we haven't started pulling a skiier or tuber yet. That's a lot to ask of 120
hp. Our OMC boats are built like tanks, but they are heavy. I've never been
on the boat with fewer that four adults on board.

3) The boat is never left in the water or even outside. The entire hull
gelcoat was waxed and buffed last spring, off trailer. Top speed with four
adults, swinging a 15-inch pitch SST is 34-36 mph (per GPS at 6600 ft ASL),
and that's turning the Buick at 4400-4500 rpm, WOT.

4) I'm planning on installing the stringer OMC hydraulic/electric selecTrim
front motor mount, so I can fine tune the prop angle for adjusting bow
atitude. It's a lot cheaper than a MerCrusier or OMC/Volvo SX comversion. I
looked into a 225hp 4.3L Chevy V6 but they cost too much and don't match the
low RPM torque of the V8.

I'm confident I'll be happy with the V6-toV8 conversion, as it will meet our
unique needs. True, a ready-made 19-ft OMC V8 boat would be easier, but I
couldn't garage it or tow it. (There's even a 69 Evinrude Rogue II 210 V8
available locally for a song.) Yeah, I know I'll use 20% more fuel, but
hopefully it won't be $5.00 a gallon this boating season. Last season I went
through about 125 gallons, so eh, whats another 25 gallons this season?

Cheers,

Lee Shuster
Salt Lake City

----- Original Message -----
From: <LeeHazen@...>
To: <omc-boats@...>
Sent: Wednesday, March 16, 2005 4:22 PM
Subject: Re: [omc-boats] OMC V6 Motor, sterndrive

> In a message dated 3/15/05 10:28:02 PM Central Standard Time,
> lib1@... writes:
>
> << My ability to store this stuff will evaporate by mid-summer, so if your
> are interested, contact me off-list and we will work something out, first
> come-first serve. Simply put, my lust for more power (especially as gas
> prices are
> going up) could be your gain. >>
>
> And - HOW FAST do you want to get a 16' boat going?
>
> Has that boat always been trailered and not left in the water ?
>
> I mention this because boats that stay in the lake all season have issues
> with algae build up that greatly affects the top speed of the boat.
>
> I found that cleaning the bottom of my 1969 Seasport 155 could yield an
> extra 10 mph top speed..
>
> I would hate for you to go to all this trouble only to find a not so
> significant increase
> in performance. I think that about 40 mph was about the best top speed I
> could get out of my boat with the V-6 engine.
>
> Another thing that may affect top speed - the fact that the stern drive
> can
> not
> be "trimmed" for maximum speed. You might want to consider a more modern
> stern drive with trim capability.
>
> You sure must want to go fast very badly to be willing to go to all the
> trouble
> and expense that's ahead for you.
>
> Just my two cents worth here -
>
> Good Luck !
>
> Lee Hazen
>
>
Received on Wednesday, 16 March 2005