Inboard motor recommended max RPM
Lew Ricker
tachometer red lines at 5200 RPM.
It has a 128HP 2.3 liter 4 cyl Ford inboard engine with an overhead cam.
It powers an OMC Cobra outdrive.
I operate it at a maximum of 5000 RPM trimmed for a top speed of
approximately 40 MPH (Depending on # of people, wave and wind
conditions, etc.) even though it it could go faster on the throttle.
Recently a marine mechanic told me I should not exceed approximately
4600 RPM for this 4 cylinder engine
but he did not have any documentation to back it up. My manual does not
state any max RPM for the boat.
Can anyone advise me if I am exceeding the recommended RPM of the
engine? Thank you.
Lew Ricker
Rick
"Lew Ricker" <lri...@magma.ca> wrote in message
news:3999F567...@magma.ca...
Lew I'm not 100% sure on the 89 model but I can tell you that in 1986 that
2.3 litre engine was rated at 120 h.p at 5400 rpm. That engine has been
around since about 1974 and is known as a high revving 4 cyl. Most i/o's ,
especially back then were rated in the 4400-4800 rpm range. By the way the
info. I got was from an old 1986 Trailer Boat article on the 2.3 engine
mated to the Cobra drive and they tested it on a 1750 bowrider. Your
performance figures pretty much match theirs.
Rick
Terry Spragg
max possible output is this: Dragsters rebuild their engines every
run. They get about 1/2 mile durability. How long do you want your
engine to live? The easier you run it, the longer it will last.
What's your hurry? You are still on the boat, no matter how fast it
goes. Absolute max fuel economy on distance over water is probably
at about 3-5 knots for a 18 foot boat, just off idle, and slow
enough that you cause very little wake, which represents power lost
to making waves in the water. That presumes your low speed setup is
at optimum for your altitude.
OK, I admit it, I don't understand, I am a Canadian... sailor ;-)
Don't think I am suggesting that wakes bother me, unless I'm boiling
tea at anchor, or you break my docklines, as has happened to me on
the Murray canal caissons. I enjoy a good splash in the face on a
hot day, and sailboats are made for the waves. Besides, speed boats
make less wake, once on plane, the faster they go.
Sail safe, eh?
Terry K
Dave Brown
Lew, I hope you don't select this 'mechanic' as the one who does the maintenance
for your boat in the future.
This engine's operating range is 52-5600 RPM at wide open throttle and will run
all day there without damaging it. The big benefit of the high operating range
on this little motor means it can be propped with a lower pitch giving it a
better hole shot than the 3.0l GM engine offered in that year as well.
Of the units we sold, we have not had a single engine failure and consider them
as reliable as any of the motors in the line up.
--
Regards,
Dave Brown
Brown's Marina
http://www.brownsmarina.on.ca/
Dave Brown
> Lew I'm not 100% sure on the 89 model but I can tell you that in 1986 that
> 2.3 litre engine was rated at 120 h.p at 5400 rpm. That engine has been
> around since about 1974 and is known as a high revving 4 cyl. Most i/o's ,
> especially back then were rated in the 4400-4800 rpm range. By the way the
> info. I got was from an old 1986 Trailer Boat article on the 2.3 engine
> mated to the Cobra drive and they tested it on a 1750 bowrider. Your
> performance figures pretty much match theirs.
Rick, the engine you're thinking of the the GM 2.5L (a smaller version of the
3.0L). The Ford 2.3l replaced the 2.5L in 1987 and is rated at 128hp and can run
all the way up to 5600 RPM.
Rick
"Dave Brown" <da...@brownsmarina.on.ca> wrote in message
news:39A93374...@brownsmarina.on.ca...
> Rick wrote:
>
> > Lew I'm not 100% sure on the 89 model but I can tell you that in 1986
that
> > 2.3 litre engine was rated at 120 h.p at 5400 rpm. That engine has been
> > around since about 1974 and is known as a high revving 4 cyl. Most i/o's
,
> > especially back then were rated in the 4400-4800 rpm range. By the way
the
> > info. I got was from an old 1986 Trailer Boat article on the 2.3 engine
> > mated to the Cobra drive and they tested it on a 1750 bowrider. Your
> > performance figures pretty much match theirs.
>
the
> 3.0L). The Ford 2.3l replaced the 2.5L in 1987 and is rated at 128hp and
can run
> all the way up to 5600 RPM.
>
> --
> Regards,
>
> Dave Brown
> Brown's Marina
> http://www.brownsmarina.on.ca/
I'm just reading from the trailer boat article Dave which is titled, "OMC's
New Ford Stern Drive", Oct. 1986 issue. Sub. heading "the 2.3 four cylinder
shows performance and economy".. It describes the engine as a 2.3 litre,
(140 ci) overhead cam rated at 120 hp. They do mention that in 86 OMC
changed from the 153 ci Chev block that they had been using for 20 yrs.
Sounds like the rpm range is about the same regardless of the engine.
Rick
Dave Brown
> I'm just reading from the trailer boat article Dave which is titled, "OMC's
> New Ford Stern Drive", Oct. 1986 issue. Sub. heading "the 2.3 four cylinder
> shows performance and economy".. It describes the engine as a 2.3 litre,
> (140 ci) overhead cam rated at 120 hp. They do mention that in 86 OMC
> changed from the 153 ci Chev block that they had been using for 20 yrs.
> Sounds like the rpm range is about the same regardless of the engine.
The 2.5/3.0L is only rated for 42-4600 while the 2.3 is rated for 52-5600 RPM.
World's apart in my humble opinion. :-)
Trivia question:
OMC marketed this engine as a 2.3L TKO. What did TKO stand for?
Dan in the bush
had a discussion that may open up another door for you as well. Mazda has a
bunch of rotary engines (the Wankle engine used in the RX-7) that are
converted for marine use. They have higher power output than the average 6
cyl. but less weight than the average 4 cyl.
They love high rpms, and because they are still unknown in North America as
a marine engine, Mazda was offering some pretty good rates on them,
including conversion kits and could quote rough pricing online for you.
Wish I could give you a link, but my system crashed and I don't have it
anymore.
Could be a powerful option for you.
--
Dan in the bush.......
"Dave Brown" <da...@brownsmarina.on.ca> wrote in message
news:39A9BF08...@brownsmarina.on.ca...