I think its a market ploy to advertise how much HP a boat has. They will tell you 250 hp @ 4400 rpms!!!!!. So most new boat owners think that that's how fast the motor needs to go all the time.It doesn't take long to find out sure the motor will turn 4400 rpms when all the conditions are right. Fresh tune,the right prop, clean bottom,lightly loaded, half tank of gas, dead calm water with lots of openness in front of you. But that comes with a price. Really bad gas mileage.Boats burn gallons per mile or another way to look at it , gallons per hour. And eventually premature motor damage as you can't redline a motor all the time. Things, expensive things will go bang. I've always found that if I ran my boats, which were gas 6 and 8 cyls at around 3/4 of the rated redline, around 3-3200 rpms. The boats would plane nicely, handle good and I got good fuel mileage. Trying to get a boat up to speed with a dirty bottom, is like dragging the anchor.,,
Boat engines and WOT
- Thread starter Nick R
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marine engines live a very different life than auto.
1. it should be geared and propped for that boat, so that WOT sits right around 4400.
2. they are always under load unless tut-tutting. Totally different beast than over-the-road.
3. lower thermostat if it's using lakewater cooling... 160F. They don't want hotspots in the heads that boil and deposit silt onto the metal.
4. Marine oil or HDEO is required. It's a humid environment, with a lot more power in use over time. most recreational folks do annual OCs at 50 or 100 hours.
My #'s. Had a marinized chevy 350 in a 22' cuddy cabin searay. Heavy for what it was, which was nice in the chop. Other compromises in hull construction made it a PITA to care for (staples through the bilge gel coat, no thru-stringer drains...), permanently mounted/inaccessible forward bilge and [failed] pump...
anyway, 2/3-3/4 throttle to get on plane. 1/2-2/3 to keep it there. More if the boat has more weight in it. Typically saw 3800 rpm to launch. minimal rpm to plane ~2600-2800, so typical cruise for me was 3100-ish. Typical mpg was 2.9-3. At the time I owned it, it was $1.00 per mile to run. I also tried a tank of gas with nothing but
I bought it well-used, at 20 years old. that's a 20 year old V8 in a thing that sits in water. It ran Great. Oil Pressure was typically ~45 at cruise.
I think prior mainenance means a lot.
x2 for marine survey (professional inspection prior to purchase). Based on my experience, HULL condition (ie, soaked transom.........) more important than mechanicals...
1. it should be geared and propped for that boat, so that WOT sits right around 4400.
2. they are always under load unless tut-tutting. Totally different beast than over-the-road.
3. lower thermostat if it's using lakewater cooling... 160F. They don't want hotspots in the heads that boil and deposit silt onto the metal.
4. Marine oil or HDEO is required. It's a humid environment, with a lot more power in use over time. most recreational folks do annual OCs at 50 or 100 hours.
My #'s. Had a marinized chevy 350 in a 22' cuddy cabin searay. Heavy for what it was, which was nice in the chop. Other compromises in hull construction made it a PITA to care for (staples through the bilge gel coat, no thru-stringer drains...), permanently mounted/inaccessible forward bilge and [failed] pump...
anyway, 2/3-3/4 throttle to get on plane. 1/2-2/3 to keep it there. More if the boat has more weight in it. Typically saw 3800 rpm to launch. minimal rpm to plane ~2600-2800, so typical cruise for me was 3100-ish. Typical mpg was 2.9-3. At the time I owned it, it was $1.00 per mile to run. I also tried a tank of gas with nothing but
I bought it well-used, at 20 years old. that's a 20 year old V8 in a thing that sits in water. It ran Great. Oil Pressure was typically ~45 at cruise.
I think prior mainenance means a lot.
x2 for marine survey (professional inspection prior to purchase). Based on my experience, HULL condition (ie, soaked transom.........) more important than mechanicals...
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...I was going to add the same as meep....if the boat has been sitting in the water or not covered, wood rot is one thing you got to look for. If you don't know how to do that, hire someone. It will save you TONS in the future. Do some research, the internet is your friend.
I have a 27' Four Winns Vista with twin 4.3l fuel injected engines. I almost never run it at WOT.
To get on plane at times I have to drop the hammers, if I have 5 or more people on board. But once I get on plane, I cruise at around 3200 RPM's, which usually keeps me around 30mph.
I boat on Lake St. Clair too - Lake Eries choppy crabby sister, LOL.
If it gets real choppy, I bring the speed down to 25mph and smoosh the bow down with the trim tabs and outdrive trim without falling off plane. Anything below that and Im plowing. My WOT speed is 46mph (and I dont do that very often, maybe twice, because its just "scary" going that fast in a cabin cruiser!).
Whoever said they drive at WOT most of the time is a person who has something wrong. Either their prop is pitched wrong, fouled, or they are severely under powered.
Just my $.02
To get on plane at times I have to drop the hammers, if I have 5 or more people on board. But once I get on plane, I cruise at around 3200 RPM's, which usually keeps me around 30mph.
I boat on Lake St. Clair too - Lake Eries choppy crabby sister, LOL.
If it gets real choppy, I bring the speed down to 25mph and smoosh the bow down with the trim tabs and outdrive trim without falling off plane. Anything below that and Im plowing. My WOT speed is 46mph (and I dont do that very often, maybe twice, because its just "scary" going that fast in a cabin cruiser!).
Whoever said they drive at WOT most of the time is a person who has something wrong. Either their prop is pitched wrong, fouled, or they are severely under powered.
Just my $.02
Originally Posted By: Nick R
Kind of curious, simply because depending on where we move, we may end up getting a boat. If we move to Ohio near Lake Erie we pretty much definitely would be. That's beside the point though.
It seems to me, with boat engines you pretty much would end up running WOT or near WOT all the time to get places. Is this pretty accurate? How do those engines hold up over time? Especially say the car engines stuck in a boat, like the GM 4.3L V6 that appears to be ubiquitous as boat engines. How do you run your boat?
WOT typically is used to see if the engine is propped correctly. Maybe on small lakes people would run WOT. But on a large lake or river, people run at cruising speed as the gas usage at WOT is crazy.
Kind of curious, simply because depending on where we move, we may end up getting a boat. If we move to Ohio near Lake Erie we pretty much definitely would be. That's beside the point though.
It seems to me, with boat engines you pretty much would end up running WOT or near WOT all the time to get places. Is this pretty accurate? How do those engines hold up over time? Especially say the car engines stuck in a boat, like the GM 4.3L V6 that appears to be ubiquitous as boat engines. How do you run your boat?
WOT typically is used to see if the engine is propped correctly. Maybe on small lakes people would run WOT. But on a large lake or river, people run at cruising speed as the gas usage at WOT is crazy.
Most boat engine suck in water and die. They do not wear out. People let the manifolds and/or risers go too long.
Originally Posted By: Donald
Most boat engine suck in water and die. They do not wear out. People let the manifolds and/or risers go too long.
But in freshwater, that's not a problem either.
My Dad had a 47' Chris Craft Commander that was new in 1971. In 2002, he sold the boat with the original risers/manifolds on them. Original engines. Boat was always in Fresh Water. Engines had 2100 hours on them in 2002.
And after speaking with several boat engine guys up in Algonac, MI....your risers/manifolds on fresh water are the least of your worries.
Most boat engine suck in water and die. They do not wear out. People let the manifolds and/or risers go too long.
But in freshwater, that's not a problem either.
My Dad had a 47' Chris Craft Commander that was new in 1971. In 2002, he sold the boat with the original risers/manifolds on them. Original engines. Boat was always in Fresh Water. Engines had 2100 hours on them in 2002.
And after speaking with several boat engine guys up in Algonac, MI....your risers/manifolds on fresh water are the least of your worries.
You fresh water guys have it so easy.
Risers are a 4-5 year replacement item in salt water, and a raw water cooled motor is a boat anchor in a bit over that.
Risers are a 4-5 year replacement item in salt water, and a raw water cooled motor is a boat anchor in a bit over that.
Originally Posted By: Phishin
Originally Posted By: Donald
Most boat engine suck in water and die. They do not wear out. People let the manifolds and/or risers go too long.
But in freshwater, that's not a problem either.
My Dad had a 47' Chris Craft Commander that was new in 1971. In 2002, he sold the boat with the original risers/manifolds on them. Original engines. Boat was always in Fresh Water. Engines had 2100 hours on them in 2002.
And after speaking with several boat engine guys up in Algonac, MI....your risers/manifolds on fresh water are the least of your worries.
I would not ignore freshwater risers/manifolds. They may last longer than saltwater, but they will rust anyway. They are not lifetime.
Originally Posted By: Donald
Most boat engine suck in water and die. They do not wear out. People let the manifolds and/or risers go too long.
But in freshwater, that's not a problem either.
My Dad had a 47' Chris Craft Commander that was new in 1971. In 2002, he sold the boat with the original risers/manifolds on them. Original engines. Boat was always in Fresh Water. Engines had 2100 hours on them in 2002.
And after speaking with several boat engine guys up in Algonac, MI....your risers/manifolds on fresh water are the least of your worries.
I would not ignore freshwater risers/manifolds. They may last longer than saltwater, but they will rust anyway. They are not lifetime.
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Originally Posted By: Donald
Originally Posted By: Phishin
Originally Posted By: Donald
Most boat engine suck in water and die. They do not wear out. People let the manifolds and/or risers go too long.
But in freshwater, that's not a problem either.
My Dad had a 47' Chris Craft Commander that was new in 1971. In 2002, he sold the boat with the original risers/manifolds on them. Original engines. Boat was always in Fresh Water. Engines had 2100 hours on them in 2002.
And after speaking with several boat engine guys up in Algonac, MI....your risers/manifolds on fresh water are the least of your worries.
I would not ignore freshwater risers/manifolds. They may last longer than saltwater, but they will rust anyway. They are not lifetime.
I've worked on engines that still had their originals from the 1930's
They last a great deal longer in cold, fresh water than they do in salt.
Originally Posted By: Phishin
Originally Posted By: Donald
Most boat engine suck in water and die. They do not wear out. People let the manifolds and/or risers go too long.
But in freshwater, that's not a problem either.
My Dad had a 47' Chris Craft Commander that was new in 1971. In 2002, he sold the boat with the original risers/manifolds on them. Original engines. Boat was always in Fresh Water. Engines had 2100 hours on them in 2002.
And after speaking with several boat engine guys up in Algonac, MI....your risers/manifolds on fresh water are the least of your worries.
I would not ignore freshwater risers/manifolds. They may last longer than saltwater, but they will rust anyway. They are not lifetime.
I've worked on engines that still had their originals from the 1930's
Originally Posted By: Donald
Most boat engine suck in water and die. They do not wear out. People let the manifolds and/or risers go too long.
You hit it right on the head. I used to always buy boats that did not run, got some great bargains that way. Overwhelming majority had water damage!
I have had several boats over the years, my current boat is a sliver with 800+ hp of supercharged Chevy 572 in it. It turns about 7 grand at top speed, but you can't take it there very often. I spend a great deal of time making sure it has no water anywhere when it is put away, as this pays off long term.
Most boat engine suck in water and die. They do not wear out. People let the manifolds and/or risers go too long.
You hit it right on the head. I used to always buy boats that did not run, got some great bargains that way. Overwhelming majority had water damage!
I have had several boats over the years, my current boat is a sliver with 800+ hp of supercharged Chevy 572 in it. It turns about 7 grand at top speed, but you can't take it there very often. I spend a great deal of time making sure it has no water anywhere when it is put away, as this pays off long term.
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Originally Posted By: Schmoe
...like others said....they still will rust. Check the draincocks and see if rust has settled in those brass cups. Makes you start thinking about that when you actually see small pieces of rust sitting in them.
Is this directed at my post about engines operating in cold, fresh water and having their manifolds lasting longer? If so, I didn't say they wouldn't rust, I said they last longer. And I cited my experience with some extremely old examples to back that up.
...like others said....they still will rust. Check the draincocks and see if rust has settled in those brass cups. Makes you start thinking about that when you actually see small pieces of rust sitting in them.
Is this directed at my post about engines operating in cold, fresh water and having their manifolds lasting longer? If so, I didn't say they wouldn't rust, I said they last longer. And I cited my experience with some extremely old examples to back that up.
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Originally Posted By: Schmoe
Not directed at you. My experience as a Mercruiser tech. in the late 80's has shown me that they are going to rust. Seen a lot of them in the shop that needed new manifolds only after the engine hydrolocked.
BTW, not sure if you'll find this interesting or not, but we had stainless manifolds on our Ford 312 Y-block in the 1931 Chris. Of all the boats I drained in preparation for winter, it always had the cleanest water (for this reason of course).
I have an old Merc 888 in a 70's Glasstron that still has the original manifolds and risers too. Boat spent its entire life on lake Rosseau, which is a cold, rather acidic lake (no weeds). That's where the vast majority of my experience stems from (boats that operated on the Muskoka lakes). I have a theory that the water the boat is operated in plays a role in how much corrosion happens. Certain lakes are going to be more kind to the iron than others.
Not directed at you. My experience as a Mercruiser tech. in the late 80's has shown me that they are going to rust. Seen a lot of them in the shop that needed new manifolds only after the engine hydrolocked.
BTW, not sure if you'll find this interesting or not, but we had stainless manifolds on our Ford 312 Y-block in the 1931 Chris. Of all the boats I drained in preparation for winter, it always had the cleanest water (for this reason of course).
I have an old Merc 888 in a 70's Glasstron that still has the original manifolds and risers too. Boat spent its entire life on lake Rosseau, which is a cold, rather acidic lake (no weeds). That's where the vast majority of my experience stems from (boats that operated on the Muskoka lakes). I have a theory that the water the boat is operated in plays a role in how much corrosion happens. Certain lakes are going to be more kind to the iron than others.
Well they may or may not rust. Either way you would pull them every few years and check. Mercruiser use to recommend they be rodded and cleaned in muriatic acid. But while this does clean them up it also makes the cast iron thinner.
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Originally Posted By: Donald
Well they may or may not rust. Either way you would pull them every few years and check. Mercruiser use to recommend they be rodded and cleaned in muriatic acid. But while this does clean them up it also makes the cast iron thinner.
We never pulled them to check. Wasn't something my grandfather was into us getting into when dealing with engines this old.
Now, that said, we only owned a few I/O's, the rest were all antique inboards, many which of course don't have risers, just manifolds. We never had a failure over the rather diverse fleet we operated
Colour us lucky I guess.
The 312 Y-block for reference:
Well they may or may not rust. Either way you would pull them every few years and check. Mercruiser use to recommend they be rodded and cleaned in muriatic acid. But while this does clean them up it also makes the cast iron thinner.
We never pulled them to check. Wasn't something my grandfather was into us getting into when dealing with engines this old.
Now, that said, we only owned a few I/O's, the rest were all antique inboards, many which of course don't have risers, just manifolds. We never had a failure over the rather diverse fleet we operated
The 312 Y-block for reference:
That's SAH-WEET.....would love to have stainless steel manifolds but, that's not going to happen. My 96 Merc....still got original factory manifolds AND impeller....believe it or not. Nothing but lake water and boat is not stored in water during summer, always pull it out and park with drive down resting on a piece of plywood to take the tension off of the rams and outdrive mounts. The 888 is what I cut my teeth on.
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Originally Posted By: Schmoe
That's SAH-WEET.....would love to have stainless steel manifolds but, that's not going to happen. My 96 Merc....still got original factory manifolds AND impeller....believe it or not. Nothing but lake water and boat is not stored in water during summer, always pull it out and park with drive down resting on a piece of plywood to take the tension off of the rams and outdrive mounts. The 888 is what I cut my teeth on.
Well then, you might appreciate the project my dad and I are toying with
We have a 1972 Century Coronado, which had a 440 Chrysler in it (and has dual 3" straight pipes......
) but this engine unfortunately dropped a valve and the cost to rebuild it was staggering (relative to the value of the boat).
The Glastron with the 888 is in pretty sad shape and the engine is tired. So we've been toying around with the idea of taking the manifolds, risers and marine accessories off the 888 and fitting them to a 302HO (with a 4bbl, since the 2bbl is a bit small) and putting that in the Century. I don't think we'll have any issues with the front-end and accessories, but I'm a bit concerned about mating the velvet-drive up to the 302, as I'm not sure what the mating interface is on the back of the 888, whilst the old 440 has what is essentially a clutch (that you can't disengage) in a manual-style bellhousing that the velvet-drive bolts to like a manual transmission. I have both items (a clutch and bell) for a 302HO, but they are the automotive versions and probably won't bolt-up and I highly doubt the spline count or shaft diameter are going to match either.
If you've got any input relative to this, I'd certainly appreciate it!
That's SAH-WEET.....would love to have stainless steel manifolds but, that's not going to happen. My 96 Merc....still got original factory manifolds AND impeller....believe it or not. Nothing but lake water and boat is not stored in water during summer, always pull it out and park with drive down resting on a piece of plywood to take the tension off of the rams and outdrive mounts. The 888 is what I cut my teeth on.
Well then, you might appreciate the project my dad and I are toying with
The Glastron with the 888 is in pretty sad shape and the engine is tired. So we've been toying around with the idea of taking the manifolds, risers and marine accessories off the 888 and fitting them to a 302HO (with a 4bbl, since the 2bbl is a bit small) and putting that in the Century. I don't think we'll have any issues with the front-end and accessories, but I'm a bit concerned about mating the velvet-drive up to the 302, as I'm not sure what the mating interface is on the back of the 888, whilst the old 440 has what is essentially a clutch (that you can't disengage) in a manual-style bellhousing that the velvet-drive bolts to like a manual transmission. I have both items (a clutch and bell) for a 302HO, but they are the automotive versions and probably won't bolt-up and I highly doubt the spline count or shaft diameter are going to match either.
If you've got any input relative to this, I'd certainly appreciate it!
Back in the mid 80's, Dad had a 28 footer cabin cruiser. Engine overheated...toast. We found a 302 out of a wrecked mustang, forgot the year and all that, but everything...I mean EVERYTHING came off the old engine and bolted right to the newer engine. Had to do some "engineering" to get the shift plate and throttle cable mounted securily on to the top of intake manifolds, but worked it out. Engine dropped in perfectly to the 888 mounting bolts. So, it can be done, just takes some time. That original engine was a Ford, you shouldn't have any problems. We used a Holley 2 bbl. and rejetted it, but this was a cruiser. For some reason, I remember when we dropped the motor in, their was no dipstick hole. We just added oil occasionally and went on with life. Had some issues with the electronics hooking up to the newer engine. Oh yeah, we had to go to the Ford dealer and get 5 studs that bolted from the crank directly to the spline hub. Here's an expensive lesson I'm going to pass on.....if you do this, torque down and tight as you can and then lock-tight them all on. We had a couple back out and had to pull the block to fix it...PITA. Anyway, I went on back to grad school and Dad cruised the stink out of that boat and worked flawlessly for about 3 years....until it overheated....He then bought a crate 350/Alpha Gen I unit as a drop in replacement.....you don't want to go there...trust me. Thing STILL isn't running.
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