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Old 09-01-2019, 07:00 AM   #41
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Very objective stuff FF,
And there’s more to it. Two JH Yanmars may weigh considerably less than the lunker FL. That would mean more speed especially cruising. Less fuel.

But the sound thing is hard to sort out.
I’m more interested in smooth than low frequency.
Sound insulation material may be better at reducing higher frequency sounds.
Nobody wants to have a picnic next to a bull dozer or dump truck at 1500rpm. But nobody would want to have a picnic next to a small car at 3000rpm.
But how much noise is generated by each? How much sound/noise is generated by small engines making the same hp as bigger engines.
Noise is created by something moving .. thus moving air back and forth. Big things move more air at lower frequencies than small things.
I’m sure there are studies that show how much noise similar engines make delivering the same amount of power. Gas engines are a lot less noisy than diesels. Chain saw engines produce very little power and make a lot of noise. I know a local guy that “loves kill’in trees”. I think he just loves the sounds of his chain saw.

Bigger engines burn more fuel and make more noise. Maybe that would be more acceptable if I had said “sound” ... noise is an irritant right?

Sound is moving air. Caused by forces that move things. An engine moves up and down shacking what it’s attached to and that moves air. And we hear it.

I’m just babbling in the night but does anything I said pull up something new re higher/lower frequency engine sound?

Just how subjective is our attitudes about engine sound?
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Old 09-01-2019, 07:47 AM   #42
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I like the sound of a straight six at low rpm, but I am a gear-head, so there is that! Four bangers, not so much.

On an engr level, the 4cyl has what is called a "2x buzz". A second order vibration that shakes the motor vertically at twice the frequency of crank rotation. This is due to the mass of the pistons not following the exact opposite motion up and down. I thought it was not possible until I was shown the math. This buzz comes on with higher rpm, and is the reason some big 4cyl engines (Deere 4045, an example) have two balance shafts in the sump. Even with those, you get another vibration at idle due to the firing pulses being further apart. That can be handled with good mounts, mostly. Still not going to be smooth at 600rpm like a six can be.

Lots of very good four bangers out there. Will absolutely do the job and live for decades. And will burn less fuel than an over sized six. But I still like my six!!

Regarding noise, everyone's response to noise is different. For me, the higher frequencies from higher rpm are annoying. I think most are like me. I know my lady plops down on the futon right over my straight six at 950rpm and in three minutes she is OUT. Same with little kids. The purr knocks them out. Me too, but someone has to drive!! Nothing similar happens when around a weedeater.
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Old 09-01-2019, 08:18 AM   #43
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Keijo if you want to cruise 8 knots then what is the power required? Your fuel consumption X sfc of your engine.

Example let’s say 50hp. Consider going with an M1 rated heavy duty, about 60-70hp, running at 70-80% power. Efficient in every regard.

Also, you stated you wanted to keep the boat for another 20 years? The resale in a wood boat, even a GB, at that time will be negligible and you likely won’t care anyway. So be careful about spending too much money or installing a 210hp fire breathing dragon in there.

If you’re in Canada, can you import a Weichai from China? A brand new WP4 would serve you well.
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Old 09-01-2019, 09:48 AM   #44
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Higher frequency sounds are more annoying, but they're also easier to block. With an engine or generator running, listen near the engine hatch. Then open the hatch and compare. You'll generally notice that there's a massive difference in volume in the higher frequency sounds but a much smaller volume difference in the low frequency sounds.
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Old 09-01-2019, 10:02 AM   #45
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Ski agreeeee.
If my big daddy gave me a credit card and kept it payed up I’d opt for a Buick straight eight.
Re smooth my boat is nice .. for a boat. A small 4 cyl. Got plastic mounts.
Yes I think your onto something. It’s not so much that higher rpm irritates it’s that low vibes “sooth”.

Re the 4cyl. Heaving up and down like you say it’s hard to imagine w two pistons going up and two going down. But I know there’s much more to it. And it’s hard to imagine a six being smoother than an eight. For in-line engines anyway. And it would seem a 90 degree 8 would be smoother than an inline but ??

But one of the smoothest engines I ever had was a BMW 3cyl motorcycle. It was interesting in that the flywheel was geared to rotate in the opposite direction. Interesting and clever those German’s.

Mako how would a gas engined 32 GB get along in the mix? There are many who think they won’t get consumed by an explosion. How many here have propane appliances onboard and no bilge blower?
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Old 09-01-2019, 11:34 AM   #46
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I think 3 cylinder motors are smoother than 4.
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Old 09-01-2019, 12:26 PM   #47
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Mako how would a gas engined 32 GB get along in the mix? There are many who think they won’t get consumed by an explosion. How many here have propane appliances onboard and no bilge blower?
Gas engines certainly have a place in boating, like with outboards and high speed boats, but I don't think they're such a smart idea when it comes to trawlers and cruisers. Fuel consumption must be a lot higher as well.

And unless your diesel is actually a converted gas engine (like my old Rabbit which kept blowing head gaskets) I'd say they're almost all quite reliable if not pushed too hard and given clean fuel. American diesels of every make. Indian diesels like Tata, Leyland and the wonderful hand started single cylinder Lister types - all fantastic. Chinese Weichai. How can you go wrong with any of those, compared to a Mercruiser in your trawler???

If the OP really wants to be a man then he should put a nice 2-71 in his Grand Banks. 60hp and acting as extra ballast down low. That would be real cool
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Old 09-01-2019, 12:41 PM   #48
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Gas would almost certainly be worse on fuel consumption. And the fuel consumption difference gets bigger as engine load gets lighter. But that's somewhat offset by the engines and parts being much cheaper.

I've figured out for my boat that a pair of modern diesels would improve fuel economy while cruising on plane by somewhere around 40%. And economy at 6.5 kts (a bit below hull speed) would improve by somewhere around 50 - 60%. But even with that huge a difference, if I were buying new engines in either case, going diesel would take at least 1500 hours to make up the difference in fuel cost and that's assuming equal maintenance costs.
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Old 09-01-2019, 12:41 PM   #49
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Isn't the JD 4045 a fairly popular choice as a FL replacement? Seems like a better fit hp wise than a 6068 or 6bt
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Old 09-01-2019, 01:07 PM   #50
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Isn't the JD 4045 a fairly popular choice as a FL replacement? Seems like a better fit hp wise than a 6068 or 6bt
All in, the final installed cost would be little different. Plus if an NA and/or non- electronic 6 were available
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Old 09-01-2019, 01:33 PM   #51
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Isn't the JD 4045 a fairly popular choice as a FL replacement? Seems like a better fit hp wise than a 6068 or 6bt
An engine distributor in Ballard “MER” comes to mind. Anyway they had developed a “shoe-in” replacement for FL’s. Used a 4cyl JD natural 135hp.
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Old 09-02-2019, 06:28 AM   #52
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Three cylinders , or multiples of 3 are smoother than 4s, BUT there are 2 concepts.

A better built 4 will have counterbalance shafts to smooth it out at various RPM..

As boat engines are frequently run mostly at one or two speeds , selecting a 4 that is smooth at the desired cruise RPM would work.
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Old 09-02-2019, 09:26 AM   #53
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FF,
I remember the buzzy fours in the cars of the 70’s - early 80’s that kept me away form almost all of them. Bought 6’s and 8’s. Only one exception.
I think they must put balancers in the engines now w/o saying anything. Usta be something to crow about. My 87 Nissan and 2000 Golf don’t vibrate .. almost not at all. Well the Nissan maybe a little at 65. But totally acceptable and those earlier cars were all unacceptable. Even my 107 cu in 4cyl boat engine can’t make me complain. What has changed? It isn’t chain or belt cam drives. With the increased need (perceived or real) for lightness for mpg you’d think reduced counterbalance weights even those on the crankshaft would increase vibration .. not decrease vibration.

But less vibration is good.
Well perhaps the answer isn’t inside the box. It’s just me.
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Old 09-02-2019, 11:42 PM   #54
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Isn't the JD 4045 a fairly popular choice as a FL replacement? Seems like a better fit hp wise than a 6068 or 6bt

You're right. I've recently discovered 3 GB 32's re-powered with John Deere engines. Two for sure were the 4045. The other is hull #16 (one earlier than mine in 1966) - I'm trying to get in touch with him to see what he put in.


If I can see and hear a John Deere in a re-powered GB 32 that will make my choice easier.


It's one thing to want a particular engine (6BT or a good Lehman 120), quite another to find one.
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Old 09-03-2019, 12:00 AM   #55
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I can confirm that the Ford 4 & 6 base diesels are still built in Turkey.
The top man in the UK for those Ford engines is Mike Bellamy at Bellamy marine. In this day and age don't be put of by distance he's full of 'hands on experience' and practical help and advice and can source and supply all Ford engine parts.
These engines are easy to rebuild by any decent mechanic.
I hope this is helpful.
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Old 09-03-2019, 05:43 AM   #56
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One thought to remember is small engines are usually installed in smaller light boats.

When installed in a heavier boat far less noise will be hull transmitted, which can be reduced to near zero with a floating engine mount and an aqua drive .Fisheries survey boats do it.

A second option also exists ,,engine balance is selected by the builder to be roughest in RPM areas the engine does not see.

If it would shake like heck, below normal idle speed ," who would notice "?

Detroit raised the idle speed in series 50 (4 cyl ) coaches for this reason.

A good machine shop can change the vibration RPM by using different weights for the rods and pistons while balancing..

Sounds extreme , but if the new engine HAD to be smooth at a specific RPM and wasn't , with new gaskets and under a boat buck at the machine shop, the problem could readily be solved.
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Old 09-06-2019, 07:46 PM   #57
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I am not familiar with the 150hp Beta. I would like to know who makes the base engine and whether it is turbo. Could be a good engine like their Kubota offerings, but could be something more obscure like some Euro car engine (???)

The BETA 150 is probably the best Lehman 120 replacement engine available. Based on the IVECO bulletproof block used in RAM diesel pickups in a 16 valve configeration. Block also used by Case/New Holland and Cummins. I installed a lot when Tier II accepted and owners love them.





https://www.tradeaboat.co.nz/reviews...-marine-diesel



Not expensive and if ordered direct shipping usually included. Ordering direct should be no problem as US BETA dealers do not seem to carry this engine, probably because the Tier II rating can only be used in commercial and replacement applications.



https://betamarine.co.uk/portfolio-item/beta-150/


Contact: Andrew BETA" <andrewg@betamarine.co.uk>


SKI is correct. 4 cylinder diesels can be shakers unless counter rotating balance installed (IVECO and Deere 4045). Soluitionis three-point mounting.


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Old 09-06-2019, 08:59 PM   #58
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The three point mounts are to control torsional/radial vibration?
Are the aft mounts traditional bell housing supported?
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Old 09-06-2019, 10:08 PM   #59
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Gas engines certainly have a place in boating, like with outboards and high speed boats, but I don't think they're such a smart idea when it comes to trawlers and cruisers. Fuel consumption must be a lot higher as well.



And unless your diesel is actually a converted gas engine (like my old Rabbit which kept blowing head gaskets) I'd say they're almost all quite reliable if not pushed too hard and given clean fuel. American diesels of every make. Indian diesels like Tata, Leyland and the wonderful hand started single cylinder Lister types - all fantastic. Chinese Weichai. How can you go wrong with any of those, compared to a Mercruiser in your trawler???



If the OP really wants to be a man then he should put a nice 2-71 in his Grand Banks. 60hp and acting as extra ballast down low. That would be real cool
Naw the 3-71 is better. The old duce has a fan belt driven fw pump and sw pump. The 3-71 has a blower end driven fw pump and cam end driven sw pump. Probably the 2nd best engine ever built next to the 4-71. I have a pair of 4-71's never had the heads off and still running commercially at 60,000 hours (1400rpm max).

Put in the Ford Lehman 6 cylinder. It is the best engine for the boat.
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Old 09-06-2019, 11:09 PM   #60
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Isnt one of thesrle

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I just spoke to the yard that's looking for a Cummins for me and they suggested looking at a Beta 150 hp, in-line six NA.
Being offered for sale in the classifieds?
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