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Outboard Motor Experts...
Posted on 7/11/20 at 3:26 pm
Posted on 7/11/20 at 3:26 pm
Yamaha made some of the most durable motors with the 90, 85, 75, and 70 hp 2 stroke inline 3 cylinder engines some would say.
Why did they go to a V4 for the 115 and 130 hp engines? Seems like adding a cylinder to the top or bottom of the inline 3 would have been a better design for them and cheaper to make since having 1 less head and a one piece gasket for instance. I remember Suzuki and Tohatsu making inline 4 115s and Suzuki had a 140 inline 4 cylinder 2 stroke.
Was just wondering as I seen an older Yamaha V4 115 pass down the canal today...
Why did they go to a V4 for the 115 and 130 hp engines? Seems like adding a cylinder to the top or bottom of the inline 3 would have been a better design for them and cheaper to make since having 1 less head and a one piece gasket for instance. I remember Suzuki and Tohatsu making inline 4 115s and Suzuki had a 140 inline 4 cylinder 2 stroke.
Was just wondering as I seen an older Yamaha V4 115 pass down the canal today...
4
Posted on 7/11/20 at 3:29 pm to GoAwayImBaitn
Torque plain and simple.
Posted on 7/11/20 at 3:33 pm to iron banks
Torque? I thought inline configurations made more torque but a V configured engine was inherently smoother due to pistons pushing against each other cancelling out vibrations
Posted on 7/11/20 at 5:06 pm to GoAwayImBaitn
Because that’s how the evinrude motors that they copied were built.
Posted on 7/12/20 at 7:04 am to upgrade
I remember the old Mercury in-line 6 cylinder engines. 115 and 150’s. Boy were they tall.
Posted on 7/12/20 at 7:22 am to GoAwayImBaitn
On a similar vein, I’ve been researching the 4 cylinder four stroke Yamaha and Suzuki engines for a possible retrofit on my boat. It’s amazing the power being squeezed out of increasingly smaller motors
Posted on 7/12/20 at 8:04 am to upgrade
quote:
Because that’s how the evinrude motors that they copied were built.
Good point
I guess Yamaha liked that OMC design and figured it was proven enough at the time so they went with that. Back then they weren't as innovative as they are today and were more into copying a design and making small tweaks here and there leading to some improvements
Posted on 7/12/20 at 8:08 am to Icansee4miles
quote:
On a similar vein, I’ve been researching the 4 cylinder four stroke Yamaha and Suzuki engines for a possible retrofit on my boat. It’s amazing the power being squeezed out of increasingly smaller motors
They have come a long way for sure. They aren't the smokey rough running machines of the past. Engine design has always been an interesting art to me. It's a slow process the evolution of the internal combustion engine buts it's amazing how powerful today's four cylinders are compared to ones from the 70s for instance.
Never was a fan of electric motors but I think once the battery tech comes a little further we are going to see electric motors do some amazing things.
Posted on 7/12/20 at 8:15 am to GoAwayImBaitn
quote:
and cheaper to make
I dont think so. Your logic is good with one less head, but the bottom end of an inline has more bearings, a longer crank, longer block, etc. I dont think theres too much appreciable difference in the overall build cost.
I think it has more to do with overall power density. You can cram more HP under a smaller cowling with a high revving V engine, I dont think the overall trend is much more complicated than that.
Some other possibles,: Once the power started getting far beyond 115 the blocks get taller and more difficult to cool upper cylidners. They also need to be heavier built as they get taller since gyroscopic forces increase the higher up you put the flywheel. Probably some torsional vibration problems as well since outboards dont have viscous dampers and inlines tend to be more torsionally abusive than V engines.
Posted on 7/12/20 at 9:09 am to DownshiftAndFloorIt
quote:Dang.
Probably some torsional vibration problems as well since outboards dont have viscous dampers and inlines tend to be more torsionally abusive than V engines.
I knew you're one of the smartest, most analytical members on this forum, but this may set a record.
Posted on 7/12/20 at 3:24 pm to dawg23
Much appreciated, but I dont know if that's right or not. Just speculation. I think theres engineering problems that would cost money and weight to address. I just suspect that after 3 cylinders, it becomes more of a size and weight thing than anything else.
What I'm patiently waiting around for is someone to make a 3 or 4 cylinder 4 stroke large displacement turbocharged gas outboard. The torque would be incredible and torque is what today's engines lack, at least the ones that arent massive.
What I'm patiently waiting around for is someone to make a 3 or 4 cylinder 4 stroke large displacement turbocharged gas outboard. The torque would be incredible and torque is what today's engines lack, at least the ones that arent massive.
Posted on 7/12/20 at 5:21 pm to DownshiftAndFloorIt
quote:
I think it has more to do with overall power density. You can cram more HP under a smaller cowling with a high revving V engine, I dont think the overall trend is much more complicated than that.
Some other possibles,: Once the power started getting far beyond 115 the blocks get taller and more difficult to cool upper cylidners. They also need to be heavier built as they get taller since gyroscopic forces increase the higher up you put the flywheel. Probably some torsional vibration problems as well since outboards dont have viscous dampers and inlines tend to be more torsionally abusive than V engines.
Interesting take considering today's Yamaha F115'are inline 4 cylinders.
Posted on 7/12/20 at 5:57 pm to GoAwayImBaitn
So are the 200's I think, so it's certainly not a hard fast rule that they quit being inlines at 115. Those are nutless 200's though.
Posted on 7/12/20 at 6:01 pm to DownshiftAndFloorIt
quote:
So are the 200's I think, so it's certainly not a hard fast rule that they quit being inlines at 115.
Seems that Yamaha just copied the OMC since it had a loyal following and decided it was good enough. I remember Suzuki having a 140hp inline 4 cylinder 2 stroke. It was said to be thirsty but reliable and overbuilt but I never had any personal experience with one
It's all interesting to me for some reason.
Have you read about the college student at UCF who turbocharged a Honda outboard with a little help from Honda?
It made 600 horsepower.
Posted on 7/12/20 at 10:20 pm to GoAwayImBaitn
quote:
turbocharged a Honda outboard
It shouldnt be much more difficult than it is for a car engine. It would have all the bottom end torque of a two stroke and great power density on the top end.
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