Cummins 6bt or Hyundai S250

[JohnV8r]

Hey Guys,

This is almost too maddening for me to put down in a post, but suffice it to say my port Mercruiser Series 72 engine decided to die three weeks after all the work I've done over the last several years - including having the heads rebuilt, carbs rebuilt, new Arco starters & alternators, etc. The bottom end on the port motor is now toast and I'm not putting another penny in gas engines.

I got a written quote I was expecting today from Tony Athens at Seaboard Marine:

Cummins Factory New RECON 6BT 210 HP w/SMX Double Digital gauges, 30' harness, Heat-X cooled, 12VDC, Factory SS exhaust, 5" 90 degree mixer, SMX Purple Isolators, Factory new ZF63A marine transmissions, 1.23 ratio mechanical shift w/troll valves. Recommended prop w/my 1.375" shafts is 17" diameter.

OR

Hyundai 250. Same package. Gear changes to a 1.5:1 ratio

Difference in TOTAL package price is $13,800. I really have zero knowledge about Hyundai diesels other than what I've now read and seen on YouTube.
The quietness, additional speed at 250 hp, fuel savings and difference in smoke with common rail engines is intriguing. The simplicity of the 6BT's and their history here is why I sought a quote for them. I'm more on the fence than I expected to be. Any feedback would be great.

Also, I thought most of the gear ratios and wheels here with 6BT's were 1.5:1 and 20 x 20-ish wheels. Do I have that wrong?

Thanks in advance.

[JohnV8r]

Here's the YouTube video with the Hyundai S250 in a Bertram 31:

https://www.youtube.com/watch?v=mHUxaZnVd74

[Tony Meola]

John

No doubt they will be find in the 31. Have no idea on reliability, but I will say, no matter how reliable they are, the questions I would have, how easy to get service if you break down far from home, and how easy is it to get parts and how expensive are they.

I have the 270 Cummins which is the same engine as the 250, and I had to upgrade from 1 3/8 shaft to 1 1/2.

[scenarioL113]

which ones are less money? Nothing would surprise me

Is seaboard marine selling the Hyundai as well?

[JohnV8r]

The 6BT 210's are the less expensive engine package. Yes, Seaboard is a Hyundai dealer. I requested a package price with extras like trolling valves, 2 x electronic SMX gauges per side, custom riser, etc. That's easily an extra $5K per engine, which is why I posted the difference in the package price between the 6BT's and the Hyundai S250's.

Tony, you're right. Reliability, service, and parts cost are unknown to me at this time on the Hyundai's. On the 6BT's it's a non-issue. That is a crucial factor.

I have to admit, I was all set to just pull the trigger on the 6BT's. I didn't even know about the Hyundai's and then Tony Athens included them as an option in the quote. He stated would be a great fit for a Bertram 31. He's got them in a handful of boats in SoCal and likes them...so far. 3000 hours in one application to date over four years. It's the fact that they're quieter and don't smoke that attracts me the most. Two additional knots at cruise doesn't get me that excited.

I was planning on doing the full Soundown treatment in the motor boxes with the 6BT's. I have never been on a B31 with 6BT's and Soundown so it's hard to figure the level of sociability with Soundown and 6BT's vs common rail engines that are quieter to begin with. I was on a friend's Bertram 31 with Yanmar 6LPA's (yes, I know they're not common rail) and could not believe how smooth and quiet they were at idle. Idle speed is where most of the salmon trolling is done in Northern California.

Looking through all of Walter Kaprielian and other's posts on the 6BT 210's, I cannot find any discussion of gear ratios AND props. Anybody have a sense if the ZF63a/68a's with a 1.2:1 ratio with a 17" diameter prop will get me the 22 knot cruise everyone seems to get with the 6BT's?

[Yannis]

John,

I would be reluctant to buy common rail engines. I feel better with my mechanical 4LHA's. This is possibly because our fuels are transported to the islands, so they might collect condensation which would harm a common rail engine.
Why don't you get a quote on Yanmars?

On the other hand:
Hyundai today, in my mind, is what were the Japanese a few decades back. Everybody was saying that the Japs were creating "me too" products, that they were of inferior quality etc etc.
Today, those Japanese "inferior" products are still on the road, while all else european or american are in the trash...
Look at the WRC. Those Hyundai i20's are smashing all competition.

You're right, this is a difficult equation to solve!

[Snipe]

John if your on Instagram check this guys install out. He is in Florida.

[Carl]

I'm running 6bt-210's with 1-1/2:1 trans turning 20 x 21 wheels. I cruise 20knts at 2300, Tom here on this site has the same setup and says he runs at 22knts. It could be my 210's are 210's, maybe a little tired...maybe because I went 1-1/2" shafts with a big shaft log protruding from bottom. Maybe its my big struts. Maybe its Toms freshly rebuilt 220's...yes 220's, that is what you would be buying as they are now rated at 220hp...I think everything after 210 hp is just more speed, especially as once your over the hump, the boat lifts up more and goes more with every extra hp offered.

Anyway, I'm really happy with the 210's. They are smooth, they do not smoke, even when pushed up to speed hard. I run a 31 Express so I am literally driving on top of the motor box...with Zero sound insulation they are surprisingly quiet in my curtained enclosure. The motors make more noise at idle than when running. At idle you hear the mechanicals...a noise I kinda still enjoy. I think they are a bit louder at idle than my gas, but at speed the 210's are quieter. My exhaust...I went 5" with the biggest muffler offered and it's quiet in the cockpit at idle or cruise. I will eventually add sound insulation just because. I expected that it was going to be an immediate need before I took my first ride. I thought my wife was going to say too loud...complain about fumes. She thinks they are quieter, noise doesn't bother her and she does not notice the diesel fumes at the dock while trolling or running. That was NOT the case with the gas motors, at dock and trolling speed she hated the fumes.

Personally, I think the 210's are considerably smoother, quieter and produce alot less smoke than the Yanmars...especially the 4 cylinder ones...friend has in his boat and they shake like hell at idle pumping out fumes...once they get up and go...the story changes.


I cannot say anything about the Hyundai motors first hand.

My "GUESS" is they are lighter, which adds to your speed and efficiency, being newer, they are more efficient with fewer emissions. Being 250hp they will push the boat faster...more efficient.

I'd bet they are computerized with electronic stuff... My thought on diesel is less electronic stuff the better. Maybe just a personal gut thing, but less is more for me...kinda why I like the 210's over the 250's with aftercooler. Just one more thing to go wrong and maintain. Although if a deal came up on 250's or 270's I would not have turned my nose up on them.

So...computerized, new and fast spinning in my head it's making diesel seem more like gas motors. Maybe head games I play...

I'd look carefully at service support, parts price and availability...I'd assume not bad if Seaboard is involved. But still worth looking into say you have a falling out with them...or one day he says, I made enough money, time to close. Hopefully, you'll never need parts aside from general service...but its nice to know what a turbo, water pump or gasket set will cost.

I'd also look and see how easy it is to work on the motors. I watch others reach and stretch like hell to get to some items, some needing specialty tools. Cummins, it's all standard tooling required, they are laid out very well with much of the items easily accessible. Thankfully I have not had that much to do.


As to the ratio...Tony may be going with less reduction so as to be less taxing on your running gear. I'm not sure, but 1-1/2:1 with bigger wheels I understood to be more efficient with the Cummins slow speed high torque. The 250 Hyundai's run more like gas...spin em fast.


In either case, I think you'll be smiling. Good luck to you!

[1962 31]

MY 210S WITH ZF63A GEARS 1.5:1 WITH 1 3/8 SHAFTS 20X22 PROPS WHEN THE BOAT WAS HEAVY 2200 RPM 20KTS ALL DAY ANY DAY AFTER COMPOSITE REBUILD 2200 23 KTS

[JohnV8r]

Carl,

Your analysis is exactly what I was looking for - how the 6BT's compare sound/noise wise to 454's. Thanks for that. I'm going to ask Tony Athens about the gears & wheels again. I was playing around with the prop calculator on BoatDiesel.com last night and it was coming up with a 21.7 knot cruise with something like 17 x 21 wheels. I get the relationship between props, gears, and cruise speed. The actual calculation of diameter and pitch behind selection is all Greek to me.

Thanks for your comments.

JohnV8r

[Carl]

The simplest way to think about propellor pitch, imagine a nut on a screw.

Each time you rotate the nut on the screw the nut moves forward a certain amount. That amount is the Pitch.

It is the same thing with a propellor in the water... each revolution moves the propellor forward a certain amount. That amount is the Pitch


So a prop with 12" pitch goes 12" ahead with each revolution.
A prop with 17" pitch goes 17" with each turn
A prop with 20" pitch goes 20" with each turn


Thats the basic idea...in theory. In water a prop does not grab the water 100%...the prop kinda slips some.

This is kinda where diameter comes into play. Smaller diameter wheels tend to slip more than big wheels...maybe consider it traction. Big ol fat tires on a car offer more traction for less slippage.


Pitch is how far the propellor should go with each turn, Diameter gives better traction.

[JohnV8r]

Geeeezaaaz, that is the BEST explanation I've ever gotten on pitch & diameter. Thanks for that, Carl!

[scenarioL113]

Geeeezaaaz, that is the BEST explanation I've ever gotten on pitch & diameter. Thanks for that, Carl!

That is called communication skills...

Nice job Carl