Reply
 
Thread Tools Display Modes
 
Old 12-02-2011, 07:38 PM   #1
Guru
 
O C Diver's Avatar
 
City: Fort Myers, FL... Summers in Crisfield, MD
Country: USA
Vessel Name: Slow Hand
Vessel Model: Cherubini Independence 45
Join Date: Dec 2010
Posts: 4,817
4 cylinder or 6 cylinder?

So I'm looking hard at a boat that I may repower. Boat has a Cat 3208 natural 211 HP. At cruise it burns 2 to 2.5 GPH which equates to 30 to 40 HP. Was thinking about a Cummins 4BT 150 HP. Talked to one of the local dealer / rebuilders who said the 4BT tend to have much more vibration than the 6BT 220 HP. His comment was that 6 cylinder motors are much smoother in general than 4s. Had a 6BT in my boat and have one in my Dodge pickup. They are smooth running engines in the ideal RPM range. Any thoughts on how much rougher the 4BTs are, or 4 cylinder diesels in general?
__________________
Advertisement

O C Diver is offline   Reply With Quote
Old 12-02-2011, 08:17 PM   #2
Guru
 
Codger2's Avatar
 
City: San Diego
Country: US
Vessel Name: "Sandpiper"
Vessel Model: 2006 42' Ocean Alexander Sedan
Join Date: Oct 2007
Posts: 5,421
4 cylinder or 6 cylinder?

Quote:
O C Diver wrote:
*6BT 220 HP. His comment was that 6 cylinder motors are much smoother in general than 4s.
*I can't comment on the 4s but I've had 3 Cummins 6BT 5.9s and never had one problem with any of them.

single************************* twins


-- Edited by SeaHorse II on Friday 2nd of December 2011 09:18:11 PM
Attached Thumbnails
Click image for larger version

Name:	med 38.jpg
Views:	105
Size:	121.5 KB
ID:	8786   Click image for larger version

Name:	mainship.jpg
Views:	127
Size:	165.1 KB
ID:	8787  
__________________

Codger2 is offline   Reply With Quote
Old 12-02-2011, 08:44 PM   #3
Guru
 
City: Carefree, Arizona
Country: usa
Vessel Name: sunchaser V
Vessel Model: DeFever 48
Join Date: Apr 2008
Posts: 6,371
RE: 4 cylinder or 6 cylinder?

Yes, 4s vibrate more. But with a good install (Barry mounts, right shaft coupling, good*cutlass alignment) and a new counter balanced Cummins or JD you may be just fine. Why not keep the Cat running? You will easily spend $25K on a new 4 install.
sunchaser is offline   Reply With Quote
Old 12-03-2011, 03:55 AM   #4
FF
Guru
 
FF's Avatar
 
Join Date: Oct 2007
Posts: 16,530
RE: 4 cylinder or 6 cylinder?

I have a CAT 1160, the non throwaway version of the 3208 with 150,000 miles or about 3000 hours.

For $1500 bucks it might be worth yanking your old engine , removing the marinization ( Wet exhaust manifolds) stuff and installing it on my engine .

With no turbo its an ideal boat engine rated 210hp at 2600.

New heat exchanger , new damper plate for your tranny , new motor mounts and exhaust hose , and your gone $10,000 cheaper .

However the 4 cyl has an excellent rep as a bulletproof motor and would be more efficient at 2 gph cruise.

Vibration at cruise , no problem , only the idle might shake more.
FF is offline   Reply With Quote
Old 12-03-2011, 06:00 AM   #5
Guru
 
jleonard's Avatar
 
Join Date: Jun 2008
Posts: 2,740
RE: 4 cylinder or 6 cylinder?

Go with the 6bt. Simple, easy to get parts for, easy to work on and maintain. You alrady KNOW that engine (and it's quirks).

No aftercooler so no issues with crudding things up if you run slow. Will have some extra ponies for those times you need it.

*
jleonard is offline   Reply With Quote
Old 12-03-2011, 06:20 AM   #6
Guru
 
psneeld's Avatar
 
City: Avalon, NJ
Country: USA
Vessel Name: Freedom
Vessel Model: Albin 40
Join Date: Oct 2011
Posts: 15,913
RE: 4 cylinder or 6 cylinder?

Noted that a Cat 3208 isn't the most fuel efficient engine...but it isn't so bad*that a repower would ever make up the diffrence in fuel burn unless you are a running 8 hrs a day 365 a year.

Now if you are looking at major maintenance...different story...but unless you are nearing 10,000 hours and the motor is showing a sudden rise in fuel or oil consumption...not quite sure why the expense and headache of a unnecessary repower...

So if you are deadset on the repower...I'll interpret that money isn't the object and therefore I would go with the 6 cyl for the same reasons already stated.
psneeld is offline   Reply With Quote
Old 12-03-2011, 06:34 AM   #7
Guru
 
O C Diver's Avatar
 
City: Fort Myers, FL... Summers in Crisfield, MD
Country: USA
Vessel Name: Slow Hand
Vessel Model: Cherubini Independence 45
Join Date: Dec 2010
Posts: 4,817
RE: 4 cylinder or 6 cylinder?

Ok, here is the situation. The Cat is 23 years old and the engine hours are suspect, likely 5,000+ hours. Without dissassembling it down to the block, it woun't fit through the floor hatch and it won't go through the cabin door to the deck. Not sure it will even fit through the cabin door dissassembled. If I rebuild it in place, there is no option to have the block cooked or do any machining work other than running a hone through the cylinders. Also, you end up with a pretty crappy paint job.

While I could run the engine as is or do a so so rebuild in the boat, engine reliability is what I'm after. My plan is to do a lot of Southern cruising during the winters and I don't want to get stuck somewhere having to do a repower and pay through the nose.

My feeling is if I'm going to cut a hole in the floor and ceiling of the cabin to pull the engine in and out to rebuild it, then I'll put in what I want new and have peace of mind going forward. Also, if any of the water, fuel, or holding tanks need to be replaced, it's a simple matter with the open holes.

As I will be doing much of the work myself, the engine install would be under $20K.
O C Diver is offline   Reply With Quote
Old 12-03-2011, 07:26 AM   #8
Guru
 
City: Carefree, Arizona
Country: usa
Vessel Name: sunchaser V
Vessel Model: DeFever 48
Join Date: Apr 2008
Posts: 6,371
RE: 4 cylinder or 6 cylinder?

Do you have the ER length for a 6BT? A certified Cummins 6BT rebuild is*likely the better price vs a 4 cylinder and a wonderful engine as Seahorse and JayN suggest. About 5 issues ago, PMM had a great article on the Cummins rebuild factory.

Contact Tony Athens' shop in CA for details. You may want to order the engine and all associated parts (fuel system, mounts, controls)*through them for best price and install guidance.
sunchaser is offline   Reply With Quote
Old 12-03-2011, 05:58 PM   #9
Guru
 
O C Diver's Avatar
 
City: Fort Myers, FL... Summers in Crisfield, MD
Country: USA
Vessel Name: Slow Hand
Vessel Model: Cherubini Independence 45
Join Date: Dec 2010
Posts: 4,817
RE: 4 cylinder or 6 cylinder?

Quote:
sunchaser wrote:
Do you have the ER length for a 6BT? A certified Cummins 6BT rebuild is*likely the better price vs a 4 cylinder and a wonderful engine as Seahorse and JayN suggest. About 5 issues ago, PMM had a great article on the Cummins rebuild factory.

Contact Tony Athens' shop in CA for details. You may want to order the engine and all associated parts (fuel system, mounts, controls)*through them for best price and install guidance.
*Yes I'm aware of the factory rebuild program. Both the 4BT HP150 and the 6BT 220 are available, that's what I was planning on using. The 4BT and the 6BT are essential the same engines other than 2 more cylinders. While I have the room for the 6BT, I can't imagine needing more than 150 HP. Look how many 40'+ trawlers were made with a single 120 HP Lehman.
O C Diver is offline   Reply With Quote
Old 12-03-2011, 09:15 PM   #10
Guru
 
City: Carefree, Arizona
Country: usa
Vessel Name: sunchaser V
Vessel Model: DeFever 48
Join Date: Apr 2008
Posts: 6,371
RE: 4 cylinder or 6 cylinder?

Diver

You seem to have the bases covered and your mind made up. Why did you start the thread - a test?
sunchaser is offline   Reply With Quote
Old 12-04-2011, 07:24 AM   #11
FF
Guru
 
FF's Avatar
 
Join Date: Oct 2007
Posts: 16,530
RE: 4 cylinder or 6 cylinder?

Removing the 3208 would seen much easier if you yanked the heads , lifted the block and dropped the crank and rods.

Still a 500+ lump of iron to remove , but lots less hassle.


Since its all steel scrap, no problem , just unbolt and carry out.

The 4 cyl might fit in with no woodwork requirements , by simply stripping the extras , alternator , starter water pumps?

150 rated HP is still plenty for a 2-5gph trawler crawler.
FF is offline   Reply With Quote
Old 12-04-2011, 07:35 PM   #12
Guru
 
O C Diver's Avatar
 
City: Fort Myers, FL... Summers in Crisfield, MD
Country: USA
Vessel Name: Slow Hand
Vessel Model: Cherubini Independence 45
Join Date: Dec 2010
Posts: 4,817
RE: 4 cylinder or 6 cylinder?

Quote:
sunchaser wrote:
Diver

You seem to have the bases covered and your mind made up. Why did you start the thread - a test?
*I was looking for opinions on how smooth running 4 cyl. diesels in general and the* 4BT in specific were compared to 6 cyl. diesels. Figured there had to be some people here with 4 cyl. diesels and maybe a 4BT that would post there opinion / experience.

Thought that was pretty clear from the last sentence in the first post.
O C Diver is offline   Reply With Quote
Old 12-04-2011, 10:29 PM   #13
Veteran Member
 
Join Date: Feb 2011
Posts: 60
RE: 4 cylinder or 6 cylinder?

OK, I'll bite*and attempt*the original question.

A 6 cylinder engine can be dynamically balanced without any additional balance shafts or other "tricks". An in line 4 cylinder engine cannot be inherently balanced, hence the lingering concern about smoothness with*4 cylinders. The cure for this is to add balance shafts to the engine that offset the imbalance. These can make the 4 cylinder close to perfectly balanced. I believe certain models of the Cummins 4B have balance shafts and others don't.

My*1962 Willard 36 has a smooth Gray Marine 4 cylinder engine. It is based on*a Continental Diesel with*a Lanchester Balancer (he was the inventor of balance shafts according to Wikipedia) and a 150 lb flywheel. It*squeezes an amazing 50 hp continuous out of a svelte 1440 lb package. It also has special "Cushioned Power" combustion chambers (I believe they are called Lenova Cells) that Continental claim make the engine smoother. With good polyflex engine mounts and close to perfect shaft alignment it is as smooth as any engine.

If you go with a 4-banger be sure it has balance shafts. They don't seem to call a 6 cylinder a 6-banger. Must be a reason for that!

Any engine will vibrate if not aligned or*with worn out mounts.

Bill
Island Cessna is offline   Reply With Quote
Old 12-05-2011, 03:42 AM   #14
FF
Guru
 
FF's Avatar
 
Join Date: Oct 2007
Posts: 16,530
RE: 4 cylinder or 6 cylinder?

Sad we cant get 3 cylinder diesels in the 100hp range.

Smooth and would be more compact , even at the same displacement.

The larger cylinders and longer stroke might even be more efficient .
FF is offline   Reply With Quote
Old 12-05-2011, 05:33 AM   #15
Guru
 
psneeld's Avatar
 
City: Avalon, NJ
Country: USA
Vessel Name: Freedom
Vessel Model: Albin 40
Join Date: Oct 2011
Posts: 15,913
RE: 4 cylinder or 6 cylinder?

Not sure I would treat the 3208 as scrap...as a working takeout there may be more than a few people interested in it...sure there's plenty out there...but it may still be worth more as a takeout than scrap.
psneeld is offline   Reply With Quote
Old 12-05-2011, 05:55 AM   #16
Guru
 
O C Diver's Avatar
 
City: Fort Myers, FL... Summers in Crisfield, MD
Country: USA
Vessel Name: Slow Hand
Vessel Model: Cherubini Independence 45
Join Date: Dec 2010
Posts: 4,817
RE: 4 cylinder or 6 cylinder?

Quote:
Island Cessna wrote:
OK, I'll bite*and attempt*the original question.

A 6 cylinder engine can be dynamically balanced without any additional balance shafts or other "tricks". An in line 4 cylinder engine cannot be inherently balanced, hence the lingering concern about smoothness with*4 cylinders. The cure for this is to add balance shafts to the engine that offset the imbalance. These can make the 4 cylinder close to perfectly balanced. I believe certain models of the Cummins 4B have balance shafts and others don't.

My*1962 Willard 36 has a smooth Gray Marine 4 cylinder engine. It is based on*a Continental Diesel with*a Lanchester Balancer (he was the inventor of balance shafts according to Wikipedia) and a 150 lb flywheel. It*squeezes an amazing 50 hp continuous out of a svelte 1440 lb package. It also has special "Cushioned Power" combustion chambers (I believe they are called Lenova Cells) that Continental claim make the engine smoother. With good polyflex engine mounts and close to perfect shaft alignment it is as smooth as any engine.

If you go with a 4-banger be sure it has balance shafts. They don't seem to call a 6 cylinder a 6-banger. Must be a reason for that!

Any engine will vibrate if not aligned or*with worn out mounts.

Bill
*The mechcanic who rebuilt my chater boat engine, also mentioned these balance shafts or something similar. He said all the 4BT coming from cummins now had them along with the new heat exchanger / exhaust manifold combination. Will have to contact cummins to verify this.
O C Diver is offline   Reply With Quote
Old 12-05-2011, 01:10 PM   #17
Guru
 
Conrad's Avatar
 
City: Calgary
Country: Canada
Vessel Name: Blue Sky
Vessel Model: Nordic Tugs 42 Hull #001
Join Date: Oct 2007
Posts: 1,553
RE: 4 cylinder or 6 cylinder?

Quote:
FF wrote:
Sad we cant get 3 cylinder diesels in the 100hp range.

Smooth and would be more compact , even at the same displacement.

The larger cylinders and longer stroke might even be more efficient .
*We've had two Albin 25's with 3 cylinder engines, one a Volvo and the other a Yanmar, and found both to be very smooth. I've heard that 3 cylinders are inherently better balanced than fours, but I've also heard the opposite.*

Thoughts?
Conrad is offline   Reply With Quote
Old 12-05-2011, 09:03 PM   #18
Senior Member
 
bobc's Avatar
 
City: Everett
Country: US
Vessel Name: Note by Note
Vessel Model: 34 DeFever
Join Date: Apr 2011
Posts: 133
RE: 4 cylinder or 6 cylinder?

As I've mentioned in another post, the John Deere 4045TFM that I've just installed is smoother and quieter than the Lehman 120 it replaced. The JD has balance shafts. They make a non-turbo version of the JD, which I think would have been fine, but I was talked into getting the turbo. The turbo is pretty simple, so I don't think it's going to change the reliability that much, and I'm not often using the extra power, so I doubt the engine is under any additional stress. Having made the switch, I have no regrets about moving from a six to a turbo four. Having said that, the JD isn't a high-strung engine like the Yanmars. I'll cruise at 1700 RPM, plus or minus.
bobc is offline   Reply With Quote
Old 12-06-2011, 04:33 AM   #19
FF
Guru
 
FF's Avatar
 
Join Date: Oct 2007
Posts: 16,530
RE: 4 cylinder or 6 cylinder?

3cyl , or better multiples of 3 are the smoothest (leaving out opposed pistons like BMW bikes).

6 cyl is 2X 3cyl and 12 cyl is 4X 3 cyl.

If you want smooth and cheap a DD 3-71 from a generator would be first choice.

With good hunting you might find an aluminum block 3-71

Sure the fuel consumption would be a half gallon/hour higher than a more modern engine , but the first 20,000 hours would be nice and smooth!

The balance shafting and all the items required to smooth a 4 or 5 cyl all require power to spin.
FF is offline   Reply With Quote
Old 12-06-2011, 08:39 PM   #20
Guru
 
Conrad's Avatar
 
City: Calgary
Country: Canada
Vessel Name: Blue Sky
Vessel Model: Nordic Tugs 42 Hull #001
Join Date: Oct 2007
Posts: 1,553
RE: 4 cylinder or 6 cylinder?

Thanks FF - you've confirmed what I'd previously always thought. So in theory a 9 cylinder engine would also be smooth, although I've never heard of them, other than in a radial configuration.
__________________

Conrad is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Perkins Range 4-200 ,,, but it is a six cylinder ????? antioch01 Power Systems 6 10-23-2013 07:42 AM
Sleved cylinder Knocks skipperdude Power Systems 42 03-13-2012 03:45 PM
6 cylinder Ford Diesel Forkliftt Classifieds 6 06-27-2011 05:03 PM




All times are GMT -5. The time now is 08:40 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012