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Old 10-01-2015, 01:08 PM   #1
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Perkins T6.354 Best Practice

What are the best upgrades for the Perkins T6.354, or is there a page dedicated to this topic already? With over 1M motors produced I'm assuming there's a lot of knowledge about keeping these engines in top shape, optimizing reliability, efficiency, performance and maintainability.

For example, I have seen the following:
  • Spin-on fuel filter at fuel pump
  • Upgrade head gasket
  • Single-piece wet elbow with EGT
  • Upgrade turbo to H1C
  • Secondary electric lifter fuel pump as primary is a point of failure
  • Put exhaust manifold in fresh water circuit

I am very interested in all the different modifications that have been done and how they affect the motor.

Thanks,
Robert Ryan
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Old 10-01-2015, 03:09 PM   #2
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I owned a 78 Mainship 1 that had this engine as oem. I ran that engine for 9 years then repowered because I could not get parts.
I also worked on several, and helped many others with their Mainship engines as I ran the NE group for many years.
Some of those you mentioned I have heard of. They are not all "upgrades".
The spin on filter makes changing more convenient/less messy, but I kept mine as is.
Never heard of an upgraded head gasket. Never knew anyone who blew theirs and had to change.
Single piece wet elbow was oem as far as I know. It was designed properly to let water always drain out.
The diaphragm lift pumps are not prone to failure like some of the others, at least not the oem pumps. Perhaps aftermarket pumps fail, but they are cheap and easy to replace. I personally wouldn't bother since they offer no performance enhancement.
IF the oem turbocharger needs replacing, a Holset H1C would fit (with air plumbing mods) but is only a very slight "upgrade". You would not notice any performance increase unless you tweaked the injection pump to get more fuel. The H1C flows a little more air
so perhaps it could handle more fuel.
Fresh water cooling the exhaust manifold would be the best upgrade of all you mentioned. They have a short life in salt water and they are extremely expensive to replace. I never did mine, didn't know or think about the mod until after I repowered.

If you want the biggest performance increase in your 78 Mainship, fair the keel ahead of the prop. I did that (ahead of my planned repower) and gained 250 engine rpm just on that alone. I was able to add 2 inches of pitch to the prop after the fairing job. See picture below
Oh...and get the injection pump rebuilt. Doing that was huge improvement in my boat. Made it run stronger (meaning it got to rpm quicker) and smoother.
Have fun.
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Old 10-01-2015, 03:14 PM   #3
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Greetings,
Mr. Rp. I've never had a Perkins but welcome aboard anyway.
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Old 10-01-2015, 03:44 PM   #4
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JLeonard,
Thanks for tips, I actually bookmarked your keel fairing post a while ago and have a separate thread on the Yahoo Mainship list for hull modifications. One of the PO's of my boat installed wedges however I believe they were incorrectly installed under the transom. This weekend I'm diving to check out the prop and condition of the keel. I wonder if there's an underwater glue that would hold a fairing - I'd rather not haul out unless also painting.

Did you ever consider increasing the rudder size? I have poor handling in seas that are anywhere aft of abeam. At 7 knots and two foot cornering seas I'm getting a workout with the knob on my wheel (that sounds profane, sorry).
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Old 10-01-2015, 03:54 PM   #5
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Wait and do the fairing right when you are out of the water.
I considered adding to the rudder, but was advised against it by the folks at my marina. I never had any trouble manoevering, just wanted better tracking.
I also installed 12 x 42 trim tabs. That made a huge difference in low speed handling. I could be "on plane" at 8 knots. Helped reduce rocking at anchor as well.
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Old 10-01-2015, 05:36 PM   #6
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I'm liking the trim tabs idea. Which vendor did you go with, and how much did that cost? I'm contemplating an extension of two feet to increase planning surface.
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Old 10-02-2015, 08:27 AM   #7
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Quote:
Originally Posted by jleonard View Post
I owned a 78 Mainship 1 that had this engine as oem. I ran that engine for 9 years then repowered because I could not get parts.

Are all the 34 Mainship and Mainship IIs powered with Perkins? All T6.354?

(An acquaintance says he's looking at a Mainship II with diesel, but he didn't know what diesel. Our Mainship III had a DD 8.2T...)

Is the Perkins a 200-hp turbocharged engine?

Are parts really hard to get?

Any significant problem areas with that engine?

-Chris
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Old 10-02-2015, 08:51 AM   #8
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Chris, they range in hp depending on turbo and exactly which version of the 6.354 is in there.

We've got twin t6.354.4m s in our 40' mainship but we've heard of the same model stock with gassers.

Big things to look for are corrosion in anything where the seawater flows through. Most of these parts, coolers, heat exchangers, are weird metals and require bonding or their own zincs. Oem parts are getting more and more difficult.
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Old 10-02-2015, 08:53 AM   #9
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Quote:
Originally Posted by jleonard View Post
I owned a 78 Mainship 1 that had this engine as oem. I ran that engine for 9 years then repowered because I could not get parts.
What did you choose to repower with?
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Old 10-02-2015, 10:25 AM   #10
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"Are all the 34 Mainship and Mainship IIs powered with Perkins? All T6.354?"


My 1978 Mainship 34 was a Perkins T6 - 354 at 165 hp and all of the ones I had seen up here on the East coast were the same - but there could be other versions I am not aware of although the power increases on that engine typically came much later on in years.


"Is the Perkins a 200-hp turbocharged engine? "
Mine was a 165 Turbocharged engine - I believe the turbo was a 'switzer'.


"Are parts really hard to get?"
As mentioned above the exhaust manifold for mine had to come form England and was expensive as boat parts go - most other things were not so bad as aftermarket or common parts were still available.


"Any significant problem areas with that engine?"
Exhaust, turbo rebuild, heat exchanger, and the rotary fuel pump that liked to 'hunt' until it was refitted with "O" rings that were unaffected by low sulfer fuels.


FWIW - My engine had a "U" in the code indicating a 'reverse' rotation engine.
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Old 10-02-2015, 10:26 AM   #11
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"What did you choose to repower with?"


There were two Mainship 34's that we saw up here over the years at the town docks that were repowered - both had Yanmar's which I believe were at about 240 Hp.
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Old 10-02-2015, 01:35 PM   #12
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I repowered with a Cummins 6bta at 270 hp. It made a whole new boat imo. I could cruise at 15.5 knots (didn't do that very often) and could get 18.5 at wot.

Re trim tab, I installed bennett hydraulic tabs.
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Old 10-03-2015, 07:56 AM   #13
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Thanks, all, very useful.


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Old 10-08-2015, 11:12 AM   #14
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Is 2600 RPMs at WOT too fast for a 1977 T6.354? This is underway with normal load.

Thanks,
Robert
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Old 10-08-2015, 11:29 AM   #15
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Is 2600 RPMs at WOT too fast for a 1977 T6.354? This is underway with normal load.

Thanks,
Robert
It won't hurt anything, but 2450 at WOT is the spec.
You should be able to add 1 inch of pitch if you choose and that will lower your WOT rpm and give you a "little" more speed. Or add some cup to the prop instead.
Or leave it and let the engine "loaf" a little. Then when you are at "vacation load" you won't be over propped.
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Old 10-08-2015, 11:30 AM   #16
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The age of the engine has nothing to do w it if it's in good condition.

As long as the rated rpm for full continious load isn't exceeded all should be well.

Fifty to 100rpm over rated is ideal for WOT in my opinion. Ask your prop man if a 1" pitch increase will reduce rpm more than 200. If so I'd run it as is. If not give it an inch more pitch. I personally don't think cupping props on a trawler is good or in anyway beneficial.

Jay,
Sorry to disagree w you on the cupping however I really like your expression "vacation load". I think I know what you mean but could you expand on that?
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Old 10-08-2015, 04:18 PM   #17
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Jleonard, I'm also going to add the keel fairing you describe, so in theory should I go up two inches? I really wish I had a variable pitch prop.

And thanks for clarifying the WOT max rpm.
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Old 10-10-2015, 08:24 AM   #18
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Vacation load is when you have 6 cases of beer on board, 2 coolers full of ice beer & steaks, 6 gallons of extra "dinghy gas", yada yada.
I remember our 1st 3 week vaca after the repower. WOT went from 2630 to barely 2500. Lol
And the cupping paid off for me because it kept my idle speed down after the repower yet gave me the speed at cruise rpm. Without the cupping I would have had to buy a new prop
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Old 10-10-2015, 11:04 AM   #19
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Question

This thread interests me as we are looking at a boat powered by a single 1999 6.3533M Range 4 with 3900 hours on it. It's a naturally aspirated 135hp, with 2008 Twindisc MG5011MC gearbox, and 23LH21 3-blade prop on a 1.5" SS shaft) It's a 19 ton full displacement boat, so the 7 kt speed is not a concern/issue... but reliability and cost of ownership are.

I know absolutely nothing right now about Perkins engines , though if we proceed with the purchase, I will definitely have to learn. The pics below show the engine (facing fwd) and 2 shots of the running gear (fresh bottom paint in April 2015). We have not been on the boat yet, so I haven't been able to get up close and personal with conditions.

Assuming visuals, surveys and oil samples come out ok, is there anything in particular I should be aware of on this power plant? Any idea how much a rebuild would cost? A SWAG is fine. If a repower were necessary, ideas for possible replacement are welcome.
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Old 10-10-2015, 11:24 AM   #20
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Trans Atlantic Diesels can rebuild it for you. Very roughly- $10-15,000.

If you want to repower it a factory remanned Cummins 6BT 210 hp would be a good choice. More hp than you need, but you can run it slow. Essentially a new engine for about $20,000 +/-. Should be slightly more fuel efficient.

But that engine should last a lot longer than 3,900 hours if maintained and run right. Sure its a 1999 engine. Many boat builders switched to the above Cummins by then.

David
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