Cummins NTA855 M450/NTA855 M Marine Engine

[hmccoy99]

Has anyone considered re powering with a Cummins NTA855 M450/NTA855 M Marine Engine?

450hp continuous rating. the new C series engines look like they have some design flaws.

like aluminum inter coolers with copper cores the dont last too long. and fail with a disaster and

are intermittent rated

Henry

 

[jim rosenthal]

What do they weigh? You might get an answer there. IIRC 855s weigh a lot. The Cummins coolers are fine if they are serviced properly.

 

[krush]

design flaws that only let them go like 5000 hours?

 

[Boatsb]

Remember we know more than the engineers designing the new modern engines. That's why we have the old engines and not those expensive new ones right.

Sarcasm off.

Someone please give me a pair of the cummins 6.7's.

 

[dsharp]

They weigh around 3200-3500 pounds without gears. I don't think you could get them under the deck on a convertible. They would be fine in a motor yacht. I put one in a 50' downeast style hull. They will run 10-15 thousand hours with normal maintenance. You only run them 1500-1800 rpm so they're much quieter than a high rpm diesel.

 

[hmccoy99]

Remember we know more than the engineers designing the new modern engines. That's why we have the old engines and not those expensive new ones right.

Sarcasm off.

Someone please give me a pair of the cummins 6.7's.

Well some of us are engineers with enough experience to evaluate designs. the new engines are
designed with a purpose. to be: cheap to build, light weight, and high hp. not necessarily that
durable everything is a compromise

no sarcasm intended ...

henry

 

[hmccoy99]

design flaws that only let them go like 5000 hours?

what are the flaws? other than being heavy. truckers get over a million miles with those engines
routinely.

henry

 

[jim rosenthal]

They are too big and heavy for pleasure craft.

 

[Boatsb]

Well some of us are engineers with enough experience to evaluate designs. the new engines are
designed with a purpose. to be: cheap to build, light weight, and high hp. not necessarily that
durable everything is a compromise

no sarcasm intended ...

henry

I'd not be too sure they are designed for cost over durability. I spent a little time going over the criteria with some cummins guys. Yes there is a price point they shoot for. They also make "automotive " type engines for lighter use. Most of the marine engines we see are goingto outlast the older technology they replaced.

 

[saltshaker]

Way too big and heavy to be practical in a pleasure boat other than a big trawler. I've seen higher HP versions in SF repowers but only a couple. If you need a 10K-15K hour heavy duty engine in the 450HP range, I'd look at a 465HP 3406C Cat. The Cat will be much easier to service and get parts for in the recreational environment. Hell the 800HP 3406E will run 10K hours. The Cummins 450C is a great engine and has a very good track record in recreational use. No it won't give you 15K hours continuos duty but do you really need that? If you run at hull speed you probably will see 15K hours out of them. Keep in mind these are 8.3L engines compared to 14L for the NTA855 and 14.5L for the 3406.

 

[krush]

what are the flaws? other than being heavy. truckers get over a million miles with those engines
routinely.

henry

I meant, the 8.3L have design flaws that "only" let them do at least 5,000 hours?

 

[Boatsb]

Krush turn on the sarcasm light.

I used to run a fleet of small trucks and had engines ready to swap out in the shop. We had to switch the distributor and a few parts and then we're done. We averaged about 90 to 100k miles on gas engines. Today's newer version of the same engine will probably run closer to 200k miles before needing to be replaced and will probably be 30% more efficient. It's called progress.

I'd look at all the factors including parts availability before going to an older design for a repower.

Also keep in mind the newer engines are straight 6 and don't need $6,000 crossover pipes that are not readily available.

 

[saltshaker]

what are the flaws? other than being heavy. truckers get over a million miles with those engines
routinely.

henry

He's referring to the 450C with a bit of sarcasm. You can't compare truck engines to marine engines. Very different applications and configuration. 3126 Cats were a disaster in marine application but very reliable in trucks and industrial applications. All marine recreational engines are much higher output than thier on or off road counterparts.

 

[Boatsb]

The engine he asked about is a 14 liter 300 to450 hp engine.

In comparison a 450c is an 8.3 liter with the same hp.

The 6.7 is a 6.7 liter with the same or more hp.

The 6.7 does not have removable sleeves but will last and is rebuild able.

It will be reliable and smoother than the others in a small boat (under 45 foot) application .

 

[saltshaker]

The engine he asked about is a 14 liter 300 to450 hp engine.

In comparison a 450c is an 8.3 liter with the same hp.

The 6.7 is a 6.7 liter with the same or more hp.

The 6.7 does not have removable sleeves but will last and is rebuild able.

It will be reliable and smoother than the others in a small boat (under 45 foot) application .

Same point is was trying to make on my previous post. Kind of like comparing the service of a 671TIB to that of a 12V71N. At 450HP the 6CTA is a very reliable engine. They would make an excellent replacement for a pair of 8V71TIs. QSM11s at 535HP would be even better and probably have no problem making it to 10K hours.

 

[Boatsb]

Your correct. It's commercial vs pleasure craft.

Worked on an 80 foot vessel the other day with 2 qsm 11's at 300 hp.

They will probably run 20k hours.

 

[krush]

In comparison a 450c is an 8.3 liter with the same hp.

The 6.7 is a 6.7 liter with the same or more hp.

The 6.7 does not have removable sleeves but will last and is rebuild able.

It will be reliable and smoother than the others in a small boat (under 45 foot) application .

The 6.7 can't survive the EMP zombie apocalypse, though

 

[Boatsb]

The 6.7 can't survive the EMP zombie apocalypse, though

Neither can i.

 

[saltshaker]

The 6.7 can't survive the EMP zombie apocalypse, though

My Detroits can.

 

[Finalee]

So can my Cummins.