Upgrading the Cat 3126TA from 350-420HP

M

MIKEOB

New Member
Jun 24, 2007
7
Long Beach Island, NJ
Boat Info
410 Sundancer
Engines
twin cat 3126ta
Does anyone have any information on the pros and cons on upgrading the engines on a cat 3126TA block putting out 350HP to the 420HP. What would be involved? Would the performance be a substantial improvement?

I love my 2001 410DA but feel it is underpowered. I have experimented with props and cups but with 6 people onboard it tops out at 27 knots with a comforatble cuise of about 23 knots.

Any ideas?

Mike O'B
 
That's what my friends 400 does. That is a good speed for that size boat.

A site named boatdiesel(dot)com is dedicated to marine diesels. I'm sure you could get an answer there. When I was looking at a 46 SR with Detroits I found out a ton there.
 
I agree...... 21-23 knot cruise combined with 'FANTASTIC' economy of scale (~1.1sMPG) equals one great boat, with plenty of room and excellent sea keeping.

To your original question......upgrading a CAT 3126-TA motor from 350HP to 385HP requires no new iron.....only a re-tuninig of the governor and re-setting the rack. Upgrading a CAT 3126-TA motor from 350/385HP to 420HP will require governor/rack retuning AND new Iron....Bigger turbo, aftercooler and injectors....and maybe a few other odds and ends.
 
Some Cat 3126's are rated with different torque rises than others. Same HP, just one is a high torque. I suspect for heavier boats. Actually, high torque versions are just detuned high HP models.

Post your ser #'s and I'll try to see what you've got.
 
hmmm, interesting. I'd like to find out about mine if you can

[FONT=&quot]8NM04150[/FONT]
[FONT=&quot]8NM04106



On the 420HP, I have them on my 450 and I cruise at 21kts. these engines aren't speed demons, but they sip fuel and move weight.[/FONT]
 
I think you have a great boat the way it is....if you want to go faster why not get a formula or fountain ? In the scheme of things is 23k vs. 28k a big deal when taking into account fuel economy and longevity of your engines?
 
Cat has a very good fuel system on their engines. Produces more power from less diesel. It's one of the best in the industry. The Cummins factory engineer said so when Powerboat Reports asked why Cat engines outperformed Cummins.
 
Caterpillar rates these engines they way they do for a reason. If Cat had felt the engines in their current configuration were worthy of a higher rating, they would have rated it that way.

The 410DA with Caterpillars is one of the sweetest running and handling boats Sea Ray has produced. It is hard to fix something that ain't broke.

If mid to high 20 kts isn't satisfactory, jucing the fuel to squeeze out a few more hp isn't going to satisfy you. I would suggest you begin looking for another manufacturer's 40' boat with 5-600 hp., but be aware that you will give up comfort, ride, handling and fuel economy.

Finally, the 3116/3126 engines are bullet proof as long as you maintain them, you do not run them hot, and you do not overload them. I suspect you "need for speed" with this particular boat is going to get you close to 2 of those limiters.

Good luck with whatever you decide.
 
BonBini said:
Some Cat 3126's are rated with different torque rises than others. Same HP, just one is a high torque. .......
Click to expand...

Ron:

I'm certainly not questioning your experience and training with CAT, however, I've looked VERY closely at the E-Rated 3126-TA HP/Torque curves that CAT publishes. Generally speaking, the 3126-TA motor, for recreational use, was offered in four HP ratings....300, 350, 385 and 420 HP. The curves for each flavor are different, but, (at least the Published curves) are what they are.....+/- the 3% power differential that CAT allows for. They all reach max Torque at approx 1600 RPM (where the turbos are spooling) and then gradually fall off. Max HP is reached somewhere around rated RPM....or close.

Are you saying that there are curves made for each motor as it leaves the factory, and that some are actually governed differently even though the ratings are the same? Interesting!!!!
 
I don’t know where the OP went, 2 post in 3 yrs. I suppose we can discuses his topic while he's out!

TurtlesBoat. 8NM04150, E-Rating, Test Spec 2T9826, Rated 420 @ 2800, 864 lb ft torque @ 1500.

Sample Boat (one I pulled up off X-Ref chart showing 9 results for 420‘s). Effective ser # 8NM04250, E-Rating, Test Spec OK1677, Rated 420 @ 2800, 529 lb ft @ 1500.

I hope the above makes some sense. As you can see the turtle has a pair of big torque girls. Both 420 ratings would push the Turtle along equally, but the lower torque rating may not even get it up on plane.

BTW Turtle: she cell tested at 427 horse. You owe Cat for 7 more pony's!
 
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Thanks Ron, interesting stuff. I guess that explains what seems like an effortless transition from plow to plane.

I'm going to change my boat info to 427HP CATS

I guess the questions is why would CAT make 9 different torque rated engines? are they designed for different size boats, keeping the 420hp rated top end?

Oh, and does it tell you what year the engines were manufactured?
 
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8NM04150 was built 29 Sept 1999. came to life in test cell #01 of the Mossville plant 04 Oct 1999. She made rated HP on run #2 and was shipped 07 Oct 1999.

Her sister 8NM04106 was built 07 Sept 1999. came to life in test cell #02 of the Mossville plant 15 Sept 1999. made rated HP on run #3 and was shipped 16 Sept 1999.

...4106 made 428 hp @ 2801. I also noticed the high idle was set a tic high at 3156, spec being 3135. Looks like the dyno operator made sure the customer got there money's worth...

Engine ratings: Of the nine 420's with 8NM serial # prefix's I pulled up, there are six different Test Specs and seven different arrangement numbers. Every time Cat uses a different part in production, for whatever reason, the engine has to go through calibration and testing. The test settings results are then posted via Test Spec# so Techs like myself can use the correct fuel/timing settings to keep there engines operating within advertised parameters.... Cat has always offered Standard, high and low torque versions of there engines. I've done alot with on hyway truck and heavy equiptment engines. Mostly just repairs on marine engines. I do believe differant hulls and size boats need differant torque needs.

20 years ago I would bump the fuel and timing some. Since then I have learned to just use what Cat has already tested and tuned to change the way customers engine runs to meet there needs. It works every time, rite down to how much more or less fuel is to be expected to burn.

Cat's philosophy is they sell horse power. Today with there electronic engines, two engines can be identical. One is a 350, the other a 400. The 350 sells for less money. For a fee, Cat will provide a password to let the ECM power the 350 to 400 horse.
 
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Some very interesting stuff Ron. That jives with paper work I have that they were installed early 2000. I'm going to print this out and keep it with my paperwork. It's great to know the baseline and what the were born with. Thanks again.
 
Many times diesel manufacturers offer several power levels on the same engine and classify them something like:

-Commercial
-Heavy Duty
-Light Duty
-Pleasure craft
-etc.

The commercial and heavy duty versions commonly have a lower rpm rev-limit and/or less power. The light duty and pleasure craft versions tend to turn more maximim RPM and make more power.

The difference is that the commerical and heavy duty engines are designed to run 5,000-10,000hrs at constant load (under high power) wherease the light duty and pleasure craft diesels are designed to run less total hours and only run the rated power (under hight power) for short periods of time.

Its a give and take on the amount of power any size engine makes vs. the longevity/reliability.
 
Good discussion! It's great to benefit from such knowledgeable forum members.
 
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