Cat 3208 turbo 435hp - Is derating possible?

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boatdriver

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Joined
Dec 22, 2024
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8
Location
New Mexico
Looking at a boat with a semi-displacement hull and twin 435hp engines. Seems excessive. Can these Cat 3208 (not sure exact model number) be derated?

Can the turbos be removed and other odd bits be replaced in situ to lower the HP without having to replace the engines? If this is foolish let me know.

Thanks for any advice.
BD
 
You derate it by not using all the throttle. If you don’t trust one of your operators then just install a cable lock on the throttle cable preventing full throttle.
 
I have never had that engine but I had SP225 Lehmans that had an aftercooler. The aftercoolers were no longer available so I asked American Diesel if I could bypass them. He said yes just run a hose from the input to the output around the aftercooler. No adjustments necessary. However he did say that the SP275 couldn’t be done like that. I think it needed injector pump modifications to derate it. So some engines are easy to derate and some aren’t. You probably should call Cat directly and see what they say. Or just run the engines at a slower RPM and periodically run them up to heat the oil up and burn off the condensation in the oil.
 
I don't think the 435hp 3208 is drastically different than the 375hp version. Both are turbocharged and aftercooled. There are lower rated turbo non-aftercooled versions and a 210hp NA version that IIRC has a different compression ratio, etc.

Removing the aftercooler and turning down the fuel on the injection pump would reduce maintenance slightly, but it won't save fuel or anything. With the 435 I would under prop it slightly for some extra safety margin (being the highest rating). Nothing is forcing you to use all of the power if you don't need it. Just don't push the throttles all the way forward.
 
I would suggest modifying the props to perform simllar to the 375. This would be done by changing the pitch and/or the diameter. This would reduce the thru the full operating rpm range. My 3208ta375’s have a 2.54/1 using a 30 inch dia x 26 inch pitch. 10knot cruise is about 1750 rpm and mile per gallon total for both engines. Boat is a GB 49!classic approx 75000 lb with full fuel-and water.
You did not state boat size and weight so performance could be different. The 10 knot speed uses about 100hp/engine.
A shorter waterline boat will perform differently.
 
Why in the world would you spend thousands of dollars on props making your boat perform incorrectly when a $3 clamp will do the job. Fuel makes HP. Don’t give that last amount of fuel that pushes the HP over 375. Most of us operate in the 100 hp range due to economics so most of us would never need to worry if we had a 425hp Cat. If the boat isn’t a sport fisher the only time it’s probably ever seen wide open throttle is on sea trial.
 
Looking at a boat with a semi-displacement hull and twin 435hp engines. Seems excessive. Can these Cat 3208 (not sure exact model number) be derated?

Can the turbos be removed and other odd bits be replaced in situ to lower the HP without having to replace the engines? If this is foolish let me know.

Thanks for any advice.
BD
i have 2x CAT 3406E 800hp easy is derated hp on this engine. this is call throttle. my engine spent per hour from 1 gallon to 40 gallon .
1 gallon in minimum 500 rpm propeller in neutral.
40 gallon on full speed 32,5 knots.
10 knots minimum 800 rpm consume 17 lliter per engine.
but if you have CAT 3406E cat C15 land version and want more power like marine is not easy task ,possible but expensive.
PS: possible this engine 0 fuel consumption very easy ,don't start engine stay on dock/anchor like previous owner of my boat . my engine in 1900 hour from 2004 have spend only 6% time in crusing rest 94% on dock.CAT dealer change 2 laptop to check data he on first think his cat software have glitch
 
The boat is a 46 footer with a displacement of about 36,000. But, the answer to my question seems pretty clear. Leave things alone if they are in good condition and just stay out of the throttle.

Thanks all.
 
36,000 lbs with 850 HP probably is capable of 25kts at 4 gallons a mile. Maybe even a bit better. I see why they chose the 425 Cat model. Cruise around at 8-10kts and that engine will live along time.

On the other hand if 4 gallons a mile doesn’t bother you than rebuilding the Cat 3208’s won’t either.
 
Most turbo diesels I know of have lower compression pistons than non-turbo engines. So removing the turbo effects how the engine runs and accelerates. You can put in different injectors, but you can do the same thing by using less throttle.
 
Newbie here with a question: So for generalized conversation, you operate a Cat 3208 @ 435hp....that would be considered a "B" Rating (heavy duty). Now if you de-rate the engine with a clamp at 375hp....would that engine be considered "A" Rating (continuous)?
 
Newbie here with a question: So for generalized conversation, you operate a Cat 3208 @ 435hp....that would be considered a "B" Rating (heavy duty). Now if you de-rate the engine with a clamp at 375hp....would that engine be considered "A" Rating (continuous)?
Maybe, maybe not. You'd probably have to ask Cat what ratings they offer and what the differences are to determine whether it's a simple re-rate or not. However, most of the info I've seen on the 375 and 435 hp 3208s in recreational boats shows them as having an E rating. I've never seen a comprehensive list of 3208 ratings anywhere online though.

I did just find some info that shows the 210hp 3208NA in both D and E ratings, both at 2800 RPM. The 3208T is shown as E rated at 320hp, D at 300hp, both at 2800. And the 3208TA shows an E rating at 435 or 375hp, D rating at 340hp, all at 2800 RPM.
 
Thanks for the explanation. Wasn't sure the rating naming convention of Caterpillar. We have a 37' RV with a 2007 Cat C9 @400hp pushing 35,000# fully loaded. Love the engine.....for sure it will outlive me :)
 
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