40 pony upgrade- worth it?

tobnpr: 01Z's will go all the way up to 475 HP. The performance spec # will be on the eng tag on the valve cover. ie: 0t**** or 2t****. The performance spec will relate to all performance related parts, gov spring, nozzels, turbo, timing adv, compresion ratio, all the cool stuff.

If you cant find it, I can figure it out with the complete ser#.

For those of you that are sceptic of a cat holding a HP upgrade. They were built to lug and tug! The 3208 will hold over 500HP.

FWIW: a 01Z 355hp @ 2800 will spec out at 366hp @ 2810 and 345 hp @ 2790. Your engines will easily hold few more rpm's! ...Ron
 
osd9 said:
Chris....I agree...but the retuned motor is the one dumping in more fuel, and making more heat, then the overpropped motor....but it's the overpropped motor that is overloaded....again...we're talking about at the rated cruise speed of 2400 RPMs....
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I think the big variable in this is the prop. Personally, it doesn't seem like the 40 hp should be that big of an issue. As many have insinuated, these stock motors leave the factory with pretty conservative settings/tune for longevity. I think it all comes down to the constant load the prop may or may not cause.
 
The 3208s I have run do a great job of moving big amounts of water!! These are 280 HP versions...no turbos...pulling 3000 GPM out of the ground. I put three of them in 3 different pump houses on 20" wells with 20' bowl sections...vertical turbine pumps. Those are 275 gallon diesel tanks. The pumps discharge into 10" underground lines that combine to feed 2: 14" lead ins to Lear's maintenance hangar in Ft. Lauderdale. They are the sole source of water supplying 7" AFFF foam water systems. They will pump 9000 GPM into the building.

These 3: 3208s have been in service since January 2001 and run 1 hour a week...every week. They are tested annually for a 4 hour run to check for any problems. I think they have close to 700 hours on them now...just getting broken in.:thumbsup:


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osd9 said:
That's exactly my question and what I'm discussing....and trying to figure out....

Why would the same motor...with the same internals....same cooling system....same turbo...same everything i.e. all the same iron...EXCEPT for a tuning of the fuel delivery system, all of sudden be overloaded in one configuration and not in the other? That's what I can't wrap my small brain around....

Wouldn't you be asking all that same iron to make the same heat and stress at the same cruise RPMs with the same props?

Been a long day here too I guess!!!
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Got you now...
I THINK (and I emphasize "think" because I'm no expert at this) it relates mostly to the exact amount and timing of the fuel injection during the compression cycle. In the overloaded engine-you have "too much" fuel being dumped into the cylinders in relation to the rpms and amount of air being pressurized. The fuel/air mixture- and the timing of the injection- is critical, along with the amount of turbo boost at any given rpm setting. If the mixture is "off", it may ignite under compression too early, or too late. The overloaded engine is running at too low rpms for the horepower demanded, which in turn is providing less air for combustion, and hotter cylinders. It's the excessive heat generated by an overloaded engine the kills it. Valves, piston tops, cylinder head bottoms get trashed.

BUT... I could certainly be wrong.
 
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tobnpr said:
Got you now...
I THINK (and I emphasize "think" because I'm no expert at this) it relates mostly to the exact amount and timing of the fuel injection during the compression cycle. In the overloaded engine-you have "too much" fuel being dumped into the cylinders in relation to the rpms and amount of air being pressurized. The fuel/air mixture- and the timing of the injection- is critical, along with the amount of turbo boost at any given rpm setting. If the mixture is "off", it may ignite under compression too early, or too late. The overloaded engine is running at too low rpms for the horepower demanded, which in turn is providing less air for combustion, and hotter cylinders. It's the excessive heat generated by an overloaded engine the kills it. Valves, piston tops, cylinder head bottoms get trashed.

BUT... I could certainly be wrong.
Click to expand...

That's the way I've always understood it as well....
 
I think most are making this more complicated than it needs to be. Here's my take....

1. Unless you're talking about a huge power increase from one engine to the next, the torque and hp curves will be rougly identical. In this case 5% difference overall is pretty negligible.

2. If identical boats are powered by two identical sets of engines, and the only difference in output is 5% or 2.5% on each engine, the props will likely be close in pitch if not identical. This translates into identical cruise speeds and performance figures.

3. The only difference that a higher torque/hp engine will do vs. one with 2.5% (5% combined) less power, is get your boat up on plane and at speed MORE quickly than a lesser powered boat. They should still have damn near identical cruising speeds.


All of the above is negated if you're comparing engines with totally different torque/hp curves.

Doug
 
Not really complicated; I think it's a pretty good discussion on basic principles of how diesel engines produce power.

Anyway, I acknowledged in my original post that the difference was going to be minute, but a knot or two is significant enough for my usage- it could knock half an hour or more off the round trip time offshore.

I may contact the prop shop and ask them to run the horsepower scenario through their software- they're pretty darn accurate.
 
douglee25 said:
I think most are making this more complicated than it needs to be. Here's my take....

1. Unless you're talking about a huge power increase from one engine to the next, the torque and hp curves will be rougly identical. In this case 5% difference overall is pretty negligible.

2. If identical boats are powered by two identical sets of engines, and the only difference in output is 5% or 2.5% on each engine, the props will likely be close in pitch if not identical. This translates into identical cruise speeds and performance figures.

3. The only difference that a higher torque/hp engine will do vs. one with 2.5% (5% combined) less power, is get your boat up on plane and at speed MORE quickly than a lesser powered boat. They should still have damn near identical cruising speeds.


All of the above is negated if you're comparing engines with totally different torque/hp curves.

Doug
Click to expand...

Doug.....percent is percent....if it's a 5% increase in power for one motor..355 HP to 375 HP......then it's a 5% increase when you have two motors....710 to 750 HP....the percent change doesn't half

In my situation above, is more like 11%....350 to 390
 
What makes it complicated is keeping the engines torque output just ahead of the props hp demand. ie: big boat vs little boat. The 01Z… 355 comes in a 7% and a 14% torque rise spec. The 14% spec puts out more hp at cruise rpm.

tobnpr: do you know witch you have?

From the beginning I felt you would have to either turn your props faster, make more hp in the upper (100 rpms max on those Cats). Or reprop and make more on the bottom. Either way pretty easy. The prop work $ I don't know! ...Ron
 
Duh... my bad! It's always the simple math, isn't it?

What I was meaning to say was 1/2 of the 40hp, or 20hp per engine.

Long day at work!

Doug
 
BonBini said:
What makes it complicated is keeping the engines torque output just ahead of the props hp demand. ie: big boat vs little boat. The 01Z… 355 comes in a 7% and a 14% torque rise spec. The 14% spec puts out more hp at cruise rpm.

tobnpr: do you know witch you have?
Click to expand...

Cool...I actually got to use this engine spec sheet that I don't understand! (well, I do get SOME of it...).

I found what you're referring to-
Under "TORQUE VALUE" there is a sub-category "AT TORQUE CHECK RPM", under that " % TORQUE RISE", with the following columns next to it "SPEC" is 14.0, "MIN" is 8.0.

Sure sounds like the info you were referring to?
Now, if I only understood what the hell it all means!

Mike
 
BonBini said:
.....From the beginning I felt you would have to either turn your props faster, make more hp in the upper (100 rpms max on those Cats). Or reprop and make more on the bottom. Either way pretty easy. The prop work $ I don't know! ...Ron
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BonBini:
By 'make more on the bottom' is that the same thing as 'overprop' to make the extra hp at cruise RPMs?
 
Torque rise: Is a diesel engines ability to produce a building torque as it's rpms begin to stall back from rated. ie: at high idle rpm of 3100 the engine makes 0 hp. As a load is applied more fuel is added by a longer fuel spray duration. At 2800 the engine makes 355 hp. As more load is applied, rpms are lugged back, the governor delivers an even longer fuel spray till the fuel rack stops against a full load stop. The higher torque rise rating simple delivers more fuel at lower rpms than the lower rating. Simple meaning the higher torque rating will carry more load, more prop in the lower rpms like cruise speeds. That be the difference in a standard 355 and a high torque 355.

Here's a really cool part. I'm not a knot person so I'll talk mph. Say your boat needs 600 hp to cruse at 25mph. You currently have to turn 2400 to make the 600. You juice/rerate your engines for more torque. Reprop. Now you turn 2200 to make 600 hp and you're still cruising at 25mph. Since your turning fewer rpms, your fuel efficiency improves and your still pushing the same amount of water out behind you.

Overproped: You guys were talking this earlier. I think what you were talking is if you overprop what you have, then bring the hp up to meet the new props demand. ...Ron
 
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BonBini said:
....
Here's a really cool part. I'm not a knot person so I'll talk mph. Say your boat needs 600 hp to cruse at 25mph. You currently have to turn 2400 to make the 600. You juice/rerate your engines for more torque. Reprop. Now you turn 2200 to make 600 hp and you're still cruising at 25mph. Since your turning fewer rpms, your fuel efficiency improves and your still pushing the same amount of water out behind you.

Overproped: You guys were talking this earlier. I think what you were talking is if you overprop what you have, then bring the hp up to meet the new props demand. ...Ron
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That's what I tried to say in my uncertain english...it means I agree with you.
"overpropping" to me, means finding the prop that gives you the highest speed at the rated cruise rpm. In the case of the 3208 I am more interested in finding the highest speed at 2500 rather than having props that will give me a maximum of 2800 rpm (max rated rpm) because I always start form the assumption that maximum speed at the maximum rpm can only be achieved the day you splashed the boat with little fuel and just your mate aboard :smt001
 
Pietro: One thing to consider is having hp in reserve. If your over propped to where your 3208’s can’t make full load at 2800: 1.. she may have a lot of trouble getting up on plane even on a good day. 2.. If you’re an big water boater, the ocean is one place where you may have to drive your boat up hill.

You want your engines tuned to stay ahead of your props hp demand, but not so much that you cavatate them trying to accelerate.

If it were me. I would have plenty of reserve hp to the point 2800 was easily meet ( a little underproped). If I lost some power on one engine I would still have enough to get on plane if I had too. Just my .02 …Ron
 
BonBini said:
Pietro: One thing to consider is having hp in reserve. If your over propped to where your 3208’s can’t make full load at 2800: 1.. she may have a lot of trouble getting up on plane even on a good day. 2.. If you’re an big water boater, the ocean is one place where you may have to drive your boat up hill.

You want your engines tuned to stay ahead of your props hp demand, but not so much that you cavatate them trying to accelerate.

If it were me. I would have plenty of reserve hp to the point 2800 was easily meet ( a little underproped). If I lost some power on one engine I would still have enough to get on plane if I had too. Just my .02 …Ron
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Good points Ron!!! When I chose my props I also did not trust my own theories because of lack of experience...and actually I did non overprop. My engines reach 2800 rpm easily with a moderate sea.
 
OK.....now I'll come clean....

I DID have my motors re-tuned by a CAT mechanic. My motors came from the factory as 350HP. Originally, the boat came with 22X23 props. The original owner, Sea Gul, right here on CSR, had them re-done to 22X22.25. The boat would just barely make 2800 loaded....maybe 2810 when I took delivery...verified during my engin survey.

Then, I started to add some weight, a dinghy, and all of the Admiral's stuff. I was then not able to get 2800 after the added weight, so I also re-did the props again...this time to 22X22. I could then get 2825+/-....until mid season when some growth, High humidity/temps would again start to limit my WOT RPMs. That's when I decided to up the HP....

So, here's some real world numbers for you all to chew on....

With the 22X22 props and mid season slime...and a FULLY LOADED boat, I could not make 2800...I was making 2780 +/- at WOT. After the HP retune....to 390HP +/-.....she spun right to 2865 WOT RPMs....without hesitation. Even in mid season, with slime and FULLY LOADED, I can easily turn 2835+/- WOT RPMs.

So...what did I do with all that extra HP...nothing yet. I left the props where they were at 22X22. But, now I am thinking that next time I may load the props a bit more to try to gain some 2400+/- RPM cruise speed...

BTW...and this is crucial to this entire discussion.....my RPM numbers that I am posting here are exact...dead-nuts...on the money. Anyone discussing RPMs and using the factory analog tachs, are kidding themselves. I replaced those pieces of garbage with a pair or Aetna digitals that have been verified with a photo/laser tach and I love them. I HIGHLY recommend them... I posted here on CSR the install.

I still run the boat at 2275-2350 RPM at cruise, but it's nice to know that I can either re-prop or just juice the throttles....

So there....I feel better now that I confessed....:grin:
 
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So this was a test, huh? :)

And ditto on the Aetna tachs- that was the very first thing I replaced when I bought the boat. The manual sync gauge wasn't working anyway- and now I don't even need it...

Pietro-
I'll probably go forward with it. Once I get the service bulletin from CAT and an estimate from the mechanic I'll know for sure. If I go down that road, I may try to tweak a bit more from them than the 375 if possible without major work.

I know it shortens engine life, but at under 1000 hours total so far- and my usage is under 100 hours per year on average, it's not much of a concern. Unfortunately, mine will die of old age, long before they "wear out"...I'll keep you informed of what I find out.
 
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