2003. 3126 CAT HP increase

JMS23

New Member
Nov 20, 2017
29
Rochester hills, michigan
Boat Info
2003 410SDA Searay Sundancer,
Engines
3126 CAT x 2, at 350 hp ea
I have an '03' 41 dancer with 350 hp 3126 CATS. looking at the engine specs, it looks like i can increase to 385 hp with very little part changes. my question is, is this something a weekend mechanic can accomplish? is there and downside to the increase in HP? I AM CURRENTLY RUNNING 200 RPM under rated WOT, 2800, will this help get back to WOT? thanks.
 
I think you want to figure out why you're low on WOT before throwing more HP. Something else is going on (bottom dirty, props, overloaded, etc) and you need to fix that to make sure your engines are not overloaded
 
The power can be increased with a few adjustments to the fuel pump on the 3126e's, however, all it will effectively do is increase your fuel consumption with no real increase in performance. The added 35 hp is at a part of the power curve you never use, i.e. above 2400 rpm, so why waste fuel and money on the mechanic to reset the pump.

The problem you really need to address is why your engines won't run rated WOT rpms. Your engines are significantly overloaded if you can only reach 2600 RPM. WOT is where the engines are hp rated. No matter what the HP rating is on the engines, 350hp or 385 hp, either configuration has WOT spec of 2800 rpm. Changing the pump settings will only increase the overloading you already have.

If your WOT rpms are only 2600, then your normal cruise should not exceed 2225 rpm until you fix the WOT problem.
 
In addition to what Frank said, I'd ask how are you determining your RPM's? If by your tachometers, I'd suggest checking your RPM's at the flywheel to make sure you're getting an accurate reading.

-Tom
 
I agree with what Tom said. My 3116s were almost 100 rpm low at the tach compared to the flywheel during the sea trial.
 
thanks for the comments, i just installed new AETNA digital tachs, and they read the same as the old TELEFLEX tachs. i am reasonably confident of the RPM numbers. i am certain i have added significant weight to the boat since purchase. my thoughts are to strip down the boat of all added items, see if the RPM improves, and have the props tuned over the winter for the added weight.
 
I'm thinking that even with the extra weight you'd still reach proper WOT but your speed at WOT would be less, but others here may know better. If I'm right it sounds more like a prop issue.
 
And I would still check the RPM at the flywheel - according to my tachs we were just under 2,700 rpms WOT during the survey. But the Cat Tech used a timing light at the flywheel and we found one engine was actually 70 rpm higher and the other was 90 rpm higher at the flywheel. So the tachs read lower than actual engine RPM. At Idle they were accurate.
 
thanks for link and info... i have ordered the Tach and will see if can wedge myself in to check RPM at flywheel.
 

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