6BTA5.9-M2 clarification

[Raymond Slingerland]

6BTA5.9-M2 clarification

Need some clarification on use. The -M2 engine is listed at 249HP, but the first data sheet listed, May 1995 shows 300bhp at 2800 rpm, yet I thought it was a 2600rpm rated engine. The data sheet for 12 May 1999 now shows 250bhp at 2600 rpm. Both show CPL of 1613. What is this??

Next question. The engine is in a 1997 Bayliner, original install, so assume the May 1995 data sheet would apply.

The notes indicate it can be operated at or below 200rpm of maximum rated rpm.

I will accept it is a 2600 rpm rated engine, not the 300 indicated on data sheet.

Don´t know if it really makes sense or not but I would like to cruise at 2400rpm.

Other than more fuel used, am I paying a big price in potential maintenance costs and life of the engine for 2400 rpm cruise, vice, say 2300 rpm cruise. I really don´t want to go down to 2200rpm if 2300 is a reasonable compromise.

Your thoughts. Thanks

Topic

[Tony Athens]

Basically all the same other than you do not have as much potential to overload the engine with the 2600 RPM version….

Tony

[Raymond Slingerland]

M2

So with the potentially higher rating at 2800 rpm I should be able to run it 400 under at 2400 rpm without great risk, which is 200 under the 2600 as indicated in their notes. Is that correct? If I get the boat will be ordering your duel fuel filter system which I used on a pair of old Cats. Really appreciated them. Thanks, Ray

[Tony Athens]

Ray,

I will do my best to try and explain what you are asking…

#1———–You have a pair on 6BTA 5.9’s CPL 1613’s.. What does that really mean?—————- it means this—Cummins 6BTA 5.9 Marine engines built to built to that EXACT SPEC at that time in the evolution of this great engine.. This particular engine spec was built between 1992-ish and 1995-ish.. During that time, this was what Cummins offered, although they were also offering a later CPL version too..

#2—So, why the 300 BHP 2800 RPM rating and the 250 BHP rating at 2600 RPM? Real simple—The 250 Rating had a “cork” installed under the throttle pedal.. The Cummins engineers decided that some of the OEM’s out there needed to restrain the majority of the “throttle jockey’s” out there so they could not over load the engines as easily.. Maybe this was also a part of the thinking—maybe Bayliner built “too much boat” and then selected an engine that was not up to the task? Ever heard the saying “too much boat and not enough engine? Maybe this was a Cummins solution to help protect the engine?

Internally, as to all the parts, the engines are 100% identical.. It’s all in the injection pump settings…Basically, the 250 version has this “internal governor” that will make it harder to overload it..……………………….Make any sense?

If you had the 300 version, would you see any difference? I’m going to let YOU answer that..

Tony

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