Have these 6BTAs been upgraded to 370hp?

[Robert Vetrano]

Buddy bought a boat. Tag on the motor says 6bta 330hp. But in neutral we got around 3100rpms. Spec for a 6bta 330 shows 2800. Assuming the tachs are “near” correct. Is there a sure fire way to tell if these motors have been upgraded?

Topic

[yeungmicah]

To the question of “if” someone was to up from 330 to 370hp

Hi there, so been trying to research the question of if somebody was to recalibrate from 330 HP to 370 HP for what ever reason. <br />I’ve bought the Cummins marine CPL1975 /2208 Manuel from SBMar (thank you guys) and started to compile a list of parts and jobs to complete the conversion??

it seems like this is a common question but no one out there gives a straight answer  

so can the SBMar experts please come to the rescue on this?

 

[Tony Athens]

Where did I say the cruise RPM for the engine is 2800RPM?  200 Below rated in applicable ( per Cummins) ONLY if the engine reach at least minimum rated rated RPM.  Of course,  just “squeaking” or reaching minimum an accurate rated RPM is not what I recommend.. 100++ over minimum rated is the target

[Howard Cates Hurst]

Howard H

tony,  are you saying the cruise for both 330 and 370 is 2800 rpm? i have a 2000 bayliner 4788 with cummins 6bta 330s.   also cummins specs from your website say cruise at 200 less rpm from WOT or 2800-200=2600 ?

thanks for your generous help!

[Tony Athens]

330 vs 370 = 315BHP/2800 vs 355BHP/3000 RPM

If the engines are “set-up” right, then will be no real different in cruise speeds between the 2 engines.. Only WOT speeds to the tune of about 40 HP per engine ( what ever that gets you and it will all take place above 2800RPM..

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Larry, Robert Vetrano

[Larry]

330 to 370 mod?

Didn’t know the 330 could be upgraded to the 370? This begs the question, how is this done?

And why would someone even want to do this?

I’m shopping for a Bayliner 4788 that uses both of these, and the comments indicate there really isn’t a lot of difference. Am I missing something?

[Rob Schepis]

3 to 5% over the rated rpm for propping purposes. Shoot for an easy 2,900 for the 330B’s. You must verify those tachs or this is all for naught……

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Robert Vetrano

[Robert Vetrano]

I got ya. I looked at those and saw the rated power number and went off that. I guess I didn’t realize the high idle # was the one to look at for neutral rpms. Thanks!

So at wot he should reach 2800, correct? We got about 2500 today, but we know the bottom wasn’t clean.

[Rob Schepis]

High Idle (No Load) for the 330 is 3,100-3,200 rpms and for the 370 is 3,300-3,400 rpms. It’s all on the Performance sheets which are on the website.

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Robert Vetrano

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