Increase HP on 4bt

[Blair Ostergren]

New to site and My first pair of Cummins. I tried a search with no luck so I apologize if this has already been discussed. I am purchasing a 1996 Bayliner 3388. Engines are 150 HP turbo 4BT’s. I am looking to safely increase the power of this without losing Reliablity. I know there is a 250 version of these and some folks are getting 300-400 hp out of the 4bts in trucks. So my question is. Is it as simple as to turn up the fuel to increase HP in these engines? And unharmful in the marine environment to run at cruise speed for hours.

Thanks,

Topic

[stuart hearn]

4btm

Good day
I was a field service technician with Cummins in Australia in the early 1970s
My work used to consist of rating 903 down the mines, that is to detune because of sulphurs and nitrous oxides, rebuilding 855 and 1710 engines
555 504
This was well before the time of bored in the block engines
In the late 70s, I started building metal yachts and then in 1986 I founded my own company building aluminium sailing yachts and commercial craft

I use a 4B engine as the main power on sailing yachts to 60 ft they were incredibly reliable
Last month I bought a brand new for BTM that had been in storage for 9 years it was built
in the year 2010
You have stated here that the 150 cannot be uprated could you tell me why that is could it be up rated by changing pistons stuff like that
It is fitted with a Hurth 1.5
Gear and I was going to put it in a planing boat displacement 2300kg unfortunately I cannot find an out Drive
shaft drive would be great but the draught is too much for Launching as a trailer boat
Yes I would be pleased to know your thoughts on uprating this motor as I often see them pushing more than 400 horsepower in pickup trucks eccetera yours faithfully Stuart Hearn

[Tony Athens]

Will need to be plumbed exactly like a post-2000 Cummins 6BT.. Drop me a note off line and I’ll send you a zip file with pics..

Exactly how fast does the vessel travel now at WOT, and what is that RPM?

Tony

[Blair Ostergren]

Thanks Tony, I travel at lower speeds most of the time but like the ability to move a little when needed. What would I have to do to upgrade the cooling system. That sounds better then messing with the adjustments on a good running engine.

[Tony Athens]

If you are buying a vessel with 4BT150’s, then that is what you are “stuck with”, in so many words.. You cannot up-rate the HP, just trust me on that.

So, if the current engines DO NOT meet you need for speed, then you need to rethink the purchase………………

But here is a caveat……………….If the vessel is fast enough at 100% WOT , loaded up the way you are going to use it WEIGHT WISE, and can make an accurate 2800 RPM or make even a tad more that that, then IMO, you could redo the cooling system on the engine and a few other things to make it reliable to cruise at 2800 RPM for many hours at at time going from Point A to Point B…

The engine is unbelievably solid inside ( shares the same base “lower end” as a 480 QSB 5.9) and it very hard to break from over stressing the components.. But you do have to do some major upgrades to the cooling system along a few other things..

Tony

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