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Cummins 4BTA mods

Old 05-10-2019, 12:35 PM
  #21  
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Default Cummins Test run

We started up the engines the other day on the shop floor to see how the raw water pumps do in the new location. Seems pretty good to me! Hope fully they fit. According to my measurements I should clear by 2 inches.
I had to post them on youtube, here are the links.



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Old 05-10-2019, 03:21 PM
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Originally Posted by boatmanmark View Post
I also love this engines. Fuel economy is out of this world. I average a total burn of 7 gal. per hour for the season cruising between 22 and 24 kts. I will keep you posted. When all set I am going to put those pumps on the classified board.

Say what ?? At what RPM ??
Nice job by the way .

Last edited by prowlersfish; 05-10-2019 at 03:33 PM.
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Old 05-10-2019, 03:38 PM
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2300-2400.
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Old 06-02-2019, 08:40 AM
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Do you have the engines in the boat yet? I am looking forward to seeing these in the boat and running.
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Old 06-02-2019, 08:49 AM
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Originally Posted by boatmanmark View Post
2300-2400.
7GPH per engine I assume

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Old 06-02-2019, 08:58 AM
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I have 4bta's in a 16k pound, 24 degree deep vee Carolina Classic 28. I average 24 knots at 2600 rpm's and burn a little more than 8gph per engine.
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Old 06-18-2019, 05:19 PM
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Engines are in and we have sea trialed her! The deck has to go back on and a few items on the punch list need to be taken care of but nothing big. I am very happy with how the engines fit in with the pumps out front. I did have to move the Racors from the front bulkhead to the rear and have to find a spot for the coolant overflow bottles but that is not a problem. I treated myself to some new valve covers to dress it up some. If anyone needs a couple of raw water pumps I have two with only 120 hours on them, but no impellers now. They had developed a set to them.

New valve covers port side

New valve covers stbd side

Stbd engine r/w pump clearance

Port engine r/w pump clearance

Engines in and aligned

Sitting pretty!
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Old 06-18-2019, 10:11 PM
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You can use an oversized pump, just trim off every other vane on the impeller.
it doesn’t cut the flow in half, but does reduce it somewhat.
i put a seaboard pump on a low hp 6b and had enough extra water to run a baitwell.
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Old 06-19-2019, 03:43 AM
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The engines look great sitting in the boat. For relatively small diesels, they make a ton of torque. When running in big swells in the ocean, I never have to jockey the throttles, like with gas engines. Keep us posted on your performance.
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Old 06-19-2019, 04:58 AM
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Originally Posted by nuffaredy View Post
You can use an oversized pump, just trim off every other vane on the impeller.
it doesn’t cut the flow in half, but does reduce it somewhat.
i put a seaboard pump on a low hp 6b and had enough extra water to run a baitwell.
While that pump is huge compared to the stock Sherwood, the way it is set up takes that into account. The Sherwood can pump up to 46 gpm at 3000 rpm. the normal set up on the Cat pump is up to 78 gpm at 2450 rpm. However, by putting in a half thickness cam, which is a stock part it cuts it down to about 56 gpm. By limiting the pump speed by using a slightly larger drive pulley brings it down to the pump max speed of 2350 or so and puts the max flow rate just above the stock Sherwood. The pump itself is about half what a Sherwood costs, has a great track record and I don't need to take the engine apart to work on it.
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