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Old 07-05-2022, 10:31 AM   #1
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Default Reference Propeller 2700

Is there an owner of Maxum 2700 SCR 1998 (1 x 5.7L engine) who can give me the reference of his propeller? Thanks.
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Old 07-05-2022, 06:41 PM   #2
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Tonight I just tested. Max speed 15 knots, 3000/3200 rpm. 4-blade propeller, 20.5 inches. What do you think ?
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Old 07-05-2022, 07:39 PM   #3
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Quote:
Originally Posted by Eric08 View Post
Tonight I just tested. Max speed 15 knots, 3000/3200 rpm. 4-blade propeller, 20.5 inches. What do you think ?
Was 3000/3200 the max rpm? If so that way too low as the WOT rpm should be 4400-4800 rpm otherwise the engines are under too much load. I’m assuming these are Bravo 2 drives to swing that large of a diameter. My 2400 has a 17 3/4” diameter 3 blade but not sure of the pitch.
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Old 07-05-2022, 09:08 PM   #4
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Was 3000/3200 the max rpm?
Yes, 3200 max, but 4500 on neutral.
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Old 07-06-2022, 01:18 AM   #5
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Yes, 3200 max, but 4500 on neutral.
Neutral rpm means nothing since there is no load on the engine. 3200 max is 1000 rpm too low.
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Old 07-06-2022, 12:58 PM   #6
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Speed is irrelevant. As Mike stated, the max rpm range of most Mercruiser engines (including yours) is 4400-4800 rpm. If you are only getting to this range there is an issue.

Diameter is a somewhat fixed value as it's dictated by the gap between the blade tip and the hull, or in the case of an outboard or I/O (outdrive) between the blade tip and the anti-ventilation plate.

Blade count (3 blades vs 4 blades) and pitch are what you are going to tune to tweak max rpm.

I would use the stock diameter and start reducing pitch. Each dop in pitch of 1" should increase max rpm by around 200.

I would tune the prop with an empty boat with full fuel and water. Then load and re-test.

A dirty bottom, too many layers of hard paint, or being overloaded can all adversely impact performance.
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