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Old 08-17-2017, 12:56 AM   #1
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I recently purchased my 3700 SCR w/twin 454 MPI (310hp Each)
I am at Lake mead about 1100 ft elevation and I can only get 4000 RPM and WOT 23mph.
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Old 08-17-2017, 02:36 PM   #2
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[Moved from an old Thread discussing fuel consumption to a dedicated thread.]

Welcome aboard Fastbri!!

I assume this is inboards? The 454 should be able to reach between 4400-4800 rpm under load. The MPI should account of the elevation, unlike a carb which would need to be rejetted.

This would typically indicate either being overpropped, overloaded, or suffering the results of growth on the hull and running gear.
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Old 08-17-2017, 07:14 PM   #3
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I suspect gear ratio or props as well. Boat only has 167 hours on each motor. Normally just two/four on board.
What prop do you run? I think this is 24' and bottom is clean
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Old 08-18-2017, 01:44 PM   #4
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Do you have inboards or IO's?
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Old 08-18-2017, 05:00 PM   #5
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Originally Posted by shrew View Post
Do you have inboards or IO's?
I believe inboards was the only power set up for the 3500 and up Maxums and the small cruisers were all I/O based. One cannot compare prop sizes between inboards and I/Os.
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Old 07-28-2018, 02:26 PM   #6
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Quote:
Originally Posted by Fastbri View Post
I suspect gear ratio or props as well. Boat only has 167 hours on each motor. Normally just two/four on board.
What prop do you run? I think this is 24' and bottom is clean
Good morning
I am hoping you figured out why your 3700SCR
Wasn't running as well as it should?
I text drive one yesterday with only 470 hours and wide open throttle the RPM's only reached 4100-4200 with a top speed of 25.
When cruising at 3200 RPM the boat only reached a cruising speed of 20.5 when trimmed in.
I worried there is a problem with the motors?
I am undecided about moving forward with buying the boat because of this?
Please let me know if you figured your problem out.
Thanks
Phil
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Old 07-30-2018, 12:34 AM   #7
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Default Speed on cape cod

3300 rpm i get 30mph COG gps speed full tank no trim taps on, 2 people full water tank no gray water . The boat has all ways been fast
1998 32SCR
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Old 07-31-2018, 03:35 PM   #8
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Quote:
Originally Posted by SummerNights View Post
Good morning
I am hoping you figured out why your 3700SCR
Wasn't running as well as it should?
I text drive one yesterday with only 470 hours and wide open throttle the RPM's only reached 4100-4200 with a top speed of 25.
When cruising at 3200 RPM the boat only reached a cruising speed of 20.5 when trimmed in.
I worried there is a problem with the motors?
I am undecided about moving forward with buying the boat because of this?
Please let me know if you figured your problem out.
Thanks
Phil

So the boats out of the water and the prop specs are as follows 21P 23 Diameter 4 blade
Hoping someone on here has experience with what is a good prop and pitch set up?
The boat is on Lake Erie if that makes any difference at all.

Again thanks in advance
Phil
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Old 07-31-2018, 04:04 PM   #9
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Originally Posted by SummerNights View Post
So the boats out of the water and the prop specs are as follows 21P 23 Diameter 4 blade
Hoping someone on here has experience with what is a good prop and pitch set up?
The boat is on Lake Erie if that makes any difference at all.

Again thanks in advance
Phil
Was everything in the water covered in mussels?
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Old 07-31-2018, 06:42 PM   #10
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Was everything in the water covered in mussels?
No Mussels, no moss, no grass....Clean boat clean bottom.
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