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RPM Question
https://www.smwebhead.com/phpBB3/viewtopic.php?f=3&t=12117		 Page 1 of 1
Author:  purdueosch [ Tue Aug 06, 2013 11:23 am ]
Post subject:  RPM Question
My H260 now has around 25 hours on it, and I was lucky enough to get almost smooth water at LOTO this weekend.....so I went WOT. I spent a few seconds getting the trim just right and here are my results.

Full take of gas, full water tank, coolers/gear, 4 people.

Image

My question is, how am I getting 5100 +/- RPM out of my 8.2? The mercury marine website says 4400-4800 "Full throttle RPM". The HO version of my engine says 4600-5000. But I don't have the HO version, unless my documentation is wrong.

I have the 8.2 DTS Merc, with Bravo 3X drive. FW put a 4 blade prop closer to the boat and a 3 blade on the outside. I know the 3 blade is a 26p. The setup I have is stock from FW. Love the engine/drive combo by the way, it's a blast to drive.

Thoughts?

Matt
Author:  97BRO27 [ Tue Aug 06, 2013 1:56 pm ]
Post subject:  Re: RPM Question
thoughts are you are under pitched by a bit, But I know nothing about duel props so I'll leave the rest to someone else. Seems like you could hit 60 going up in pitch though, and that's pretty awesome. :wink:
Author:  deafwish [ Tue Aug 06, 2013 4:34 pm ]
Post subject:  Re: RPM Question
Is that GPS or water speed on the dial?
Not bad on the dial for a 26 footer! 8)
Author:  Walt [ Tue Aug 06, 2013 5:18 pm ]
Post subject:  Re: RPM Question
That's like 95 in Canada! I can't comment on the tach, however I would get a GPS to confirm your speed. During my test drive, my boat hit 60... by speedo; about 53 by GPS.
Author:  230 Mike [ Tue Aug 06, 2013 5:27 pm ]
Post subject:  Re: RPM Question
5,100 is a little high for a big block, but not by that much. You might want to call FW and verify that the dealer put the right props on it, and also whether or not (for sure) you have the HO version. Now that would just suck to find out you had an HO big block unexpectedly. :wink:
Author:  schoolsOut [ Tue Aug 06, 2013 8:56 pm ]
Post subject:  Re: RPM Question
230 Mike wrote:
Now that would just suck to find out you had an HO big block unexpectedly. :wink:


Heart breaking.
Author:  Flying Sushi [ Tue Aug 06, 2013 9:25 pm ]
Post subject:  Re: RPM Question
Our 08 H260 with VP8.1Gi DP and F6 prop (Similar to Merc 26pitch Bravo III) had about 250RPM error at maximum RPM (4600) on tachometer (about 75 rpm error at idle) so your boat could have similar issue…. Also our speedometer had about 5MPH error at top so I feel your boat might be same… I hate to disappoint you but you are likely going about 54 to 55 MPH GPS. :roll:
Late model Bravo III props have 4-blade front and 3 blade rear… A set of 26 pitches should be OEM from factory…. Our new E6 has same engine and same drive and she tops around 55MPH (GPS) as well… Still not bad for a such a big bowrider.

Image
Author:  purdueosch [ Wed Aug 07, 2013 12:51 pm ]
Post subject:  Re: RPM Question
Thanks for the replies everyone!

Someone asked if my speed was water speed or GPS, it's indicated speed on the speedo which would be water speed. However, I agree that indicated speed is usually not correct. I know it's close simply because my buddy has a boat that runs 51mph (GPS) and I can easily walk away from from him at WOT. I'm going to talk to FW and see if my dealer put the correct props on, and I'm also going to GPS my speed next time I'm out. I'm really curious myself. I was mostly concerned with my RPM maximum, but its clear that may not be correct also. The boat runs extremely well so I won't be changing anything, but knowing where the speedo and tach errors are will keep me from damaging something.

I'll update this thread with my results in a few weeks. 8)

BTW Koji, the cover you sold me is working out great. Fits perfect. Thanks again!
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