Tony k

2007 256 ssx top speed

10 posts in this topic

I just bought a 2007 256 SSX with a Volvo 8.1 non HO. The tach is showing 5000 rpm and tops out around 47 mph on my phone GPS. I'm at around 1500 ft elevation. Everything I have seen on previous posts and tests were on Mercs and topping out around 56 mph. Any thoughts or suggestions would be great. Thanks

 

Has F5 props on it now.

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I would expect to see 54-55 mph on that setup. How's the bottom of the hull? Is it painted or dirty?

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8 hours ago, Tony k said:

I just bought a 2007 256 SSX with a Volvo 8.1 non HO. The tach is showing 5000 rpm and tops out around 47 mph on my phone GPS. I'm at around 1500 ft elevation. Everything I have seen on previous posts and tests were on Mercs and topping out around 56 mph. Any thoughts or suggestions would be great. Thanks

 

Has F5 props on it now.

5000 RPM is the sweet spot on an 8.1 as far as max speed goes so it sounds like she is propped right. If we assume that you have experimented with trim, keeping the bow as light as possible without loosing forward thrust, then it is what it is. Bottom paint and marine growth can make a big difference so as others have asked, is she clean. Last is weight of gear and passengers aboard, and if she's kept in a slip, has the hull taken on moisture? You can't really twist a stock 496 tighter than 5 grand so I'd say you are getting everything from your ride she has to offer. Did you do your speed test in both directions on the same day to compensate for wind and current? I don't think altitude had anything to do with it, and if she could achieve 5,000, then air density was decent as the thing was making close to rated horsepower. My Merc is an HO so my numbers won't do you much good.  W

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3 minutes ago, Wingnut said:

5000 RPM is the sweet spot on an 8.1 as far as max speed goes so it sounds like she is propped right. If we assume that you have experimented with trim, keeping the bow as light as possible without loosing forward thrust, then it is what it is. Bottom paint and marine growth can make a big difference so as others have asked, is she clean. Last is weight of gear and passengers aboard, and if she's kept in a slip, has the hull taken on moisture? You can't really twist a stock 496 tighter than 5 grand so I'd say you are getting everything from your ride she has to offer. Did you do your speed test in both directions on the same day to compensate for wind and current? I don't think altitude had anything to do with it, and if she could achieve 5,000, then air density was decent as the thing was making close to rated horsepower. My Merc is an HO so my numbers won't do you much good.  W

This pretty much sums it up. At 1500 ft elevation, you are down about 4.5% in power. That will make a bit of difference, but not 9 mph. Big question is has the boat ever run faster? I only get concerned when something changes in a boat's WOT performance. My guess is the boat is running fine. 

brick

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When was the last time the spark plugs were changed. Mine would get up and go with old plugs,  but with new ones it would REALLY go.

 

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Thank you for all the input! I just picked it up last month and I am the 3rd owner. It was lift stored by the original owner and trailered by the second. Bottom is clean and no paint. The drive does have a little paint missing from being in the water, but not much corrosion. It was serviced last winter, so I am going to have it all done again this winter. 

I had a 97 Four Winns 240 Horizon with a 7.4 and seemed like it had better throttle response between 4500 and 5000 rpm. I could get that one over 52 anytime. The Chaparral rides a lot better and is about 900 lbs heavier, so that may be one reason it doesn't feel as quick. 

Anyways, it's a nice boat and just want a little more top end. Nice to be in a Chaparral again. My dad ordered a new 94 Signature 29 with twin 350s and that was a great boat with zero issues. 

Thanks!

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I had a 2005 255 (cuddy cabin version of your boat) with a Volvo 8.1Gxi (HO version) and I topped it out at 54MPH on GPS when I bought it in 2015.  Was a very nice boat.  Only sold it because we actually moved to a smaller lake and didn't need a cuddy cabin anymore and wanted a slightly smaller boat.

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my '07 256 w/496 Mag will top out at 55 on GPS.  I'd be suspicious of your phone GPS.  

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