Understanding Volvo DP-S Propellers?

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BRICH1260

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My 26` Chaparral with the 5.7 320 HP engine and DPS-A outdrive is currently carrying F7 stainless props. According to specs my engine should redline at 5200 rpm. I am only able to achieve about 4500 rpm at WOT. If I want to get closer to the 5200 rpm figure, should I consider going to a smaller number or a larger number. Volvo range is F2-F9 on their charts. Does anybody understand the VP pitch question? Thanks.
 
bruceb58

bruceb58

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I run a F5 on my boat in my sig. My brother has a 26' formula with a fuel injected 7.4L and he runs an F4. We likely have diff gear ratios than you do though.

Service manual has some pages giving RPM ranges of the different props based on boat lengths. From the charts, you can see what each prop step would do for RPM ranges.

i will look at my service manual when i get home and post what I see.

BTW, you don't need to get to redline. There is a RPM WOT range spec for your engine so you need to find what that is.
 
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bruceb58

bruceb58

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If you lived near me, I would let you borrow an F5 set! With a deposit of course! :)
 
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BRICH1260

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I think the range on my engine is 48-5200 rpm. I don't necessarily want to peg it out but would like to get up in the 48-52K range.
 
bruceb58

bruceb58

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I looked at the chart in the Service Manual and it doesn't give much help. It lists an engine and the speed per propeller number. If you just do some simple calculations of what the speed increase is per prop number it looks to be around 250 RPM but not sure how accurate that is.
 
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BRICH1260

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Now I`m debating between F5 & F6. I just wish there was an easy way to try both without buying and re-selling if I didn't get it right. Especially with me buying used.
 
bruceb58

bruceb58

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You can buy on eBay and recover your cost minus listing fees pretty easily.

I actually did that for my brother once.

Personally, I wouldn't buy a used prop on eBay if it has ever been repaired. Lot of repair shops around that don't have any idea what they are doing. I did buy a set off ebay that I had to return to the seller because the repair was so bad, the props were not proper pitch anymore. This was verified by a place near me that are experts at prop repair.
 
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