High RPM's

[Bear Cove]

Have a 31 foot Bounty, weighs 9 tons. I removed the twin diesels, podded it and put twin 350 Suzuki's on it.

Not happy with the performance so far, so looking for some help. Running at about 25 knots the motors are turning at 5200 RPM, that seems high to me

Have dual 3x15.5x19.5 props

Any insight or help wood be greatly appreciated

Cheers

[Moonlighter]

What is your rpm ‘s at WOT?

[Bear Cove]

Sorry, had my information wrong that I posted earlier, those numbers were with a different set of props.

So WOT is 5900rpm at 31 knots, with dual 3x15.5x19.5 props, cruise at 28 knots now at 4800rpm burning 32.5 gph.

Still seems high on the rpm side

Any thoughts or ideas would be appreciated

Cheers

[Moonlighter]

Rpm’s sound normal to me, of course not knowing your boat. But its a very heavy vessel!

The Suzuki’s do like to rev, and since you are able to reach 5900 at WOT than you are pretty good in terms of propping, perhaps a bit low given the 5700-6300rpm rev range. Usually Suzuki dealers suggest targeting an easy 6000-6200rpm trimmed out at WOT. But if yours are brand new, they usually loosen up and you might pick up 100-150rpm after 60-80 hrs.

Cruising at 28 knots at 4800rpm sounds good to me too.

You do need a “mindset reset” to get used to the high revving Suzuki’s. Especially after being used to low revving diesels!!

But even other 4 strokes and 2 strokes are different to the Suzuki’s. For example, I have a friend with an etec 115 on his boat and his WOT is 5300 whereas my Suzuki DF115 hits 6150. Crusie revs for both boats, unsurprisingly, vary by similar amounts. He might cruise on 4000 while I will be doing 4700 at the same speed.

Its just how they are.

[Bear Cove]

Thanks for the feed back, my 250 Suzukis hit about 5800 and I cruise at about 4200. Might just take some getting used to is all, it is running at a more preferred rpm now. Now to get that GPH dow, lol

Thanks for taking the tie to respond

Cheers