89 Sunsport performance

[johnba]

Hey Folks,
I've been tweaking and tuning my 89 sunsport and need some help. Currently I'm running a 3 blade Acme prop and getting about 32 WOT at around 4800 RPMS. I'm at about 6K feet in elevation so that's a factor.

I can't help but think I should be able to get more top end out of this boat, or that my RPM's shouldn't be quite so high at this point. I've talked with the folks at Acme and they helped me with the prop so I think that's dialed in right.

I was wondering if there was anybody else out there with a 1989 Sunsport that I could compare some performance info with? I did a compression test last fall and things were good there, but who knows where they're at now. This may just be the characteristics of this boat so thought I'd ask before I continue digging at the motor and prop.

We slalom as opposed to wake-boarding so that's why the interest in slightly higher speeds.

Thanks,
John

[Pdowling1]

4800 RPM should be getting you more than 32MPH, more llike high 30's or low 40's. Is that a 13X13 prop?

[DKJBama92Mariah]

4800 is a little too much if you've got a 351. I would suggest adding another 2 inches of pitch on the prop to bring the WOT RPMs down to the recommended range of 4000-4400. That will probably get you up into the high 30s at least.

[johnba]

I forgot to sign up for notifications on this post and didn't think anybody responded. Hopefully folks will see this again.

So the prop I have is a 3 blade ACME 13x11. We went with this to deal with high altitude and initially when I changed the prop I was running around 40 MPH at 4700 rpm, shaped my wake up nicely got the hole shot I wanted and life was good.

Unfortunately we put our boat in on a new lake/ramp and dinged the prop on the frame of the trailer (rather not talk about it :)) Sent the prop in for rework, got it back and here I am with max RPM of 4600 and top end of 32 MPH.

Sent the prop back to have it checked and specs out as new. Wondering: Could there be an issue with the shaft (hitting the trailer frame may have damaged more than the prop) or should I consider getting a new prop again and see what happens? Wouldn't kill me to have a spare anyway but man they ain't cheap!

If I could just get around 35 without wrapping out the RPM's I'd be happy. I just wanted to make sure that I wasn't asking something of this boat that it won't do with it's deeper hull and little bigger size.

Thanks,
John

[Salty87]

i took a look under a buddy's 89 sunsport. he's running an acme 422...12.5 x 15.5. no elevation to deal with here. i'm sure acme recommended the prop based on whatever he told them at the time...he doesn't board too much, it hauls butt. going from memory (and speedo), he's getting near 40 at 4k rpm.

[csuggs]

I have an 86 Sunsport and I was told by two dealers that the "right" prop is a 13 x 13 OJ. That's what I am running now with the 351 engine and getting right at 4000 rpms - don't know the speed because the speedos are never reliable (but indicated speed is 37-39)