Fuel Consumption

[mal247]

G'day guys, I am new to TMC & the Malibu boating world. I am having some trouble with my 2006 247 Wakesetter with 8.1ltr Indmar 450HP engine that I have just purchased. The history is the boat has a brand new engine, reco gearbox and new V drive (installed by the local Malibu dealer) due to the previous owners misfortune. I am having drama's with cavitation, vibration and fuel consumption. The boat wont get out of the hole with wedge down and all balast tanks full, when on the plane and wedge down it is doing 4000rpm and using 45 litres per hr of fuel for a day's wakeboaring at 20 knots. I am now putting my faith in the stock prop causing the problems (which I have just had repaired along with checking the prop shaft for any runout). Specs on the prop are 13.5x17.5. Comments on Fuel Consumption, poor hole shot, poor prop performance, vibration and cavitaion would be great!

[Chia]

someone with a 247 will chime in soon with advice. Not sure why they would put a 13.5" prop on that boat with that power. You need a 14.5" prop, maybe the ACME 1235.

You can also call ACME direct for advice on which prop to run: 1-888-661-ACME.

[Baddog]

Are you cetain the trailer was detached from the boat?

[Pistol Pete]

You really need to sort out the cavitation and vibration first.

[winddawg]

You have something bent, out of alignment, or assembled wrong to give cavitation and vibration. And like others have stated that needs to be addressed first and most likely by the shop that did the install.

I have an 8.1 in my 23 with an OJ 14.25 x 14.5 and have an awesome hole shot with the wedge down, ballast full, and 5 people in the boat. Depending on how you drive it you should be in the 5 to 8 gallons an hour.

With that prop my top rpm is 5200 and top speed is close to 50mph.

Hope that helps.

-Dave

[mal247]

Thanks Dave, it is good to get some benchmark figures on performance. I can get my hands on a trial 14.25x14 prop as I am not sure how badly bent the original was before the repair or if it has been repaired correctly. If this fails it sounds like I will need to revisit the engine and driveline installer. It'd be good to hear of anyone who has had similar vibration or cavitation issues and how they fixed it?

[footnlongline]

You have something bent, out of alignment, or assembled wrong to give cavitation and vibration. And like others have stated that needs to be addressed first and most likely by the shop that did the install.

I have an 8.1 in my 23 with an OJ 14.25 x 14.5 and have an awesome hole shot with the wedge down, ballast full, and 5 people in the boat. Depending on how you drive it you should be in the 5 to 8 gallons an hour.

With that prop my top rpm is 5200 and top speed is close to 50mph.

Hope that helps.

-Dave

5200rpm @50mph with wedge down?

[mal247]

Hey Guys, I tried the other prop, it improved slightly but still wasn't getting the power to the water and vibration was still severe. I checked the coupling alignment and found it was running out more than 0.030"!!! After many hours of freeing up corroded engine mounts, cursing and reading very helpful posts on this site, we got it running within 0.003". I am happy to say it is now starting to run like a 450HP Malibu should!!! I would have thought that the Malibu dealer would have checked the coupling runout and fixed it with the new engine and driveline install? Is this a reasonable expectation?

On another note, the 14.25x14 prop I currently have on it seems abit small, it has great hole shot but soon reaches the Rev limiter at 5400RPM and 45MPH.

[Baddog]

Hey Guys, I tried the other prop, it improved slightly but still wasn't getting the power to the water and vibration was still severe. I checked the coupling alignment and found it was running out more than 0.030"!!! After many hours of freeing up corroded engine mounts, cursing and reading very helpful posts on this site, we got it running within 0.003". I am happy to say it is now starting to run like a 450HP Malibu should!!! I would have thought that the Malibu dealer would have checked the coupling runout and fixed it with the new engine and driveline install? Is this a reasonable expectation?

On another note, the 14.25x14 prop I currently have on it seems abit small, it has great hole shot but soon reaches the Rev limiter at 5400RPM and 45MPH.

What kind of top speed are you looking for? These boats are all about torgue, and top speeds of 45-50 are usually all you get.

[winddawg]

5200rpm @50mph with wedge down?

You really read my post that way?

-Dave

[winddawg]

Hey Guys, I tried the other prop, it improved slightly but still wasn't getting the power to the water and vibration was still severe. I checked the coupling alignment and found it was running out more than 0.030"!!! After many hours of freeing up corroded engine mounts, cursing and reading very helpful posts on this site, we got it running within 0.003". I am happy to say it is now starting to run like a 450HP Malibu should!!! I would have thought that the Malibu dealer would have checked the coupling runout and fixed it with the new engine and driveline install? Is this a reasonable expectation?

On another note, the 14.25x14 prop I currently have on it seems abit small, it has great hole shot but soon reaches the Rev limiter at 5400RPM and 45MPH.

My prop is an OJ XMP 14.25 X 14.5, so it has an extra 0.5" on the pitch and I think the cup on mine is 0.090". If you are hitting the rev limiter that is a very good indicator you need to re prop. I spoke with Eric at OJ Prop's and he was very helpful in sizing the prop for my boat. I like the OJ props because of how "meaty" they are.

Regardless of what prop you go with it will be extremely difficult to get the boat over 50 mph, the hull, drive train, and weight of the boat were not designed to go fast.

-Dave

[mal247]

Thanks again Dave, I am not looking for rediculas top speeds, I would rarely go over 35MPH due to the excessive thirst for gas these motors have up in that rev range. I just need to stop it hitting the rev limiter at WOT but still keep that hole shot with a loaded boat. After reading some of the posts other forums on here, I will probably try for something similar to what you have, or possibly the ACME 14.5 x 14.25 am thinking if I go anymore I am going to loose too much bottom end.