Mercury 110 Optimax jet on 860 War Eagle

[ndebolt3]

I had a couple questions I am hoping someome can answer. I recently bought a 860 LDSV War Eagle with a Mercury 110 Optimax jet. With three people, its max speed was 33 mph at 6,000 rmp. My first question is how fast would you expect this set up to go? I was figuring 40+, but this is my first boat so I may be out of line. My second question is reguarding the rpms. On the mercury site, the stats said the max rpm at wot are around 5700. What could be the problem here and is 6,000 rpms bad for the motor?

Thanks for your help.

 

[Willyclay]

Re: Mercury 110 Optimax jet on 860 War Eagle

I am guessing that you are getting the speed and RPM readings from the onboard gauges. First, water pressure speedometers are notoriously wrong, can be either high or low. You need to use a GPS to determine an accurate speed. Next, double-check your built-in tachometer with a portable unit like EZ-Tach, laser tachometer, vibra-tach, tec. Once you have good data, then you can decide if you have a problem or not. Good luck!

 

[ndebolt3]

Re: Mercury 110 Optimax jet on 860 War Eagle

Thanks for the reply. Reguarding the speed, I was using a GPS, so the speed I mentioned should be pretty accurate. Regaurding the RPM's, I took it in today and found out the wrond impeller was used, so I am getting a 4 blade stainless steel impeller. Do you have any idea how much this will help the speed?

Thanks

 

[Willyclay]

Re: Mercury 110 Optimax jet on 860 War Eagle

I looked at your boat on War Eagle's website. It is a BIG boat at 18.5 feet long with 12 degrees of deadrise. Not sure what you should expect for performance. However, some of the experts on this forum, which I am NOT, have previously commented that jet drives are fairly inefficient and you might only be getting the equivalent of about 60% of your rated horsepower. Good luck!

 

[ndebolt3]

Re: Mercury 110 Optimax jet on 860 War Eagle

I was thinking the same thing about loss of power, but I did some research and found out it is rated 110 for jet and 150 for prop. I took it in the other day, and there were two thinks wrong with it. One was the motor was one to two inches low and the other was the wrong impeller. It turns out there was a 3 balde aluminum in it when there should be a 4 blade stainless steel. Haven't had time to take it out yet since the changes, but i'll let you know after next weekend where or not these changes make a difference. I don't see how it would'nt though so I am hoping for the best.

Thanks

 

[ndebolt3]

Re: Mercury 110 Optimax jet on 860 War Eagle

I got my boat back today and took it out on the river for a quick test drive. They raised the motor about an inch and put the new impeller in. There is a lot more power, but the handling was completely different. As soon as i would get to about 30 mph, the boat would swerve right or left out of nowhere and I tried changing the plane, but everytime I would start going fairly fast, the handing would disappear and the boat didn't seem to respond much to countsteering and the boat would make a 90 degree turn. Any ideas what would cause this? Also, the guy who fixed it took it out and said he was running 47 mph at about 5,500 rpms and didn't say anything about steering problems. The highest rpms I got was about 5,150. I must be doing something wrong, but I have no idea what I am missing. Any help or anything you have experienced with jets would be great.

Thanks