Engine Height

[mboy]

Originally Posted by UaVaj

As for clean water. Here is another viewing angle. I think the clean water was because the before photo was taken on a smoother day.

So if I can get out this weekend I will take another set of photo in the bay where there is minimal chop for comparison.

One more piece of info: The before photo was taken with the engine trim at ~55. The after photo was taken with the engine trim at ~10. If that makes any differences.

After the prop scan. It is time to buy new prop or put it back down to hole #3. (There is no more room to go up and I am not excited about putting more hole into the transom)

Water being not as smooth and engine tri will have significant impact on your numbers.

[inletsurf]

Originally Posted by Hawkeye

1970 233 formula 2008 250 suzuki. I can hit 51 mph at 6100 rpms. Cruise is around 35 mph at 4600 pulling 11.5 gph.

Awesome data, thanks. I have very similar hull type, and the same motor.

[UaVaj]

Originally Posted by mboy

Water being not as smooth and engine tri will have significant impact on your numbers.

Those numbers are accurate (actually the are the means). They are NOT off just one run. They are off multiple runs to ensure the data are consistent. The photo just happens to be taken when it was a little rougher. It was probably 1-2 seas.

By raising the motor to the proper height - the prop somehow lost it's bite. That lowered the fuel economy due to the increase slip.

[nodoubt]

Originally Posted by Hawkeye

1970 233 formula 2008 250 suzuki. I can hit 51 mph at 6100 rpms. Cruise is around 35 mph at 4600 pulling 11.5 gph.

hey hawk, how do you like that new zuke?? what did you have on there before?? ive had my zuke 250 for about 8 months now and love it...makes the yam 250 i took of seem weak...i picked up a solid 6 mph top end and it will throw you out of the boat if your not careful now....pretty good for a boat thats pushing 6 grand......sorry to sidetrack guys....

[Hawkeye]

Originally Posted by nodoubt

hey hawk, how do you like that new zuke?? what did you have on there before?? ive had my zuke 250 for about 8 months now and love it...makes the yam 250 i took of seem weak...i picked up a solid 6 mph top end and it will throw you out of the boat if your not careful now....pretty good for a boat thats pushing 6 grand......sorry to sidetrack guys....

Oh I like the 250 just fine. Like the extra range, quite and no oil to burn. I replaced a 225 2 stroke efi suzuki. here are some numbers from the other day I posted on another post. Got to love it...

RPM MPH GPH
3900 30.3 9.0
4300 34.0 10.0
4600 37.0 11.5
5000 42.1 13.8
5900 49.9 21.0 WOT

[MakoMyDay]

"Proper engine height" is out of the window with Zukes. They need to be buried. I can only imagine that there is turbulent water flow around the gear case. The numbers you had with the first set up were not bad at all. You need to get in touch with knotreel on here---he has done extensive experimentation with height of his 300 Zukes. They had to be several holes lower than his mercs he replaced even though a Zuke is about 3/4" longer than a merc. I personally think you were correct on height the first time--that's just how they need to be run. It's unfortunate b/c Zuke is leaving several mph on the table with the goofy gearcases...

[UaVaj]

Originally Posted by MakoMyDay

"Proper engine height" is out of the window with Zukes. They need to be buried. I can only imagine that there is turbulent water flow around the gear case. The numbers you had with the first set up were not bad at all. You need to get in touch with knotreel on here---he has done extensive experimentation with height of his 300 Zukes. They had to be several holes lower than his mercs he replaced even though a Zuke is about 3/4" longer than a merc. I personally think you were correct on height the first time--that's just how they need to be run. It's unfortunate b/c Zuke is leaving several mph on the table with the goofy gearcases...

When you get the chance - I would greatly apprecaited if you can post photo of your setup? another setup to compare to.

I think I am gonna try some rev4 from ken and if that does not yield any improvement. I gonna buried it back to the original height and accept it for what it is.

[UaVaj]

Update.

If the pitot speed pickup (part of the LU) on these DF300 have anything to do with proper engine height.

The motor being at the current hole (#5) is too high and the pitot is having trouble picking enough water pressure to accurately display water speed. At fast idle speed (1000 RPM) - the pitot is reading 1.64 mph on and off while gps is reading steady 6.1 mph. At cruise - the pitot is reading 27.7 mph and gps is reading 32.3 mph.

I did not record this data when the motor was at hole #3 so I do not have anything to compare to.

[MakoMyDay]

I fished yesterday and should have taken pics of the lower units in the water, but forgot. Sorry. I can tell you that my props stay hooked up very well at the height I have them at. I can tell they're low b/c I can use a tremendous amount of engine trim without breaking the props free. With a full( and I mean very heavy) load my #'s are like the following---this is from memory and might be a little off

3800---34---18gph
4000---36---21gph
4400---40---25gph
4900---46---30gph
6000---55---????

22p Zuke 4 blades. Om Zuke's website, their #'s are better than mine with the Zuke 3 blades. That's what i'm going to try next

[davidkuhlmann]

Originally Posted by MakoMyDay

"Proper engine height" is out of the window with Zukes. They need to be buried. I can only imagine that there is turbulent water flow around the gear case. The numbers you had with the first set up were not bad at all. You need to get in touch with knotreel on here---he has done extensive experimentation with height of his 300 Zukes. They had to be several holes lower than his mercs he replaced even though a Zuke is about 3/4" longer than a merc. I personally think you were correct on height the first time--that's just how they need to be run. It's unfortunate b/c Zuke is leaving several mph on the table with the goofy gearcases...

Good info thanks for sharing.

Also never trust the spedo off of a pitot tube only go by numbers on a GPS of SOG. That is the only way to be correct on the numbers. My spedo on pitot is about 15-20% off of the numbers on my GPS

[markt111]

you could also have the props modified to bite better at your new height and possibly gain high end MPH and definately improve criuse speed. Most people raise the engine to gain MPH on top often loosing in the middle depending on prop, it's all a trade off situation.

Your boat looks very bow heavy, your props may need to be buried to hold it up. I would either try a REV 4 prop which bite like a Pitbull or call Brett Anderson @ BBlades Propellers, he is the Guru lab man direct from Merc racing and see if he thinks your props are worth working!!!