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Donziweasel
07-31-2006, 11:08 AM
Can anyone give me some feedback on props. I need to go to a 17 pitch. Any feed back on manufactures would be great. Someone recommended a turbo 1 and someone else said to stay away from Mercury/ Mercuiser props. Anyone know anything about Stilleto?

Donziweasel
07-31-2006, 11:09 AM
Also, how will diameter affect my boat?

boldts
07-31-2006, 01:34 PM
DWEASEL - what kind of boat are you running a 17" pitch prop on. If it's a Donzi, I'm guessing a Ragazza? 17 is pretty small for the Classics and ZX boats. Maybe it's an inboard though? Hard to recommend a prop with out knowing how you want to use your boat. Waterskiing? Kids toy towing? All out speed? cruising the lake with the best fuel milage? All kinds of varibles in there depending on what your trying to do with the boat.

Adding diameter usually adds better grip. Less prop slippage and requires less pitch to keep the engine in the correct RPM range. However, because of the bigger prop blades, it may also add bad handling charactoristics. Chine walking to name one of the biggest.

Decreasing the diameter may result in more prop slippage. The prop is less effecient in the water. However, because less diameter, usually you can run more pitch. Pitch = the distance a prop will move in one revolution of the prop. More pitch usually means additional speed.

Which prop to try is anyones guess without knowing what you want the boat to do and without knowing what type of boat it is. Take a 22' Classic for example. Some here like the Mercury Mirage Plus prop. Others like the Turbo1 from Pression Propellars on a 22. It's all about again what you prefer, what you want the boat to do and even your driving style weighs into the equation.

I'm no expert in prop science. There are many here who have a better grasp on props. What I've given you is what I believe is true when it comes to the diameter question. I may be totally wrong and if so, we'll both learn from someone more knowledgable.

Sorry, disreguard most of this. Just read you have a 16' Classic and are high up in altitude which explains your need for the 17" pitch.

Donziweasel
07-31-2006, 08:26 PM
Thanks Scott. I will take any help on setting this boat up. If have any info on high altitude you can share, let me know.

John Pearson

BigGrizzly
08-01-2006, 08:03 AM
John, again what boat are we talking about. Steletto is a good prop also and made by the Precision Propeller guys, different than the turbo but good non the less. also Solas is another good prop that works well in the lower pitch range. I sell props and can tell you every application is different. Let us know what the application is and we can help. Maybe the 17 inch isn't what you need. In my former job which I just retired from in June we tested all props to find what worked best on our motors with different boat combinations. You would be surprised what works an doesn't on different applications. I own 3 Donzis and they all prop different. My 22 I have several props each one is different.

wrussellw
08-01-2006, 08:39 AM
Not to hijack this thread, but. I am about two weeks from putting my 1969 sixteen in the water. 351w with an alpha one. trim tabs and ext latham steering.
I will be running in New Orleans area, so no altitude issues. Mainly is rivers but also Lake Pontchatrain with 1-2 foot chop.
My thoughts were to buy 3 props and use my GPS to compare performance. any ideas would be appreciated. also any additional things to consider because of the left hand drive?

Donziweasel
08-01-2006, 08:59 AM
Randy, here are the details. The boat is a 16 ft classic that came from Iowa. On the speedo, (i will try and gps this weekend) the former owner ran 62 mph at 4600 rpm. I ran the boat this past weekend at around 5600 ft and could only run 51 on the speedo at 4000 rpms. I would like to get the boat in the 4700 rpm range. The 16 classic has a 19 pitch Vengence on it running 1.47 gears in the alpha. The boat is a 1997 with a 5.7L carburated mercruiser. The rule of thumb for altitude is a loss of 3% of your horsepower per 1000 ft above sea level, so I am down about 17 % of my original 250 ponies. I know I need to drop a pitch in the prop, and maybe a gear in the outdrive. I have used stilletos before, but not on this type of boat. Any help on prop selection or high altitude setup would be most appreciated.

John Pearson

mrfixxall
08-01-2006, 09:29 AM
Randy, here are the details. The boat is a 16 ft classic that came from Iowa. On the speedo, (i will try and gps this weekend) the former owner ran 62 mph at 4600 rpm. I ran the boat this past weekend at around 5600 ft and could only run 51 on the speedo at 4000 rpms. I would like to get the boat in the 4700 rpm range. The 16 classic has a 19 pitch Vengence on it running 1.47 gears in the alpha. The boat is a 1997 with a 5.7L carburated mercruiser. The rule of thumb for altitude is a loss of 3% of your horsepower per 1000 ft above sea level, so I am down about 17 % of my original 250 ponies. I know I need to drop a pitch in the prop, and maybe a gear in the outdrive. I have used stilletos before, but not on this type of boat. Any help on prop selection or high altitude setup would be most appreciated.
John Pearson

sounds like you need to start rejetting your boats carb to bring up the rpm's and not the prop..Are you sure your running on all 8 cylinders that would be the first thing i would check..1 cyl not fireing would cause a 600 rpm loss..

Donziweasel
08-01-2006, 09:35 AM
No, the boat is running fine, all 8 are firing. This is my 6th boat out here and all of them have had to be set up for altitude. Simply less O2 in the air, so the boat loses HP. The last boat I had was a 21 ft Milan Sport Boat with a 454, thru hull. I had to drop a pitch, one gear ratio and rejet from 1.06 to .96. When the secondaries in the carb opened, the boat would bog, running rich. It took 2 years to get it set up. Living at 6000 ft is a pain in the ass, but all boat owners living here have to go through this. Most the dealers in this area are good at setups, but I bought this boat used from Iowa and do not have a dealer near me.

Donziweasel
08-01-2006, 09:39 AM
Also, a good freind of mine who has lots of experience in High Altitude setups suggested advancing the timing from 8 DTDC to around 12-13 DTDC. Any idea on this as well as prop selection and sterndrive gear ratios?

Greg
08-01-2006, 09:40 AM
I have a Stilletto on my 21' Scarab and am very well pleased with it.

Donziweasel
08-01-2006, 07:22 PM
I think I will try the Stiletto.

Sam
08-01-2006, 09:10 PM
Donziweasal, prior to severl mods to my 16 I had your set up but never had to contend with the altitude issue. From my experience and others as well we were all running around 56 mph or so @46-4800rpm. Most ran 3 blade props in the 21-22" range on a ALPHA GenII drives with 1.47 gear ratio. I hope this will give you a benchmark as you move forward.

Donziweasel
08-02-2006, 08:31 AM
Thanks for the input on the timing. I will probably leave it alone. I am kinda pissed that I have to run a 17 pith prop when it seems that everyone at sea level or slightly above is running a 21 or 23. One idea I had was to possibly replce my 2 barrel carb with a 4. The reasoning is that a bigger carb means more air in the engine. I know I would have to get a new manifold, but does anyone have any suggestions on this conversion?

Donziweasel
08-02-2006, 09:23 AM
Thanks for the info. By the way, how hard is it to rejet a carb? Never done it, but would like to learn as the nearest mercruiser dealer is over 90 miles away.

Donziweasel
08-02-2006, 04:20 PM
I have a new Stiletto 17 pitch on the way from Dans Prop Shop. I also have the local boat guru rejetting my carb next Tuesday. First I want to get the boat dialed in at it's current configuration. Next, I want to boost the horsepower from 210 (actually 173 at my altitude).
I am a gear head. I guess you need to know that man behind the boat. For example, 2 years ago I purchased a stock Arctic Cat M-7. I mmediatly put an 800 big bore kit on it. Next came a Boondocker EFI adjutment module. Shortly thereafter came a Big Daddy pipe and a Racin Station Can. Still not satisfied, I drilled the track and inserted ice racing screws. Still not done, I drilled out the running boards. Reeds and Vlaves were next and then to top it off I put an ICE systems nitrous kit on it. From the original 140 respectable horses I now have well over 200 and use eberyone of them.
I then started eyeballing my wife's sled. Although she wanted no mods, I could not resist and put a pipe, can, drilled track, running boards. She then said if I did anything else I she would divorce me:wink: .
I guess modiying high performance things is half of the fun for me in owning high performance things and I am sure this Donzi is no different. Knowing me, next I will probably figure out a way to squeeze a 496 Mag with a blower and 700 hp into the Classic. Just kidding, although I wonder..........
One thing I am sure of is that a Mercruiser 5.7 is much different than a snowmobile.

Donziweasel
08-03-2006, 11:59 AM
Just got my Stiletto 17 pitch in. I am heading to the lake this afternoon and going to run both props on the GPS. If anyone is interested, I can post speeds and RPM's at 5600 ft. Also will pull a couple of plugs and see if she is running rich. Will take some digital pics and post if you guys like.