Okay - what should the WOT RPM be for a 2002 115 Ficht Envinrude. I have a 17 P SST on it and getting 5200. What is this going to do to the engine? Lugging? I have a 15P aluminum and get 5500. I suppose the motor should be turning 5500; if not will it harm it much?
WOT for that motor is 5800 rpm, check this site...http://www0.epinions.com/content_29609070212
OK, Everyone act like you did Not see this......6000.
Okay - so all I could get with a 15P was 5500 WOT- but it has awesome holeshot and 32 mph with that 15 and I can't see why I should go down to a 13P??? However - if I need to get the rpms up to 5800 or 6000 at WOT?????? I need your advice. I guess I should take the 17P off as I can only get 5200 rpms?
I posted "Act like you didn't see this"
JeeeeeeeeeeeeeeeeeSUUUUUUUUUUUU I'll be down to a 12 in pitch
I have a 2000 115 25" RAM. I played around with engine mounting height till I dialed in the RPM at 5800 with a 17" Rapture and 3 to 4 person, full gear, full gas. A raker 18 gave about the same. The 2000 115 Ram had an RPM range of 5500 to 6000 RPM. Also with a light load 1 or 2 person, half gas I can run a ballistic 19 and even a Raker 20 and still get 5800 RPM with a top speed of 44.9MPH. One day I am going to break the 45 mark! My boat is a Sea Chaser 210 deep vee that weighs 1950 for the hull. The boat has a pulpit so it compares more to a 19 foot boat for comparision purposes.
With the motor mounted low the way it came from the dealer the rpm struggled with a 17" aluminum. The first remount was to the lowest hole to bring the motor up a high as possible. This caused bad cavitation. I lowered it one hole and that did the trick. Increased RPM and speed and it was like a new boat. If you can't do it yourself a dealer charges about an hour of labor to remount it. (Some of the tech guys can be more precise on this one).
By the way I am not a fan of the SST prop. I tried one on my rig and did not like it at all. I am fortunate to know other V6 gearcase owners and we trade props from time to time to see how they do.
And one last thing. I assume you are properly working the trim guage. That is crucial in getting the best performance. If I trim mine in all the way it runs at about 5400 RPM. I trim out to the sweet spot and get 5800 and the best speed. It will trim a bit further and push 6000 but there is no speed incease on my hull and the rooster tail is about 15 feet high! You can tell when you hit the sweet spot cause the motor howls like at no other setting.
SC
Thanks SC; someone interested in this. The boat is a V20 wellcraft; a heavy boat but it rides up on the strakes and can be fast. It went 45+ with a 175 on it. The 115 gives 35 with the 17 prop but only 5200 rpms. The 15 aluminum cavitated a lot when trimmed out but got 5500. The holeshot with the 15 was incredible for a heavy boat; the transom creaks when you gun it. If I could find the proper type prop in a 15 so I can trim it to 5800????? I think the LU on the 2002s is the smaller v4 recent type?
Gaz the only thing I can suggest is to suck it and see, beg , borrow or buy another prop test it before you buy, if its close to the magic number 5800/6000 a good prop tuner can take it up or down a few RPM's.
Another tidbit to consider. You were getting 45MPH with a 175HP. The general rule of thumb is an increase/decrease with each 5HP of change relates to 1MPH gain/loss. In your case you reduced 60HP. This would mean a 12MPH decrease in speed. If you are getting 35 this is a great speed for a 115HP that has replaced a 175HP. To get the best hole shot and top end I would try this. Get the 15Â Michigan match stainless prop. Not the rapture, apollo or ballistic. This will in effect increase the RPM by about 100-200 at top end but not have much impact on the hole shot. It will also let you trim out a bit more without cavitating and could get you a few more RPM with the added trim. If you go to a lower pitch on an underpowered boat (in my opinion) it will not accelerate as you would think. Prior to my 90 Hp etec I had a 48HP on my rig. Top speed with a 15Â was about 28 with the RPM stuck at 5000. I tried a lower pitch but it would not accelerate. The power was awesome but the pitch was to low to accelerate the boat. I could have probably been a tug for an aircraft carrier but that was about it. Since your boat probably weighs in the neighborhood of 2500 pounds without the motor your prop choices are limited.
SC
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