Prop Help Nitro 170 w 115 johnson

[Mark -RI]

Hey guys, I been reading these posts, I have a similar issue, I just boat a 1993 Nitro 170TF 115 Johnson Pro it has a 14x17 prop , aluminum. At 5100 rpms, max. According to my dealer this motor is ok to 5800 rpms. My max mph is 41mph on gps, and cant even get the motor to over rev by trimming. I get into the second stage of the trim. I tried a 13x19 prop, well I stayed up in the air for a week and would go 7 mph and only 2500 rpms and then after I got rid of my passenger I was able to get the bow down after 3 days in the air,same rpms till I got the bow down then boat went 50 mph and the rpm's was about 4800. Its the original motor. runs great, its all the way down on the transom. I dont know what the original prop would be? But I see you guys saying 24 to 26 pitch prop I couldnt see that kind of pitch on this motor. I had a 98 700lx with a 90 Force/Merc dont remember the prop it came with, but that boat did 53 mph all the time. Also for info my plane is great when its going the wave off the back is only up from the back about 3ft, so most of the boat is out of the water. Compression is good with the motor an again it works fine, I just think someone changed the prop a few times, the guy I got it from pulled skiers. The holeshot is ok withthe 14x17 not good but ok.

I will raise the motor up I guess if thats what some of you recommend? Other than that I am baffled. Oh, less than a half a tank of gas some water in the live well. and the 41mph is the same with a passenger.



Thanks in advance

Mark

 

[TritonGlenn]

Are you sure it's a Johnson "Pro"??? I've heard of Ocean Pro, but that's about the extent of the "Pro" designations. Johnson made several models of 115, but I'm having a hard time looking up anything on Johnson props after 2001 for some reason. Most of my prop selectors are rejecting the numbers I'm typing into it.



What are your RPM's on holeshot?

Do you have a water pressure gauge, and if so, what is your pressure at WOT?

If you don't have a water pressure gauge, that would be my first recommendation before you start playing with engine height changes.



All the best,

Glenn

 

[Mark -RI]

It says right on the motor, Tracker Johnson 115 Pro, probably just what BPS calls it. Its a 1993 and the motor is Black or very dark grey metallic. From the prop that puts me in the air forever, its about 2500 rpms, I remember that one well because of how long it took to plane out, the prop I currently use the 14x17 I think its around 3000 bt I am not positive.



This boat does NOT have a water pressure gauge, The water coming out the engine when running is very hard and with muffs on comes out several places pretty strong.



The reason why i think the motor needs to go up is that i can NOT get it to red line the tach while under WOT at top speed, from what I have asked around at the local boat dealer they said your motor is to deep. I go well into the second stage of the lift, and nothing.



Its sad that it only does 40mph, 50 with the other prop, but the tournament would be over before the bow would come down to do that speed, lol i asked the dealer if he could set it up, he says I need to get him max rpm and speed and tell him the prop I have now and he will give me the right prop, well when i told him the figures he says I need a 12-13 pitch prop, and I said by rpm I do not by speed, I could walk faster if I do that.



Glenn I appreciate your help, thanks , any info you need let me know.

Mark

 

[TritonGlenn]

Mark,

I'm sure you could go up with your engine. I've never seen a boat perform correctly with the engine all the way down (mounted in the top holes). But I'm extremely hesitant to do any engine moving without a water pressure gauge. The water coming out of the tell-tale gives you an indication of water cooling at idle, but you shouldn't be looking back at your engine at WOT - you should be keeping your eyes up front, scanning the water in front of you and looking at gauges. That is why I'm hesitant to tell you to move it - although I'm absolutely certain that it will help drastically. Water pressure gauges are cheap, and easy to install.



I'm about 99.9% sure your dealer is dead-wrong on the prop pitch. Scratch that - make it 100% wrong. Yeah, it will get your RPM's up all right - but you will probably be doing 25-30mph.



I had a 1994 Johnson 120hp. I ran a 22 or 23 pitch 3 blade stainless on it - wish I could remember the size. It was a Michagan Wheel prop though. Top speed was somewhere around mid-50's with that setup on a 17' boat. The difference in aluminum and stainless was night and day. Positive that will hold true for your rig too - stainless is the way to go.



Do me a favor - Go look at your engine, where the trim / tilt unit is. There should be a little plate or sticker somewhere on there with the year and model number of that motor. Please post that info. That should get me where I need to go to make more determinations.



By the way - "second stage of trim" is actually "tilt". We need to get you to where you aren't going into that area.



I'm also going to see if I can get ahold of some of my prop buddies and see what they recommend as well.



All the best,

Glenn

 

[TrepMan]

Mark - I'm one of the guys running at 25pitch Turbo 3 blade, and have run a 26p Turbo 3 blade.



When you say "I had a 98 700lx with a 90 Force/Merc dont remember the prop it came with, but that boat did 53 mph all the time." I assume that 53mph was speedo, not GPS, as with my jackplate/prop/setup i can get 54 GPS with my 115merc.



But for your current boat, I would think going with something like a 22-23 pitch stainless vented 3 blade like Lazer II, ballistic or Turbo would be about right.

 

[Mark -RI]

Thanks guys for your help so far. Ok before I forget, the model # of the motor is TJ115TLETS its a 1993 Johnson 115 oil injected.



Ok UPDATE! Took my brother as a passenger to look at the motor while i am driving, at all times I have a great stream coming from the water port. I am looking into a water pressure gauge. My local dealer said he didnt have one. But i found out he really did as I had a friend call for one just after I walked out the door. so looks like the local dealer wants to do the repairs but not just sell me the parts.



Part 2, Went out again saturday after I raised the motor 2 holes, holy batman! what a difference, the holeshot was incredible and top speed was 48 and I went to 6000 rpm, so now I know I can raise the pitch. I was tempted to rais it all the way up but I hear Glenn saying get that water pressure gauge so i will do that now.



I am willing to sacrifice some holeshot for topend.

Again guys thanks for the help, I am getting there.

My brother shot video of my test, I will see if I can upload it somewhere.

Thanks, Mark

 

[Mark -RI]

here is the link to the video, I think it takes off quite well now. so I think I can raise the pitch. I ordered a water pressure kit also, should be here friday?



Thanks

Mark


http://www.youtube.com/watch?v=jXfbw0nq11M