more WOT rpm and prop selection

[thosch]

1991 Johnson 90hp. on a 17.5ft Tracker deep-V alum. hull. Currently have a 2-piece 13.25x17 Hustler prop. With just me in the boat and no other cargo, I can get 5000rpm at WOT. With more people and some cargo, the best I can do is 4800rpm. I recently rebuilt the carbs, with no effect on rpm. Correct Champion plugs (77's), compression is 120 all cylinders. Recently did a decarbon by spraying SeaFoam into the carbs and letting it sit. Lots of smoke for a short time after that. Motor is running better than it ever has. I'm thinking a different pitch prop. Looking at the Hustler props on this site, I see a 14x13 that I'm thinking should get me up around 5500-5600rpm. My Clymer manual says operating range of 4500-5500, so should I be targeting WOT of around 5500rpm? Also going from 13.25 to 14' diameter is going to reduce the amount of space between the prop and the L/U just above the prop. Anyobdy have any experience or concern about that? Maybe a call to Hustler customer service would answer that.<br /><br />Thanks for any input/advice.

 

[thosch]

Re: more WOT rpm and prop selection

My apologies for this double post. Please disregard.

 

[Rex]

Re: more WOT rpm and prop selection

Shoot for the top range.<br />PROP: I would say 13.25/14 pitch.<br />REX

 

[cmjust0]

Re: more WOT rpm and prop selection

Just FYI, there's another good forum out there for Tracker/Nitro owners, located at www.trackerowners.com . You can get there by going to www.nitroowners.com as well.. You'll surely get the answers you need on this forum, but you might enjoy going there as well. <br /><br />Again, just in case you hadn't seen it and were looking for a "Tracker Support Group"!!

 

[Dhadley]

Re: more WOT rpm and prop selection

It seems kinda strange that a V4 on a small light aluminum boat can only swing a 17" 5000 with a light load. We run a 19" (SST or Stiletto) on the 21' Starcraft with V4 crossflows and turn them about 5600 with an average load.<br /><br />You sure your tach is set on position 6?

 

[thosch]

Re: more WOT rpm and prop selection

I too think it is strange that I only get 5000. I know the previous owner and he confirmed that number as his WOT rpm when he owned the boat. The motor is hard-mounted to the hull, and I'm wondering if the motor not correct in the vertical. I have been doing alot to this motor this year in terms of making sure it is in good running condition. I believe it is, and I have no symptoms of any problems.<br /><br />So,...as an update, here's what I did. I bought the 14x13 Hustler prop housing. Results are what I wanted. WOT is now at 5800 with no load. My local OMC mechanic says I should have no problem turning 5800. I lost 6mph top speed (43 down to 37), but I never considered the top speed as useful for me. The holeshot went from pretty good to outstanding. The boat planes almost immediately, and the rpm's almost instantly go from idle to the 5,000's with no hesitation.<br /><br />As always, Dhadley, I value your opinions.

 

[Dhadley]

Re: more WOT rpm and prop selection

Again -- are you sure the tach is set on 6?

 

[thosch]

Re: more WOT rpm and prop selection

Sorry, missed that question. Yes, tach is on 6.

 

[MGuckin]

Re: more WOT rpm and prop selection

13 should be a great hole shot with a loss of top end.<br />17 is about right for your hull/weight. <br />Sounds like the motor is mounted at the wrong height (too low), which is very common in dealer installs. <br />But if your happy with it now.