Prop questions

[Chris_94_Sprint_TX]

I have a 1994 Sprint 262 with a 94 Johnson 2 stroke 88hp. Currently has a 3 blade 19P prop and was wanting to switch to a 4 blade and maybe go up to a 21P or should I stay with a 19P to achieve a little more lift out of the hole and top speed? I think I read where I should not be revving over 5K but with the 19P it revs to 53-5400 rpm.

Also, does anybody know the difference between Turning Point Legacy Turning Point Patriot and the Turning Point Express? Or is there another one I should look at?

Chris

 

[Starcraft5834]

" I think I read where I should not be revving over 5K but with the 19P it revs to 53-5400 rpm."

that's your starting point.... know what your engine's WOT (rpm) range is....and what you are currently achieve with your present prop.... if your current 19p hits the recommended range, moving to a 4 blade in same pitch will be close.. moving to a 4 blade will certainly jump you out of the hole quicker

 

[Chris_94_Sprint_TX]

So would a 21P get the RPMs down to the recommended range, a little more top speed and better hole shot? Or should I make a smaller jump if there is one in between?

Chris

 

[SkiDad]

You never gave your current GPS speed ?

 

[SkiDad]

i would guess your boat is good for about 45 mph ? - I don't think you could gain much if you change to a 21p prop - maybe 1 mph. But it will cost you on hole shot. As for TP props - they tend to drop the rpm alot in my experience. I also think the RPM you are running is fine

 

[Starcraft5834]

So would a 21P get the RPMs down to the recommended range, a little more top speed and better hole shot? Or should I make a smaller jump if there is one in between?

Chris

again, what is recommended range for your motor at WOT? we know what you currently hit, and you suggest you need to drop down.. to what? answer that and you will get some suggestions

 

[Chris_94_Sprint_TX]

GPS has my speed at 35-37mph and motor RPMs over 5K. I believe it somewhere on here that I read where the motors redline was supposed at 5K and mine will rev to almost 5,500. I want to be in the mid 40s on the water with 3-4 people and gear. This is the information I was able to find a while back.
http://boatspecs.iboats.com/Johnson__J88TSLER_SPL__88hp__1994/bpe/57e9900 [h=1]1994 Johnson 88 HP
J88TSLER SPL[/h]

This 1994, 88 hp Johnson is made for saltwater. This outboard engine weighs approximately 301 pounds. It has 4 cylinders. The pistons have a 99.6 displacement. The bore width is 3.5" and the stroke length is 2.58". This model has a electric starter and power steering. Serial Number: ER RPM Information: 5000 Your engine's RPM range is important in choosing the right propeller for a given application. For example, if you look at your tachometer at top speed and it is not within the engine's RPM range then that is generally not good. You want your RPM's to be within the proper range while at wide open throttle (WOT). Be sure to do your testing under your normal boating conditions and with a good propeller (not bent, cracked, or excessively chipped). Information on this page is provided to you as a free service of iboats.com. Because this information has come from many sources we can not guarantee its accuracy. Even if this information is the same as the original factory specs, boats are sometimes modified. Thus, for safety and other reasons, it is a good idea to verify information here to make sure it matches up with your boat.

The iboats Outboard Motor Forums are another excellent source of information. The iboats Forum Directory can likely help you find a lot of outboard information as it is arranged by subject.

Engine Manual: Johnson Outboard Manual

Chris

 

[SkiDad]

your engine can run up to 5500 rpm just like mine - nothing wrong with dropping the rpm down to 5000 but I wouldn't go below that. The 5000 you mentioned is where max HP is reached. Your engine is pretty much the same as a Johnson 90 - the main difference was the lack of VRO - i think you have the pre-mix your fuel.

as for speed I'm not sure what is up with that - i run 37 mph on my boat with a 15 pitch prop. with a 19 you should be closer to low 40's. I could be that you have a lot of weight on board ? Does this motor have trim on it, i know it was an option and might not have it and maybe you are plowing ?

is your prop in good shape ? It seems to be inefficient - maybe try another 19p prop that is more efficient.

 

[jimmbo]

Your are currently propped as good as it gets for rpm. Going up in pitch will drop your rpm, and your top speed will probably be about 1/4 mph faster, with a loss of hole shot. Adding an extra blade n addition to the pitch increase will result in very poor holeshot, a big drop in rpm and a lower top speed.

 

[Starcraft5834]

you could go to a 4 blade in same pitch, increase hole shot and lose top end a bit... rpms might push over 5500, boils down to whats more important to you.... hole shot, water sports power= 4 blades. top end speed, average hole shot, average water sports= 3 blade, no perfect bullet.... 4 blades best for heavier boats..

 

[Chris_94_Sprint_TX]

So if I stay at the same 19P but switch to a 4 blade will that give me a better hole shot. The motor does have tilt and trim. When all the way down it runs 35mph but if I play with it I can get to 37mph some days. Its a bass fishing boat, my main goal is to generate a little more lift, better hole shot, and still be able to get across the lake to my spots fairly quickly.

Chris

 

[SkiDad]

Well It seems your current prop is slipping badly. A new prop might actually get you better speed.

 

[Chris_94_Sprint_TX]

I got it to 40mph on the GPS the other day but it seems as if it needs more lift. I see other bass boats like mine that have more of the hull out of the water while on plane. It has a hydrofoil which helps tremendously. I think it may be running badly though too. I took a video today and will post it in the Johnson outboards section.

Chris

 

[Sea Rider]

Perform a slip test on current prop to know if working spot on before going for other pitch or prop. Stated 5.5 K revs over revving was achieved while lightly, medium or highly loaded. State number of passengers when over revving.

If you add more weight/passengers wot rpm will drop accordingly. Current over revving will improve hole shot, top end speed will be slightly reduced. Can run OB at less throttle while maintaining good plane and fuel consumption.

Happy Boating

 

[Chris_94_Sprint_TX]

I was out by myself with just my fishing gear. How do I do the slip test? WOT seems to stay at 5500 even with 2 adults and 1 or 2 children and gear with livewell full. Hence the reason I thought a higher pitch 4 blade for more lift and speed. It seems that even with just me in the boat on plane that the hydrofoil and the 3 blade is not generating the lift to get the boat up like other bass boats I see running across the lake.

Chris

 

[Sea Rider]

WHST (Wot Hub Slip Test)

Remove prop and turn it over, with a marker, mark 2 straight lines as in pic, go for a wot spin for some minutes, remove prop and check if marked lines have moved away from originally marked., if so, you have a hub slip and won't know if current prop was a good performer before went spun. Dilemma, go for same prop and pitch or maximize with other, but with which prop ?





Engine health & height, trim, healthy prop, boat's overall total weight and deck weight distribution adds enormously if running with less lift than yours. When on plane, does doel fin rides near or parallel to water level ?

Happy Boating

 

[Chris_94_Sprint_TX]

Not sure about where the fun rides. I'll have to take a buddy next time I'm out on the lake and see if they are brace enough to lay on the back deck while on plane.

I will check for slip tomorrow before I winterize it. Going out of town and it's supposed to freeze while I'm gone.

Chris

 

[Chris_94_Sprint_TX]

Got it winterized and decided to compression check. Have 1 dead cylinder, gonna fix that before throwing props at it.

Chris