Turbo, or Stiletto??? 3 or 4??? (Kenny/Dhadley)

[Boilermaker]

I need to buy another prop anyway to have a good backup, & wife wants to get me a Fathersday gift .... <br />Current prop is a Stiletto 13.25 x 17 - 3 blade....17.5 ft modified-vee (heavy), 1978 Johnson 115, 37-39mph GPS @ 5200-5300 RPM. Engine mounted up 1 hole from top, prop vents at aprox 3/4 trim.<br /><br /> I know I should be spinning the engine faster, but my main thing is that I can't keep the boat on plane with a normal load below 4000 RPM, and the holeshot is not very good. <br /> Would I do better dropping to a 15 pitch 3 blade.... or 4 blade??? OR keeping the 17 pitch and changing to a 4 blade???<br />Do you think I would keep the top speed I have now if I went to a 15 pitch & got the RPM up???<br /><br /> I REALLY don't want to lose any top speed...just want a little better holeshot, and stay on plane at lower RPMs for crusing & ruff water operation. Should I step up to the TURBO or a different brand prop from the Stiletto???<br />THANKS FOR ANY HELP.... hope I'm not asking to much!

 

[AguaSki]

Re: Turbo, or Stiletto??? 3 or 4??? (Kenny/Dhadley)

I don't have much to offer as I am getting similar results with a healthy (120 psi on all cylinders) 1978 Johnson 140, 13.25 X 15 Rapture. I have watched some of your other threads in hopes of finding a way to increase my RPM's. I still have not tried raising my motor, but that is the next thing I will do. Once you decide on a prop, please post your results. I will be interested to see if you are successful in getting the RPM's up. Good luck.

 

[walleyehed]

Re: Turbo, or Stiletto??? 3 or 4??? (Kenny/Dhadley)

Boiler, email me...<br />ktsander@st-tel.net

 

[Boilermaker]

Re: Turbo, or Stiletto??? 3 or 4??? (Kenny/Dhadley)

OK>>>Thanks Kenny.<br /> <br /> NOW>>>> 3 Blade or 4....?<br /> 15" Pitch or 17".....?<br /> Stiletto or Turbo...???<br />Vanilla or Chocholate...???<br />

 

[Boilermaker]

Re: Turbo, or Stiletto??? 3 or 4??? (Kenny/Dhadley)

Walleyehed,<br /> Did you try a 5" setback with your old 115hp engine, and if so>>>how much did the rpm rise with it???<br /> I still don't know if I can use a jackplate on my boat>>>>but it has me thinking of ways to alter the setback if it would be worth it.

 

[walleyehed]

Re: Turbo, or Stiletto??? 3 or 4??? (Kenny/Dhadley)

Yes, that's when I started messing with all of this stuff...Dhadley walked me through quite a bit of work to end up where I did. I've played alot since, and have learned some on my own, and 1 thing I might add is that 2" transom shims will help some too, and it may not cause any steering issues with the set-up you have.<br />Now, when you talk 3 or 4 bld, that can be a double-edged sword. If we can't run the prop high enough to utilize the 4th blade, we are waisting the technology of that prop. A 4-bld is also slower on top if we can't raise it.<br />My best over-all prop for all uses on my 115 was actually a Nauticpro 13-3/8X17 with the jackplate, or setback plate, I should say...<br />For top-end performance and all-out speed an 18P OMC Raker was the ticket, and I could turn it right at 5800RPM with the engine 5-1/2" back and up in the 4th hole....this put my AV plate about 3-1/4" above boat bottom.

 

[Boilermaker]

Re: Turbo, or Stiletto??? 3 or 4??? (Kenny/Dhadley)

What was the performance like prior to the setback plate??? Did you try a Turbo or Stiletto prop with that setup???<br />Do you think that I would get that big of an improvement (500-800 RPM) with a jackplate??? Does the setback improve the performance do to the prop having "clean water" to bite into??? Or is it a function of being able to raise the engine more do to the way the water comes off the transome at the bottom??<br /> Do you think my Stiletto Prop is a good choose for my heavy old boat?<br /> I would get a jackplate if I can convert my steering linkage & having the clearance for the linkage....I have been thinking of getting a new steering cable anyway (it sticks if not used for a while). I could post a picture of the engine well & steering cable if you like. <br /> I'm sorry if I ask a lot of questions>>> I'm trying to learn & have it clear in my mind, exactly whats going on. <br /> Thanks again for the help.<br /> Jim

 

[walleyehed]

Re: Turbo, or Stiletto??? 3 or 4??? (Kenny/Dhadley)

Performance with no setback or engine heigth was minimal compared to how it turned out.<br />The setback can do a couple of things..1 is it changes the CG of the boat which can change how much wetted surface you have, and yes, it does get it back in a somewhat more stable water condition and that in itself depends on the hull structure and how true the bottom really is, and I can tell ya first-hand, rivet heads don't help the situation.<br />Adding setback can also change the required prop, but I don't think you'd have any problems with the Stiletto...you're starting with a good prop.<br />I ran alot of different props on the 115...the Raker, Nauticpro, Ballistic, Michigan match, some merc aluminum props, several OMC SST's and a few other odds and ends, oh, and 1 powertech I bought on ebay, then found out it was a copy of an SST original. I couldn't pull the Raker enough RPM until I added the plate and got the engine up...Dhadley also walked me through plugging the top 2 holes on the lower unit water pick-up, by tapping then inserting machine plugs loc-tighted in place, then filled over them with some body work and repainted, but there is a 1/8" drain hole below the 4 main water inlets, Dhadley had me drill that 1/8" hole out to match the others in size and then done some grinding to make the entry pockets match those above. This is a great way to gain a couple of inches in heigth without loosing water pressure, and I was able to raise the engine enough to really make that Raker come alive...the hull responded very well to the mods and all worked out quite well. from the RPM the Raker originally ran (5400), I gained about 175-200 just raising on the transom, but after the plate and water inlet plugs and some more heigth, I ended up between 5750 and 5800RPM.<br />So I went from basically 40MPH to right at 48MPH, and during Feb. of 1 year, I did see 49.2MPH. Now I had done a few other items to the engine as well..at my altitude, I went 2 steps leaner on the main jets, advanced timing by about 3 degrees of max, which most will recommend against both of these to some extent, but through the years(22) of my Father selling Jonnys and Glastron boats, he found this to be the best combo (jets and timing) on the V4;s for 3600-4000ft.<br />I think there is more potential in your rig, it's just a question of how much do you want to do????

 

[Boilermaker]

Re: Turbo, or Stiletto??? 3 or 4??? (Kenny/Dhadley)

Ken<br />Was this the old x-flow 115???<br />Thats some pretty impressive increases! Think how many thousands of dollars it cost to get speed increases like that on a 1/4 mile drag race/hotrod car. <br />I didn't think it would be so involved to mod the water pickups>>>> I figured that there would be an aftermarket plate or something. I know that aftermarket lowercases with high water pickups are available....but I don't think I would be going THAT route ($$$$) <br /> Funny you should mention GLASTRON boats...No one seems to be familure with WESTWIND boats (Mine)>>>But it is very similar to the Glastrons of that period, (early 1970's)...except I think the 18ft Glastron was a deep-vee & the Westwind is a modified-vee.<br /> The thing is I don't think I will be keeping this boat for more then a few more years anyway. I wanted to step up in size to allow more coastal fishing. Going out into the North Atlantic in an 18ft boat is VERY weather dependent & you have to hug the coast for a QUICK return if things start to change.<br /><br /> BUT... this is a GREAT learning experiance & I am fascinated by the engineering & mechanics of it all !!! >>>And the thought of another 5 to 10 MPH is VERY tempting! <br />I will have to see how much it would cost to change my steering, and add the jackplate. <br /> SPEED IS MONEY...HOW FAST CAN YOU AFFORD???<br /> Thansk again<br /> Jim

 

[Dhadley]

Re: Turbo, or Stiletto??? 3 or 4??? (Kenny/Dhadley)

Cubic dollars. That's all it takes.<br /><br />Just some food for thought -- the reason we went with adding and filling water intakes hole vs. adding a low water pick up was the speed range that we were dealing with. At 50 mph (and even a little more) the added surface area on a nose cone can actually slow you down. Extra drag. <br /><br />Here's a little background about how we started using nose cones. It started with the V6's but it trickles down to each gearcase size. As a gearcase goes thru the water the blunt end pushes water away from the gearcase. As the case moves forward the water comes back to the case and flows toward the prop. Thus creating an air pocket or a vortex. As you go faster and faster eventually the air pocket gets to the prop. Thats when we get true blowout. The prop hits an air pocket and loses all bite. At that point the boat takes a hard, and instant, left turn. Once is enough of that, thank you.<br /><br />So the idea was to add a sharp point to the gearcase to cut down on the size of the air pocket. At first folks simply used a Dixie cup as a mold and epoxied around it. That worked as long as the gearcase was running straight in the water. A little positive trim and it created a worse air pocket. Then Steve Stepp (Velocity Powerboats) got the idea to add a curve or crescent shape so that positive trim didn't affect it as much.<br /><br />OK, so now we got past blow out and everybody was going in a straight line. But as props got better we started running higher and ran out of water pressure. Next thing ya know Bob Iceanogal started Bob's Machine Shop and decided to add a water passage in the nose cone. His manual jackplates worked well but everybodys motors were getting hot. Add the water pick up to the bottom of the nose cone = problem solved.<br /><br />So, with Kenny's boat we weren't running fast enough to warrant a nose cone but we needed to lower the water pick ups while raising the gearcase. OMC actually made some scoops at one time that worked really well. They were so small that people didn't believe they did anything. Those of us who tried them know they did work.<br /><br />Besides, folks who look at Kenny's gearcase won't notice anything unusual and wonder "How'd he get that to work?"

 

[Boilermaker]

Re: Turbo, or Stiletto??? 3 or 4??? (Kenny/Dhadley)

Dhadley, Thats some cool history>>>>what happened to the dixiecup noses when someone tried to turn???<br />I like the "sleeper" job you guys did on Kennys rig.....I'm sure he had a few guys scratchin' their heads.<br />What do you think I should do with my old x-flow 115 now? <br /> What would you do??? I don't want to sink a ton of money into it, BUT I still want the most bang I can get.

 

[KCLOST]

Re: Turbo, or Stiletto??? 3 or 4??? (Kenny/Dhadley)

"So, with Kenny's boat we weren't running fast enough to warrant a nose cone but we needed to lower the water pick ups while raising the gearcase. OMC actually made some scoops at one time that worked really well. They were so small that people didn't believe they did anything. Those of us who tried them know they did work."<br /><br />Dhadley,<br />Do you think the intake modification would work on a V6? And are the scoops still around anywhere...

 

[Gammabusa]

Re: Turbo, or Stiletto??? 3 or 4??? (Kenny/Dhadley)

Very interesting what you say about plugging the top 2 holes on the lower unit water pick-up, I have raised my engin to plate 6 inch above bottom and have still 30 psi water pressure but I will be testing a new 24 Raker one of the following days and recon I have to adjust height to get my rpm upp and right, got 6200 with my 22 Raker,<br /><br />...thanks for all the good info here Kenny and Dhadley ;-)))

 

[walleyehed]

Re: Turbo, or Stiletto??? 3 or 4??? (Kenny/Dhadley)

KCLost, that Mod IS on my V6....

 

[Boilermaker]

Re: Turbo, or Stiletto??? 3 or 4??? (Kenny/Dhadley)

So I take it that other then a jackplate & low water intakes>>>the only way to increase RPM on my engine with this hull, is to lower the pitch, or use a less effective prop.>>>is that correct??? <br />Would using a 17" pitch prop with less "bite" (less effeciency) be a better alternitive>>><br /> OR should I get a TURBO 15" pitch & hope to keep my top speed????>>>>>><br />OR should I get the 4 blade 17" & raise the engine to its top mounting position???<br /> ALSO>>>Would increasing the size of the vent holes on my Stiletto prop help with the hole shot & mid-rpm planing?? <br />HELP!!!

 

[walleyehed]

Re: Turbo, or Stiletto??? 3 or 4??? (Kenny/Dhadley)

See what DH thinks, but I'd lean torwards the 15P 3-bld Turbo..

 

[Boilermaker]

Re: Turbo, or Stiletto??? 3 or 4??? (Kenny/Dhadley)

That's the way I'm leaning I guess>>the 15" pitch Turbo 1. <br /><br />What do you think Dhadley???

 

[Dhadley]

Re: Turbo, or Stiletto??? 3 or 4??? (Kenny/Dhadley)

I'd like to try a 4 blade. In fact I thought I had one but I don't. Well, I do but it has a Yamaha hub so that's not doing us any good.<br /><br />So.......I guess we're back to what you've already been talking about -- a 15 3 blade.

 

[Ron G]

Re: Turbo, or Stiletto??? 3 or 4??? (Kenny/Dhadley)

Are the scoops still around?and were can i get some?

 

[Dhadley]

Re: Turbo, or Stiletto??? 3 or 4??? (Kenny/Dhadley)

OMC discontinued them and BRP hasn't picked them up as far as I know for the gearcases with the old standard 4 holes on each side (398185). There was a different set for the gearcases with the removable plastic pick up. 339247