Lets Talk about a Jet W/ a Gearbox...

[396_WAYS_TO_SPIT]

What about running a jet with something similar to a casale box to change the impeller speed? Whachs think??? :idea: :idea: :idea:

[wet77]

I was just thinking of something like that a few days ago :rollside:
I was watching some monster truck show and how they use planetary drives on the wheels to go so fast with big wheels
Wonder if something like that could be used to spin the impeller fast at a lower motor rpm :idea: :rollside: :220v:

[cyclone]

a few guys have used gear boxes successfully. Steve Brule used to run one back in the day. I think Mike Miller told me he tried it but it didn't work in his application. Maybe they'll chime in here...

[396_WAYS_TO_SPIT]

I was thinking about spinning 5500r's on the motor and 8000r's on the pump

[Riverat84]

that would be badass if you could go 65 w/ the engine thinking its running 30...kinda like an overdrive...anyone know how much the overhead cost would be to convert such a boat say like mine?

[FILUCKY]

Garry Snow (SDBA069) runs gear box's in some of his race boats. 500ci prostock style N/A motors that need lots of rpm 8-9000rpm. I'm sure he will chime in later on this subject. :)

[hack job]

do a search this has been covered many times;)

[Riverat84]

Garry Snow (SDBA069) runs gear box's in some of his race boats. 500ci prostock style N/A motors that need lots of rpm 8-9000rpm. I'm sure he will chime in later on this subject. :)
alright, well BUMP until he does.

[djunkie]

What about running a jet with something similar to a casale box to change the impeller speed? Whachs think??? :idea: :idea: :idea:
Why don't you just get a real boat then? Like a v-drive. :jawdrop: LOL!!!!!!! :D :D

[Nicked prop]

is to set up the gear box in an "underdrive" configuration. That is, spin the motor at higher rpms while using a larger impeller at an rpm lower than the motor is turning. In theory this allows a high performance motor to turn the rpms needed to make power while using a larger impeller which is, in theory, generally more efficient thana smaller impeller. The rub is the power robbed by the gear box (primarily friction) generally offsets the advantage offered by a larger impeller. And, the gearbox usually requires moving the motor forward which is not always a good thing, either. Others more knowledgeable than I may be able to explain it better.

[Riverat84]

is to set up the gear box in an "underdrive" configuration. That is, spin the motor at higher rpms while using a larger impeller at an rpm lower than the motor is turning. In theory this allows a high performance motor to turn the rpms needed to make power while using a larger impeller which is, in theory, generally more efficient thana smaller impeller. The rub is the power robbed by the gear box (primarily friction) generally offsets the advantage offered by a larger impeller. And, the gearbox usually requires moving the motor forward which is not always a good thing, either. Others more knowledgeable than I may be able to explain it better.
ahh...i think i understand.

[dmontzsta]

How about...just getting a V-Drive? wouldnt that be easier? :idea: :)

[shaun]

I was thinking about spinning 5500r's on the motor and 8000r's on the pump
doesnt make sense to me, if your motor can only turn 5500 rpms with the impeller spinning 5500RPMs also then your motor definitly wont be able to spin it self to 5500 and the impeller to 8000...
It would have to underdrive, so say 2:1 so you get up to the speed at which you run 3300RPMS faster and then shift it into 1:1 the rest of the way.
Just my thought, i'm no expert.

[Devilman]

What about running a jet with something similar to a casale box to change the impeller speed? Whachs think??? :idea: :idea: :idea:
Instead of a gearbox, why not just put a transmission in it? You gotta Chevy, put a 2-speed Powerglide behind it. Or go all the way & put a TH350 or TH400 in it? Then you can throw a second gear roost.... :rollside: Or get really wacky, put a stall in it.... :cool:

[Rondane]

What about running a jet with something similar to a casale box to change the impeller speed? Whachs think??? :idea: :idea: :idea:
i'm not sure they make it any more but casale made a Z drive for jet boat about 10 years ago...it was like $3000 if i recall.
rondane

[BrendellaJet]

doesnt make sense to me, if your motor can only turn 5500 rpms with the impeller spinning 5500RPMs also then your motor definitly wont be able to spin it self to 5500 and the impeller to 8000...
BINGO! Save your money and build more motor.

[Beer-30]

I'm not a jet guy, but here is one option. Super stout. As tough or tougher than a T400. One speed under or overdrive.
http://www.gearvendors.com/images/gears21.jpg
http://www.gearvendors.com/custom.html

[Red Rocket]

I tried one in my race boat and never found a hardware combination that was any quicker than without. I tried it at 4 different events and was off a tenth and 5mph no matter what I threw at it. But I do know several people that had success with one.

[old rigger]

i'm not sure they make it any more but casale made a Z drive for jet boat about 10 years ago...it was like $3000 if i recall.
rondane
Bingo.
Back in 1980 when I went to work for Roger Weiman, he had just finished a 18 with a Z drive in it. It was built before I started so I never saw it in person, just pitures of it. It worked great, was fast, but was very costly (for the time. Remember, this was the height of the energy crisis, money was tight and the boat shops were going tits up like crazy).
With todays engines, and the horsepower they make compared to what was going on 27 years ago, that set up would be killer.......I think. :cool:

[Cs19]

Ive heard mixed things about them.If your making power really high up, its worth trying I guess.The only boat i know of thats running one at NJBA currently is MJ680, im sure he'll tell you all about them once he sees this topic.
motor at 5k and impeller at 8k? sheesh.

[h2oboy]

I know there are still a few guys out there that are running the gear reduction system in the jets.... I think Steve Brule was one of the first guys to drive a jet with one in it successfully... I beleive a guy by the name of Scott Owens puts this gearbox out... the idea is to run the motor high, and spin the impeller at a lower speed thus making the impeller more efficient... the more water you can cram in there and pin out the better you will be...

[centerhill condor]

speed and torque are inversely related... as speed increases torque decreases and as torque increases speed decreases.. kinda like granny gears in a truck...
add gears add weight, and friction, and something new to break, leak, freeze, seize, etc.. like the guy says you might as well have a prop or build more engine! :)

[DansBlown73Nordic]

I think I know what your looking for......Its a V-DRIVE :D

[Wicked Performance Boats]

I've talked about putting a gearvendors overdrive in a boat for years! It's light and bulletproof. AND my motor is already forward enough to fit I think. How much is a Lenco? Probably too much. Budlight AND if we wanted a vdrive we'd already have it. Their a dime a dozen and besides their only one speed also till you put in a transmission. BL :crossx:

[Wicked Performance Boats]

I'm still waiting for some jetboat racers to chime in with imput! BL

[bp]

propduster ran a casale, mj680 ran a casale, most everyone ran a casale that had an nhra type prostock engine, because those engines make their power at 8500+. nowdays, they're making their power at 9500+. in the biz, we ran a scott owens reduction gear to set the current pgj records, 132/7.81. engine spun around 8550, and the legend A was spinning between 6560-6600. we tried some different things, like different impellers, different gearing, running a tiny impeller with no gear. there was always the concern about "how much" hp loss to the gear, but considering all the info we had at the time (hp curve, etc.) the gear with the legend A was the best combo we had up to that point.
for an engine with an hp curve that's way up there like that, the gear is something that needs to be considered to improve pump efficiencys...

[Wicked Performance Boats]

Thanks bp, I love this topic! Has anybody tried like a gearvendors overdrive? My thought was leave the line in 1to1 and after the boat accelerates to say half track, you click it into overdrive, say 10%, maybe the rpm would drop and maybe a little more topend. If not for recreational use, once you were on cruise you could 'click it' and lower the rpm. Either way, race or cruise, would it work? Budlight

[mickeyfinn]

Thanks bp, I love this topic! Has anybody tried like a gearvendors overdrive? My thought was leave the line in 1to1 and after the boat accelerates to say half track, you click it into overdrive, say 10%, maybe the rpm would drop and maybe a little more topend. If not for recreational use, once you were on cruise you could 'click it' and lower the rpm. Either way, race or cruise, would it work? Budlight
Would probably work at least as good as overdrive in your car when you are on an extended uphill grade. I think that is the reason overdrive is generally not gonna work on a get. You don't ever get the advantage of inertia working for you for a long period of time. As soon as you reduce power you start to slow down. Shifting into overdrive works on the premise that it takes less energy to keep you there than it took to get there in the first place. I don't believe that is true on a boat (not considering the getting on plane part. Now if you have an impeller that is cut to need more RPMS than the engine is turning but only needs the horsepower that you are making at lower RPMS then the overdrive may come in handy. Remember besides being a new piece of hardware with the bragging rights to go with it, it is still a lossy power retransmission device. So no matter what you do, you will always have some amount of net available horsepower loss at the pump shaft. No transmission is 100% efficient.

[LVjetboy]

What if you knew pump efficiency for impeller cut size and rpm. A pump chart. And what if you knew gear box efficiency based on rpm, gear reduction and gear cut design? Those combined with your engines power curve? Other than performance drag by the extra gear box weight...you'd know the answer.
Problem is, we don't really know these things. Average 2% loss for a gearbox? Doesn't account for gear reduction or rpm. Just as impeller curves don't account for pump efficiency because the power to spin the impeller stops short of how much of that power is converted to thrust.
My point is, if we really knew pump and gearbox efficiency along with the engine power curve, the value of a gearbox would be clear. Yet here we are talking about this and trying to re-invent the wheel. Guess what? The basic principles and physics of a gear box and pump performance are already known. Just because gearbox or pump mfgs don't measure or publish efficiency data doesn't mean that the understanding and knowing of that data is not the answer behind what happens in a gear box or a jet pump. Or that an engine power curve and performance is mysterious and something we need to discover all freakin' over again.
jer

[bp]

What if you knew pump efficiency for impeller cut size and rpm. A pump chart. And what if you knew gear box efficiency based on rpm, gear reduction and gear cut design? Those combined with your engines power curve? Other than performance drag by the extra gear box weight...you'd know the answer.
Problem is, we don't really know these things. Average 2% loss for a gearbox? Doesn't account for gear reduction or rpm. Just as impeller curves don't account for pump efficiency because the power to spin the impeller stops short of how much of that power is converted to thrust.
My point is, if we really knew pump and gearbox efficiency along with the engine power curve, the value of a gearbox would be clear. Yet here we are talking about this and trying to re-invent the wheel. Guess what? The basic principles and physics of a gear box and pump performance are already known. Just because gearbox or pump mfgs don't measure or publish efficiency data doesn't mean that the understanding and knowing of that data is not the answer behind what happens in a gear box or a jet pump. Or that an engine power curve and performance is mysterious and something we need to discover all freakin' over again.
jer
all very good points. i don't know that anyone is trying to reinvent anything, but had asked if anyone had ever done this. as far as the physics and the absolute values you're thinking about with respect to the owens gearbox we used (can't remember who bought that thing, either mm or rp), neither scott nor any other searches could really give us any concrete absolute data with respect to the efficiency and hp loss. that's just the way it was. casale may have more info with respect to their gearset. the owens gear was a planetary gear, but was entirely custom.
the second part to that is, the more you cut an impeller back, the less efficient it's going to be. that's not to say it's not going to work, just to say it's not going to be as efficient as it would have been if it were full size. how much? at one race, we took the A out, installed a C with exactly the same tolerances, changed the gears to keep the rpm at the same point, and ran the boat. dropped almost 4 mph, and more than 0.4 seconds et. that was the end of that experiment right there. the idea being, if we could go in that direction (go smaller with the impeller), maybe we could eliminate the gear. reinstalled the gear and the A, and we were right back to 7.8's at 130+. this was one of those "trial and error" kind of deals, where someone had a theory, and it needed to be proven one way or another. there were a couple times things like this came up.
as far as shifting, i would think you'd need an engine that made one heck of a lot of power at low rpm to make it work, even for a cruiser. something like a very large cubic inch blower motor...

[superdave013]

the new Trident deck boat with the dual pump set up runs an underdrive gear box with a real slick dry sump oil system.
The Casale's that are in jet boats are a lot different then a v drive or the z drives you see in hydros. They have 4 gears instead of only 2. If you used a typ 2 gear style box your pump would spin backwards.

[Jim Brock]

Tom Rainville put a overdrive in last year, was running 96mph, ran 76mph with overdrive shifting at half track,

[Rondane]

the new Trident deck boat with the dual pump set up runs an underdrive gear box with a real slick dry sump oil system.
The Casale's that are in jet boats are a lot different then a v drive or the z drives you see in hydros. They have 4 gears instead of only 2. If you used a typ 2 gear style box your pump would spin backwards.
The z drive i mentioned was made specifically for a jet boat....this was over 10 years ago. Dont know how many were made or for even how long. Not even sure if casale made it either to be honest.
rondane

[Cs19]

Isnt rainville one of the njba guys?

[bp]

Tom Rainville put a overdrive in last year, was running 96mph, ran 76mph with overdrive shifting at half track,
seems like tom went at least that fast before, and has run close to the same numbers for at least 2 years, so.. if there was an overdrive in his nordic, what were the pros/cons?
Isnt rainville one of the njba guys?
yes, has a jacket that looks almost just like yours... :cool:

[pce680]

the new Trident deck boat with the dual pump set up runs an underdrive gear box with a real slick dry sump oil system.
The Casale's that are in jet boats are a lot different then a v drive or the z drives you see in hydros. They have 4 gears instead of only 2. If you used a typ 2 gear style box your pump would spin backwards.
With a 2 gear casale all you have to do is turn the motor around backwards.
Its been done before. :cool: