Is a jet boat easier on parts than a drag car?
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Is a jet boat easier on parts than a drag car?

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    Resident Ford Nut Sleeper CP's Avatar
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    Default Is a jet boat easier on parts than a drag car?

    For sake of argument lets say you build a 700 hp engine. As a Ford guy I know a I can build a 512" budget storker with an off-set ground stock crank (4.14") get a set of Scat 6.536" BBC rods and some off the shelf pistons and a decent set of heads, with an .060-.080 over two bolt stock block and make 700hp+ on pump gas pretty damn easy.

    That engine will live in a jet boat river racer very easily,like forever even with some Nos on it. Now if that engine where in a drag car with a set of 10.5-12" slicks would the "shock" of the drive-train be more likely to kill parts? Broken block, crank etc ?

    Would the factory Chevy parts have the same issues or is the problem going to be more RPM related and "load" related ?

    Sleeper CP

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    Senior Member Ronboats's Avatar
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    Shock load depends a lot on the rest of the drivetrain. 4-speed,w high clamp load clutch, 4 speed with slipper-type clutch, automatic with or without transbrake, etc.I think rpm is the biggest limiting factor for any factory parts. Aftermarket internals are pretty much manditory if you want to get into any high rpm-like over 7000 . Just my $.02

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    Senior Member GT Jets's Avatar
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    I hope this is not another attempt at another pissing for distance contest

    I would say the jet, being a centrifugal pump, would be a bunch easier on parts as a whole...

    The only thing about the jet that could be "deadly" to an engine would be a venting, or over rev...just like missing a shift or tossing a DL on a car...

    But what do I know?
    GT


    Quote Originally Posted by Quickjet View Post
    Put a 300 on the back of it, Flywheel it and a nosecone. $15,000 later you'll have a 65 mph pile of shit......

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    Senior Member Xerophobic's Avatar
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    Quote Originally Posted by GT Jets View Post
    I hope this is not another attempt at another pissing for distance contest

    I would say the jet, being a centrifugal pump, would be a bunch easier on parts as a whole...

    The only thing about the jet that could be "deadly" to an engine would be a venting, or over rev...just like missing a shift or tossing a DL on a car...

    But what do I know?
    I think it greatly depends what kind of jetboating you`re doing too because I would nearly be willing to bet whitewater marathon jetboat racing is a ton harder on a motor than drag racing.

    Not too many guys build car motors that you hold at WOT for an hour at a time, add in to that jumping thru aerated or slightly rough water when you`re putting 1000+ hp thru the pump and you have the sad lesson alot of guys that build car motors soon learn about jetboat motors

    A decent unlimited motor for marathon racing is like 50k minimum, and even those dont seem to last a few races
    If you ain't hittin bottom...you ain't jetboatin!

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    Senior Member hotbo's Avatar
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    CAR would be harder on parts imo

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    Quote Originally Posted by GT Jets View Post

    I would say the jet, being a centrifugal pump, would be a bunch easier on parts as a whole...
    I'd would tend to think so, even with running a Turbo, but I don't know much either

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    Senior Member VDRIVERACING's Avatar
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    It's certainly harder on the hull !

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    Senior Member GT Jets's Avatar
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    Quote Originally Posted by Xerophobic View Post
    I think it greatly depends what kind of jetboating you`re doing too because I would nearly be willing to bet whitewater marathon jetboat racing is a ton harder on a motor than drag racing.

    Not too many guys build car motors that you hold at WOT for an hour at a time, add in to that jumping thru aerated or slightly rough water when you`re putting 1000+ hp thru the pump and you have the sad lesson alot of guys that build car motors soon learn about jetboat motors

    A decent unlimited motor for marathon racing is like 50k minimum, and even those dont seem to last a few races

    That's what I mean....If you put our B motor in a drag car, I would bet against it holding up to much abuse in the car...You don't run a drag car for 40 miles at a time, so how do you compare? I was going boat drag to car drag to keep an even playing field...

    marathon motors really have it pretty easy comparatively speaking, they get to run at desired temps and low shock load (for the most part) and are (normally) held back pretty softly..(again for the most part)..

    I keep thinking about Tim's turbine deal, not much shock load there...

    Good question I guess....
    GT


    Quote Originally Posted by Quickjet View Post
    Put a 300 on the back of it, Flywheel it and a nosecone. $15,000 later you'll have a 65 mph pile of shit......

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    Boat Nut sleekcrafter's Avatar
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    I would say yes easier in the jet boat, cause you not tring to twist up the drivetrain/body on launch, and second no direct connection to the surface. Now I'm second guessing, definely yes, cause jet boats are way slower
    Upper Midwest Power Boat Association
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    BTC cardcarrying member sunkisst's Avatar
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    Default Jet Boat vs Drag Car

    I, personally took the engine out of a transbrake car and put it directlty in my jetboat.Having never owned a jet, I first noticed the maximum attainable RPM. I was really surprised. It would only turn 5800 rpm. B/C cut impeller. Now,my 468 13:1 468 BBC ran 10:00s in the 1/4.mi. 3200 lb. car.Short shifting at 6200 RPM on its VERY BEST DAY. After running this combo for about 6 yrs,in the boat, I had made a decission that this engine was on VACATION being in a boat.I have since built, and been running the [email protected] out of a PUMP GAS motor. Really liking this combo also. Run it low on gas...buy pump gas ANYWHERE!!!! Is it harder? Dunno... My opinion, VACATION at BAHAMAS!!! My Crankshaft man told me,sitting at the starting line , On the transbrake ,ON the rev limiter ,Is HARD on the crank.
    Last edited by sunkisst; 01-18-2010 at 05:23 PM.

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    Distinguished Member David 519's Avatar
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    Like some of the others, I'd say jets are easier on parts simply because they're lower RPM engines. Our race car shifted between 6800-7200 and through the traps around 7500-7700 RPM.
    On the onset, it looked like transbrakes would be hard on engines, but after running them a few years, I don't think it's as bad as many think. Generally you chip the motor to a bit below the stall so when you release it, the motor doesn't rev that much further before it locks. By then, the entire rotating assembly has so much inertia, it launches off that. Another thing is lots of throttle stop racers slam the throttle shut even before the car moves (0.05-0.2 seconds after the release), again, softening the hit.
    Quote Originally Posted by gn7 View Post
    ....... David 519 is 100% correct........

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    Senior Member Xerophobic's Avatar
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    Quote Originally Posted by GT Jets View Post
    That's what I mean....If you put our B motor in a drag car, I would bet against it holding up to much abuse in the car...You don't run a drag car for 40 miles at a time, so how do you compare? I was going boat drag to car drag to keep an even playing field...

    marathon motors really have it pretty easy comparatively speaking, they get to run at desired temps and low shock load (for the most part) and are (normally) held back pretty softly..(again for the most part)..

    I keep thinking about Tim's turbine deal, not much shock load there...

    Good question I guess....
    As I said the way I look at this is: how many high HP drag motors would survive an hour at WOT? Even on a dyno.

    The fact they can`t wind out to 7k in a jetboat isnt because they couldnt be impeller matched to do so(Im sure in a drag boat they do) its that they wouldnt last very long if you did. I still say in some applications the jet is harder simply for the high rpm and long durations at it. Sure you dont have the shifting loads etc, but hammering on a crank with any form of harmonics or vibrations from the pump at 6k+ on and off for 45 mins plus is going to kill alot of motors, and does.

    How many unlimited boats finish the big races, not many...

    Of course the average lake jet or weekend jetdrag racer isnt as hard no.

    (and yes the main reason why it amazes me no one has done turbine till very recently, it makes a TON more sense for marathon racing)



    If you ain't hittin bottom...you ain't jetboatin!

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    ^^^^^

    I wasn't trying to compare extremes. I think I mentioned a river racer and budget build. The intent wasn't to compare it to the extreme of endurace jet boats more like drag boats at 9-11 sec WOT and the vast majority of river races don't last that long.

    S CP

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    Senior Member GT Jets's Avatar
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    Quote Originally Posted by Xerophobic View Post
    As I said the way I look at this is: how many high HP drag motors would survive an hour at WOT? Even on a dyno.

    The fact they can`t wind out to 7k in a jetboat isnt because they couldnt be impeller matched to do so(Im sure in a drag boat they do) its that they wouldnt last very long if you did. I still say in some applications the jet is harder simply for the high rpm and long durations at it. Sure you dont have the shifting loads etc, but hammering on a crank with any form of harmonics or vibrations from the pump at 6k+ on and off for 45 mins plus is going to kill alot of motors, and does.

    How many unlimited boats finish the big races, not many...

    Of course the average lake jet or weekend jetdrag racer isnt as hard no.

    (and yes the main reason why it amazes me no one has done turbine till very recently, it makes a TON more sense for marathon racing)
    Preaching to the choir here...Ran the Rogue a few times in the late 90's...the first year all we had to show for it was a boat full of powdered motor LOL...

    The second year, steering gremlins put us up the bank on the third leg...

    Definitely hard on stuff, but if run times are being equal, hands down, jet motors have it easy....
    GT


    Quote Originally Posted by Quickjet View Post
    Put a 300 on the back of it, Flywheel it and a nosecone. $15,000 later you'll have a 65 mph pile of shit......

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