[Question] Monitoring bowl pressure
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Monitoring bowl pressure

  1. #1
    Senior Member HomeBlown57's Avatar
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    Default Monitoring bowl pressure

    Do you simply measure the bowl pressure at the water line? Or does the bowl get drilled and tapped somewhere? The suction housing is already tapped.

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    Senior Member bp298's Avatar
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    Quote Originally Posted by HomeBlown57 View Post
    Do you simply measure the bowl pressure at the water line? Or does the bowl get drilled and tapped somewhere? The suction housing is already tapped.
    many are tapped near the suction piece flange. same location in the sucton piece as the cooling wate port, but on the opposite side... add on from there...

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    Senior Member zacho!'s Avatar
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    Quote Originally Posted by bp298 View Post
    many are tapped near the suction piece flange. same location in the sucton piece as the cooling wate port, but on the opposite side... add on from there...
    Close to a year ago, One of the true dragboat racers from tucson said I need to have a gauge on the bowl as well as the two on the suction. Is there a ratio to shoot for? Or do you need to figure that out through tuning?, hence him not giving up any more info?

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    Senior Member bp298's Avatar
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    Quote Originally Posted by zacho! View Post
    Close to a year ago, One of the true dragboat racers from tucson said I need to have a gauge on the bowl as well as the two on the suction. Is there a ratio to shoot for? Or do you need to figure that out through tuning?, hence him not giving up any more info?
    no, there's no ratio to shoot for. these pumps create pressure independently from suction pressure. in that an increase in suction pressure does not automatically result in an increase in bowl pressure. what the pump needs is a steady flow of water in the suction piece, that is slightly more than the pump will process. honestly, i don't know how anyone can get valuable information from gauges. i've seen pics of duane's old setup, which was a couple of 5 or 6" gauges temporarily installed. with 1 1/2" gauges, especially fluid dampened, there's no real way to see what trends are occurring especially when you're driving down the river or track at 90+. it's just not realistic. i'm at the point where i can remember to glance at the tach, or glance at the oil pressure during a pass, and i've made over 1000 1/4 mile passes. i suppose, if they were mounted in a cluster behind the steering wheel, right in front of your face, you'd have more of a chance to stare at 'em, but even then you should be watching what's out in front.

    the first thing you're trying to see is whether or not the suction piece is pressurized, and to what pressure. is it 0, or is it 80, or somewere in between. after that, you're looking for any trends in the suction prssure - does it spike up or down? as you go down track, is it somewhat stable, or does it trend up or down?
    suction pressure is always oscillating to some degree. as long as it's not oscillating down too far, it''ll continue to provide enough water. but even that is subjective, depending on how far the down oscillation goes. and it'll be a subjective number because all boats are different. if someone says "what do you like to see?" i'll tell 'em. but that doesn't mean it is an adequate number for them. and if they're looking at a gauge, god knows at what point in an oscillation they'll look at it.
    how much is enough? whatever it take to raise and maintain bowl pressure as high as it will go, for the pump setup. at the hit, you want bowl pressure to steadily climb with no dips whatsoever. bowl pressure also oscillates, and can change by several psi depending on what's done with the engine/pump/etc.
    this just kind of scratches the surface. next time we have a race at firebird, come by and i'll show you more of what i'm talking about.
    Last edited by bp298; 06-18-2011 at 04:38 PM.

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    B1 Racing cs19's Avatar
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    Well said BP.

    The inlet pressure thing in relation to bowl pressure is an interesting one, stared at data before and have seen events where the inlet spiked hard and the bowl pressure also spiked and it sorta mirrored the intake spike, doesnt always happen but Ive seen that plenty of times.

    I agree, a guage on the bowl pressure is about as useless as an ashtray on a motor cycle (been wanting to use that saying for like a week now) intake pressure with a guage is another story and can be useful if the boats not real fast and you can actually watch the guage and catch things happening.

    Chris

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    Senior Member motormonkey's Avatar
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    BP,
    Would reading the bowl pressure after the bowl vains tell anything as opposed to right after the impeller? I know nozzle inserts affect pressure so what would reading discharge pressure tell us??

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    83 Crusader - 468 BBC SNiC's Avatar
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    Old thread, but search sent me here....

    I would like to know the approximate water pressure on the "engine cooling" line which comes off of a split bowl. (468 BBC with an A impeller, open flow cooling with no thermostat FWIW) Looking to install a "strainer" on this water line and am interested in knowing the approximate PSI +/- I am dealing with.

    TIA
    Randy
    Last edited by SNiC; 06-11-2015 at 08:57 PM.



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    Senior Member bp298's Avatar
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    Quote Originally Posted by SNiC View Post
    Old thread, but search sent me here....

    I would like to know the approximate water pressure on the "engine cooling" line which comes off of a split bowl. (468 BBC with an A impeller, open flow cooling with no thermostat FWIW) Looking to install a "strainer" on this water line and am interested in knowing the approximate PSI +/- I am dealing with.

    TIA
    Randy
    what rpm do you see at wot? the cooling water tap is bowl pressure. bowl pressure varies from low rpm to max. as an example, at 5000 rpm, I see about 180psi AT THE PORT. at 3000, about 60psi AT THE PORT. pressure is less in the line to the engine for two reasons; there is flow, and there are line losses. at max rpm, I see a lot more pressure at the port. which is why I've used a regulator for 17 years. strainer is a good idea if you have a need. but at the least, you should have a valve off the pump just in case you break the thing...

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    83 Crusader - 468 BBC SNiC's Avatar
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    Thanks bp298,
    This is exactly the info I was looking for.
    WOT is 5100 RPM.... and 10-4 on the valve.... got that covered.

    Thanks Again,
    Randy



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    Senior Member bp298's Avatar
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    Quote Originally Posted by motormonkey View Post
    BP,
    Would reading the bowl pressure after the bowl vains tell anything as opposed to right after the impeller? I know nozzle inserts affect pressure so what would reading discharge pressure tell us??
    don't think I ever saw this 4 years ago. sorry.

    from a data collection perspective, "in the heat of the moment" there is very little to be gained from multiple bowl pressure readings. there is an energy conversion process taking place from the impeller exit to the nozzle exit. pressure increases, slightly decreases, then increases again. when bowls are blueprinted, the objective is to improve this conversion process. so if you are doing some detailed deep analysis of bowl/nozzle performance, to be analyzed or extensively evaluated at a later time, there might be value. but on a track (or river/lake boat) it is pretty much what it is. using the one bowl pressure tap near the impeller exit point, you are using that info to compare with other information. it is a data point.

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    Cocoloco cocoloco's Avatar
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    Quote Originally Posted by HomeBlown57 View Post
    Do you simply measure the bowl pressure at the water line? Or does the bowl get drilled and tapped somewhere? The suction housing is already tapped.
    I agree that reading a gauge or gauges on a pass would be difficult. I too have made lots of passes and checking the OP and HT just before launch and at the finish is distraction enough. That said I know that drag racing asphalt has jumped way forward in power and application of that power with computers reading many areas of the cars performance. Particularly when it comes to the clutch, slippage and application. Making 8,000 HP and getting it on the ground are two very different things. At least in boat racing the surface is a constant value. I know it changes with conditions but water is water and it has a baseline consistency. Enough of the debate shit. Pump pressure has to be as relevant to application as clutch application point on asphalt. I bet that if someone starts putting a computer to at least the pressure, suction, cylinder temp and RPM on their boat they will figure some things out. Like, my boat nosed over at seven hundred feet down course. Hmmm, did the motor lose power? Did the jet pick something up? Did the impeller crack? Did a line plug? How about monitoring the fuel pressure, fuel consumption rate? I know in drag racing the computer educated a lot of people about some long standing beliefs they held. I bet after a season of analyzing data vs. performance you could learn more from pump pressure and suction than you ever imagined. My two cents.

  14. #12
    Senior Member bp298's Avatar
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    Quote Originally Posted by cocoloco View Post
    At least in boat racing the surface is a constant value. I know it changes with conditions but water is water and it has a baseline consistency.
    while true that water is water, the stuff that's dissolved in that water varies greatly from one place to another. "fresh" water is a subjective term anymore. and this isn't related to conditions. just as an example, you could have a setup that would be fine at ming, but would cause all kinds of problems at firebird. you could see certain pressures at parker that might not be the same at dexter. all these bodies of water have different sources, and can have an effect on jet boat performance. if all a person does is run on one body of water over and over forever, it will probably be relatively consistent from one time to the next.

    got a message yesterday from someone; "went from track A to track B, weather was "about" the same. boat running the same, lost 2 tenths??? thoughts???" water difference wasn't all of that, but it was certainly a factor.

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    Quote Originally Posted by cocoloco View Post
    I bet after a season of analyzing data vs. performance you could learn more from pump pressure and suction than you ever imagined. My two cents.
    Loco, Where have you been?? Computerized data acquisition systems have been used on drag racing jet boats to monitor the engines and jet drives since the late 90's ! There are racers out there with books full of data and they pretty much know what it means.

    Cs

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    senior member turbo wog's Avatar
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    Default 4th of july?

    tried to delete but no go!
    Last edited by turbo wog; 07-02-2015 at 06:26 PM.

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