Someone Give me some Bowl Pressure #'s

[RiverDave2]

I need some Bowl Pressure #'s for what a triple digit Riverboat would make, as well as a drag jetboat.
What pressurization does the bowl reach when the boat becomes unstable (I.E. in a drag the motor dies and the boat spins out) As well as what a safe Bowl Pressure would be to reingage a popoff valve while driving..
Do these need to be variable dependant upon setups??
Is that HandHole the same on all jets??
As well as are most people in high performance applications running one particular jet?
And finally are most high performance installations setbacks?
Thinking about designing a better PopOff valve (well I'm not designing it, but I'll have some of the engineers that I work with do it they get off on designing this kind of stuff http://free.***boat.net/ubb/biggrin.gif ) for you high performance jet guys..
Thanks in Advance for your Help!!! I really appreciate it.
RD
[This message has been edited by RiverDave2 (edited October 25, 2001).]
[This message has been edited by RiverDave2 (edited October 25, 2001).]

[Oldsquirt]

Dave, its not the BOWL pressure that causes problems. It's the pressure on the INTAKE side of the pump that the pop-off is dumping. Engine stops = pump stops. Stopping the pump causes intake pressure to increase(due to momentum of incoming water and momentum of boat), lifting the tail of the boat and pushing the nose in. There was one such incident at Ming on Saturday - luckily no injuries. A racer was thrown from his boat when it made a hard left after an engine failure.
Not all pumps have handholes.Hand holes are ahead of impeller.
Not all are set-back installations.
If you want an answer to the pressure question- intake and bowl- try posting this on the RJB message board.
http://disc.server.com/Indices/152642.html

[Ghighway]

RD the road to success is through knowledge. The wise one Oldsquirt has just enlightened your path.........follow it my son....RJB http://free.***boat.net/ubb/biggrin.gif

[Jungle Boy]

RD2, You may want to call Rob or Dale at Eagle Power Boat in Sylvan Lake Alberta (403 887-2544). Rob has a ton of knowledge on intakes, grates and bowls on river racing boats. Our intakes are alot different than the picture of the one on a lake set-up that I seen on another thread, but he may be able to help. My boat isn't triple digit (mid 80's), but if I remember correctly it runs between 15 and 45 lbs depending if you are into a corner or running stright and which grate is in the boat. Rob has built some CNC split bowls that are really a piece of art that work great. I think you can check them out on the jetboatracing.com site.

[RiverToysJas]

Dave, let me ask you this - what's the square root of 7?
RTJas

[RiverDave2]

Believe it or not I actually discovered that late last night. So I knew I was going to take some crap for it this morning.. http://free.***boat.net/ubb/biggrin.gif
Lets rethink this through then.
PoPOff valve...hhhhmmmm at Lake Ming RacingRascal was told by a guy that it cost 2500.00 dollars and that it took a tool to reset it everytime it released.
Now that OldSquirt has edumucated old Johnson, I'm REALLY CONFUSED.
If it's on the Suction side of the pump wouldn't it be under "Vacuum" most of the time? Until Engine failure or sudden throttle release? Also being that it is on the suction side it's an extremely Low pressure enviroment (compared to the propulsion side) so why wouldn't a "spring loaded" pressure relief valve work? That will reseat itself after usage.
My main point is There is no justifiable reason that I can think of why something that low tech. Costs that much.
There is REALLY no reason why it shouldn't reseat itself instead of requiring a tool.
If the guys that designed it incorporated the "reseating" feature into the valve it would open it up for all fast jet boats..
OldSquirt, If you don't have a setback do you still run a "popoff?" Or would you run a jetaway setup?
Keep in mind guys I know very little about jets... But I know a little about valves, so I believe I can have something designed and machined thats better then the current product.
Does anyone have a link to the MFG of these PoPoff valves?
RD

[rivercrazy]

I think you should by a jetboat. That way you could become acquainted with them! hehe j/k Dave.
From my understanding, a setback setup usually is always better for top end performance. It moves more weight toward the rear which makes it easier to elevate the bow. It also allows for easier and more efficient installation of a machined ride place and shoe. One of the side benefits of a set back is the handhole is usually outside the boat. This makes it easier to clear the pump if you suck up some weeds or debris. You can get a handhole extension on a non-set back pump that allows you to reach into the intake without flooding the bilge.

[jim lee]

Popoff valves..
Old Squirt is correct in what he says. Here are some #s.. The Biz's popoff is set to "blow" at 90 psi. Its electric. There is also a "Panic Button" on the wheel so the driver can pop it off it if things don't feel right.
The set point of 90 was chosen because it is very close to the actual psi that is in the intake while on the run. What? Not a vacuume? Correct. At speed there is nearly 90 psi in the intake in front of the impleller. There is something like 350 psi behind the impeller.
As for having a tool to reset it. If it is set up incorrectly, this is true. Spent nearly two years fighting the stupid thing. They can be a total nightmare to reset. But, if you know Harld Traylor, you can get some of his magic slime and the tool is no longer nessisary. Can be done by hand.
For racing I -think- I heard that it is not legal to reset them automatically. For lake boating, I'm sure a resettable one would be better.
Why $2,500? Think of the amount of people that would want them. A couple hundred racers, not many. The R&D is expensive as are the bits that go into it. This drives your cost out the roof. You don't get to pay it all off over bizillions of units. Now, if you were to make a lake boat version, you might be able to sell more units. This would lower the cost a bunch.
Racers don't jump on the High Tech. bandwagon in a big hurry. I've run into this a lot. But that's a different story alltogather.
Good luck!
-jim lee

[schiada96]

I wonder if they have a patent on it before one of us smart a//s goes and knocks it off.

[froggystyle]

There are several different kinds made as well Dave. There is a spring pop-off designed to give you another left foot pedal that actuates it, and allows a "neutral" for holding the line at an elevated rpm. I don't believe this type is made any more, and was relatively complicated. A jetaway is a lot cheaper, and the cool thing about it is that you can disengage the pump for service and whatnot. Takes up a good 8 inches though I believe.
Not really a neccessary item for a lake boat. It was however the next investment I would have made for the Daytona. Every squirt running past the bill should have one. Unfortunately, most of us saps are too busy spending money to get to 100 to have the foresight to plan a couple of g's and motor placement into the equation. I don't believe the majority of your target audience builds a 100mph boat. I think the build an 80 mph one and work up to it.
Either way, If you do one, I'll test it on OTR for you. It is set back and easy to get to. Berkeley by the way http://free.***boat.net/ubb/wink.gif