need quick answer, water line pressure at wot

[SuperJETT]

What is a good number to use for water line pressure at wot on a SJ? I'm talking a single cooling line, with just one bypass.

 

[Big Kahuna]

hmmmmmmmmmmmmmmmmm never measured........ strong steady stream, more of a spray.

 

[freestylegeek]

I was really hoping Chuckie (Supertune) would chime in here and help us out...

 

[Matt_E]

Busy guy.

 

[Rickster]

Ok, I'm not an Hydrological Engineer, but I would think this pressure would be contingent on the following.

Pump specification
inside dia of lines
length of line
type of head
type of pipe
electrical
etc...

Anything that affects the speed of the prop (flow of water through the prop) or has a resistant effect on the water flow, would change the water pressure.

:bigeyes:

***Now I have a Headache***

 

[SuperJETT]

Actually, it's just:
nozzle size
impeller pitch/design
pickup design in the stator section of the pump
hose/tube length

After that, I'm not worried, just needing pressure coming through the bulkhead really. I may stick a gauge on mine this weekend on the trailer.

Ok, I'm not an Hydrological Engineer, but I would think this pressure would be contingent on the following.

Pump specification
inside dia of lines
length of line
type of head
type of pipe
electrical
etc...

Anything that affects the speed of the prop (flow of water through the prop) or has a resistant effect on the water flow, would change the water pressure.

:bigeyes:

***Now I have a Headache***

 

[Idok]

here's another good question for you to ponder....


what is the pulse pressure, or bottom end cranking pressure of a 701?

 

[WAB]

I'd think the type of intake grate makes a diff. also.
I went to a more agressive style top loader and noticed it made the pissers shoot harder.

 

[Mark44]

I hear if you pull an intermitant vacuum on the crank case you can get another 10 HP.

Mark44

 

[Rickster]

Actually, it's just:
nozzle size
impeller pitch/design
pickup design in the stator section of the pump
hose/tube length

I just changed engines in my ski, both engines had 61x jugs, one with a shaved stock head and the other with an ADA head.

all hoses, pump, etc stayed the same during the switch.

There was a noticable increase in the pressure of the water that came out of the pisser.

:biggthumpup:

 

[freestylegeek]

I just changed engines in my ski, both engines had 61x jugs, one with a shaved stock head and the other with an ADA head.

all hoses, pump, etc stayed the same during the switch.

There was a noticable increase in the pressure of the water that came out of the pisser.

:biggthumpup:

Because the ADA head is FAAAAAAR less restrictive.
You had more flow, not pressure.

 

[Rickster]

would restricton not cause pressure or lack of?

Look at the venturi of a carb, this increases the speed of the air rushing through, which surely would increase the pressure....

Just trying to get my head around this....:biggthumpup:

 

[SuperJETT]

A venturi actually decreases pressure (increases vacuum) to aid in atomization/drawing fuel through the carb.

 

[SuperJETT]

The highest pressure will be at the pump fitting. Everything from there on drops pressure, every restriction, every length of tube, every fitting, etc as there is nothing else to increase pressure.

 

[robertg]

I would guess 25 psi at least, it depends where you take it. Your presure will be the highest right at the pump and it should be slightly lower as you go down stream. If you reduce your pisser size your pressure will go up. That's why some of us open up out B pipe screws more than others.

 

[Speedfreak]

I have a low pressure gage that could be T'eed into the inlet line at the pump to find out but you would have to view it in the tray while at WOT. If no one finds out by next summer I can find out but the water is way too cold for me to get in.

A low pressure gage teed into the puls line would give you a reading also. An automotive gage for a fuel system that has 30 psi pressure and 30 in of vac. would be great then you could see how far it goes both ways. I will try to do this this weekend if I can get my gage back from a friend...LOL

 

[romack991]

would restricton not cause pressure or lack of?

Look at the venturi of a carb, this increases the speed of the air rushing through, which surely would increase the pressure....

Just trying to get my head around this....:biggthumpup:

this is a overly simplified slide of whats going on...

basically you have a certain amount of energy coming from the pump due to your engine pump setup, this stays constant at a given rpm. your flow rate at the end of the system will be be determined by how much restriction/friction loses you have. (There is no pressure once the water leaves the pisser/stinger/whatever.)

note, this is a very simplified chart, if you just pugged in numbers, it is not the right answer but this does describe the relationship.

 

[waxhead]

never really worried about the pressure coming out
just the flow

 

[romack991]

never really worried about the pressure coming out
just the flow

water has zero pressure when i comes out of your pisser, by then all the energy has been converted into kinetic energy (simplified is your water flow) or been lost due to restrictions/friction.

i believe jet is asking what the water pressure is when it comes from the pump throught the bulkhead.

 

[FLY6584]

I don't think anyone has asked this yet, but why do you need to know the pressure? just curious.