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1997 GTX off season rebuild start.

You don’t want forged in these because the cooling water never heats up so machining clearances have to be more and long warm ups. Best quality pistons are OEM then Pro-X and verified by Harry. Harry sells Pro-X.
For break in I have been following group k recommended procedure for decades.

Oil is the oil you will keep in the ski. So for me XPS full synthetic and an additional 50:1 premix in only the first tank of fuel.

Break in is all about heat cycling and varying throttle.
First half tank run no more than 1/4 throttle but get it up on plane then back off to 1/4 and very the throttle the entire time. Never hold throttle in one position. Run 15 minutes then let cool 15 minutes.
Next half tank is same procedure but up to 1/2 throttle.
Refill tank with straight gas.
Half tank same procedure but up to 3/4 throttle.
Last half of the second tank you can go full throttle but don’t hold it wide open for more than a few seconds.

You are done with break-in. Enjoy your ski.
 
mikidymac said:
Just run the oil pump at close to 1500 rpm and make sure oil is coming out of it.
I honestly don't worry about them. In 35 years of working on these and tens of thousands of threads here I think I only ever heard of 1, that is one, ever failing.
Click to expand...
Test bench "almost" completed. Going to use a combination of ml syringes & sensitive scales to help validate @ 1,500 rpm for 30 sec. Output on single hose then the next hose. Moving forward on rpms up to 7,000 rpm & measure amount within 30 sec. Then after that, various "out of the box" experiments.
It's all in the details & I must know.
Yea, I have issues.......IMG_3951.JPGIMG_3952.JPG
 
AquaEye said:
Test bench "almost" completed. Going to use a combination of ml syringes & sensitive scales to help validate @ 1,500 rpm for 30 sec. Output on single hose then the next hose. Moving forward on rpms up to 7,000 rpm & measure amount within 30 sec. Then after that, various "out of the box" experiments.
It's all in the details & I must know.
Yea, I have issues.......View attachment 68680View attachment 68681
Click to expand...
Dang.... you just graduated to the most ANAL guy I've seen on the forum. :) That ain't a bad thing. LOL
 
Dang man, that is some guru stuff. Nice work.
Honestly I have never tested one. If oil comes out when spinning they have been good to go. Never personally seen one faol, ever.
 
Last edited:
mikidymac said:
Dang man, that is some guru stuff.
Honestly I have never tested one. If oil comes out when spinning they have been good to go. Never personally seen one faol, ever.
Click to expand...
There is one aspect of the oil circuit that I would like to explore besides the fundamentals. Want to "connect the dots" to see if what I know about hyd circuits can crossover to the oil circuit. Hydraulic static pressure, is the pressure exerted by a fluid at rest due to the weight of the fluid above a specific point.(this can be a long story on theory so I'll keep it short) Simply put, is oil amount delivered change as the oil tank level decreases?Must take into account that rise in the line as it terminates onto the pump. Instead of ounces, shall use weight of oil in tank.
Is supply to pump determined solely by atmospheric/weight pressure to keep pump supplied or does the pump exert, (beyond atmospheric/weight) a sustaining suction/vacuum so as to draw fluid in. Reason why I ask is that on those all day excursions to the islands & beyond I would like to know if running tank low(not critical low) @ low rpm( little above idle) so as to explore coves, up/down river or troll.
That's one aspect I wish to find out during this bench test.
Sure, I could bring spare oil to solve that dilemma or that single malt scotch for the island camping & create a dilemma.
See what happens when you have too much time on your hands.🤪
 
Well, pressure is 1 psi per 2.31 feet so the ol tank is about 5" deep and that is less than 0.25 psi so no. Also it is a volume based system so it should provide the same amount of oil at a full tank or a low tank. It is a gravity fed and also an open discharge pump so outlet/inlet pressure really isn't an issue.

It will be interesting on what you find though. But in the real world your engine will have no issues with a low tank oil level as opposed to full, unless you run out.

Sitting here with nothing to do so let's get crazy....

Flows are calculated in gpm and psi
787 fuel consumption 11 gallons per hour at full throttle = 0.18 gpm
Oil consumption is average 40:1. 0.18 / 40 = 0.0045 gpm of oil
Atmospheric pressure 14.7 psi but inlet and outlet pressure are the same so that is nominal. Hydraulic head pressure is only about 12" so let's call it 0.5 psi.
3/32" oil injection line per cylinder for about 18", but that delivers 50% of the oil so we would have to look at the friction losses of two hoses.
Hydraulic friction loss is 0.0008 psi.
So you are still gaining pressure at the oil injection outlet at the intake manifold just from gravity, 0.4 psi with a full oil tank and 0.3 psi with an empty oil tank with the pipe friction and the oil tank location above the engine.

I think your findings will be interesting.
1. Does rpm change the output volume or just the lever.
2. What pressure does the pump need to make to overcome the check valves?
3. Does the intake vacuum of the engine change the flow?
 
Last edited:
mikidymac said:
Well, pressure is 1 psi per 2.31 feet so the ol tank is about 5" deep and that is less than 0.25 psi so no. Also it is a volume based system so it should provide the same amount of oil at a full tank or a low tank. It is a gravity fed and also an open discharge pump so outlet/inlet pressure really isn't an issue.

It will be interesting on what you find though. But in the real world your engine will have no issues with a low tank oil level as opposed to full, unless you run out.

Sitting here with nothing to do so let's get crazy....

Flows are calculated in gpm and psi
787 fuel consumption 11 gallons per hour at full throttle = 0.18 gpm
Oil consumption is average 40:1. 0.18 / 40 = 0.0045 gpm of oil
Atmospheric pressure 14.7 psi but inlet and outlet pressure are the same so that is nominal. Hydraulic head pressure is only about 12" so let's call it 0.5 psi.
3/32" oil injection line per cylinder for about 18", but that delivers 50% of the oil so we would have to look at the friction losses of two hoses.
Hydraulic friction loss is 0.0008 psi.
So you are still gaining pressure at the oil injection outlet at the intake manifold just from gravity, 0.4 psi with a full oil tank and 0.3 psi with an empty oil tank with the pipe friction and the oil tank location above the engine.

I think your findings will be interesting.
1. Does rpm change the output volume or just the lever.
2. What pressure does the pump need to make to overcome the check valves?
3. Does the intake vacuum of the engine change the f
Click to expand...

mikidymac said:
Well, pressure is 1 psi per 2.31 feet so the ol tank is about 5" deep and that is less than 0.25 psi so no. Also it is a volume based system so it should provide the same amount of oil at a full tank or a low tank. It is a gravity fed and also an open discharge pump so outlet/inlet pressure really isn't an issue.

It will be interesting on what you find though. But in the real world your engine will have no issues with a low tank oil level as opposed to full, unless you run out.

Sitting here with nothing to do so let's get crazy....

Flows are calculated in gpm and psi
787 fuel consumption 11 gallons per hour at full throttle = 0.18 gpm
Oil consumption is average 40:1. 0.18 / 40 = 0.0045 gpm of oil
Atmospheric pressure 14.7 psi but inlet and outlet pressure are the same so that is nominal. Hydraulic head pressure is only about 12" so let's call it 0.5 psi.
3/32" oil injection line per cylinder for about 18", but that delivers 50% of the oil so we would have to look at the friction losses of two hoses.
Hydraulic friction loss is 0.0008 psi.
So you are still gaining pressure at the oil injection outlet at the intake manifold just from gravity, 0.4 psi with a full oil tank and 0.3 psi with an empty oil tank with the pipe friction and the oil tank location above the engine.

I think your findings will be interesting.
1. Does rpm change the output volume or just the lever.
2. What pressure does the pump need to make to overcome the check valves?
3. Does the intake vacuum of the engine change the flow?
Click to expand...
Outstanding info. And this is why I chose to contribute. Nothing like "picking the brain" of an experienced PWC enthusiast that "been around the block" a time or two.
You may or may not have already seen this vid but I found it very informative.
www.youtube.com/watch?v=wi_BOVtUAWg&list=WL&index=5&t=351s
 
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