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True. Since a carb meters by volume, when you add more oil it causes a lean condition. But it is kind of a moot point if you run a synthetic 2 stroke oil at a 100:1 ratio.





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My lesson came cheaply just two and a half gallons of high test and some castor oil was all it cost me. Plus I was racing karts, not bikes. I could have remixed the fuel by adding more gas, but I didn't want to chance getting it wrong so I burned it in the 'yard wrecker. For a little while running it smelled just like the pits during a race! BelRay and Klotz (among others) were selling synthetic 2stroke oil even back then, but castor was what I learned on so I stuck (no pun intended) w/it throughout my kart 'career'. 


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If you can't accept that the Chevy gear pump can be for comparison purposes defined with a math formula found in a hydraulics handbook than that is your right. The formula i used is available online and in the Womack Educational Publications fluid power data book used by hydraulic engineers the world over, it's on page 25 titled "replacement of pump or motor" Please feel free to present a more satisfactory formula that shows pump output so we can make a definitive comparison. 


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What you need to have any credible comparison is a graph for each pup that looks similar to this: http://www.dynafloweng.com/pics/gear.../g34curves.jpg Notice, pump speed, pressure, flow, fluid, and fluid temperature are all included. This is how REAL hydraulic engineers start to compare pumps. FWIW, I know this because I do use it at work when dealing with water conveyance systems. And yes, I am a licensed engineer, so **** about what "engineers do". "Engineers" do all sorts of different ****, and SOME of it is even useful and correct, as a member of the club I can say there are a LOT of engineers that aren't worth the paper their degree is printed on. There are also some damn good ones who really do know what's going on. 


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As for the formula I provided it, you plot the system curve on the pump curve and viola you have expected pump output. That's not sidestepping, THAT IS THE FORMULA. You can also do it by the displaced volume method as he originally did but then you need to multiply that by the pumps efficiency, which is variable and can also be plotted on a chart. If you're really bored you could model it with a differential equation but that will vary depending on how complicated you get, you would need at least a variable for size, type, pressure, flow, two for efficency, pump speed, at least four for fluid properties. Again you can account for any variance in your equation but then you're getting more complicated than it would ever be worth. Also, if you're going to go this far you may as well develop an equation for the system curve. REAL engineers use pump curves and plot the estimated (or sometimes measured if its for a preexisting system) system curve. 


You did NOT provide a formula. At best you gave a half baked formula for a formula, totally lacking in anything specific.



I think you missed your calling. You ever consider politics?



I think the problem is, AP72 is saying that coming up with a formula tedious and more than likely inaccurate due to real world variables, and as such is meaningless. The only way to rate a pump is to control as many variables as you can and make a graph since that is the true representation of what is going on. There will be no way to find the efficiency of a pump unless you measure it first.
Besides once you get the graph plotted out, who is to say that you can even retrofit a nice equation to fit the graph. 


We can solve it from here
Learning to put together a formula is why we took Algebra in high school.
Many problems can be explained and solved through Algebra. With algebra you don't need a formula becuase by using the rules of Algebra you can biuld your own formulas. A complete equation can be a formula within a formula within a formula. I presented part of an equation and invite any and all to particapate in the analysis of this mechanical device. for me this is one of the things Hot Rodding is all about. Last edited by Cridder; 07182012 at 06:51 PM. 


You're gonna need some heavier math than just algebra, I'm afraid.



have your cake and eat it too
[QUOTE=ap72;1574873]What you need to have any credible comparison is a graph for each pump that looks similar to this:
http://www.dynafloweng.com/pics/gear.../g34curves.jpg Notice, pump speed, pressure, flow, fluid, and fluid temperature are all included. This is how REAL hydraulic engineers start to compare pumps. QUOTE] I looked at this dynfloweng.com graph you provided and i noticed that the pump has almost perfect lineairity, As i recall you said: "The fact that you think the pumping volume is linear and that you would see anything close to 100% efficency shows me your WAY off. Also, you didn't mention any properties for the fluid your pumping, which will have a HUGE impact, even something as simple as switching from 5W20 to 10W30, hell even going from 120º to 220º with the exact same oil will have a HUGE impact." First you say i'm way off in my calculation because i assume linearity and then you show me a graph that illistrates a pump with perfect linearity. would you say that that is a contradiction? please explain 

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