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  #31 (permalink)  
Old 07-19-2012, 12:45 AM
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I'm not speaking for anyone but myself. But one big difference is the viscosity of water and motor oil at different temps. And the work required is going to be greater at a higher pressure than a lower pressure if the volume is equal.

On another note, your question was "Has all the taboo talk about high vol. high pressure been misinformed speculative Voodoo?" has been answered. There are reasons to use- and to NOT use- pumps based on their performance. In a larger sense this is basically a moot point. The pumps that are available define the pumps we are going to use. There are off the shelf pumps that offer adequate pump performance versus cost, and the selection as it stands today is sufficient for 99.9% of the applications out there.

I understand this is not an answer to how to estimate a pump's performance using a formula. But when there's no real application for such a formula (given the pumps available are what is going to be used anyway), why is it even an issue, except as a mental exercise of some sort? You could find the formula, and then what?

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  #32 (permalink)  
Old 07-19-2012, 11:15 AM
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[quote=Cridder;1575092]
Quote:
Originally Posted by ap72 View Post
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 5W-20 to 10W-30, hell even going from 120 to 220 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
Apparently you don't know what linear is... Also gear pumps as a general rule are "more linear" than other types, but that is not linear, its a curve. Also, this is ONE particular pump, a pump that is not at all related to an SBC oil pump.

Instead of using faulty logic to convince yourself you know something just find or develop the pump curve for each pump. Melling may have curves for all of those pumps on file. If you do get a pump curve pay attention to the fluid properties used for the developement.
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  #33 (permalink)  
Old 07-19-2012, 11:45 PM
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Logiclly linear

[quote=ap72;1575190]
Quote:
Originally Posted by Cridder View Post

Apparently you don't know what linear is... Also gear pumps as a general rule are "more linear" than other types, but that is not linear, its a curve. Also, this is ONE particular pump, a pump that is not at all related to an SBC oil pump.

Instead of using faulty logic to convince yourself you know something just find or develop the pump curve for each pump. Melling may have curves for all of those pumps on file. If you do get a pump curve pay attention to the fluid properties used for the developement.

If a pumps output volume is proportional to it's rpm input, then that is linear, it's output being proportional can easily be calculated at any rpm.
If the pump cavitates after a particular rpm then output will suffer and the pump becomes non-linear.

I just want to make a basic comparison of 4 pumps.
To do that i don't need to develop any curves.
All I'm saying is "this is the cubic inch displacement and if i multiply by rpm i get volume over time".

There's no faulty logic in that

If i say i want to compare any pump for that matter, Cubic inch displacement is as good a place to start as any.

There's no faulty logic in that!

You need to stop trying to prove that i've made a false comparison, when the math is so simple it's embarrassing
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  #34 (permalink)  
Old 07-20-2012, 12:38 AM
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If Albert Einstein were a gearhead?

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Originally Posted by cobalt327 View Post
why is it even an issue, except as a mental exercise of some sort? You could find the formula, and then what?
I was thinking this whole website is like that.
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  #35 (permalink)  
Old 07-20-2012, 04:55 AM
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Quote:
Originally Posted by cobalt327 View Post
...why is it even an issue, except as a mental exercise of some sort? You could find the formula, and then what?
Quote:
Originally Posted by Cridder View Post
I was thinking this whole website is like that.
And you are welcome to your opinion. But I find that the vast majority of the info provided here has an interest and even a use to a broad segment as opposed to something as esoteric as this.
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  #36 (permalink)  
Old 07-20-2012, 05:43 AM
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Just as a casual, non-threatening , point of interest i am changing the HV Melling pump in my SB 347 for a Standard Melling Pump after communicating with Melling direct. I have C/R clearances and Mains that are on the minimum allowable spec. and considering mild street use, a HV pump was not required. THe information I supplied to the Tech. Dept there was, oil weight and temp of operation ( sump oil temp sender fitted) and max operating RPM for the engine.
The communication was FRIENDLY and helpful.
I worked with an engineer years ago at our bearing manufacturing plant who had an attitude problem, despite having three degrees. They fired him.
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  #37 (permalink)  
Old 07-20-2012, 06:07 AM
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Quote:
Originally Posted by 67Mustang Al. View Post
Just as a casual, non-threatening , point of interest i am changing the HV Melling pump in my SB 347 for a Standard Melling Pump after communicating with Melling direct. I have C/R clearances and Mains that are on the minimum allowable spec. and considering mild street use, a HV pump was not required. THe information I supplied to the Tech. Dept there was, oil weight and temp of operation ( sump oil temp sender fitted) and max operating RPM for the engine.
The communication was FRIENDLY and helpful.
I worked with an engineer years ago at our bearing manufacturing plant who had an attitude problem, despite having three degrees. They fired him.
Was it you that was talking about installing a temp sender a while back, possibly through the drain plug? If it was, how did it turn out?
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  #38 (permalink)  
Old 07-20-2012, 07:37 AM
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Quote:
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Was it you that was talking about installing a temp sender a while back, possibly through the drain plug? If it was, how did it turn out?
HI Co 327. Must be some other dude going in through the sump plug. I ended up turning up a lump of aluminium into a small boss of about 1.5inch dia. drilled and tapped the BSP thread typical of a sender in the centre and then fastened it to the opposite side of the sump to the drain plug with a few rivets and a gasket. ( sump off)I have always been a "gauge watcher" and my work with the design of tri and bimetal brgs forced me into it.
Our summer just gone a few months ago saw my 10/30 Fuchs GTO reach 90 C but now in winter here 70 c seems to be the mark. The only difference i have noted between the two seasons is that the hotter oil in summer drops about 5 psi lower at idle to 50 but still stays at 60-65 when the relief kicks in.The Milodon has a large capacity as you would know and takes a while to warm up compared to the water temp.
I can post a pic if you want to have a look at the setup Cob .
Cheers from downunda.
Al
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  #39 (permalink)  
Old 07-20-2012, 08:46 AM
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[quote=Cridder;1575365]
Quote:
Originally Posted by ap72 View Post


If a pumps output volume is proportional to it's rpm input, then that is linear, it's output being proportional can easily be calculated at any rpm.
If the pump cavitates after a particular rpm then output will suffer and the pump becomes non-linear.

I just want to make a basic comparison of 4 pumps.
To do that i don't need to develop any curves.
All I'm saying is "this is the cubic inch displacement and if i multiply by rpm i get volume over time".

There's no faulty logic in that

If i say i want to compare any pump for that matter, Cubic inch displacement is as good a place to start as any.

There's no faulty logic in that!

You need to stop trying to prove that i've made a false comparison, when the math is so simple it's embarrassing
Its not that you did anything wrong, its just that you're assuming your calculations carry some merit. Yes you calculated the theoretical maximum displaced volume, unfortunately those pumps you're looking at are not close to 100% efficient, and the efficiency varies, and it is NOT linear. As far as I can see the graphs I provided are parabolic, but that's just a guess.

Instead of getting all worked up over 13 seconds of calculations just CALL MELLING! They may help you out.




As far as an oil temp sensor, I've heard you can use some water temp sensors, which I may wire into one of my MS systems just for fun some day.
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  #40 (permalink)  
Old 07-20-2012, 09:46 PM
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Quote:
Originally Posted by 67Mustang Al. View Post
HI Co 327. Must be some other dude going in through the sump plug. I ended up turning up a lump of aluminium into a small boss of about 1.5inch dia. drilled and tapped the BSP thread typical of a sender in the centre and then fastened it to the opposite side of the sump to the drain plug with a few rivets and a gasket. ( sump off)I have always been a "gauge watcher" and my work with the design of tri and bimetal brgs forced me into it.
Our summer just gone a few months ago saw my 10/30 Fuchs GTO reach 90 C but now in winter here 70 c seems to be the mark. The only difference i have noted between the two seasons is that the hotter oil in summer drops about 5 psi lower at idle to 50 but still stays at 60-65 when the relief kicks in.The Milodon has a large capacity as you would know and takes a while to warm up compared to the water temp.
I can post a pic if you want to have a look at the setup Cob .
Cheers from downunda.
Al
That's a very innovative way to mount the sender, I like. If you have a photo I'd like to add it to the CC wiki, probably on the Chevy oiling system page, w/your permission.
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  #41 (permalink)  
Old 07-21-2012, 12:55 AM
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Quote:
Originally Posted by cobalt327 View Post
That's a very innovative way to mount the sender, I like. If you have a photo I'd like to add it to the CC wiki, probably on the Chevy oiling system page, w/your permission.
Hi Co 327. Thats fine.
Thanks, i should make a dozen or so and put them on ebay. From memory i used 5/32 stainless metal threads from the marine shop as the original 1/8 rivets i used didnt get an even crush on the "O" ring i have sitting in a groove i machined on the mating face. Consequently there was oil weeping out. Now its okay as you can apply even pressure with the metal threads. I also used a smear of RTV before fitting off. No more leaks .
Cheers
Al.
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