BillA's test results for White Water
 

BillA's test results for Cathar's White Water block are up at Overclockers.com

Test results here.

A very nice block. I e-mailed Stew about buying one a little while back, but I decided to wait a bit since I have so many other unfinished items to deal with (actually getting my testbed running, for example).

I wonder if you can get a discount by doing a group order? Might be worth looking into for the .ca people...

:shrug: now I know I have to expect a fairly high pressure drop :(

Excellent work Cathar, congratulations!

The fact that it works very well in a low flow configuration, is a tribute to your design.

Cathar's White Water has set a new high mark in BillA's wb performance testing.

The big block makers wb's if tested will have a hard time coming up to this mark.

Congrats to Cathar for a great wb.

Someone on the OC forums asked about using an Eheim 1250. Here's my reply:

More comments added: doubling the flow rate also means quadrupling the head. The Iwaki MD-20RZT won't quite get you there. (by Since87, now there's a familiar name:D )

This blocks C/W is VERY impressive. This beats anything I have seen on the market. Is this going commercial? I missed the picture of the blockdesign. Is this posted somewhere?

NICE!

Here's the original thread.

It's now 42 pages long...

You have the link to that thread :)

Thanks :)

I think I may faint, someone is finally beginning to realize that substantailly increasing flow requires a lot more pump power yet yields only small benefits. What's the world coming to? All sarcasm aside, I think you left out the impact of doubling flow rate on the radiator. Though minor, it also has some small, positive effect.

Bill's data let's you pinpoint the "knee" in the performance curve for a block. Working to get flow above this point is (pun intended), pointless.

Thankie :D

Ben, with the 1250, a heater core and the WW the flow is more like 6.5lpm, a bit more than you have estimated. Let's see, 1250 = 2M head, 20RZT = 7.x M head so yeah, its almost 4x better, not quite. I would guess around 10lpm with the 20RZT... and the difference between the 2 would be roughly 1 C/W so a decent theoretical temp drop with just a pump, albeit a bit pricey...

they're really nice :D

http://hlh1.netfirms.com/LRWB.jpg

Sorry for the green horn questions but all these charts and figuring is making my head hurt. So what you guys are saying is that for max performance a person would need a pump that is ??? at minimum and over ??? is a waste.

Yeah, you got it. A Eheim 1250 is good, a Iwaki MD-15R is high performance & MD-20rzt is about the most powerfull of reasonable pumps. Anything bigger is not only a waste but will often give worse performance as the larger pump adds more heat to the water.

A Eheim 1250 = 317gph with a potential head of 6.5 ft.

A Iwaki MD-15R = 300gph with a potential head of 11.1 ft. This is a very good one.

A Iwaki MD-20rzt =175gph with potential head of 23 ft. If you can handle the cost and demand the last possible C then enjoy.

Note how the pump with the lowest gph rate will give the highest system flow and lowest temps. While the 1250 with the highest flow rating will have the lowest system flow and poorest cooling, due to it's lower pressure.

But the price differance between the 1250 and the MD-15R stiff. The Eheim is a good pump at the price. Iwaki's are one of the very best pumps so the MD-15 is also a good value when you cnsider the differance in pressure rate and the quality of build. The MD20 can deleiver even higher preformance, but at even higher prices.

1250 = $65

MD-15 = $120

MD-20 = $160

The biggest problem with the MD-20 rzt is the size of it. many cases don't have room for it.

I believe the issue with Ben's estimates is that he was taking BillA's radiator pressure drop results, and possibly using the BigMomma radiator, which in BillA's tests had 3/8" barbs fitted. Using nicely bored out 1/2" barbs results in a much lower pressure drop for a radiator.

As nikhsub1 stated an estimate of 6.5lpm, I'm seeing 6.7lpm flow rates here with an Eheim 1250, a heater-core and a White Water. 5.0lpm flow rates using a Eheim 1048 instead of the 1250.

Hmmm, speaking of "nicely bored out 1/2" barbs " do you bore the ID of your barbs before putting them on the blocks? I ask because I noticed as soon as I opened the box how much flow they allow. I was wondering if you buy them like that or tweak them. I also notice in the pic above with the two blocks that the 3/8" fittings seem much thicker walled.

peace.
unloaded

there is unfortunately only one way the commercial block makers can keep up with the Shade-tree Technicians..... Copy&past....

That's correct. Since no one has anything closer, in terms of a curve for a rad/HC, I had to use that one.

Glad to see that the pressure drop can be lower!

Can you guys tell me how it is that you figure this stuff, I just don't understand. There are a shit load of variables and now this thing with the lower flow and stonger head being a better match for this hi restriction, and how do you know how restrictive it is, waterblock. This is worse than x+y=z to the nth power over pi of the abcdefg...hijklmnop...qrs..tuv...we need a new science wawaology. Anyways thanks for the input fellas I am just trying to better understand this stuff and I am very interested in cathars block, I am going to buy myself one for christmas.

I've used two different 1/2" barb makers. The original barbs were locally made (Australia) items and had thicker walls. The 3/8" barbs are from the same maker.

About 2 months ago I switched to a different 1/2" barb maker. These are barbs made by SUN, and Indonesian based company. They come bored out like that, both for the barbed and threaded sections in stock form. I don't have to touch them. I was very to be able to source them. The local supplier was sadly out of stock of the 3/8" barbs at the time.

Cathar, are you gonna have your Hydra block tested? I know its designed for pelts, gpus, and such but it would be nice to see how well it stands up to mainstream blocks.

In order to answer the flow rates and hence pump selection question, I'll post a summary version of a post I made over at Overclockers.com on this subject, which basically explains how to work this stuff out.

-------------------------------------------------------------------------------

Bill's data typically consists of two important graphs. The "flow vs C/W" graphs, and the "flow vs pressure-drop" graphs.

Looking at the White Water review we find the following:

Flow vs Head-loss (Pressure drop)

http://www.overclockers.com/articles692/WWhlSI.gif

Flow vs C/W

http://www.overclockers.com/articles692/WWcwSI.gif

Where it can get tricky is attempting to predict where one will fall in terms of flow rate. Every 0.01 C/W difference correlates to anywhere from 0.5-1.1C full-load temperature differences depending on how aggressively one over-clocks/over-volts their CPU.

In order to answer the flow-rate question, we must have a pump's PQ (flow vs pressure-drop) chart handy. For the Eheim 1046, 1048 and 1250, these charts look like the following:

http://www.employees.org/~slf/images/eheimpq.jpg

So how does one predict how much flow they'll get? First it's important to understand the pressure drop increases roughly proportional with the square of a flow rate increase. If you attempt to double the flow rate, you will enounter 4 times the pressure-drop resistance. If you half the flow rate, you get one quarter of the pressure-drop resistance. This is nice, because it means that even fairly restrictive blocks can still benefit from decent volumetric flow rates because the pressure backs off quite rapidly if the flow rate is dropped by even smallish amounts.

The best place to start is to first figure out how much flow you have through your pump, and then your pump/heater-core.

For my Eheim 1250, it pushes 14lpm through 2m of Tygon tubing alone, and 12lpm through 2m of tubing and my "Big Arse" heater-core which has 1/2" fittings of 11mm inner diameter. ie. the heater-core has fairly low restriction fittings on it.

Looking at the 1250's PQ curve above we see that 14lpm translates to about a 0.85m pressure drop, and 12lpm translates to about a 1.2m pressure-drop.

Now the pressure drop of a full system is the sum of it's individual pressure drops. In order to work with pressure drops as a result of differing flow rates, we need to bring them all back to an arbitrary reference flow rate. Let's choose 10lpm as a fairly convenient flow rate.

At 10lpm, the pump + 2m of tubing exhibits 0.85m / ((14/10) * (14/10)), or 0.85m / 1.96, or 0.43m of pressure drop. Much of this pressure drop resistance will actually be due to the pump's barbs/fittings as a pump's PQ curve is calculated without the barbs in place.

At 10lpm the pump + 2m of tubing + the heater-core exhibits 1.2m ((12/10) * (12/10)), or 1.2m / 1.44, or 0.83m of pressure drop.

ie. At 10lpm, the heater-core itself offers a pressure drop resistance of 0.4m (being 0.83 - 0.43 = 0.4)

The above gives us a good idea of what the pressure drop resistances of various items in our system.

Okay, so how about if we now plug the White Water block into the system?

At our 10lpm mark, the White Water offers around 3.25m of pressure-drop. In our hypothetical full system, the total pressure-drop at 10lpm is 0.83 + 3.25, or around 4.2m of pressure-drop.

Working out some data points to plot against the 1250's PQ graph.

10lpm => 4.2m PD
9lpm => 3.4m PD
8lpm => 2.7m PD
7lpm => 2.06m PD
6lpm => 1.51m PD

Looking at the 1250's PQ curve, we can see that it's going to push somewhere between 6 and 7lpm. So let's work around there:

6.5lpm => 1.77m PD

Actually this pretty much meets up with the 1250's PQ line almost exactly.

So we can predict that the 1250 will push about 6.5lpm in our hypothetical setup.

In real life, I measured 6.7 in this exact setup. The differences are probably due to my measuring errors, but the theory and the in-practise values do seem to meet up quite nicely within a 3% margin of error.

So with an Eheim 1250 you'll be at or slightly below the 0.18 C/W mark.

With an Eheim 1048, it works out to around 4.9lpm. With an Iwaki MD-20RZ you'll get close to 10lpm (haven't done the exact math at this time).

When the time comes...

It'd sure do well on JoeC's new P4 die tester. ;) (Just a little bit of humor for those who understand why that particular P4 die tester isn't an accurate simulator at all)