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Intercooler pump gpm flow bucket test


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I hate surprising test results.

I was expecting to see around 3-4 PSID system head, and the Bosch OEM intercooler pump doing 5-6 gpm.

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Cadillac, in bucket, out bucket, extra coolant

This morning I ran a bucket test on my Cadillac STS-V. A bucket test is a simple way to measure gallons per minute of flow in an operating system. To do the test, measure how much fluid comes out of the system over what period of time. Record the result in gallons per minute.

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Bruce

2016 Cadillac ATS-V gray/black

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I think it may have been a tiny bit better flow if the FROM bucket would have been a little higher... but not enough to make much difference in real world driving conditions.

I am surprised at the low flow rate...

I would have thought it would have been better than that.

I have known farmers that had to pump water from a river or a pond, over a levee and into the fields.

They have to figure the LIFT HEIGHT that the water goes over to get the correct pump size.

The downslope on the other side doesn't figure into the calculations very much.

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I agree to an extent, but in a closed system it matters more. The pump has to pump against 1.4 psi to get the coolant up to the intercooler (0.42 psi per foot of water lift), then some PSID to push it through the intercooler.

The coolant flows down-hill to the heat exchanger, through one then the other, and back to the pump. Whatever down-hill pressure still remains when it hits the pump makes it easier for the pump to pump.

Bruce

2016 Cadillac ATS-V gray/black

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The V was battery on engine off for the bucket test. This might yield only 11-12 volts. I could re-do the test with engine on to compare (12.7-14v).

Bruce

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That might make more difference than you think...

If it isn't too much trouble... I think I would do it again...with the engine running... to more closely simulate driving conditions.

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Relatively easy test to repeat - takes an hour or less. It seems to me that something is wrong -- zzp got around 4-5 gpm for a cobalt with same s3 hx. Would be handy to have several other Sts-V results to compare. Example one crimped hose would drive the result, but I don't see that when checking system.

Bruce

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Re-ran the intercooler pump bucket test.

New test setup: FROM bucket at intercooler level, V engine on during pump tests.

Photo0660-e1338051677979-597x1024.jpg

With the pump not even running just the 1.4 psi gravity siphon flow pushed 1.2 gpm through the system. Big difference.

With the pump running the system settled at 3.5 gpm which equates to 6 psid system head. Note that in fluid dynamics system psi increases nearly with the square of the flow delta.

So as flow in this case went up by 3.5/1.2 or x2.9 we expect psi to go up by (3.5/1.2)^1.8 = x6.9. We observed it go from less than 1.4 psi, so say 0.9 psi up to 6 psi just to make the math come out right.

Read More: http://caddyinfo.com...dpress/?p=12911

Bruce

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This whole topic has been a good refresher on fluid dynamics. Fluid flow can be counter-intuitive because it doesn't always act the same way as solid objects, or seem to any way.

Today I am thinking through how to improve one really tight hose turn going into the original Heat exchanger. The new HX sits so close to the original heat exchanger there is little room to turn down, and the hx fitting is a hose barb coming out of the heat exchanger. I hate to modify the fitting on the hx, but I may end up needing to trim it down, or even bend it or solder a fitting on to it to get that improved.

I have a new mounting plate on the way to use with the new pump, so will go in soon. Also want to add in the new tank one of these days.

Bruce

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Added more info to the post based on observed system resistance. I do think that I still have some flow resistances that can be improved, but this is the data today:

pumpandsystemflowpredicted.png

Pump rated flow vs head pressure and system pressure curve

Now, my system resistance of 6 psid may still be higher than it should be; I am looking at the fittings to see if they can be improved further.

If the system numbers are correct than the system flow resistance would be shown by the green line on the chart above. The Y axis shows pressure head. The X axis is in gallons per minute of flow. The blue line is the Bosch OEM pump spec. The red line is the Jabsco pump spec. Where the system flow line crosses the pump lines are where we would expect that pump to operate in gpm and PSID in this system.

So in other words, if the Bosch pump is doing 3.5 gpm against 6 psid, and the system characteristic curve is correct, then the Jabsco pump will do 4.3 gpm which will raise the system pressure head to 7.7 psid.

Bruce

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  • 2 weeks later...

I keep trying to think of ways to improve the methodology for the flow testing, but I had a moment of rare insight -- the important thing at this point is NOT to change the method. All we really want to know is does the system with tank have less flow than without, and to what degree, and does the system with inline tank and new pump have more flow, to what degree, and how the resulting IAT2s change. We don't want changes to the test method, we just need trends. If my current test result of 3.5 gpm should have been +x or -y that's not as interesting as how the system changes and new pump perform on the same test.

Bruce

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Bucket test 3, with inline tank: http://caddyinfo.com/wordpress/cadillac-sts-v-intercooler-flow-gpm-bucket-test-3/

Intercooler cooling flow Result:

We measured a flow of 1 & 3/4 gallon per 30 seconds, or 3.5 gallons per minute (GPM). This is identical to the flow measured in the earlier test without the inline tank. I conclude that the inline tank presents no more resistance to flow, or that the changes in hose routing during the tank install improved flow sufficiently to offset the resistance of the tank.

Bruce

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It may seem like overkill to test with just the change of adding the tank in the system, but I am trying to avoid any head-scratching when we get to the Jabsco pump results.

The way that the tank is used in the system should cause it to look like a pipe, which it does. I test because sometimes the results are not expected.

Bruce

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It may seem like overkill to test with just the change of adding the tank in the system, but I am trying to avoid any head-scratching when we get to the Jabsco pump results.

The way that the tank is used in the system should cause it to look like a pipe, which it does.

I test because sometimes the results are not expected.

I know the feeling well... :):)

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Oh this would be nice to have for bucket tests since it shows the measure. Have to look around at the paint stores / hardware stores and see if I can snag one for tests:

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Amazon:

http://www.amazon.co...c/dp/B000ZZY7LS

Although hopefully one more test and we're done.

Bruce

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It is called a mixing bucket, or measuring bucket. I like this one because it is transparent, but doesn't have to be. Lowe's seems to have a couple of them, but I'll run by there this week and see what my store carries.

Bruce

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Intercooler pump test 4: Testing the Jabsco pump vs the Bosch OEM pump:

http://caddyinfo.com/wordpress/intercooler-pump-test-4/

IMG_0042-1024x764.jpg

Bruce

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The change out is taking an extended length of time. I am not sure what the cool, quick, easy way to get heater hoses off plastic fittings is. The intercooler pump is in a network of heater hoses, plastic fittings, and unreachable clips that don't have the space to release widely enough to slide off anyway lol. I did some judicious surgery and got the pump out, and tomorrow I hope to clean up all the fittings carefully then put new hoses in where needed. I also have to finish designing / modifying the bracket for the new pump and get it to fit. Then I can get out and test.

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This should conclude the intercooler cooling test series, although somewhat related is the idea of methanol injection for air stream cooling.

Bruce

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