Category Archives: Intercooler

Intercooler pump test 4: Jabsco 29 gpm pump

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Update: IAT2 test results added

Today I performed an intercooler pump test on the Jabsco 50840 12v pump as a replacement for the Bosch OEM intercooler pump in my Cadillac STS-V.  The Cadillac STS-V uses the Bosch 00 392 022 006 pump.

My Cadillac has a 2nd heat exchanger, an S3 provided by Timmy C, and uses a 1 gallon AVS inline intercooler tank.  The goal of these tests is to improve intercooler cooling, which will enable the supercharged V8 to make more power.

Test setup with Jabsco pump in the loop

Intercooler pump test setup

To run a bucket test I put a FROM bucket at intercooler height, flowing into the pump and system, and out from the intercooler to a TO bucket.  This is similar to my previous intercooler pump test setup, for continuity.  I have added a TO bucket that is a mixing bucket which makes it very easy to measure output.

Predicted intercooler pump test flow:

Pump rated flow vs head pressure and system pressure curve

The Jabsco centrifugal pump does 29 gpm against no resistance, and the Bosch pump does 8 gpm against no resistance. In an actual system the pump curves overlaid with the system resistance curve predict where the pump will actually run in that system.

Intercooler Pump Test Results

In today’s test the Jabsco pump measured at a steady 2.25 gallons per 30 seconds, or 4.5 gpm (gallons per minute).  Previously, the Bosch OEM pump ran at 3.5 gpm, which would suggest the system pressure at that flow was 6 psid.  As flow increases, the resistance pressure in the system increases roughly at the square of the flow.  I expected the Jabsco pump to run 4.3 gpm, so the 4.5 gpm is good.  The Jabsco has 1/3.5 = 28.5% more flow than the OEM pump.

I still have more work to do to complete pump installation.  I will retest with the pump in place.  I will follow-up the intercooler pump test with IAT2 tests to see how the new higher flow impacts intercooler cooling.

Continuing to modify and fit check the Jabsco pump on the OEM bracket.

Intercooler Pump Test Update

Today I completed the pump install and conducted a test run with the new pump:

Intercooler pump test showing IAT2 over time during a 20 min drive

Click on the graph for a larger version.

What this graph shows is temperature in degrees F on the Y axis, over a 20 min drive on the X axis.  Spikes in the graph represent acceleration runs.  The red line is the OEM pump without the inline tank; the blue line is the OEM pump with the inline tank; the green line is the Jabsco pump with the inline tank.  Today it is 92F ambient; on the prior test days it was 90F ambient air temperature.

I read this test result to show that the jabsco pump’s greater flow allows the system to reach an IAT2 equilibrium temperature of 118-120F, an improvement of 7F.   The acceleration spike is a 20F increase, an improvement of 5F in addition to the lower equilibrium, so that at peak temps are 12f lower than previous hot day.

Intercooler pump test conclusion:

The Jabsco pump has a 1 gpm higher flow than the OEM Bosch pump.  This 1 gpm greater flow lowers the operating IAT2 temps by 7F

Ambient temp 92F; ambient air temp resets to 32f until the ecm can determine actual temps. Near gear change at top of 2nd gear.  Losing 1 degree of advance to IAT2 retard.

Cadillac STS-V Intercooler Flow GPM Bucket Test 3

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Today I conducted a new flow test on the intercooler cooling system for my Cadillac STS-V.  Previously I ran a bucket test to determine the actual flow through the intercooler cooling system.  Since that test, the system has been modified to add an inline intercooler tank.  I plan to change the pump from the OEM Bosch pump to a Jabsco 80540-12 pump soon, so today’s test confirms the flow rate prior to the next mod.

The overall purpose of this series of tests and changes is to improve intercooler cooling, which will result in lower intake air temperatures after the supercharger, and let the engine make more power.

To run the test I place a ‘from’ bucket on a table, which has replaced my earlier box due to box degradation.  The From bucket flows into the first heat exchanger.  The To bucket is flowing out of the intercooler.  The goal of the test method is to measure the flow as if the test were not going on — to not impact the flow.  This is why the From bucket is in a raised place.

Today my Son assisted me with timing and checking the test setup.  We ran the test with the car engine on, to simulate working conditions for voltage.

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.

 

Cadillac STS-V intercooler pump bucket test

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UPDATE:  Re-ran the test with a change in the test setup, yielding closer to the expected results.  See Below.

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.

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.

First I calibrated my bucket. I used a “TO” bucket that was shaped like a cylinder, with no slope to the sides. That simplifies measurement. I took a large 1/2 gal kitchen measuring cup and put 1/2 gallon of water in “TO” my bucket. Then I measured how many inches of depth were in the bucket. My bucket measured 1&1/4″ per 1/2 gallon. I added another 1/2 gallon and noted that the bucket was at 2.5″; good.

Next, I put the STS-V up on jackstands, and removed the undertray. I disconnected the hose from the hard pipe out at the bottom of the V coming out of the intercooler, and put a “out” hose there leading to my “TO” bucket. I put the hose that had been connected there in my “FROM” bucket. I added coolant to my “From” bucket, and ran the test.

The pump in the test is the Bosch OEM intercooler pump. It is pumping through the intercooler, and pulling from both heat exchangers so that the flow should exactly model what the pump sees in operation.

What I measured was a meager 1 & 1/2″ of flow per 60 seconds. Since 5/4″ was 1/2 gallon, 6/4″ is 20% more or 0.6 gallons per minute (GPM). That means that the current pressure head in the system as tested is nearly 7 PSID. The Bosch pump can only pump against a max of 7.3 psi.

I plan to test with a Jabsco pump next. The Jabsco pump is rated up to 8 PSID, and at 7 PSID might be able to push 4 or 5 gpm.

What would you change in the test setup? Hit the comments!

Did my test setup effect the outcome? If the “FROM” bucket was elevated to the same level as the intercooler at the top of the engine, would that be more fair? Or does the down force from the intercooler height to the bucket get ‘counted’ in the flow out the “TO” hose already and so is not ‘lost’?

Next:

  • Re-run the bucket test
  • Check all hoses for crimping
  • Raise the “FROM” bucket to intercooler level
  • Test with the engine on, not just battery/pump on with engine off as before — full voltage

Update — Raise the Bucket:

Re-ran the test with the from bucket at intercooler height. New pump flow 3.5 gpm, much closer to expected.  40″ of water height is a static 1.4 psi into the system that is there in operation but missing from my initial result.

For this test I put the “FROM” bucket at 42″ height, or the intercooler height in the car.  I did that because the hoses and pipes leading to where I put the “FROM” bucket are the downhill flow from the intercooler.   I pushed water through the FROM line to prime the line and ensure that I got gravity siphon flow through the line and into the car.   With the bucket and line in place the system actually flowed 1.2 gpm with NO pump running.  So the height of the bucket makes a difference — each foot of height of water gives 0.42 psi, so 3.3 feet equates to 1.4 psi or so.  My original test had the FROM bucket on the ground, so inadvertently took away this 1.4 psi of system pressure.

FROM bucket at intercooler height, TO bucket at ground level

I ran the engine at idle when I was testing the pump.  With the pump on in the retest the system did a steady 3.5 gpm flow.

This suggests that at 3.5 gpm the system pressure head is around 6 psi assuming the OEM bosch intercooler pump is operating to spec.

It also ties with the first test result given the setup difference.

The test perhaps also points to the system psid curve versus flow — 1.4 psi at 1.2 gpm flow, and 6 psi at 3.5 gpm flow.  We expect psid to go up as a function of nearly the square of the change in flow, so this also seems appropriate.

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.