I think I’ve just about reached the point of having diminishing returns with respect to upping the boost (26 psi out to redline) on the FrankenTurbo F21’s. Back pressure on the exhaust side is getting up there and FATS times aren’t coming down as much as they were when going from 22 to 24 psi.
I’m working with Daz on the tune, and he’s looking to clean a few things up before I head off to the dyno to get numbers for these turbo’s.
26 psi Intake Manifold versus Exhaust Manifold Pressure
This chart above illustrates what happens to exhaust back pressure when there is a leak on the intake side. A few pulls later a hose clamp slipped off and I had an audible boost leak. The chart below was made after eliminating the air leak.
Note: I had to switch pressure sensors to create the chart above since the 4 bar sensor on the exhaust manifold was being maxed out at 26 psi of intake manifold pressure. There is possibly some accuracy discrepancy between the two sensors. I would allow for up to 2 psi of error when comparing the exhaust manifold pressure from the chart immediately below with the two further down the page.
27 psi Intake Manifold Pressure vs Exhaust Pressure
This is a comparison made holding approximately 24 psi.
24 psi Intake Manifold vs Exhaust Manifold Pressures
This is the F21MF version of the boost profile used with the BW K04’s.
22 psi Intake Manifold vs Exhaust Manifold Pressures
Over the weekend I received a shipment of BMW N54 engine turbocharger inlet pipes for flow bench testing. I’ve tested a couple other sets of these inlet pipes in the past and I was interested to see how another take on these parts would perform.
This set was supplied by FrankenTurbo, the same vendor that had shipped the stock BMW inlets to me several months ago for flow testing.
Here are a couple pictures of these FrankenTurbo inlets on the flow bench:
FrankenTurbo Inlet on Flowbench
Second FrankenTurbo Inlet on Flowbench
The test was performed similar to how I did in the past, affixing the inlet to the flow bench and drawing air into the pipe.
Inlet Flow Results:
The chart below is a compilation of all of the BMW turbo inlets that I have flow tested.
BMW N54 Engine Turbo Inlet Pipe Airflow Comparison
In a departure from the presentation that I used in the past I am limiting the chart to airflow readings that occurred at a test depression of 28″ of H20.
There are two reasons for this; firstly 28″ of H20 is a commonly used test point for flow bench airflow tests.
The second reason is that the chart I produced previously included extrapolated data, going out to test depressions two to three times what I recorded on the bench. Estimating out that far introduces errors, which are magnified the further one extrapolates. To better assess how the products compare, I am limiting the results to the range that the flow bench can directly measure.
Something else to point out, I am not familiar with how these pipes attach to the N54 engine, so the labeling scheme that I used may be incorrect. That is, I have labeled one pipe number one and the other number two. I’m not sure that this is the proper naming convention for all of the products, in some cases I may have mislabeled pipe two as pipe one. Keep that in mind as you review the chart data and compare airflow readings between the pipes.
Here’s an additional chart showing the FrankenTurbo inlets with the adapters added for coupling them to the turbochargers. Airflow decreases with the addition of the adpaters.
