Aftermarket vs Stock Intake Hoses
Why go aftermarket? Vendors say:
- When adding a performance filter, intake, or tune the stock inlet hose can start to show it’s weakness…
- The factory hose also has internal ridges which disrupt air flow.
- (Aftermarket is) engineered to increase air flow through to the turbocharger…
- Replaces the entire restrictive rear factory plastic ‘bellows’ pipe
- Back-to-back comparisons with the factory pipe on our flow bench reveals an impressive improvement in airflow.
- Put simply, you’ll be wasting a chunk of the hard-gotten gains from your high-flow intake system if you leave this pipe standard.
Time to put these products to the test on the flow bench:
On one end of the inlet hose is the top half of the airbox, this is primarily to help guide air into the inlet of the hose in a smooth manner.
On the other end is a turbo inlet elbow and an adapter that simulates the entry to the IS20/IS38 turbocharger compressor wheel.
The aftermarket inlet hose used in this test is from Racingline.
Testing at 28″ of H2O produced nearly identical results from the Racingline hose and the stock accordion hose. The Racingline hose just edged out the stock hose flowing 403 CFM versus the stock hose 401 CFM.
Interested to see if at higher airflow rates more of a difference would be measurable the test was repeated but with the removal of the inlet elbow and turbo simulating adapter.
For this second round of tests the hoses were attached directly to the flow bench via an adapter that has the same outer diameter as the inside diameter of the hoses.
For all intents this test was of just airflow through the hoses and a depression of 20″ of H2O was selected because at 28″ the airflow would have exceeded the bench maximum flow rate of roughly 610 CFM.
This time the aftermarket hose generated a higher airflow than the stock hose, 554 CFM for aftermarket versus 533 for stock.
With enough airflow the aftermarket hose starts to show an airflow benefit over the stock accordion hose.
Note: The 533 CFM that the stock intake hose flowed is roughly what the engine draws when operating at 28 psi of boost at 6000 rpm.