When I received the Turbo Concepts Stage 1 turbochargers I had inquired about what boost level to operate them at.  I was advised to aim for an initial ramp up to 18-20 psi then start tapering the boost off, try to reach 15 psi by 5000 rpm and down to 12 psi by redline. About what the blue lines on the chart below look like.

Initially after installing the TC turbo’s my intent was to record some basic performance data that I could compare with the other turbochargers that I have recorded.  That meant I had to operate the Turbo Concepts turbochargers at a boost level higher than  was recommended.

With the initial data collection behind me I’ve taken the opportunity to drop the boost and see what happens. The chart above is the result of the first revision to the tune.  The red boost lines are the Turbo Concepts turbochargers, the blue boost lines are the product of BorgWarner K03’s and the NVR Stage2+ tune.

Just by chance the NVR tune with the K03’s is a close boost profile to that recommended for the Turbo Concpets turbo’s – this provides an interesting case to look at for similarities and differences.

There are a couple of notable differences in the K03’s vs TC Stg1 results, first is that the TC turbo’s are being operated at a slightly higher boost level.  This was the first revision to the tune and I was taking a stab at the values for LDRXN that I thought would produce a boost curve close to what Turbo Concepts had recommended.  The second notable point is that the log with the K03’s was made during the summer time, with air temperatures of 70 degF.  The Turbo Concepts data was recorded in December with air temperatures of 20 degF.  The large gap between the Intake Air Temperatures is evidence of these different conditions.  The K03’s are the dashed lines and TC turbo’s the solid lines.

Given these two considerations, higher boost and colder air, one would expect higher mass airflow readings from the Turbo Concepts turbo’s, which is the case.  I would expect that if the conditions were more alike, similar boost and similar air temperature, the mass airflow would also be more similar.  This leads to an interesting conclusion, it’s likely that the engine would perform about the same with the TC Stg1 turbo’s as it would with the BW K03’s when operated at this boost profile.  I’ve found mass airflow to be a good predictor of wheel horsepower.

This leads to a question, how can the Turbo Concepts Stage 1 turbo’s reach the advertised 380 whp if they are being operated at the recommended boost level?  According to the results I’ve obtained the TC Stg1 should be making about 300-310 whp at the recommended boost level.

To get close to 380 whp the boost will need to be raised.  When I’ve operated the TC Stg1 at around 22 psi I am seeing close to 380 g/s towards the top end which should put the car close to 380 whp.

This leaves an unresolved issue, how to reach the advertised wheel horsepower at the boost level Turbo Concepts recommends operating these turbochargers at.