A set of data from the 605 turbo’s is included for comparison.  Not surprisingly the F4H spools-up more quickly.

Goal 2: Top end like a RS6

This assessment was more difficult to make due to a few reasons.  First was an interest on my part not to push the F4H turbocharger past a perceived safe operating level.  Being a new product without much information to go on this safe level was somewhat arbitrary.

Second was a shortage of information about the RS6 turbo boost and airflow on my part.

With the TiAL 605’s being fairly similar to the RS6, and the abundance of information I had on the 605’s, I decided to assess the F4H against the 605. 

Below is a chart showing the comparative boost profile of the F4H and 605 with ambient temps and intake air temperatures within 5 degrees for each data set.  The result is not surprising, the F4H holds higher boost earlier, resulting from the quicker spooling nature of the turbo, and the 605 has higher boost toward the upper rpm region.  To reiterate the point that was made before, with additional hardware it is certain that this comparison would look different.

In terms of airflow, both turbo’s are capable of achieving flow rates that exceed the stock sensor limit in an 85mm housing.  A calculation is made based upon intake air temperature, manifold air pressure, engine speed, and estimated volumetric efficiency to predict the airflow in cases where MAF sensor values are unavailable or the sensor reading is scaled such that a direct comparison is not possible.  The sensor reading and calculated airflow values are shown below for each turbo in the boost case shown above.

As would be expected from the boost profile, the F4H is moving more air at lower rpm’s and the 605 more air at higher rpm’s.

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The Results

Goal 1: Spool like K03

Unfortunately I lack appropriate logs from my car when it had K03’s to be able to make a direct comparison.  I do have a number of logs from when my car was equipped with K04’s and from that comparison it should be possible to conclude if it is likely that the F4H will spool up like a K03 turbocharger.

The chart below shows a comparison of the F4H boost rise versus that of a K04.  There doesn’t appear to be a significant difference in the rate of boost rise between the K04 and F4H.  Outside factors such ambient air temperatures, and exhaust system, which can affect the rate at which the turbochargers spool-up are not being accounted for in this analysis.  Considering the K04 turbochargers were operating with a smaller downpipe system and a smaller exhaust pipe, conditions that would inhibit spool-up rather than help, it seems unlikely that there is any significant difference in the rate of boost rise between the K04 and F4H.  Knowing that the K03 turbocharger spools-up quicker than a K04, the conclusion is that the F4H does not spool up like a K03 turbo.