Thermal Coated FrankenTurbo

Back from having thermal coating applied to the FrankenTurbo F21 turbine housing.

Next for these will be reinstalling them, date TBD, to try and determine if any changes can be measured that arise from applying the thermal coating.

FrankenTurbo F21 turbine housing with Thermal Coating applied
FrankenTurbo F21 turbine housing with Thermal Coating applied


FrankenTurbo F21 turbine housing with Thermal Coating applied
FrankenTurbo F21 turbine housing with Thermal Coating applied

White Dog Racing RS4 TB/Bipipe

Another product from White Dog Racing was sent to me for flow testing and comparison to the White Dog Racing bipipe products that I previously flow tested, along with the few other Audi B5 S4/RS4 bipipe options.

This time I received a 60 mm bipipe with RS4 throttle body.

White Dog Racing 60mm Bipipe on Flowbench
White Dog Racing 60mm Bipipe on Flowbench

I was interested to see how much of a difference adding the RS4 throttle body would make to the flow performance of the 60 mm WDR bipipe versus the S4 throttle body that was used with the prior tests, and also compared to the full RS4 intake setup.


White Dog Racing 60mm RS4 Throttle Body Bipipe Combination
White Dog Racing 60mm RS4 Throttle Body Bipipe Combination


The flow through the WDR-60/RS4 product far surpassed that of all the other bipipe combinations I have flow tested thus far.

Curious about how the flow would be affected by adding the silicone adapter/couplers to the inlet of the pipe, I compared three setups: bare metal, a 2.5″ coupler, and a 2.5″ to 2.25″ hump hose coupler.

WDR Bare Metal Inlet
WDR Bare Metal Inlet
WDR 2.5" Coupler
WDR 2.5″ Coupler
WDR 2.5"->2.25" Hump Hose
WDR 2.5″->2.25″ Hump Hose

Results of these three cases measured at 16″ of H2O were:

WDR Inlet Comparison
WDR Inlet Comparison

The addition of the 2.5″ coupler improved airflow measurably.  The reduction from 2.5″ to 2.25″ caused a small decrease in airflow.


The White Dog Racing 60mm bipipe combined with the RS4 throttle body has achieved the highest airflow through a bipipe / throttle body combination that I have measured.

FrankenTurbo F4H data

The FrankenTurbo F4H turbocharger is no longer offered, but I had it for a while on my S4.  During that time I collected a significant amount of basic performance data on the car.  Recently I have been looking at turbocharger alternatives to the BW K04 and the metric shown below, 2-11 time, is something I have recorded for the candidate turbocharger systems.

Just to see how the F4H stacks up I pulled this data to compare the F4H to one of the top contenders, the TTE550.

FrankenTurbo F4H vs TTE550
FrankenTurbo F4H vs TTE550

The F4H uses a smaller compressor wheel and turbine wheel as compared to the TTE550, so the outcome is not surprising.

Below is the F4H under a range of ambient temperature conditions.

F4H 2-11 time with grouped by Ambient Temperature
F4H 2-11 time with grouped by Ambient Temperature

No surprise that as the ambient temperature increases the 2-11 time grows longer.

More TTE550 Boost Onset Data

Taking advantage of some unseasonably cool weather I had the opportunity to record the boost onset characteristics of the TTE550 turbochargers under conditions more like those when the BW K04’s (and FT21’s) were logged.

Shown below is the 2-11 time for the BW K04’s and TTE550’s.  The 2-11 time represents how much time passes during boost buildup from when pressure reaches 2 psi and then builds to 11 psi.  This measurement is made beginning at a variety of engine speeds typical of my normal driving state.

Chart of BW K04 vs TTE550 2-11 time
BW K04 vs TTE550 2-11 time

While the TTE550 clearly trails the BW K04s at all engine speeds the difference becomes less pronounced with increasing engine speed.

Ambient temperature does come into play when measuring boost onset.  The chart below illustrates the response from the TTE550 under different ambient temperature conditions.

Chart of TTE550 2-11 time with ambient temperature represented
2-11 time with ambient temperature represented

The various measurements are grouped in range categories (degrees F) to make the presentation clearer.

This does obscure the fact that some of the differences in ambient temperature may be minor, or significant.  For example, a reading can be made at 48 degF and compared with another at 50 degF that resides in a different category despite there only being a 2 degF difference.  Also, within the same category one reading could be made at 50 degF and another at 59 degF.

Looking at this boost onset in a more familiar form, I have charted the boost onset at various starting engine speeds against engine speed.  This chart was made from measurements taken at an ambient temperature of 41 degF.

Chart of TTE550 Boost Onset
TTE550 Boost Onset

Impressively, at lower engine speeds the TTE550 is reaching approximately 17.5 psi at 3000 rpm.

Revised Water Shock Accumulator

Prompted by a suggestion that a different orientation of the water shock / anti-surge accumulator would be better for this setup I took the time to rearrange the hoses for the accumulator and the nozzle supply.

Aquamist Water shock accumulator

The new orientation of the accumulator off of the tee has the fluid exiting the pump proceeding directly toward the accumulator, and then veering off 90 degrees to go to the nozzles.

A log with this new orientation is shown below:


Overlaying the two accumulator orientations leads to the chart below:


The difference around 3000 rpm is almost certain to be related to the manner in which boost built during the two sessions, rather than a result of the different orientation.

It is hard to discern if there has been any change to the quality characteristics of the flow with the change to the placement of the anti-surge accumulator; but there has not been any detrimental effects from the change so I plan to leave the accumulator in the new location.

Audi B5 S4