Category Archives: The Turbo Engineers

Posts with a significant portion of the discussion involving The Turbo Engineers products

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.

Claim: TTE550 has RS4 K04 response

With the TTE550 turbochargers installed on my S4 I can start to measure the performance of this product and compare the results to those obtained with some of the other turbochargers that I have used.

The performance claim that leads off the description for the TTE550 is:

RS4 K04 response with near RS6 unit power yet still keeping RS4 turbine housings.

Because keeping K04-like response is one of my top features to have from a turbocharger I am quite interested to see how that claim works out.

Initial results do not bode well for the product to live up to the claim.  Shown below is a chart comparing the 2-11 time for the K04’s and TTE550’s.  This metric is used to illustrate how long it takes for each turbocharger to build from 2 psi to 11 psi, for a given starting engine speed, that is when 2 psi is produced.

TTE550 vs. BW RS4 K04 2-11 psi response time
TTE550 vs. BW RS4 K04 2-11 psi response time

This chart does a good job at showing that the K04’s, the blue dots, increase pressure measured by the MAP sensor more rapidly than the TTE550, for all of the engine speeds I have measured thus far.

A couple of points about the data on the chart.  The K04 data was collected when the temperatures were generally cooler than during the two days that I recorded TTE550 data.  The lines would likely get closer together, meaning more similar performance, under the same temperature conditions.  With that, I do not believe temperature affects would be great enough to bring the lines together.

I’ve also not completed tuning with the TTE550’s.  Past experience has shown that fine tuning is more about controlling overshoot on initial boost ramp, not how quickly the turbocharger spools up.  I believe it is very unlikely that tuning will do anything more to increase the 2-11 time of the TTE550’s

While these initial results cleary show that the TTE550’s do not have RS4 K04 response, from the perspective of looking at the turbocharger dimensions this is not at all surprising.  The TTE550 is essentially an RS6 center stuffed into a K04 housing.  Beyond that, it uses a compressor wheel that is larger than the RS6 compressor, and it uses an extended tip compressor wheel on top of that.  On the turbine side an RS6 size turbine wheel is found, but also with a clipped wheel, not a feature that increases responsiveness.

Given the physical differences between the two products it is not surprising at all that the TTE550 does not match the RS4 K04 in response.