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.