The C15 Acert went through a few different variations from 2004-2010 during their production time. First there was the BXS, then MXS, and NXS, and then finally the SDP.
While each version was slightly altered from the last, one thing that remained constant was that the Acert came with two turbos - a high pressure turbo and a low pressure turbo. Often times people refer to the C15 Acert as a "Twin Turbo", but these turbos are NOT the same. The high pressure builds boost right off idle, where as the low pressure turbo is used to make power in the top of the RPM range. The turbos were designed to work in unison so as to eliminate turbo lag.
(High Pressure Turbo Pictured Below)
Unfortunately, these turbos are prone to failure. One of the leading causes of failure is oil contamination. The turbo is extremely sensitive to inconsistencies in oil. The BXS, MSX, and NXS turbos are journal bearing, which means that the turbine shaft has brass bushings (the journal bearing) that rides on a film of oil. If this oil has any debris or excessive soot content, the contact patch will become compromised and the turbo will ultimately implode on itself. This is illustrated by excessive shaft play that can lead to losing oil, low power, and other assorted issues.
(Low Pressure Turbo Pictured Below)
The SDP C15 Acert has one benefit over its older siblings, this engine comes with BALL BEARING turbos. These units are much more sophisticated as ball bearing CHRAs are know to spin much more efficiently, thus achieving target boost levels quickly with less turbo lag. The downside here is that replacements units are MUCH more expensive then journal bearing variants.
(Example of Ball Bearing Setup in a Turbo)
The high pressure is normally the first to go as the shaft spins at a great rate because the turbo is essentially smaller. The low pressure turbo is much larger and spins at a slower rate of speed (compared to the high pressure unit). While we recommend replacing these turbos at the same time, you can simply replace the failed unit and continue to run the other if you have no reason to believe it is compromised.
Momentum Worx Carries both High and Low Pressure complete replacement turbos for BXS, MXS, and NXS. These units are NEW & Assembled in the USA:
High Pressure Turbo (BXS, MXS, NXS), check out the link below:
Low Pressure Turbo (BXS, MXS, NXS), check out the link below:
Momentum Worx also carried GENUINE GARRETT ball bearing replacement cartridges for SDP C15 Acert turbos:
High Pressure Ball Bearing CHRA (SDP), check out the link below:
Low Pressure Ball Bearing CHRA (SDP), check out the link below: