what you need to know about turbo reliability
Recently we were asked: I just got a set of new SteamSpeed turbos, what do I need to now to keep running like new? I am glad you asked.
The short answer:
We recommend running lower boost, like under 25 psi on our JB turbos. If you want to run higher boost, go for with a BB CHRA. If you keep your car maintained, and tune your turbo to practical boost levels, your turbos will be reliable for a long time.
The longer answer:
Turbos are mechanical parts with bearings like an engine. If an engine is maintained and not abused, it can run trouble-free for for the lifetime of the car. The same is true with our turbos, but like engines, turbos can also wear out.
To obtain high boost, like say 30+ psi, a turbo has to have a very high shaft speed, like maybe over 150,000 RPM. To run lower boost, say 15 psi, it takes like 100,000 RPM. Running a turbo over 150k RPM all the time will wear it out much faster than running it at 100k just like revving out your engine over 9k all the time will wear it out much faster than 6k.
My point is that running a turbo a say 18 psi, is like only ever revving your engine up to 6k. Running your turbo at a conservative boost level, like OEMs do with stock turbos, our aftermarket turbos should last the lifetime of your car with proper vehicle maintenance.
Our turbos are fully balanced on a VSR (vibration sort rig) to around 100k. 100k covers at least two harmonics, the point where the rotating assembly vibrates the most, so that is good. We actually balance to higher tolerances that Garrett does at least in our testing. So, it is also ok to run high boost. The CHRA (center housing and rotating assembly) is well balanced. Just understand that your turbo might have to be rebuilt or replaced more often the more stress and wear and tear you put on the bearings. This might not be as big of a deal for the aftermarket crowd vs OEM, as we tend to modify our cars often.
There is also a distinction between JB and BB turbos.
BB turbos require somewhat higher shaft speeds to achieve the same boost of a similarly sized JB turbo. BB turbos are more reliable running high shaft speeds than JB turbos.
In general, we recommend running JB turbos under 25 psi for this reason, and to go to a BB CHRA if you want higher boost than that. Using that rule of thumb, our turbos shouldn't have to be repaired or replaced.
For reference, compare the compressor map we developed when we gas bench tested the JB STX 71 against a Garrett GTX7071R
Here they are together: