Project GD STI, Installing an Upgraded Precision Ball Bearing Drop In Turbo and Larger Injector Dynamics Injectors

In our previous article, we had gotten a new Precision Turbo ball bearing center section drop in factory replacement turbo to replace our previous turbo that was choking our engine out limiting it to a pretty inefficiently obtained 500 whp.  Please read the details here.  Our goal is to perhaps only make a little more peak power but to make that power over a wider range at a much lower boost pressure with less exhaust backpressure and less intake charge heating.  We also want to show that you can make impressive power with a great powerband without going to a rotated mount turbo.

Project STI is a very in-depth well integrated modded car with a lot of engineering, to read about all we have done click here. 

Stock position turbos have their advantages.  The biggest one is that the factory has positioned all the heat-sensitive components away from the turbo.  If you plan on tracking your rotated mount car, you need to reposition and refabricated your power steering lines, AC lines, and other things.  Stuff not easily moved will have to have heat shields with thermo wrap protection.  We have found that a turbo on the track can melt things over 18″ away and even melt parts on the other side of heat shields.

The first step in our installation was to disconnect the charge pipes, oil, and coolant line from our old turbo. We also removed the heat shield from the compressor housing.  Since the Precision turbos are direct drop-in replacement turbos, this was really easy.

Next, the downpipe was removed and the up pipe was unbolted from the turbine housing.

We had previously compared our new turbo to the stock IHI turbo and the size difference was huge.

The A/R and the turbine size of the Precision turbo were also quite a bit bigger than stock.  What we like about Precision vs other stock location turbos on the market is that many of those simply carve out the stock housings for bigger wheels.  While this flows more, it is not the best for compressor and turbine efficiency.  Precision uses compressor and turbine housings that are engineered to work the best with the wheels.  So diffusers and volute volumes are correct for the flow level and boost pressures expected.


  1. Dreams I tell you. Dreams. I wish I can just be a spectator at the tuning session. Seriously. DM me on IG lol

  2. Re stock location: BCP x500r please explain to me why this $2k journal bearing turbo is just hype and not real… don’t let me be fooled

  3. It looks like there’s quite a difference between the 55mm and 58mm compressor wheel beyond the size. 7 primary vanes vs 6. The leading edge is swept vs straight. Is the 58mm a newer generation wheel vs the 55mm or is it just the size warrants different vane geometry to improve flow?

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