Project GD STI, Dyno Tuning for Big Power with Reliability

Well, it’s finally time to get Project STI started and tuned.   As with many of our projects, we enlisted the help of Shawn Church of Church Automotive Testing to get this critical task done.  Shawn is super well-versed in the tricky art of tuning the OEM ECUs of modern cars and has often straightened out the mistakes of other tuners on our cars.

With a brand new motor, it is important to get it started and up to 2000-3000 rpm quickly to break in the cams and seat the rings quickly. It’s not good for break in to grind the motor on the starter and not have oil pressure either so we wanted to have the best assurance that the car would start off the bat. Lucky for us Shawn is close enough to us to do a house call.  Shawn also has enough experience that he can get really close right off the bat. Important since we are running big 1300cc injectors and are converting from Mass Airflow load calculation to Speed Density.  Shawn flashed our ECU with his best estimate and guess what, our car started right up!

After running our car with no load between 2000-3000 rpm for about 30 minutes, while Shawn did more adjustments to the fuel map and tweaked the warm-up enrichment curve.  We went out for a test drive, and Shawn did some more adjustments while leaving our boost control solenoid wide open to limit boost.  We did some short wide open throttle bursts to check for detonation and to help seat the rings. The car’s tune including the difficult part-throttle driveability stuff was pretty damn good.  After the initial tune, we changed our oil to get rid of the dirty break-in oil and drove the car for 500 miles, changing the oil and filter again. In the meanwhile, Shawn did some minor tweaks to improve the cold start and cold after-start warm-up driveabilty.


    1. Funny thing, I was comparing results with a guy that had an ETS kit with a rotated mount G30-660 and the results were just about equal to our car and we were running slightly less boost. He made a little more power, we made a little more torque. This shows that at this power level, it’s not worth going rotated mount and that this turbo works pretty well.

  1. So it sounds like you basically ran the engine 500 miles then started doing power runs? What is your engine break in philosophy / understanding? The wide spectrum of ideas about “how it should be done” is confounding at the least. So I’m definitely curious to hear Mike’s break-in theory.

  2. I’m getting ready to do a very similar setup in my 2019 STI. How does that turbo drive on the street? What’s spool like in second? I have no access to E85 so that turbo at low boost looks very tempting on 93.

    1. Subaru’s are kinda laggy but it starts at 3500 rpm and is really pulling by 4000, look at the dyno chart and compare to the stock but bolt-on mod car. That stock car had variable exhaust cam timing so it had a little more low end but a similar year car with variable intake timing would have about the same lag as our engine.

  3. Love reading through your posts! Is there a page that has your full build list by chance? Couldn’t find one! Thanks!

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