Project Scion FR-S Part 4- Exhaust and Tuning Frustrations


Next we dynoed the system and installed the catless, race only downpipe.
Like the catted system, the catless pipe fit well.
The results were mixed. The catted pipe made only 1 more peak hp but gained 2-3 hp throughout the curve.  The race pipe gained almost 4 more peak hp over stock and gained 3-5 more hp throughout the curve for a total of 150.7 whp and 125.5 lb/ft of torque.  Berk had told us that many people were getting 5-9 more hp on cars with fewer modifications than our car.  This was leading us to believe that the car's ECU was limiting power.  People in other parts of the country with 93 octane fuel were reporting much better gains than us with similar modifications as well.  The car was starting to piss us off.
To try to get to the bottom of our ECU woes, we enlisted the help of John Visconti of Visconti Tuning.  John is perhaps the guy with the most experience tuning the FA20 in North America.  John is from Westport Connecticut but he was in Southern California to tune some cars for various clients so we talked him into giving us a hand.
John told us that our loss of power was normal for a 12.5:1 compression FA20 on poor quality 91 octane California pee water fuel.  John was amazed how bad our fuel is compared to other states.  John told us that he might not be able to get us a lot of power that would stick around but he could tune the car and reduce the knock count and clean up the air fuel curve to make the car less likely to dial back the power after driving.  John felt that the car would still dial back quite a bit and recommended that we switch to E85.  John's E85 NA tunes make the FR-S come alive and we have seen mildly built cars at right around the 200 hp mark on E85.  Unfortunately, there are only a couple of E85 station in SoCal so we asked him to do his best with 91.  John uses ECUTEK software to reflash the factory ECU.  Since the FR-S is so new, not all of the ECU's workings are currently understood.  It is likely that in the future more capability will be found.  For now, only basic tuning to fuel and spark maps is available.
John used a wide band O2 sensor to monitor the air fuel ratio.  He found that our car was running lean in a few places and had some knock count.  John was able to add fuel and smooth out our AF curve and tweak the timing to reduce the knock count.

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