Project Scion FR-S Part 4- Exhaust and Tuning Frustrations
By Mike Kojima
When we last left off, we had just installed some bolt ons onto our Scion FR-S's motor and picked up some quick power. Since we had gotten power gains so easily we were confident that the car would respond well to more mods and were ready to test and install additional parts. To make for more accurate testing, we typically rebaseline a car everything we install new parts. We strapped the FR-S to Technosquare's Superflow dyno and were both surprised and dismayed to see that our car had somehow dialed out nearly all the power we had previously gained.
We double checked our readings and the dyno's calibration and we are certain that the car did indeed lose power from our last test.
Our stock power levels were 145hp and 119 lb-ft of torque and after a few weeks of driving our power levels had returned to 147 whp and 122 lb-ft of torque for a big WTF. We didn't (and still don't) know why this happened, perhaps the increased VE of our intake and exhaust caused the super high compression 12.5:1 FA20 to have some detonation (which we could not hear) to which the ECU reacted negatively or perhaps there are some torque limiting algorithms in the ECU itself which so many late model cars suffer from. Determined to keep adding power, we continued with our testing.
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|For the next step in uncorking the FA20 motor we acquired these front pipes from Berk Technology. We got a catted downpipe and a race only uncatted pipe to test. The Berk pipes are made from smoothly mandrel bent 2.5″ diameter 304 stainless steel and TIG welded. The catted version features a metallic cell high flow cat.
|It's a little hard to see in the picture but the Berk part is much larger in diameter with smoother bends. The stock part gets crushed down in a few places as well. The stock part has a resonator in the back. We wonder why some of this stuff was not left off. If they were then you probably wouldn't need the cabin noise amplifier thing that we removed in our last installment.
|First up is the catted downpipe. It installs easily with just two bolts in the front.
|Two bolts in the rear and the mount in the center. Since our car was new, we were able to reuse the stock gaskets.
|The Berk piece fit well and really looked like it would produce some worthwhile gains.