Quote:
Originally Posted by 86MLR
Punched out 17+ OEM header, 2.5" overpipe, 2.5" resonated front pipe, 2.5" cat back
Then
Replaced cat back to OEM with zero change to performance...
Then
Replaced 17+ punched out header with Tomei UEL header, zero performance gain...
For NA The OEM system flows great once the restrictions are removed.
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So based on that above, your saying there’s no performance gains, and therefore likely no unnecessary restrictions in the stock headers and cat converter of the OEM system of 2017+ vehicles.
What about the rest the of the exhaust system post the converter? Has any testing been done to see if the aftermarket sports systems actually reduce any restriction and provide gains? Did you dyno test your 2.5” system against an OEM setup? Is the cat back different on 2017+ models compared to earlier models?
According to DSPORTS’s article <
https://dsportmag.com/the-tech/scion...programed-ecu/ >, quoted below, the ECU limits further power gain to no more than an additional 5% of the stock power. Do you think that had any effect on your dyno testing without returning for each of the changes?
Quote:
The 5-Percent Rule
Because the ECU in the Scion FR-S has tables built in that essentially limit the amount of additional power that can be made, dyno testing bolt-on products on the vehicle proved extremely challenging. Based on over 250 dyno runs that we conducted, we found that the ECU seems to only allow performance gains on the order of about 5.0 percent. Adding the additional components to allow more additional power production with the factory-programmed ECU still only delivers that 5.0 percent gain.
1+1 = 1
Let’s say that you have an intake that adds about 5.0-percent more power when installed on a stock vehicle. Now, let’s say you have an exhaust system that adds about 5.0 percent of power on a stock vehicle. While you shouldn’t expect to get a 10.0-pecent gain from the two, it’s realistic to expect to see a performance gain with both items in the realm of 6.0- to-9.0 percent. Yet, the factory- programmed Scion FR-S ECU says 1+1 = 1. We confirmed the severity of the 5.0-percent rule when we found that the Scion FR-S simply didn’t gain any additional power when an aftermarket exhaust was added after the addition of an aftermarket intake system. On DSPORT’s DynoJet 424xLC Linx dyno, the number that could never be exceeded was about 182 wheel horsepower. Stock horsepower figures checked in between 173 and 176 horsepower when tested on different days.
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