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Old 06-28-2022, 06:31 PM   #10 (permalink)
Master EcoModder
Join Date: Jan 2012
Location: United States
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spyder2 - '00 Toyota MR2 Spyder
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Yea I've seen that, here's a direct link:

They raised the boost in later years but as far as I can tell it's basically the same engine. Like the other Honda offerings, it's a little down on efficiency because they never really updated the basic design to optimize for high volume cooled EGR like Mazda/Toyota did, thus the relatively poor 37% peak BTE.

The good thing is that since it's only 1.5L, the average mechanical efficiency will be very good while pulling bigger/heavier cars. Paired with the CVT, tests have shown a very fast 0-60 so my assumption is on the lowest gear ratio the engine will give maximum torque (and run rich) if you give it a lot of throttle, but it'll back off at higher speed and medium throttle to use less boost.

With full ECU control, it should be easy to lean out the low-medium load fuel map and add a little timing to gain a few % efficiency, but not gonna do that in the warranty period. I just realized a custom rear O2 emulator can be used to spoof the catalyst monitor and resulting fuel trim correction by reading the amperage from the front sensor, but it's a lot more involved than a narrowband emulator.
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