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sorry the final drive is 3.73 not 3.23. no highway cruising mpg has actually stayed same if not worst. the engine is definately working harder. but i never trust instruments they are mostly fed from the MAF sensor and it does not compensate for enrichment. my instruments are always off at least by +/- 2%. i used pen and paper at the gas pump. in terms of speed sensor, the pcm was updated by dealership to make up for different ratio. gps verified speed and its good.
just confirmed its about 2200rpm at 65mph (300 rpm lower and 10% higher load). I can also cruise at 1200rpm now going 37mph and get about 40mpg. kind of hard to measure difference in mileage at crusing still as its so variable but it seems the same. The car runs pretty lean checked AFR logs too. im suspecting that the AWD is working harder. this project cost me 1500$ so far.
I have added some engine mods as this had been going on but I thought they would increase or not affect mileage:
- same diameter exhaust and headers but better flow (no resonator and high flow catalyst).
- delta camshafts, oneset for low rpm and other for high rpm use to keep bottom end friendly
- aggressive spark advance table (48 deg at 2500rpm cruising)
- leaner cruising rpm AFR (but richer full throttle)
dyno indicates more low and high end torque with BSFC at 2500rpm (full throttle).
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Last edited by ever_green; 10-09-2013 at 04:39 PM..
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