Hp.

Getting 60 mpg up here is a simple explanation: the ecu for the f.i. reads oxygen content to get the optimum combustion. At 8,000' elev. there is only about 70% of the oxygen you have at sea level, so the ecu reduces the a.f.r. to the f.i. for a complete burn. Here, the computer is way smarter than we are, making 3,000 calculations per second to find the best "map" still within the EPA requirements.

Before I installed the V&H FuelPak, I was getting 70 mpg, which I knew was much too lean for piston longevity. I could have easily re-mapped the ecu to a better a.f.r. but I would have lost my good mpg. That's why I like the FuelPak so much--it only adjusts a.f.r. at half throttle and up.

I could re-map the ecu to boost the power up 35-40 hp more from stock settings, but then my gas mileage would drop to maybe only 35 mpg. That's mostly why you will see an S&S 95" motor put out nearly 100 hp on the dyno. It may not even get 30 mpg, but they don't have to worry about EPA mandates.

Another case to think about: Ducati increased the hp on their 1200 v-twin from 121 to 180 simply by installing a very advanced computer. Fuel mileage really sucks, but they don't care because they fall into an "exempt" EPA category due to very small volume. They made it water cooled only because the air cooled motor would not survive very long with 180 hp heat. Also, they know that a Ducati (not just the motor) will be completely shot in 20-25,000 miles.