Quote:
Originally Posted by sarguy01
It makes sense the local dyno was able to find more power. SCT didn't have your specific car to tune, they were only doing some basic modifications.
What are your before and after numbers for the highway mpg increase?
How much do you have into the SCT and tuning? I am curious.
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I was getting 21.5 mpg on a daily 112 mile (103 highway mile), 60 mph average (72 mph peak), commute before I purchased the SCT XCalibrator I (bought on Ebay for $125 at the time when the XCal2 was just out).
The first let me say, the tune that I got from SCT was not the standard "canned" tune that they sold for every other Mustang GT at the time. I asked for some particular changes when I sent them my PCM and short list of upgrades.
Out of the box, It did make a noticeable difference in throttle response, reduced throttle hang time, corrected the odometer measurement and smoothed the cruise control operation. The corrected odometer didn't help the mileage as it reduced the odometer reading by 7%. Still the corrected odometer mpg went up to 22.1 mpg (a less than 2.8%).
What I really did not like was that this tune was for 93 octane gasoline and yet did not yield more noticeable power or mileage.
I took the GT to one of the first Dynojet all-wheel drive unit equipped shops in town, with a couple of friends. We rented out the shop two weekends in a row for a little less than $300 each.
I flashed back the stock calibration to start the. I got a peak power - 195 hp at 4450rpm, peak tq - 260 ft-lbs at 3400rpm, but torque off idle just 220 ft-lbs at 1500rpm.
The canned map only added about peak 12 hp and 8 ft-lbs.
We started out by changing the rpm and load scaling on all the maps, Smaller rpm increments from 1200rpm to 3000rpm, stock increments up to 4000rpm, then large increments in the upper rpm. Also expanding from small TPS percentage changes from 5% to 30%, stock through the middle openings, and then a couple large throttle openings.
Then we changed the entire ignition timing map, altered a lot of fuel tables, extended the idle fuel trim allowances, added the correct LB/h flow ratings for the injectors.
After at least a dozen pulls, in 3rd and 4th gears, running 89 octane gas the peaks were only up another 6 hp and 10 ft-lbs, but down at 1500 rpm we had a 20 ft-lb increase.
The next months mileage average was up to 26.4mpg (That's a 22.7% increase). Throttle was crisp, power for passing was good, I probably could have nursed a few more mpg out of it by driving more conservatively.
That was how I kept the tune until a couple years later when the engine got drown in a tropical storm and hydro-locked.
The replacement crate motor had different heads, cams, exhaust, injectors and more, so I can't compare the mileage and power numbers I got when I tuned it with the same tool.