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Today I went out and did an MPG run on Kittystiva, the blue Festy that I did all my previous runs in when it had a stock motor. Apparently when I wasn't looking, someone swapped in a B6 and then rear-turboed it. I thought Hmmmm, this would be a good time to check its mileage.
Did my usual 85-mile loop around St. Louis, at 60 MPH. Wind was almost nonexistent, partly cloudy, 68 degrees. I decided to make it a completely real-world test, so I left in the back seat, spare tire, and pass. mirror. The lights, fan and radio were on. Tires were 185/70x13 on 4.5" steelies, inflated to 35 PSI cold. I figure most motor swaps are gonna get bigger tires anyway. It was in 5th gear the whole time. I'm using 93 octane pump gas.
The result: 40.0 MPG, on a car that dynoed at 111 wheel HP at about 9 PSI of boost. I estimate that 54 WHP is stock.
Next I will try the exact same run but in 4th gear, on the theory that it will be more efficient when the motor is more in its optimal power band. I don't think this is true, but we'll see. Keeping the next test at 60 so that wind resistance won't be a second variable, as it would be if I tried the test at 70 but in 5th gear.
Edit: for the sake of turboing, ignition timing was reduced from 7 BTDC to 2 BTDC. This lowers HP when not in boost, which it never was in during the test. Better results should be gotten on a non-turbo B6 with stock timing, or higher timing and using high-octane gas.
Did my usual 85-mile loop around St. Louis, at 60 MPH. Wind was almost nonexistent, partly cloudy, 68 degrees. I decided to make it a completely real-world test, so I left in the back seat, spare tire, and pass. mirror. The lights, fan and radio were on. Tires were 185/70x13 on 4.5" steelies, inflated to 35 PSI cold. I figure most motor swaps are gonna get bigger tires anyway. It was in 5th gear the whole time. I'm using 93 octane pump gas.
The result: 40.0 MPG, on a car that dynoed at 111 wheel HP at about 9 PSI of boost. I estimate that 54 WHP is stock.
Next I will try the exact same run but in 4th gear, on the theory that it will be more efficient when the motor is more in its optimal power band. I don't think this is true, but we'll see. Keeping the next test at 60 so that wind resistance won't be a second variable, as it would be if I tried the test at 70 but in 5th gear.
Edit: for the sake of turboing, ignition timing was reduced from 7 BTDC to 2 BTDC. This lowers HP when not in boost, which it never was in during the test. Better results should be gotten on a non-turbo B6 with stock timing, or higher timing and using high-octane gas.
Kittystiva is in honor of your daughters since they are into Hello Kitty. Thank them again for the plastic dinosaur BTW, and Nina for all the help she provided in the background to make the little get-together such a success.
And since it was cold, I knew I was mostly driving into a headwind at 75MPH. Might explain that 20 MPG tank of gas.
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