KJ Jones
June 1, 2013
Photos By: K.J. Jones

On The Dyno

Tuning the transplanted Three-Valve Mustang to run smoothly and perform well in Javier Rivas' 1999 Mustang GT was the last piece of our swap project. Logan Motorsports uses SCT tuning software for its plug-and-play calibrations for this engine exchange, and when creating the tunes, DeWayne Logan's primary area of focus is in the spark tables and calibrating the engine's timing through the limited parameters of the Two-Valve's PCM.

"A significant difference in the two computer systems is the number of spark tables," Keith says. "The Three-Valve engine with VCT has as many as 60 degrees of total timing variation. However, the Two-Valve has no variation or ability to control VCT.

The Two-Valve's PCM does not have knock control like the Three-Valve's does. Without this feature, DeWayne had to spend a lot of time on the dyno (using Logan's '98 development ‘Stang) trying to find optimal timing for stock Three-Valve engines.

"The combination of the CMRC delete plates, our high-flow air intake, a better combustion chamber, and larger intake-valve area with the Three-Valve heads also allowed us to be more aggressive on air and fuel in the tune," Keith says. "DeWayne has spent countless hours with cars on the dyno and the street developing a tune that incorporates driveability and performance."

In our case, the result is a 1999 Mustang GT that makes more than 300 horsepower at the rear wheels and a whopping 346 lb-ft of torque to go with it. That's almost 50 percent more power than the Pony's stock Two-Valve, and according to Javier, the 'Stang now accelerates quicker, the engine is much smoother, and it gets better fuel economy than the Two-Valve.

With the drop in price for low- mileage Three-Valve engines, we think supplanting one in a 1996-2004 Mustang GT is a great cost-friendly alternative to rebuilding or replacing the Two-Valve engine. And, per Javier's feedback, it's a lot of fun to drive, too.

Baseline
Logan
Difference
RPM Power Torque Power Torque Power Torque
2,500 123.01 258.42 135.02 283.66 12.01 25.24
2,600 128.37 259.32 139.73 282.27 11.36 22.95
2,700 133.54 259.77 144.78 281.64 11.24 21.87
2,800 138.52 259.83 146.09 274.03 7.57 14.20
2,900 143.46 259.81 149.43 270.64 5.97 10.83
3,000 149.82 262.29 153.70 269.08 3.88 6.79
3,100 157.89 267.50 160.15 271.32 2.26 3.82
3,200 167.29 274.56 166.82 273.79 -0.47 -0.77
3,300 175.76 279.73 176.81 281.39 1.05 1.66
3,400 184.04 284.29 188.97 291.89 4.93 7.60
3,500 189.94 285.03 204.63 307.05 14.69 22.02
3,600 195.95 285.88 215.95 315.05 20.00 29.17
3,700 203.18 288.41 224.63 318.86 21.45 30.45
3,800 210.78 291.32 236.20 326.45 25.42 35.13
3,900 217.36 292.71 246.32 331.71 28.96 39.00
4,000 224.23 294.42 255.77 335.83 31.54 41.41
4,100 230.40 295.14 267.08 342.13 36.68 46.99
4,200 237.73 297.28 277.27 346.73 39.54 49.45
4,300 241.40 294.85 283.98 346.86 42.58 52.01
4,400 245.20 292.69 287.23 342.86 42.03 50.17
4,500 248.55 290.09 290.70 339.29 42.15 49.20
4,600 251.66 287.34 295.08 336.91 43.42 49.57
4,700 253.88 283.71 300.18 335.45 46.30 51.74
4,800 256.24 280.38 305.01 333.73 48.77 53.35
4,900 257.41 275.91 310.20 332.49 52.79 56.58
5,000 258.02 271.03 311.05 326.74 53.03 55.71
5,100 256.79 264.46 313.32 322.67 56.53 58.21
5,200 256.44 259.01 306.65 309.74 50.21 50.73
5,300 255.70 253.39 308.10 305.32 52.40 51.93
5,400 253.84 246.89 304.73 296.39 50.89 49.50
5,500 252.09 240.73 301.06 287.49 48.97 46.76
5,600 250.30 234.75 294.99 276.68 44.69 41.93
5,700 247.20 227.78 296.23 272.96 49.03 45.18
5,800 n/a n/a 297.61 269.50 n/a n/a
5,900 n/a n/a 299.52 266.63 n/a n/a
6,000 n/a n/a 298.44 261.24 n/a n/a
6,100 n/a n/a 296.65 255.42 n/a n/a
6,200 n/a n/a 292.74 247.98 n/a n/a

Photo Gallery

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Here’s the installed Three-Valve engine, all hooked up and ready to fire. Some of the underdrive pulleys from the Two-Valve’s original accessory-drive system were retained (water pump), which enabled us to reuse the GT’s original serpentine belt. Logan Motorsports’ Two- to Three-Valve Conversion Kit makes everything look like it really belongs between the fenders of Javier’s Pony. 5.0