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

The ins and outs of mixing and matching Mustang engines is our focus this month. We're really excited to finally bring you details on one particular powerplant exchange that's perfect for SN-95/New Edge Ponies, which are now getting on in years and can use a bit of life support.

That's right, after covering swaps that have run the gamut from standard to a bit more exotic, we're now bringing you details on Logan Motorsports' Two- to Three-Valve exchange. It's an installation concept that we touched on in our last report on this subject ("Heavy Rotation," June 2006), but until now, have not had a chance to execute. In today's world of spendy Coyote-powered ponies, we believe this swap's relatively low cost—approximately $1,500-$19,000 for the Logan components; quality 2005-2010 engines range anywhere from $600 to $1,500—and the wide availability of suitable 'Stangs make the effort alluring.

Yes, 2011-2013 Mustang GTs are fantastic cars and their Coyote engines' aura radiates over all of the earlier late-models (1979-2010), simply because the bullet can easily be loaded into the engine bay of any one of those earlier platforms. While some enthusiasts see this adaptability as a curse for other engine swaps, Keith Logan and his son, DeWayne, of Logan Motorsports in Sycamore, Illinois (makers of killer sheet metal intake manifolds for Two-, Three-, and Four-Valve modulars), do not. And to support their position, the duo developed a complete system of parts and PCM calibration that makes supplanting the Two-Valve in SN-95 and New Edge Mustangs with a Three-Valve.

The unique concept became a reality in 2006, when a customer brought an ailing 2001 Mustang GT to the Logans. "He wanted something different," Keith explained. "So, DeWayne thought it would be interesting to put a then-current, 4.6-liter Three-Valve engine in the earlier car. We knew it would not be realistic to completely adapt all of the Three-Valve's systems, so we chose to stay with the Two-Valve's engine systems and adapt them to the newer engine."

Like Keith, we think this project is perfect for 1996-2004 'Stangs; those with non-Performance Improved 4.6-liter Two-Valve bullets, or PI Ponies with tired powertrains. With that in mind, we're making the swap with Javier Rivas' 1999 Mustang GT. This Pony is deserving of the upgrade, as it is a high-miles mash-up of both SN-95 and New Edge components that could stand such a renovation.

We turned to the crew at GTR High Performance in Rancho Cucamonga, California, for their help with executing the engine transfer. While Ricardo Topete, Eddie Zapata, and Jose Serrano are well versed in engine extracton-and-installation procedures for all years of late-model 'Stangs, the Logan Two- to Three-Valve swap is a new challenge, which the trio was anxious to take on.

Horse Sense: Fox, SN-95, New Edge, or S197. Which Mustang do you think would be the best platform to use for an Ecoboost 3.5-liter engine swap? Weigh in with your thoughts at 5.0mailbag@sorc.com.

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The Energy Suspension urethane engine mounts from Javier’s Two-Valve engine were still in great condition, so they were transferred onto the Three-Valve.
A Three-Valve engine does not have a mounting point for the Two-Valve’s coolant-temperature sensor. Most Three-Valves used for this swap will have a crossover, but it will require drilling and tapping for the sensor. Logan provides a new factory piece (bottom) that is already prepared for the coolant temp sensor.

Parts Relocation Program

Our project's Three-Valve aluminum block shares the same dimensions and basic layout characteristics as their iron or aluminum Two-Valve counterparts. However, cylinder head and intake manifold differences mandate relocating the throttle cable (a new cable is included) and several important sensors from the Two-Valve setup, as their mounting locations are different on the Three-Valve.

Logan Motorsports supplies three slick aluminum brackets and adapters for mounting the new throttle body and cable. They also provide adapters for the Two-Valve's IAC and fuel-rail sensor, which are repositioned on the new engine. The conversion kit even includes the wiring for extending the TPS to the throttle body, and the fuel-rail sensor, which moves to the passenger side.

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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.

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

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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