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Fox Body Fairmont 3V Motor Swap Dyno

Created by Jeff Jimenez
Date Created: 12/11/2013
Last Updated: 9/2/2021

Well it is “D-Day” better known as Dyno Day for our Fox Body Fairmont 3V Motor Swap Project! Check out the dyno graphs below.

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Fox Body Fairmont 3V Motor Swap Dyno - Fox Body Fairmont 3V Motor Swap Dyno

I recently had an opportunity to dyno the ole 3v Fox Body Fairmont Project. I felt like it was time to go ahead and make some pulls with it, since the car had racked up some street miles and all the bugs had been worked out. I wanted to report what the numbers were, and I was curious to see if any power was to be had with custom tuning.

So far, the Ford Racing Mustang crate engine with the FRPP harness and controls package has performed flawlessly. The car idles and sounds awesome. Drivability is very good for such a modified car. I had zero complaints about the as-delivered performance of the Ford Racing engine and computer package. I did, however, believe that there was power to be had. There wasn't a hint of detonation on 87 octane fuel, so I suspected the car needed more ignition timing. It didn't have that "snap" of timing and a good tune. From what I'd seen on S197 Mustangs, I felt it could also make more horsepower with a JLT cold air intake.

For my dyno session, I loaded the car and took it to Gunter Specialty in Valley Mills, Texas. Jody's facility is top notch, and he has a mobile Dynojet on site. Mike Wilson ran the dyno and performed the tuning mods using an SCT's software and an X3 hand-held tuner. Luckily, SCT had already performed some tuning on the FRPP PCM, so the strategy was already loaded in the programmer.

After a good warm-up and preparation for the dyno, the first couple of pulls were made without any additional tuning. As-delivered, the FRPP Hot Rod 4.6 engine netted 291.25peak rear-wheel horsepower. Outside air temperature for all pulls was approx 78 degrees, pressure was 29 in-Hg, and humidity was 67%. Calculating a 15-18% driveline loss, that number was almost dead-onFord Racing's advertised 350 engine horsepower. The a/f ratio told the tale that the car could use a bit more fuel, but timing was the true teller. At 22 degrees total timing, there was definitely room to make more power. Torque was good, but fell in the mid-range due to the lack of timing.

Fox Body Fairmont 3V Motor Swap Dyno - Fox Body Fairmont 3V Motor Swap Dyno

The next pull was made after a custom tune was loaded with the SCT tuner. Timing was bumped to a total of35 degrees, and fuel was added to get the car to a safe a/f ratio. I'd hit the rev limiter a few times with the stock programming. The car felt like it had room to rev, so we increased the stock rev limiter from around 6200 rpm to 6600 rpm. Those few changes netted a staggering 325.75peak horsepower. Torque was even more impressive, as the dynojet reported gains of as much as 50 lb-ft in the critical 3500-4500 rpm range. Torque peaked at 314.

Fox Body Fairmont 3V Motor Swap Dyno - Fox Body Fairmont 3V Motor Swap Dyno

"Impressed" did not begin to describe our attitudes toward the numbers that the FRPP mill generated with the new-found timing. With numbers that strong, we were ready to call it a day, but decided we would test the JLT cold air kit we brought home for the car. We were certain that the much-larger JLT kit would provide more air and power to the 3-valve than the smaller, more restricted-looking Ford Racing Bullitt style cold air kit that came standard with the harness and controls package. To our surprise, the JLT intake only made about a2hp improvement over the Ford Racing kit on our application. Final peak hp with the JLT was 327.21. Torque stayed the same. We re-installed the FRPP cold air kit to keep cost down on the project.

Fox Body Fairmont 3V Motor Swap Dyno - Fox Body Fairmont 3V Motor Swap Dyno

We're anxious to get to the track with the car. Shakedown runs have been made at some of the local strips, but a faulty shifter lug in the TKO600 lead to several missed gears. With the new-found power, and the shifting problem resolved, I’m hoping to see some times. We should find out at our 10th celebration on the 14th!!

Thumbnail image of the author of this article, Jeff Jimenez.

About the Author

Jeff has written for LMR for 12+ years and has owned multiple Mustangs and an SVT Lightning. His passion for writing comes from a love of the Mustang community & creating a great customer experience. Read more...