Steve Baur
Former Editor, Modified Mustangs & Fords
June 21, 2010
Photos By: Justin Cesler

If you've been following our Street Smart Windsor engine buildup in the last couple of issues, then you'll be happy to know that we finally have the Windsor in our late-model Mustang, we've flogged it on the dyno, and we even took the car to the track just for good measure.

If you're just joining us, what you need to know is that we've set a plan in motion to make a super-streetable engine that makes in the neighborhood of 350-400 hp at the crankshaft. We've specified a stock idle, which meant making concessions on the camshaft specifications, and we kept the Windsor fuel-injected and running off of the stock A9L engine management computer to make this as much of a bolt-in installation as possible.

Our basis for this endeavor is a budget 351W, or more precisely, a 359ci rebuilt short-block from Latemodel Restoration Supply that retails for $999. It comes with cast pistons and connecting rods, but more importantly, it's full of cubic inches-57 more than the stock engine that came out of our subject '89 Mustang GT. Said 5.0L ran very strong with 125,000 miles on the ticker, but in today's world, 225 hp just doesn't get it done, especially when there are four-door grocery-getters packing 40 or more ponies than that.

We looked to fortify our GT with a powerplant of modern horsepower proportions, and so added a set of RHS 200cc Pro Actions cylinder heads, a custom camshaft and rocker arms from Comp Cams, and a stout intake manifold from Trickflow Specialties. Anderson Ford Motorsport opened up the intake tract with one of its Power Pipes, and reading the incoming air charge is an Abaco programmable mass air meter.

At the other end of the combustion process, we made the simple choice of BBK Performance 351W swap shorty-style headers that drop right in and accept any common 5.0L X- or H-pipe. We went with BBK's X-style midpipe with catalytic converters to be somewhat environmentally friendly, but also to keep down the audible presence. Dynomax offered to help out with the sound dynamics as well, and provided us with a set of its brand-new VT series mufflers that feature a pressure-operated door inside the muffler case. This is designed to quell the exhaust note during normal operation, while offering unrestricted, unadulterated flow at wide-open throttle.

While assembling and installing our Windsor, we encountered a number of minor setbacks. Boken-off bolts, incorrect parts, and lack of the proper tool all put us behind the deadline eight ball a number of times. To finish the story in time for this issue-for continuity's sake-we enlisted the help of several good friends, who spent a number of late nights turning wrenches, eating pizza, and of course, breaking balls. We have to thank George Xenos, Rob Baldwin, Chris Crosby, and Brian Bohnsack for helping us get the job done in time. And while we were lucky enough to have a great bunch of friends to call on and bail us out, it just goes to show that no matter how simple a job is, it can be slowed to a snail's slide by the smallest of details. An engine swap is a major job and shouldn't be taken-or planned for-lightly.

A week later, we arrived at Ramsey's Performance In Lutz, Florida, where proprietor Dennis Ramsey offered up his dynamometer services for Muscle Mustangs & Fast Fords. Dennis has been tweaking late-model Mustangs since they were new, and he continues to turn up the heat in Ford's finest today.

With a base '89-'93 Mustang 30-lb/hr mass air meter program loaded in the Abaco DBX97B, we made a hit on the Dynojet and took the Windsor up to 5,500 rpm before clicking it off. On our first pull, we saw 317 rwhp. We were unable to obtain a torque reading using the Dynojet tachometer lead, and despite our best efforts, could not achieve one on subsequent pulls. The Windsor did consistently drop rear-wheel-horsepower figures in the 320s as we fine-tuned the DBX97B using the wide-band air/fuel meter from the dyno and the free tuning software from www.abacoperformance.com. However we surmised that the numbers might have been slightly skewed due to spikes in the reading.

The Abaco tuning software, like any other software, is slightly imposing at first, but once you have a basic understanding of how it works, you can really take off on your own. We noticed a slight spike in the air/fuel mix that went as high as 14.5:1, and by making changes to the meter's programming, we were able to knock down that area of meter voltage to a consistent 13.0-13.3 across the pull. While our relatively mild camshaft doesn't really show off the DBX's metering capabilities like it would with a big lumpy camshaft, it will provide accurate air measurements for our profile and anything else we may throw at it in the future.

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With a dyno session behind us, we loaded up the GT for a quick trip to Gainesville Raceway in Gainesville, Florida, for some quarter-mile fun. Our GT had been sitting so long that the tires were dry-rotted and not even worthy (or safe) of being run on the dyno; we swapped them out for a set of Weld Draglite big 'n' littles wearing Toyo Proxes slicks and front runners. We used this setup most recently on our Mercury Capri project and it has provided plenty of traction for mid-12-second e.t.'s. While assembling the Street Smart Windsor, we reinstalled what looked to be the stock 5.0L clutch, as the clutch disc was true and still had a good amount of material on it. The pressure plate was in decent shape as well, and a new clutch wasn't really part of the engine buildup.

Knowing we had a stock clutch and some very tall (and stock) rear gearing, we couldn't expect great 60-foot times without sacrificing the clutch, and therefore quarter-mile e.t.'s times would not be optimal either. Still, we gave it a go. Our first run, starting with a 2.14 60-foot time, culminated in a 13.81 at 103.78 mph. Since we hadn't put hardly any street miles on the car prior to or after the engine swap, this was just an easy pass just to get acquainted with the car. The stock gears had us crossing the finish line in Third gear at about 4,800 rpm. Shift points were made at 5,500 rpm, as we knew the engine was making power at least up to that point.

Our second pass was the best of the day. The short time dropped to 2.00 seconds flat, and two powershifts later, we arrived at the stripe with a 13.06 at 106.32 mph. Confident that there was a 12-second slip available, we pulled the car around for another try. While loading the clutch to get a smooth but quick launch, we could feel that it took a bit longer to grab and recover, and drove to a 2.02-second 60-foot time. On the 1-2 shift, clutch slip occurred, but recovered on its own-we took it easy on the 2-3 knowing that the extra load of the taller gear would mean certain death for the clutch. The clocks read 13.30 at 103.31 mph. With a better rear gear and a new clutch, we would expect to drop short times by two tenths, which would put our quarter-mile e.t. around the mid-12-second range. Not bad for a naturally aspirated Fox Mustang with a stock idle.

The following week, we found ourselves taking the GT back to Ramsey's Performance for another dyno session. We had found some bad spark plug wires that could well have been causing the poor tach readings, and the shop had ordered a new lead to hopefully cure the problematic reading. The changes worked, and our first pull netted 307 rwhp and 359 lb-ft of torque. The air/fuel ratio looked very good, so Ramsey opted to make an ignition timing adjustment, moving our initial timing from 16 to 18 degrees. The Windsor responded with 306 rwhp and 358 lb-ft of torque.

We then decided to go in the opposite direction by moving the ignition timing back to 14 degrees. The Street Smart small-block liked what we were doing, offering 310 rwhp and 362 lb-ft of torque. Ramsey then decided to try 12 degrees; his change netted 312.88 hp and 365.30 lb-ft of torque. Allowing for a relatively efficient 15 percent drivetrain loss, our 312 rwhp comes out as 359.8 hp and 419.75 lb-ft of torque at the flywheel.

In the end, we met our goal of 350 flywheel horsepower and, what's probably more noticeable, nearly 420 lb-ft of torque. While our idle quality is not quite as smooth as stock, it is very mild, and we think we can smooth it out a bit with more tuning on the DBX97B meter. We've heard it idle smoothly without the meter plugged in, so we'll keep hitting the keys. The engine drives smoothly and you can lug it at 1,200 rpm without it bucking or surging, which were also goals for the build.

At this point, we could pull it back out, toss in some good pistons with bigger valve reliefs, and bring the lift up on the camshaft a bit to improve power output. We could also stroke it for more cubes at the same time. We're pretty content with the power output now, but if you would like to see us pursue this combination, then drop our editor a line at evan.smith@sorc.com. If we get enough interest, we might just keep going with it.

In the meantime, we've got a few other non-engine-related stories using our GT. It sure is nice to have a lot of horsepower on the street, but it doesn't have to have a lumpy camshaft or a power adder to be fun. Windsor power will get the job done.

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