Muscle Mustangs & Fast Fords
1989 Ford Mustang GT 351 Windsor Engine Part 3
Our Smooth-Idling Street Motor Gets Strapped To The Dyno.
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 email@example.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.