So, with the Stinger downpipe assembly and the Edelbrock exhaust system in place, we got the car up and running and trailered it back to Mustang Magic for more dyno time. With the car strapped down onto its Dynojet 248c, we went for an initial run. To our surprise, we witnessed the boost gauge jump to nearly 22 pounds-a lot more than it originally had. Technician Joe Lauzardo quickly let off the throttle, and we lowered the boost pressure to 18 psi to avoid harmful damage to the engine. As we let the car cool and went for our next run, we could hear the car spool up much quicker, and the car really began to make power. Halfway through the run, however, we quickly noticed a plume of smoke coming from under the hood. It didn't take long to realize something was amiss when the car began to fall on its face. Our day was over.
It was apparent that our first run with too much boost had caused some damage to the 90,000-mile engine, and there was no turning back. Back home, we found 40 percent leakdown in the two middle cylinders-a sure sign of a blown head gasket between the two bores. Without adequate time to properly fix the engine for our deadline, we decided to give you what we had and (try to) write a halfway decent story instead of spending our late nights thrashing on the engine to get it running. So, the car sits, and we've thrown together some words for your pleasure.
The good thing is, we were able to salvage some of the dyno data up to 4,250 rpm, and it was encouraging. Compared to our previous dyno pulls, we found an incredible jump in torque starting as low as 2,400 rpm. This proved that the turbo was indeed spooling up sooner, making more boost earlier. By 3,600 rpm, we witnessed a 32-lb-ft increase in torque compared to the previous peak of 280.5 lb-ft, and at 4,250 rpm-the highest rpm point we could record with our wounded soldier-we saw an incredible 37 rwhp gain. This means at just 4,250 rpm, we already were making over 200 rwhp where it used to be just 164 rwhp without the new exhaust setup. Had the car been able to rev cleanly all the way up to redline, we're confident that a 45-rwhp gain would have been realized at about 5,300-5,400 rpm.
Despite being sidestepped by mechanical maladies, we uncovered a few things in this test. For one, the SVO factory exhaust components, consisting of a small-diameter downpipe, a choked-up catalytic converter and some crush-bent tailpipes, were incredibly restrictive and robbing us of power. Had we known how much power was being bottled up in the first place by the exhaust, we probably would have performed these mods first before the first bolt-on was ever secured to the topside of the engine. Secondly, we proved that by freeing up everything after the turbo, torque and horsepower gains can be found not just on the top end but throughout the entire rpm range. As boost came in earlier, torque also swelled. Of course, this was all before the engine decided that it was time to call it quits on us.
Replacing the factory manifold's...
Replacing the factory manifold's lumpy legs with the header's smoother and larger-diameter pipes drastically improves performance. Although we never tested it on our car, we were able to see what someone else had gained from this work of stainless steel art (see sidebar).
An obvious mismatch can be...
An obvious mismatch can be found at the manifold's turbo flange. This E3 casting has an absolutely tiny outlet. Ford swore this would improve spool-up efficiency, but larger E6 castings offer more power with no loss in turbo response. In actuality, lazy turbo action was largely due to the turbo's elderly design.
Because we were trying to...
Because we were trying to add some beef to the soundtrack of our SVO, we went with the deep-sounding pipes of Edelbrock's after-cat exhaust. With 2.5-inch mandrel-bent pipes and free-flowing mufflers, we knew it would give us improved performance and looks. Once hooked up, the car sounded more like a V-8 than a four-cylinder.
With our new exhaust in place,...
With our new exhaust in place, we headed back to Mustang Magic for dyno testing. We did not have enough time to take the car for a test drive to dial in everything, and on the first dyno pull, we overboosted the engine, hurting it in the process. The exhaust upgrade certainly proved to uncork the car because without adjusting the boost controller, we saw the gauge rise from 18 to 22 pounds of boost. Bringing it back down to 18 allowed us to make another pull, but the damage was done. Anything over 4,250 rpm was a struggle for the engine to rev. But up to that point, we noticed a significant gain at 3,600 rpm of 32 lb-ft and at 4,250 rpm, and just before the car began to buck and wheeze, we saw an incredible 37hp gain at the wheels. Had the car been able to rev to redline, we're sure we would have seen a 45-rwhp gain.
While we were at it, we decided...
While we were at it, we decided to install a UPR Blu Thunder shifter and adjustable handle for more accurate shifts. The billet design is rather robust and its reduced throws make shuffling the cogs within the T5 more enjoyable.
Side by side, the differences...
Side by side, the differences in shape and size of the two downpipes are readily apparent. The Stinger piece is not only larger in diameter, it's smoother mandrel bends free up power that would normally be sucked up in negotiating exhaust gasses around crushed bends and small tubing sizes. Although our Stinger downpipe was an off-road-only model (PN S3MD; MSRP $300), we did the ozone layer a favor and welded in a 3-inch high-flow cat that we picked up from the local auto parts store.