Saul "The Surgeon" Gutierrez of Extreme Automotive in Canoga Park, California, preps a set
Unless you've been living under a rock for the last 20 years, you must be aware of the impact that superchargers, turbochargers, and nitrous oxide-the Big Three power adders-have had on '86-to-the present Mustangs.
While some 'Stangbangers install the power-enhancing systems as a way of giving their bone-stock Ponies more zip, other enthusiasts turn to power adders for taking highly modified, hard-core Mustangs to the next level.
Forced induction (blowers, to be specific) appears to be the power builder of choice for the S197 crowd. We've seen several '05-to-present 'Stangs at shows and prowling the boulevards sporting the latest Roots-, screw-, and centrifugal-style superchargers offered by all of the leading manufacturers. Today's S197 supercharger systems are completely bolt-on. They include fuel-system components and programming updates for a 'Stang's PCM that will allow its Three-Valve engine to operate efficiently while under the influence of boost.
Despite all of the benefits of adding a blower to an '05-'09 Mustang, one of the nuances we've heard about more than a few times is that supercharged S197s occasionally experience spark issues that can affect driveability and performance in a big way. Spark plugs are the root of this problem.
Blower upgrades are made retaining the OEM plugs, and their high heat range and fixed gap are no match for the higher cylinder pressure and hotter temperature that a blower promotes. While supercharged Three-Valves can be tuned to make great power on pump fuel, a lot is left on the table because of the overall inefficiency of the spark plugs once boost gets at them. Stock plugs are hotter, and there's less contact area between their ceramic inserts and the metal inside the plugs, so heat remains trapped in the ceramic.
Phillip's Pony gets its giddy-up from this Paxton Novi 2200 supercharger system. The blowe
Simple handtools are all that's needed for making the spark-plug exchange. The main necess
Use a 1/4-inch-drive ratchet and extension to clear the wire harnesses.
Just as they are with pushrod engines, adjustable-gap, colder heat-range spark plugs are the answer for blown modular bullets, including Three-Valves. Cold plugs are designed with more contact area between the metal and ceramic. The space prevents pre-ignition of fuel (gas ignites before spark actually fires), which is critical for any power-adder-assisted engine.
Phillip Lewis' '06 GT shows all the symptoms of a supercharged 'Stang in need of spark relief. The engine has a slight intermittent miss while idling, and the trey valve stumbles and falls off precisely at 4,700 rpm when Phillip tries to accelerate and the Paxton Novi 2200 starts making boost.
The stock plugs (left) in Phillip's engine showed signs of attempting (and not doing too g
Factory Three-Valve plugs are typically gapped at 0.055-inch. Saul sets the gap on our new
A small piece of vacuum hose serves as a great handle for installing spark plugs in cylind
Although gapping tools for Three-Valve plugs are available, we decided to try Brisk USA's new racing spark plugs (PN 3VR14S) in Phillip's Mustang. The plugs were developed specifically for the Three-Valve cylinder heads on '05-'09 Mustang GTs. In addition to their long shanks, they feature conventional-style electrodes and ground straps at their tips, which allow for easy tuning (gap adjustments) for forced-induced or high-performance naturally aspirated applications.
The following photos and captions depict Saul "The Surgeon" Gutierrez's easy plug swap, and the dyno information shows the difference proper spark plugs make with this type of performance enhancer on a Three-Valve engine.
We saw a marked improvement in the Paxton-blown, stock engine's performance when we locked it down on Extreme Automotive's chassis dyno. However, while the dyno numbers with Brisk plugs better reflect what we've come to recognize as the ballpark average horsepower of blown trey-valve stockers, please don't think that the power gain in our dyno figures represent the gains that come from just adding plugs. Phillip's engine was in duress and wouldn't rev anywhere near the 6,000 rpm that is standard for our dyno evaluations. The addition of Brisk's spark plugs corrected the stumbling issues, thus enabling the engine to perform as we'd expect it would and present impressive final horsepower and torque figures for an S197 that's equipped with a bolt-on supercharger.
Click here for the Mustang spark plug dyno chart