KJ Jones Senior Technical Editor
April 1, 2009
Photos By: KJ Jones
Those of you who frequent the 5.0 Mustang & Super Fords website and keep up with our blog entries probably recognize Logan Motorsports' Three-Valve intake as a hot, new product we gave you a sneak preview of back in the June '08 issue. Now it's time to put this blingin' beauty to the test.

Horse Sense: Before we go forward with this report, let's backtrack for those of you not sure what we mean when we refer to the Three-Valve powerplant. We understand that all of our readers aren't Melvins when it comes to technical knowledge about Mustangs, and there are folks out there who hear the term all the time but just don't know what it means. The new-Mustang engine's Three-Valve moniker is derived from the addition of a second intake valve in the cylinder heads. Basically, the extra valve per cylinder allows more air to fill each hole, which in turn enables the '05-'09 4.6 engine to make more horsepower than its Two-Valve (one intake/one exhaust valve per cylinder) predecessor, which was found under the hoods of '99-'04 Ponies.

As living, breathing creatures, we all depend on air in some way, shape, or form. As gearheads, we understand that although engines are mechanical, they also rely on air for the same reason--it enables them to function.

Air and "breathing" are just as critical for engines (especially the force-induced Three-Valve engines we're seeing a lot more of in modified '05-'09 'Stangs) as they are for all of us. Since new technology for tres-valve modulars hits our radar with the same almost-daily frequency that the Fox gear did years ago, we've been keeping a close eye on all of the upgrade induction pieces being developed to further enhance the performance potential of supercharged and turbocharged S197 GTs.

Johnny Morris spins wrenches and does all of the dyno tuning at Image One Motorsports in Blountville, Tennessee. He was kind enough to lend us his beautiful Vortech V2 S-Trim-blown '05 Mustang GT as the test Pony for this project. The GT's SCT-tuned engine is based on a D.S.S. SuperMOD short-block, and features ported heads and Comp's Stage 2 camshafts.

While S197 CAI systems, throttle bodies, ported cylinder heads, and even aggressive camshaft profiles have led the new-parts hit parade for a while, many aftermarket companies are now making steady inroads in their development of aluminum intake manifolds for Three-Valve engines. This definitely has us hyped. The news of aftermarket intake manifolds is important, because although the composite-plastic, variable-length intakes that Three-Valve engines are equipped with from Ford are good (capable of supporting as much as 500 rwhp in many cases), they tend to be restrictive and much less efficient in the higher-revving, bigger-horsepower turbo and blower applications that many 'Stangbangers are building for the street.

From a low-budget perspective, bolt-on pieces such as throttle-body spacers and delete plates for charge motion runner controls are available, and they do help improve high-rpm performance of stock intakes by smoothing out turbulence as air enters the manifold and travels through the intake path to the cylinder heads. However, as many of you know or are experiencing, it's a tough battle trying to maintain any true sense of low budget when your intent is to go far above and beyond the 460ish-horsepower capacity (with stock internals) of a Three-Valve engine.

Making big steam--horsepower far beyond the 550 ponies at the feet that these days seem to be, well, entry-level for modified 'Stangs--requires investing in a short-block (which in some case includes the engine block itself) outfitted with a forged crankshaft, rods, and pistons that are up to the task of performing consistently under severe-duty conditions. On the top side of said engine, pressurized airflow is best managed with a larger throttle body, camshafts with increased duration, ported heads, and an unrestrictive aluminum intake manifold. Focusing on the manifold for a second, the design and construction (material, runner shape/length, and so on) of the intake manifold probably is the most critical factor in an engine's overall volumetric efficiency.

Keith Logan and his son, Dwayne, of Logan Motorsports in Elgin, Illinois, think about VE all the time, including methods of manipulating it for improved performance from 4.6- and 5.4-liter Ford engines. Airflow, of course, is key, and the Logans have developed a series of absolutely gorgeous aluminum sheetmetal intake manifolds for Two-, Four-, and now Three-Valve bullets that help maximize airflow in these engines. ['Net surfers may have already seen KJ's sneak-preview photos of the Three-Valve intake that were posted in our website's blog section last June--Ed.].

Off with the old is the first order of business. Johnny (right) and Dale Minton of Fat Boy Fabrication remove the 'Stang's original composite intake manifold. The quick-and-easy task requires removing the inlet tube, the main fuel line (if factory rails are used) or aftermarket fuel rails, the five bolts that secure the intake, vacuum lines, and the wiring connector for the CMRC valves.

"If we just did a generic, out-of-the-box type of Three-Valve intake, the average enthusiasts--for the amount of money they're spending--wouldn't be happy," Keith says. "We tailor our manifolds to not only the engine's specifics, such as its displacement, type of camshaft, and so on, but also to all of the particulars of the Mustang itself, including the manner in which the owner intends to drive it. Those variables all have to be considered in order to produce an intake that will help make any sort of significant power."

Our initial plan was to install and dyno-flog the new manifold on a twin-turbocharged S197 that we hoped would be complete around the time of our proposed test, but as many of you know, timetables for elaborate Mustang projects oftentimes are thrown off track. After receiving word that our original test subject wouldn't be ready, Johnny Morris of Image One Motorsports in Blountville, Tennessee, stepped front-and-center and offered us his supercharged '05 Mustang GT to use as a test mule, which prompted your tech editor to board a plane headed for Rocky Top to finally have an opportunity to assess this dynamic new piece.

We've recently been on a tear with reports on ways to maximize the power potential of a Mustang's pushrod engine through heads/cam/intake swaps. This time, however, the blown, built Three-Valve modular takes center stage, with a sheetmetal intake manifold that's designed to take high-rev tres-valves to performance levels that aren't achievable with the factory's composite piece.

Every Logan Three-Valve manifold comes together on paper first as the company's chief engineer, Dwayne Logan, works through elaborate mathematical equations for performance, taking into account port shape and position, runner length, plenum volume, and so on. The main objective is to create a system that allows air to pass through contours and transitions as smoothly as possible. "From there, Dwayne applies data into the physical world by creating two-dimensional CAD blueprints from which our prototypes are developed," Keith says. "Our manifolds probably go through six or so different iterations before they're released. The final manufactured design doesn't come about until we're completely satisfied with a prototype's performance on the dyno." With prices that start in the $2,500 range, a sheetmetal intake manifold clearly isn't something that's bolted onto a 400hp Three-Valve engine with hopes it will make a Pony instantly take off. However, when you consider the amount of time and development put into creating a piece like this--specific to a high-performance Mustang's needs--the dollar figure really doesn't seem as great.

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After bolting Logan Motorsports' Three-Valve intake manifold on the D.S.S-based 4.6 in Johnny Morris' '05 GT 'Stang, we returned to Image One's dyno cell and once again strapped the Pony to the rollers. The new intake showed its stuff on the first pull by prompting an immediate adjustment to the low-rpm fuel trim (added fuel), because of the level at which boost and higher airflow (brought on by the manifold) leaned down the air/fuel mixture at tip-in.

One thing that's interesting--and a true validation of the Logan intake's potential for making really big steam in the higher rev ranges (Keith Logan feels the intake will thrive at 7,500 rpm and higher)--is the comparison between the stock manifold's performance and its aluminum replacement. With the stock piece, power appears to fluctuate up and down dramatically as rpm increases from approximately 5,500 to 7,000. However, with the Logan Motorsports intake in place and performance charted within the same rpm window, power steadily increases in a smooth curve and really takes off right around the point where the stock intake is clearly finished (6,500 rpm).

Had there been more camshaft (and valvespring) in the ported heads on Johnny's engine, with the Logan Motorsports Three-Valve intake manifold installed we probably would've seen close to 600 pump-gas horsepower (more with race gas and more boost) at the rear wheels.

The stock intake proved to be more torquey in our test, but we believe this may be due to the specifics of the test manifold's design. Remember, the project's original plan was for installing the intake on a twin-turbo Three-Valve 4.6, not Johnny's Vortech V2 S-Trim-supercharged engine.