5.0 Mustang & Super FordsHow To Engine
S197 Mustang Turbo Kit - Bottom-Fed Boost
Serious Thunder Down Under For S197 'Stangs
Horse Sense: Although Fox Mustang twin-turbo systems might have been slightly ahead of their time (actually, commercial production of hard-core, 'Stang-specific single- and twin-turbo setups took a brief hiatus from 1995 to roughly 1998, possibly due to their cost), the technology is now at the forefront of the power-adder game with bolt-on systems available for all Mustang platforms from 1987 to 2009.
Turbochargers have arguably become the most menacing power adders known to 'Stangbanging over the last five years. However, despite bolt-on turbo systems' meteoric rise in popularity, the concept of using turbochargers as a way of enhancing street-based late-model Mustang power isn't new to the high-performance 'Stang game.
Some of you may be too young or too new to the scene to know this, but contrary to what you may think, turbocharging a 'Stang wasn't founded on strapping a single 65mm head unit (and related plumbing and accessories) to a '99-'04 Pony's stock 4.6. Our involvement with the third power adder in the big three (turbos for Mustangs became popular after nitrous and superchargers) goes back quite a bit farther to a time when fuel-injected Fox-body Ponies reigned supreme on the street and the strip.
Initial performance turbo systems featured large, single-head units that easily transformed appropriately modified (with fuel- and ignition-system upgrades, or beefed-up long-blocks) street Mustangs into top-end rocket ships. It's interesting to note that a 64mm turbocharger was thought of as big back then; the 76mm, a unit that today is viewed by some as an entry-level turbo, was gargantuan.
While having the ability to achieve warp speed with a turbo is great, one of the drawbacks to the single-turbo setup in a street application is a loss of torque and low-end acceleration due to the time it takes a single turbo to make boost.
Unlike superchargers that get their go from a belt or gear connection with an engine's crankshaft, turbochargers use an engine's exhaust gases to turn their impeller shafts, which subsequently drive turbine wheels that force compressed air into the engine. Obviously, the blowers' direct connection with the crank allows them to build boost instantly. The process is longer with turbochargers, as it's also somewhat hindered by a myriad of tubes that channel air through the system before it reaches the engine.
In an effort to reduce the amount of time in which a turbocharged 'Stang builds boost (something we refer to as "lowering the spool time"), companies such as Cartech Racing began offering twin-turbocharger systems for street-driven, 5.0-powered Ponies. 'Stangbangers found that when using two smaller (44mm) turbos, boost comes in much sooner, thus improving the low-end performance that is a must for the street.
In the last three years, we've taken a look at and reported on several different single-turbo systems for S197 ('05-'09) Mustangs. At this point, turbo kits for new Ponies are totally dialed-in packages and offer great performance gains for stockers. However, one thing we've noticed about a majority of the single-turbo systems is they're also fairly cookie-cutter from a design standpoint with similar tubing layouts and turbo placement. Rear-mount has been the only game in town for new 'Stang owners who want to go the twins route-that is, until now.
We say "until now" because prior to the '07 PRI show, we were completely unaware of the innovative, new twin-turbo kit that Team Performance of Simi Valley, California, has been developing specifically for S197s.
In a strategic alliance with Exile Turbo Systems, Team took conventional turbo-system design and threw it out the window with its new, radical Heritage GT twin-turbo system-a high-end ($10,000), bolt-on power enhancer that's centered on twin Garrett 2871R turbochargers (53mm) mounted below-that's right, directly underneath-'05-to-present 'Stangs.
Why twin turbos, and why mount them down under? The system uses twins to achieve the broadest power and torque curves possible. "By using two highly responsive dual-ball-bearing turbos, we can get into boost by 3,000 rpm," says Exile's Rick Head. "Because of all the tubing involved, the total amount of usable power and torque is much smaller with a big single.
"From a design standpoint, we wanted to offer a system that doesn't require any modifying (cutting, welding, and so on) of the vehicle's chassis or body structure. Nothing underhood is compromised or relocated."
After inquiring about details on this water-cooled/oil-cooled setup, we were invited out to Team's new development facility for an in-person look at the Heritage GT twin-turbo kit as it was installed on a nearly bone-stock (with the exception of Corsa mufflers), five-speed '07 Shelby GT Mustang.
Rick says the Heritage GT system is good for roughly 465 rwhp (at 8 psi of boost) on an unmodified S197, so our study naturally includes dyno testing-before and after the 'Stang was double boosted-to see how close the system will come to this claim once the rollers start spinning at full speed.
Data was captured with our '07 Shelby GT 'Stang strapped to the rollers of a Dynojet chassis dyno at Los Angeles Power Division before and after installing the Team Performance Products Heritage GT twin-turbo system.
After laying down an initial 282.22 rwhp and nearly 300 lb-ft of torque in the baseline test, the twin-boosted 'Stang showed its stuff when we revisited the dyno, churning peaks of 456.52 horses and 493.14 lb-ft of torque at the back tires using only 8 psi of boost. While the dyno session left us with no doubt that Team is onto something with its low-mount turbo setup, we also had a chance to feel the boosted performance of the otherwise-stock S197.
In a nutshell, boost is good. After a brief cruise through the streets of Simi Valley-with sporadic, tire-blazing boost blips where traffic permitted-we guided the Shelby to the 118 Freeway and let the twin turbos get busy. The power was smooth and hit instantly when the hammer dropped. Once the rear tires finally got a significant hold of the road, the speedometer display swung around beyond normalcy-and we were still in Third gear!