KJ Jonesx
February 21, 2014

Horse Sense: Most discussions about turbochargers indubitably include some reference to a turbo's size— in millimeters. For those who have always wondered exactly what area of the turbocharger this metric measurement refers to, it's actually the inducer diameter of the unit's compressor wheel. That's the diameter of the point where air actually enters the wheel.

This question is for all of our die-hard Fox fans. How many of you occasionally find yourselves mulling over the idea of parting ways with your beloved '86-'93 GT or LX, simply because the lure of newer models is so strong?

Let's be real about this. While there are all sorts of upgrades that help make them more comfortable as they go on in years, the early cars will never match the tightness and plushness of later Ponies. And, with the Coyote, Roadrunner, and Trinity engines nestled under the hoods of the coveted '11-'14 'Stangs, the choice between keeping your 20-something-year-old friend or opting for a younger thoroughbred can be a bit intimidating.

However, despite the performance-and-aesthetic plusses of the newer rides, at the end of the day, cost is often the critical factor in electing to either step up or stay put. The latest Mustangs deservedly garner a pretty handsome sum. When you factor in the tab for modifying a later-model Pony, you're looking at potentially handing over a lot of bread.

Of course, such investments certainly are worth it in most cases. But, when your budget won't support making such moves, there still are a lot of cool options for making a Fox worth keeping. One option that hit our radar is a twin-turbocharger setup from CXRacing. This SoCal-based company recently starting making moves in the Mustang game after many years of forced-air-inducting sport compacts and intercooling anything on wheels that's fitted with forced induction.

Of course, the concept of adding a pair of turbos to a pushrod-5.0 'Stang's engine is nothing new. However, until now, we haven't seen a complete intercooled turbo system for as low a price as the kit we're working with in this report.

When considering turbos, the bigger-is-better adage doesn't completely apply for the street 5.0s. Even with 331ci and 347ci engines that can support huge 88mm, 94mm, or 101mm turbochargers, bolting those behemoths on daily driven Mustangs doesn't accomplish much. The amount of time it takes for sufficient exhaust pressure to build up in bigger turbos results in turbo lag. Subsequently, boost, rear-wheel horsepower, and torque don't truly come into play until you're going well over any legal speed limit, making the big-single setup much more appealing for 'Stangs that are purpose-built for quarter-mile action.

While a matched pair of smaller turbos (65mm to 76mm) may not produce as much boost as their giant single counterparts, they might sacrifice some top-end power, but they definitely will spool much quicker and still can provide the engine with a sufficient amount of air. This actually makes going with two small hair dryers a much-better option for a street-centered '86-'93 'Stang that no doubt would be a lot of fun to drive when boost and peaking well before 6,000 rpm.

Priced at just a nudge over $2,000, CXRacing's twins set (PN TRB-KIT-MUSTANG-TT-GT35-2-IC; $2,089) is one of the lowest-priced, Fox-specific, bolt-on turbo kits. And in July 2013, CXRacing owner Kevin Xie gave us an exclusive opportunity to evaluate his company's affordable twins, using Greg Montoya's '84 Mustang LX coupe.

Before your Melvin instincts get the best of you, no, the turbo set isn't designed for carbureted 'Stangs. Despite its pre-EFI build date, Greg's sleeper is retrofitted with a 306ci short-block and a complete replica '93 Cobra EFI setup (mass-air, GT-40 heads, Cobra intake, and so on), a big reason why we selected the Pony for this upgrade. The new-tech-for-old-'Stang concept is taken another step further with the removal of the coupe's engine-management and replacement of the EEC-IV hardware with Holley's Dominator EFI system.

Keep reading to see the install performed by CXRacing's Ascension Sanchez and Rene Franco, and learn the details on tuning the turbocharged 306 using Dominator EFI (and the all-important dyno results, of course), all of which can revitalize an old Fox with cool technology for modest cost.

Ascension Sanchez (right) and Rene Franco hang a pair of CXRacing’s turbos on the 306 in Greg Montoya’s ’84 coupe. While installing CX’s Fox-specific twin set may be a bit much for novice ’Stangbangers, the kit’s intuitive design and good fitment will allow mechanically skilled enthusiasts with appropriate workspace and tools to bolt on the system.
This is the eye-catching promotional photo that piqued our interest in working with the CXRacing twin-turbo kit for ’86-’93 ’Stangs (PN TRB-KIT-MUSTANG-TT-GT35-2-IC; $2,089). The system was developed completely in house by Rene using a convertible ’Stang that company-owner Kevin Xie says was purchased specifically for producing the twin set, as well as a big-single turbocharger kit for Foxes. “When we come up with a new turbo idea for a particular vehicle, we go out and buy that exact car before any pieces are made. Having a live model to work with gives Rene the best opportunity to create jigs and templates for our turbo-systems’ tubes that are spot-on accurate, and as such, can be duplicated by our own people—not outsourced—to ensure proper fitment in our customers’ cars.”
The once-carbureted, stock-block 5.0 in Greg’s coupe now displaces 306 cubic inches and benefits from a ’93 Cobra-style induction upgrade (GT-40 heads, Cobra intake, and E303 camshaft).
With a plan to start on the project right away, we turned to our friend Mario Nadel of M&M Towing Service for assistance with transporting the test Pony to CXRacing’s headquarters.
Twin-turbo installation actually starts with the removal of several parts, the most-notable being the ’Stang’s front bumper cover, which must be modified before it is reinstalled.
Headers are also taken out for replacement by CX’s 15⁄8-inch, stainless-steel turbo headers.
If the Mustang still uses a stock K-member, raising the engine slightly to facilitate removing the oil pan is one of the project’s few heavy-lifting requirements.
Engine oil is used to ensure the twin turbochargers are well-lubricated and properly cooled. The oil is sourced directly from the engine (oil filter housing), and is returned to the oil pan afterward via a hose and fitting that must be welded into the pan.
Here’s a comparative look at a basic, upgrade header for Fox Mustangs (top), and CXRacing’s stainless-steel turbo header. Like the bolt-on short-tube, turbo-swap tubes also measure 15⁄8 inches and are designed for standard-port cylinder heads.
Rene bolts the new turbo headers in place using CX’s high-heat exhaust gaskets, which are included with the system.
Both of the kit’s 65mm turbos sit on T-3 housing flanges, which measure 2x2.5 inches. Single-turbo systems typically use turbochargers that require a T-4 flange, like the one that’s shown here (top) for comparison, which is approximately 0.25-inch bigger.
CXRacing uses a pair of oil-cooled T-3/GT35 single-ball-bearing (compressor)/journal-bearing (turbine) turbos that are capable of producing 25 psi of boost. The hair dryers feature 4-inch air-inlet (w/anti-surge venting) and 2.5-inch discharge portals, a 61.3mm (inducer)-by-82mm (exducer) compressor wheel, 62mm (inducer)-by-67.8mm (exducer) turbine wheel, and turbine A/R of 0.82. This tight A/R helps the units spool quickly. The anti-surge shroud on the compressor housing helps prevent the intake manifold from being overloaded under boost by releasing excess pressure from the turbo itself.
Rene handles some of the bench assembly that’s required for each turbocharger (oil fittings, and such) before they’re installed. CXRacing provides all of the hoses, fittings, and miscellaneous hardware that’s necessary for installing the turbo kit.
The position of the driver-side wastegate makes moving the oil filter a requirement. An adapter for the filter housing, as well as the lines and fittings for feeding oil to the turbos, are all standard equipment.