Tom Wilson
December 12, 2013

With so many unsolved problems in the world, thank goodness the too-much-is-just-right crowd now has a legal supercharger for the Boss 302. It was getting hard to go on without one, what with only 444 hp in the exquisitely balanced, rpm-happy Boss. Imagine, not even close to 500 hp to the rear tires off the showroom floor. What was Ford thinking?

Luckily, J Bittle of JBA Speed has been on the case (for about 28 years now) and recently inked a deal with Vortech Engineering to be the sole developer and distributor of a 50-state emissions legal Vortech supercharger kit for the '12 and '13 Boss 302s. The resulting blower kits are just now hitting the streets, and with J putting us in his development car for a couple of breathless days of evaluation, we thought you'd like to tag along on this way-over 600hp ride.

It all starts with the hardware, and here there are no surprises. A Vortech V3 supercharger—that's a quiet one with helical gears—is the main attraction. Because there is no CARB-acceptable replacement for the hydrocarbon trap in the air filter box lid, the JBA installation retains the stock air filter assembly in order to remain smog legal. There is, however, a 98mm mass air meter included as part of the roto-molded, Vortech supplied air tubing, along with a large-capacity racing by-pass valve to vent excess blower air, an air-to-air charge cooler, and larger capacity fuel injectors. The whole shebang is given an all-important electronic integration by JBA's Bruce Tucker, with an SCT hand-held tuner included in the kit.

Because the V3 supercharger employs self-contained oiling, there is no need to break into the engine's lubrication system. For old hands, that means no one is going to drive a punch through your oil pan in order to install an oil return line. That's just as well because the Boss 302's cast aluminum oil pan doesn't take well to hammer and punch treatment. And thanks to the Boss's already high-volume fuel system, only a voltage-boosting module is needed to supply the necessary fuel to the big injectors.

JBA elected to keep a subdued presence on the outside of their Boss demonstrator. The supercharger does all the talking that’s needed.

Compared to the Mustang GT, the Boss kit development presented several fabrication challenges. Most are found near the oil cooler and lower radiator hose plumbing, where the Vortech's charge cooling ducts must also pass through. JBA techs worked up the necessary molded hoses, reshaped ducts, and trimmed fan shroud to suit. Similar changes were necessary around the throttle body, which sits higher in the Boss than in a GT, and there were wiring harness extensions to deal with as well.

Of course, the big deal here is the 50-state emission exemption, making the boosted Boss legal anywhere in the U.S. The calibration is written for 91-octane premium pump gasoline, a nominal 9 lbs of boost, and JBA guestimates—the combination has not been tested on an engine dyno—it generates 640 hp and 524 lb-ft of torque at the flywheel. On JBA's DynoJet, the rear wheel numbers are 571 hp and 472 lb-ft of torque at the rear tires. It's a lot of steam no matter how you measure it.

Pricing is listed at $8,195 for the kit with JBA asking an additional $2,000 for the installation. But, if you hurry you might get in on some early-bird specials that salesman J is offering.

One consideration so far is that the Track Key calibration, with its lumpy idle, is incompatible with the Vortech. JBA knows they can make the two play nicely together, but it's a task they'll tackle after getting the main kit fully sorted and selling.

There are a few options, starting with the blower finish. Satin is standard while polished or black is extra. There's an upgrade to 8-rib drive pulleys from the standard 6-rib arrangement if you really feel the need, and a $50 extended warranty that covers the supercharger for three years. A 1-year blower warranty is standard.

So much for the numbers, what really matters (besides bragging rights) is what does it feel like from behind the wheel? Very fast would be the glib response, but it's more accurate to say it's a Boss 302, but with more. It has a lighter, snappier feel than a Shelby GT 500, if that helps any, although the sledgehammer Shelby feels more muscular.

Perhaps we should first note that with stock suspension, brakes, and tires, the blown Boss rode and handled like a Boss 302, which is to say perfect. The Boss is the Mustang we've been waiting for the last 30 years, and each time we're able to pedal one, our enthusiasm for the precision and easy speed is rekindled.

Adding the Vortech to the mix is a good thing in that the centrifugal blower is perfectly matched to the stock Boss 302 power curve. Unlike positive displacement superchargers that require removing the Boss's distinctive and personality-making short runner intake manifold, the Vortech works with the stock intake. This translates into stock-like power off idle and through the lower portion of the tach, then a building rush of extra thrust the higher the engine is revved. Redline remains stock, but the urge from 4,500 rpm to over 7,000 rpm is magnitudes greater.

In practice, with the JBA demonstrator and its 3.73 rear gears, this means First gear was far too short to get usable blower power down before the tires went up in smoke; Second gave exciting acceleration until the last 1,200 rpm when the tires broke loose every time. A short shift into Third works best, where the force-fed Boss gets into some serious acceleration into the felony-fast zone.

For puttering around town, the JBA Boss is and feels stock, and your mom might wonder why you spent 10 large for a blower. But in daily driving, the blower isn't a factor, and even a quick shot of full-throttle typically isn't enough to bring the supercharger into play given slumbering cruising rpm. The Vortech supercharger is also notably lighter than its positive displacement competition. JBA corner weighted their Boss, finding the blower added under 65 lbs to the front axle—not enough to feel at the strip or in the corners in all but back-to-back testing.

In other words, the car feels showroom until you leg it out a little, and then it rages. Blower assist is rarely used on tight winding roads, but if the corners are spaced a little wide it can provide a thrilling rush. It would be a scream at an open track or the drags where you can keep the engine on the boil all the time. And we should say, it's not like a nitrous car where it's all or nothing, but the big joy is still at the top of the tach.

Looking like it grew there, the Vortech V3 was back in black on the Bittle Boss. Revved up, it puts 571 hp to the rear tires on Bittle’s dyno—enough to spin the tires at the top of Second gear every time.

All said, the blower Boss easily passed our bottom line test; it's the sort of car that makes you look for excuses to go drive it. Part of that appeal is its sound. JBA chose to open the blocking plates in the Boss side exhaust, resulting in a snarling, crackling deceleration and a real call of the wild bellow when in the boost. It's too loud for daily use in the 'burbs, but everybody loves it for the first 15 minutes, and you could always keep the plates in the sound tubes for a near-stock sound. The blower itself is all but inaudible.

Also lending hot rod tone is a mad-cat hiss from the blower's bypass valve. This comes into play under deceleration when the still-spinning supercharger's output is vented to avoid excessive charge air heating. This is sound engineering (to play an atrocious pun), but not what impresses your wife with its industrial white noise. That said, the big racing bypass valve is proper for this hard-charging installation and sounds off only when the engine is already loud with rpm and exhaust noise, so it isn't overbearing by itself.

But, add the racy rpm, raucous exhaust, and by-pass whoosh together and Ford's Boss sophisticate turns into a hot rod, just the way Texans like Bittle like it. If you prefer your speed a little quieter, simply keeping the exhaust plates in place would make the difference. That, and rolling up the windows, definitely distances the mechanicals in these modern, heavily sound-proofed Mustangs.

We uncovered no glitches in J's demonstrator. Everything started, stopped, and ran as advertised. There was a slight plateau, or step, in the acceleration at part-throttle, but only sometimes and Tucker and Vortech were still fine tuning the combination when we drove it, so it will be long gone on production kits.

If you want to be long-gone with one of these kits, JBA has what will cure your urge. Given Vortech's high efficiency and time-tested durability, we think it would be a great ride for the dedicated performance fan, track drivers, or those simply wanting that little bit more of the Boss 302 feel.

On the Dyno

Boss 302 Naturally Aspirated

RPM HP Torque
3,918 256.0 338
4,109 271.2 347
4,238 283.2 351
4,366 290.6 350
4,495 297.5 348
4,623 297.8 338
4,751 304.7 337
4,880 312.1 336
5,008 319.8 335
5,137 327.4 335
5,265 336.7 336
5,394 351.4 342
5,522 358.5 341
5,650 361.6 336
5,779 365.5 332
5,907 372.4 331
6,036 379.7 330
6,164 384.0 327
6,292 379.9 317
6,421 378.5 310
6,549 379.9 305
6,678 377.0 297
6,806 376.9 291
6,935 377.6 286
7,063 383.7 285
7,191 388.4 284
7,320 390.6 280

JBA Boss 302 Supercharged

RPM HP Torque
3,918 346.6 457
4,109 315.3 403
4,238 332.0 411
4,366 357.4 430
4,495 383.3 448
4,623 398.9 453
4,751 411.5 455
4,880 423.8 456
5,008 437.7 459
5,137 452.4 463
5,265 468.1 467
5,394 481.3 469
5,522 495.1 471
5,650 507.3 472
5,779 519.1 472
5,907 531.1 472
6,036 540.1 470
6,164 543.7 466
6,292 555.2 463
6,421 558.7 457
6,549 563.2 452
6,678 569.7 448
6,806 571.5 441
6,935 563.9 427
7,063 556.8 414
7,191 514.6 376
7,320 N/A N/A

Data provided by JBA using their in-house DynoJet chassis dyno. Baseline naturally-aspirated data obtained using standard key (non-Track Key).