KJ Jones Senior Technical Editor
September 1, 2008
Photos By: KJ Jones

Horse Sense: This report marks the close of what has become known around the office as "Version 1.0" of our Boss 340 engine project. This first iteration of our experiment with canted valves features Edelbrock's Performer RPM 351C 2V heads, a Wilson-modified original Boss 302 intake manifold, and a Probe Industries-built short-block based on Ford Racing Performance Parts' new Boss 302 engine block. While it ends with the dyno test detailed in this report, you can rest assured that we'll probably be deep in the throes of Version 2.0 activities by the time you read this. That's right-there's plenty more to come for this project, including the construction and running of a full-on, who-knows-how-many-second drag 'Stang by the time it's over.

Westech's Ernie Mena and Steve Brul put the finishing touches on our Boss 340 project engine. With its Edelbrock Performer RPM 351C 2V canted-valve heads, a beyond-radical '69 Boss 302 intake manifold by Wilson Manifolds, a Comp Cams hydraulic-roller bumpstick and valvetrain components, and Probe Industries' forged rotating assembly, we think this version of the Boss (we're calling it Version 1.0) should be capable of sending nearly 400 naturally aspirated horses to a street 'Stang's rear tires.

Ernie is Westech's resident EFI guru, and our engine test is his first look and tryout of ACCEL's Thruster EFI engine management system. "I'm really looking forward to working with this system," he says. "We've been getting calls from people asking for information on how it performs. Having this opportunity to work with it will be helpful."



Based on comments we've seen on our Web site's message board and notes we've read on some of the Mustang-specific message forums we peruse, it appears our Boss 340 (a modernized version of Ford's legendary Boss 302) engine effort has developed a fairly strong fan base since we first introduced the idea in our Mar. '08 issue ("The Comeback," p. 82). The attention our engine is getting is cool, and we hope the project has thus far been entertaining, but even more informative, especially for those of you who have been as curious about building canted-valve-headed 302s for Fox Mustangs as your tech editor has been since Ford brought back the Boss.

In retrospect, our fuel-injected, Boss-style bullet was done the hard way. While the short-block is comprised of the same internal gear that's used for 347 strokers-with the exception of pistons, which are Cleveland-head-specific pieces made by Probe-the cool, matched-set, top-half pieces (heads/intake manifolds, headers) that are now available, such as Edelbrock's new Performer RPM Clevor setup for 302-based engines and Kooks' Boss 302/8.2-deck, bolt-on, 2-inch headers for '79-'93 'Stangs, were still in development when we got started. We had to figure out what was needed and how to make it all work.

The FRPP oval-shaped Mustang air-cleaner assembly includes a slimline, 1-inch element that will do more harm than good on an engine such as ours, so Eugene is replacing it with K&N's 3-inch cleaner for greater airflow into the Wilson 1,130-cfm throttle body.

Putting it succinctly, we figured it out, and we must say that we couldn't have done it without the great help we received from the many manufacturers and service providers who believed in what we were trying to do-break new ground with engine technology in our ever-evolving Mustang world. In many instances, they went above and beyond with their assistance and support of this effort.

With that said, it's finally time to light our 340's fire and see if it indeed lives up to the "Boss" name. We've taken you through all of the conceptualizing, parts-gathering, and building stages of the engine in previous stories, and we're now at a point where our finished product must be put to the test.

It's all going down on the SuperFlow 902 engine dyno at Westech Performance Group in Mira Loma, California, where Ernie Mena and Eugene Walde are set to handle every step of the test process, which includes developing fuel and timing maps with ACCEL's newest addition to its DFI lineup, the Thruster EFI. The following photos and captions highlight events and processes that preclude our date with the dyno. Of course, the Boss engine's all-important performance statistics are also included.

We selected Edelbrock's Performer RPM 351C 2V closed-chamber (60cc) heads (PN 61629; $975 each) for our first segment of the project. The heads include stainless steel, 2.05-inch intake valves and 1.60-inch valves on the exhaust side, as well as 1.540-inch double springs, stud-mount rocker hardware, 7-degree locks, and chrome-moly retainers. While they're small compared to true '70 Boss 302 cylinder heads, which are noted for their 2.19-inch and 1.71-inch intake and exhaust valves, we think the Edelbrock pieces will work great on our modern-day Boss or any naturally aspirated 302-based engine of 347 ci or less. Edelbrock's new Performer RPM Clevor heads/E-Boss 302 intake package makes building a similar bullet a lot simpler than our effort, but our project was a lot of fun nonetheless.

Eugene Walde threads AFR's 3/8-inch head studs (PN 100-1404; $110.03) into each head. Edelbrock's and Air Flow Dynamics' Cleveland-style heads (AFD heads will be featured on Version 2.0 of the Boss 340) have offset header-bolt patterns, as opposed to the inline-exhaust bolt holes that are more common to most small-block Ford cylinder heads. While using the studs is another break from the norm (there are quite a few such deviations with this project), we believe the studs will also make installing individual header tubes a lot easier, especially once the engine is installed in a 'Stang.

The 5.0 Mustang & Super Fords fender badges on our project '86 T-top coupe and the "Fox 500" seat embroidery for Editor Turner's project '88 T-top LX have kicked off a personalization trend. In accordance with our modern-day/throwback theme for the Boss engine, we thought it would be cool to add custom replica valve-cover decals to let people know our Boss really is special. The folks at Jim Osborne Reproductions (a Ford-licensed manufacturer of shop manuals; owners' manuals; underhood-, interior-, and trunk-detailing decals; and stripe kits for early and late-model Mustangs, as well as all sorts of vintage Fords) made us a slick set of exact-dimension (13/16x45/16-inch) polyester stickers with a custom-blend silver that matches the natural aluminum finish of the FRPP 351C valve covers. These decals are one-off and produced with the permission of Ford Motor Company. If you're a Boss fan of any sort, you have to admit they're way cool!

Until now, headers for an 8.2-deck, Cleveland-headed engine were a dream, or they were expensive, custom pieces that you could only acquire through a friend of a friend of a friend-if you were lucky. Kook's Custom Headers shares our vision of putting true Boss engines in '79-'93 Mustangs and has developed a set of 2-inch, mild-steel headers and 3-inch merge collectors based on individual tubes that are flanged for Cleveland exhaust ports. When assembled, the Fox-specific headers fit cleanly around a 5.0's block and SFI bellhousing and allow more than ample access to the starter and oil filter. Although the headers are custom, they're not one-off pieces for our project engine. If you're building a 302-based Boss for your Pony and need to get the exhaust out, contact Kook's and reference 5.0&SF's Boss 340 engine project to ensure you get the right set. Specify what type of oil pan is used, as pans with kickout panels on the passenger side require a different No. 4 header tube that's bent with proper clearance.

Making Connections
With the Boss 340 mounted and locked down on the SuperFlow 902 engine dyno, Ernie Mena, one of Westech's top dyno techs and tuners, and your tech editor completed the hooking-up process of installing the Thruster EFI in short order.

With well-labeled weatherpack connectors and generous length, the system's main- and injector-harness installation is simple enough for any do-it-yourself enthusiast to have the Thruster ready to rock in no time. "Anybody with basic automotive electrical knowledge can set up this system," says Ernie.

Accel-DFI's Thruster EFI is the engine management system we've selected for bringing the Boss 340 to life. This new processing setup is a cool, user-friendly derivative of the more widely known Gen-7 DFI system that controls engine functions in many hard-core race Mustangs. Thruster EFI can be tailored to suit an application's simple or exotic needs. The Boss 340's setup is based on a wideband-capable processor (PN 7701W) for Ford V-8 engines and ACCEL's DFI 6A ignition box (PN 75606), along with a single-channel wideband O2 sensor controller (PN 77062) that includes a Bosch sensor. ThrustMap calibration software also is included for downloading into a laptop and putting it straight to work after a simple installation procedure and tutorial.

This important piece of the wiring scheme is Thruster EFI's dual-synch distributor harness, which sends timing signals to the distributor (PN 77201) from the camshaft and crankshaft. With sequential fuel-injection systems (Thruster EFI can operate in sequential- or batch-fire modes), the dual signals allow tuners to make fuel corrections as needed for individual cylinders. ACCEL's Extreme 9000 Series spark plug wires send the distributor's firing signal to the engine's eight Autolite 3924 spark plugs.

Getting Hosed
We've mentioned more than a few times that this version of our Boss engine features a modified OEM Boss 302 intake manifold. Technicians at Wilson Manifolds really did a number on the stock Boss intake by opening up its plenum for maximum flow, perfectly matching each runner to the heads, and plumbing the classic intake for fuel injectors.

Since a good fuel system is a requirement for any engine, we sought the expertise of Joel Orme of Orme Brothers in Northridge, California, for guidance on how to lay out and set up a hose/fitting scheme that will ensure our EFI engine receives its proper dosage of fuel at all times. Orme Brothers offers dialed-in AN -8 and AN -10 fuel-system plumbing kits (from tank to rails and back; pumps not included) for carbureted or EFI Fox-body 'Stangs that feature mandrel-bent, high-flow fittings by Red Horse Performance of Chatsworth, California.

For our fuel-feed setup, Joel decided to use black, AN -6, braided hose and fittings, as he believes style trends (in some cases, there may be appearance protocol that an engine must adhere to) have swung toward the dark look as opposed to the high shine of steel-braided line. "Look at the matte-black paint jobs that are coming out on many custom cars," he says. "Black works with everything." After seeing his completed plumbing job on our engine, we agree.

Before cutting, Joel places a fitting alongside the hose and marks the hose 1/4-inch back from the nut at the end of the fitting. The 1/4-inch distance equals the amount of thread that actually captures the nipple when the hose/fitting combination is assembled. White lithium grease is used as a lube for mating hoses with their fittings. To reduce the chances of scratching the fittings, Joel strongly recommends using polished-face wrenches when tightening them to their hoses.





Teflon taping 101: Time and time again we see performance-plumbed Mustangs with fittings that are improperly sealed with Teflon tape. We support using tape, but there's a correct way to place it on a fitting. Little do people realize that when the tape is on backward, it has a tendency to back off a fitting as it is tightened down. Joel says the best way to wrap a fitting with Teflon tape is to hold the fitting in your left hand and place the tape on top. Always wrap Teflon in a clockwise rotation, going with the threads of the fitting and holding it taut to control the tension. Leave a few threads exposed to decrease chances of stray Teflon material entering an open orifice (fuel pump, regulator, and so on) and causing damage.

"Black is the new chrome," says Joel, regarding the latest swing toward using prepolished, black-anodized Red Horse fittings for high-performance plumbing applications. "People are tired of the red and blue anodize that has been the standard color of AN fittings for 30 years." Unlike traditional braided hose that is made with steel, the covering on the black hose we're using in our system is made up of a polyester material. However, steel-braided and poly-braided hose are internally identical.

On The Dyno
We've finally reached the point where we can give you the information you've been waiting for. Although our ultimate mission with this effort is to see where the limit is for this Boss combination (without blowing it to smithereens, of course), we also want to check out some of the functions of ACCEL's new DFI system, which we chose as our engine management setup for the Boss 340 after seeing it at the '07 SEMA show.

Just prior to our date with the dyno, fellow 'Stang-mag scribes, editors, and industry associates were asked for their predictions on the total amount of horsepower our experimental bullet would make. Guesses ranged from the low 400s to as high as 500 flywheel horsepower. Here's the final tally: 472.70 max horsepower, 416.70 lb-ft of max torque.

Who's the winner? Your tech editor-who else? With a guesstimate of 470 hp, KJ came closest to the impressive actual number for power at the crank, which really had the folks at Edelbrock buzzing. "Wow-472 hp out of a 302-based stroker with our 2V Cleveland heads is absolutely awesome," said one Ford tech guru after hearing the details.

Version 1.0 of this engine is set up with street use in mind, so our testing was performed using 91-octane pump gas and capping revs at a max of 6,700 rpm. Comp's hydraulic-roller camshaft used in this engine measures 0.580-inch intake/0.577-inch exhaust, with 236/242 duration at 0.050.

While the results are excellent, we believe this street combination is just a valvespring change away from posting more crankshaft horsepower. We experienced valve float at about 6,400 rpm, so an upgrade to a stout set of Comp's valvesprings and titanium retainers might be the answer for those of you who plan on going after this same setup and want more power than we achieved.









EFI tuning at Westech is a two-man operation. Eugene handles the dyno's functions (that's "the hammer" in his left hand) and Ernie manipulates the Thruster EFI's settings. "We initially just watch and adjust the VE (fuel) tables as the engine breaks in," says Ernie. Trims are scaled according to MAP/kpa (vacuum) and load (rpm), with the objective of achieving consistent air/fuel readings in the 14.7 range at low load. After approximately 20 minutes of run time at varying rpm, hard-core testing begins, and power is made through changes in fuel and timing parameters in our Thruster program. "Thruster EFI works well. The software is clean and it holds the maps (fuel/timing) steady in individual cells, which is helpful for someone who might be new to EFI tuning," says Ernie. "The processor does seem to take time to save or retrieve global file changes, but it's fine otherwise. A first-time enthusiast won't have any problem using this system." We plan to explore this new engine management system's capabilities as we go forward with our Boss series.

RPM POWER TORQUE
3,{{{100}}} 204.20 346.00
3,{{{200}}} 209.00 343.10
3,{{{300}}} 215.30 342.60
3,400 222.{{{90}}} 344.40
3,500 231.00 346.70
3,{{{600}}} 239.70 349.60
3,700 248.60 352.90
3,800 257.20 355.50
3,{{{900}}} 266.40 358.{{{80}}}
4,000 276.30 362.80
4,100 286.90 367.60
4,200 298.10 372.70
4,300 309.70 378.30
4,400 321.30 383.50
4,500 334.80 390.70
4,600 349.00 398.40
4,700 363.10 {{{405}}}.80
4,800 375.20 410.50
4,900 386.10 413.80
5,000 396.00 416.00
5,100 404.80 416.90
5,200 412.60 416.70
5,300 419.60 415.80
5,400 426.10 414.40
5,500 432.20 412.70
5,600 438.40 411.20
5,700 444.70 409.80
5,800 451.00 408.40
5,900 456.70 406.50
6,000 461.50 403.90
6,100 465.60 400.90
6,200 469.10 397.40
6,300 472.70 394.10
6,400 438.30 359.70
6,500 418.70 338.30
6,600 404.20 321.60
6,700 394.10 309.00